Blooze Own: An F355 Six Speed N* Build Thread
Topic started by: Bloozberry, Date: 04-24-2010 08:32 PM
Original thread:

Bloozberry MSG #1, 04-24-2010 08:32 PM
      Well enough procrastinating… it’s finally time to get some order in my digital shoebox of photos, so I figured: "What better way than to start a build thread?" That'll force me to sort through the photos and notes I've taken, bit by bit, on a regular basis and avoid having to tackle the whole shemozzle at the end... when I definitely will be more interested in driving the car than writing about it. The problem I’ve seen with many rebodies though, is that too many of them end up looking like accidental explosions. They start off with someone banging away on something that would be best left alone, and end up with parts strewn all over the place with no hope of being reassembled, let alone ever being driven again. So I vow to keep this thread alive until the only semblance of an explosion near this car are the ones inside those eight high tech cylinders, and the one I feel in the seat of my pants as I hit the gas.

So like the title says, this thread is about building a Ferrari F355 coupe on a 3” stretched ’88 chassis powered by a ’97 Northstar and Pontiac G6 six speed manual transmission. Not exactly breaking new ground, except that I think I’ll be the first one to start and finish an F355 build thread here on PFF. To start the show, a little background first: About ten years ago a friend saw my completed 308 rebody with 305 TPI and decided he wanted something similar. He bought an '88 GT auto with 97,000 kms on the clock and, after buying and returning his first F355 body kit from IFG due to stunningly poor quality panels, he got an exchange for one that was head and shoulders better. (That doesn't say alot if you 've ever dealt with IFG bodies though.) He lost interest in the car after having had the frame professionally stretched the necessary 3" behind the passenger compartment and installing the rear quarters and doors. I bought it as-is a year ago and have been working away to do it justice ever since. Afterall, an '88 GT deserves better than to languish as an unfinished kit.

So here it was in all of my excitement as the transport truck pulled up in front of the house to deliver the car to Nova Scotia from Cornwall, Ontario.

For the price that was being offered, I bought it sight unseen and wasn't disappointed. Obviously it would need lots of work, money, space, and patience to make it look anything like a real F355, but I'm no stranger to this kind of work as my 308 kit was no better when it started its life. Here it is once it was unloaded and dragged up to the back of my workshop, and like everything else, it soon found a happy spot among some cool other cars.

Edit: Seeing how this build thread has grown to an unwieldy number of pages, I've decided to add an index here at the beginning to help new and old readers alike find certain phases of the project more easily than by having to scroll through it all:

Pg1. Introduction & Northstar teardown and inspection.

Pg2. Northstar engine case separation, block machining, installation of threaded inserts.

Pg3. Rebuild of case halves, installation of crank, pistons, heads, and rebuild of starter.

Pg4. Installation of timing chains, oil pump, chain cover; disassembly and modification of intake manifold.

Pg5. Intake manifold painting & rebuild; throttle body rebuild; installation of CHRFab valve covers, oil filter mount, water pump, and water pump manifold.

Pg 6. Installation of pulleys, rear main seal; alternator rebuild; fuel rail installation.

Pg 7. Fuel injector harness and serpentine belt installation; F40 notching; jackshaft bearing support fabrication.

Pg8. Fuel injector cleaning; F40 to engine installation; stock engine/trans/cradle removal; three-view stock '88 cradle drawings; front cradle cross member removal; Held parts for '88 rear 6" track width increase; rear strut to coil-over conversion; rear knuckle rebuild.

Pg9. Cross drilling Corvette C4 rotors; installation of rear brake caliper, rotor, pads; three-view drawings of F40 transmission, and stock rear knuckle, strut, links, bearing, rotor, and complete rear suspension assembly; discussion and drawings of stock '88 rear swing arm length, roll center, camber change, toe change, and anti-squat.

Pg10. Stock front suspension removal and cross member refinishing; Held parts for '88 front 6" track width increase; installation of Held front suspension components and Corvette C4 brakes.

Pg11. three-view drawings of stock '88 front cross member and stock upper control arm.

Pg 12. three-view drawings of stock '88 front lower control arm, knuckle, bearing, ball joints, tie rod, and complete front suspension; 3D coordinates of major stock front and rear suspension points; discussion and drawings of stock '88 front anti-dive, roll center, swing arm, and roll axis; stock front suspension kinematics graphs & discussion on stock '88 suspension vs Held 6" track width increased control arms vs Held 6" increase with 2" drop springs and 3" wheel base increase.

Pg13. Stock '88 rear suspension kinematics graphs & discussion on stock '88 rear suspension vs Held 6" track width increased control arms vs Held 6" increase with 2" drop springs and 3" wheel base increase. More kinematics graphs and discussion of the effects on '88 front geometry by swapping out 2" drop springs with 1.5" drop spindles, and shortening and relocating the upper control arms; modification of front cross member and Held upper control arms; discussion and drawings of potential modifications to '88 rear suspension including raising the cradle and links, and adding larger wheels and tires.

Pg14. A continuation of the discussion from page 13 including shortening springs, and modifying the fenders; rear suspension kinematics graphs & discussion of negative effects of above modifications; discussion and brainstorming of alternative short and long A arm (SLA) geometry to solve problems identified with McPherson strut design.

Pg15. Continuation of discussion and design of SLA concept; three-view drawings of '88 rear frame; discussion and drawings of pushrod and bell crank coil-over shock concept; three-view drawings and discussion of conceptual SLA suspension in full jounce and rebound.

Pg16.Refinement of SLA component locations; kinematics graphs and discussion showing benefits of SLA design over previous McPherson strut designs; three-view drawings of new '88 cradle design to support SLA suspension and Northstar engine and F40 transmission; three-view drawings of prototype SLA suspension; final wheel selection.

Pg17. Wheel and tire mock ups; new cradle fabrication; three-view drawings of Northstar and F40 transmission mounts; fabrication of engine and transmission mounts.

Pg18. Continuation of engine and transmission mount fabrication; engine bay preparation (removal of decklid hinge boxes, dog bone mount, and various brackets); first attempted test fit of new cradle with engine and transmission; strut tower trimming.

Pg19. Second attempted test fitting of new cradle with engine and transmission, with further engine bay modifications; third test fitting of cradle with engine and transmission following revised engine/transmission mount relocation on cradle; parts list for SLA suspension; removal of F355 body from chassis; QA1 coil-over build up.

Pg20. Upper and lower lateral link mount fabrication; discovery of upper forward outboard link interference with wheel rim and discussion of possible solutions; flipped knuckle design drawings.

Pg21. Kinematics graphs and discussion of impact of flipping knuckles side to side; fabrication of outboard upper lateral link mounts (on knuckle); relocation of lower lateral link mounts due to knuckle swap; fabrication of new upper inboard lateral link mounts; mock up of 5 link design (less bell crank and coil-over); mock up of bell crank and lower bell crank mount; Nissan 300ZX headlights; design and fabrication of trailing link mounts; upper knuckle camber bolt fabrication; suspension travel cycling to determine jounce and rebound limits due to chassis interference;

Pg22. Upper frame rail notching for jounce clearance; upper frame rail reinforcement fabrication; discussion on crashworthiness; 1:1 bell crank ratio design; coil-over and bell crank drawings at full rebound, jounce, and ride height; redesign of bell crank to 1:0.88 ratio; three-view drawings and discussion of bell crank mounts; bell crank fabrication;

Pg23. Bell crank completion; bell crank mount fabrication; cabin firewall cross member fabrication;

Pg24. Coil-over mount fabrication; shock absorber discussion; final rear suspension and cradle welding; 2nd test fitting of engine, transmission, cradle with suspension; Youtube video of suspension travel;

Pg25. Discussion on axles, CV joints, tripot joints; disassembly and measurements of Fiero and Cobalt SS axles;

[This message has been edited by Bloozberry (edited 03-18-2014).]

17Car MSG #2, 04-24-2010 09:18 PM
      Good luck on the build, that is probably one of my favorite replica rebodies. Curious as to what you have planned for the interior, are you going to be using Amida's interior or something of your own?

Dracor MSG #3, 04-24-2010 09:22 PM
      Nice. I think mine is like the one that was sent back.

What do you plan on doing for wheels?

Bloozberry MSG #4, 04-24-2010 09:27 PM
Originally posted by 17Car:

Curious as to what you have planned for the interior, are you going to be using Amida's interior or something of your own?

Luckily, my wife has owned her own automotive upholstery business since '93. The interior is the only thing that I don't need to worry about!

Bloozberry MSG #5, 04-24-2010 09:33 PM
Originally posted by Dracor:

I think mine is like the one that was sent back.

What do you plan on doing for wheels?

That's funny. Maybe you got my friend's returned kit! As for wheels, I've seen several really nice designs that replicate the 355's pretty darned close, but all of them are discontinued. I''ve got my wheel-money set aside while I wait for one of the many wheel manufacturers to come up with something that turns my crank. That's one area I'm not rushing into until I see the perfect wheel.

katatak MSG #6, 04-24-2010 10:22 PM
      I'll be watching this one! This will be a great thread. I like the looks of your shop too Blooz. Best of luck on your project.


James Bond 007 MSG #7, 04-24-2010 11:06 PM
      Nice car collection,you got going there.

rourke_87_T-Top ( MSG #8, 04-25-2010 12:49 AM
      Thanks for sharing, I'll be watching for the Northstar related technical and fabrication. Is that a 32-34 model B cab on the right of the photo ?

Genopsyde MSG #9, 04-25-2010 03:36 AM
      I look forward to observing this build. Maybe I can steal some ideas to use on mine if I decide not to sell.

mcaanda ( MSG #10, 04-25-2010 08:52 AM


Bloozberry MSG #11, 04-25-2010 09:36 AM
      Thanks guys for the interest (BTW Rourke, it's my '29 model A five window you noticed... it's out on the 5-year build-horizon though... the F355 is gettin' done first).

I'd be posting an update right now except that 'someone' said it would be better for the longevity of the thread if I used PIP instead of Photobucket for my pictures. OK, I thought... I'll go along with that... except I keep getting a "Run-Time Error '13' Type Mis-Match" error message every time I try to open PIP. What's up with that? I've reloaded PIP three times now and still get the same thing. Damned software gremlins! Arrrggh.

[This message has been edited by Bloozberry (edited 04-25-2010).]

bowrapennocks MSG #12, 04-25-2010 09:51 AM
      I am looking forward to your build.

I used to own a 355 on an 86 chassis. I purchased it assembled after somebody installed the body, but then when they lost interest, did a really poor job on the interior and sold it to the guy I bought it from. It sat for many years and I was bold enough to drive it home 25 miles with an engine barely running on 5+ year old gas. After an oil change, all filters, and new plugs, the car ran great after I used up all the old gas. The engine was a 3.1, blueprinted and balanced, roller cam etc. It had an automatic which only had 200 miles on a rebuild. After all the money dumped into the body, engine and transmission, it was sad what a poor job was done on the interior. I pulled all of the interior out. It had a 355 interior kit, which I reglassed in some areas an then recovered. It had brand new Mr Mikes seats, which were fine. After new carpeting, headliner, and gauges, the interior came out great. While the body was installed well, the unkown builder did the following strange things:

* The mirrors were Ferrari replicas and were fixed mounted. A subsequent owner to me broke one of them off. Also, the passenger side mirror was mounted in such a way that you could not adjust it to actually see anything useful.
* The body was mounted over the battery and there was no way to remove it.
* The body was not stretched, but the wheel wells were moved foward
* The body was mounted over the air filter and I had to cut the assembly to change the filter
* The replica dash dumped almost all the air out the center vents
* The only way to open the engine cover was by the solenoid. A dead battery meant you were dead.
* The only way to lock/unlock the doors were via aftermarket lockers. A dead battery meant you also had a problem.
* The center console was one piece and did not vent the ECM. So to get to the ECM, you had to remove part of the dash, then remove the whole console. When I did the custom console on my 87 t-top coupe, I made it in two pieces, so I could access the engine computer
* The vents were not cut in the rear decklid and the engine had headers. It never overheated, but I bet it was very hot back there.

A 355 is a cool looking car and it really drew attention. I wonder where it is now. It went from WA to OH and then to CA.


Bloozberry MSG #13, 04-25-2010 10:20 AM
      OK, PIP worked this time... I think it heard me threatening to post the error message on Photobucket.

I want to apologize for anyone who was hoping that I'd spend the first ten pages of this thread with the body work. It's just not going to happen in that order. I'm an engine-man at heart so that's where I first really delved into it. After lurking for years on the forum and drooling over threads by Will, Daviero, Ryan Hess, Zac88GT, AJXTCman, and others, I fell in love with the notion of an all-aluminum, 4 cam, 32 valve V8. I give credit to those guys for being among the pioneers who learned alot of stuff the hard way and took the time to write about it so the rest of us could benefit from their experiences. From those threads I learned I wanted an early engine for their "relative simplicity" (as compared to say, a nuclear reactor) and cheap initial purchase cost. But I knew it would cost every bit as much to get one running as it would a later engine. I had it in mind that regardless of the claimed mileage or exterior condition of the block, it would need to be overhauled for my own peace of mind.

In the end, I bought two '97 VIN Y's, one from a car in a local yard with 250K kms on it, and one on eBay from Ontario that had 100K kms on it (yeah right!). I bought two because the first one came with anything and everything I wanted for $450 and the eBay one which was supposed to be better was more or less just a long block... no beauty cover, accessories, wiring harness, PCM, MAF, etc for about the same price. In Canada we call it a "two-fer" (two for the price of one). I know that the VIN 9's are the more desireable engines because of the 300 HP output, but I'm OK with 275 HP. Besides, this leaves growth potential!

So enough background, here's what they looked like when I picked them up in our trusty-dusty utility trailer and unloaded them in the shop. From the crustiness of both engines, I don't think either Caddy-owner ever cleaned anything except maybe windshield every now and then with the wipers.

[This message has been edited by Bloozberry (edited 04-25-2010).]

dratts ( MSG #14, 04-25-2010 11:02 AM
      I'm jealous! My garage just got sold so I'm using plastic ones until I find another one. Sure interested in the drivetrain as you know. My 355 spider has the N* and fiero auto, but I have two f40s, jstrickers intake, and pbjs turbo.

Tony Kania MSG #15, 04-25-2010 12:50 PM
      Blooz, you are one of the most knowledgeable folks that we have on this forum. You are always helping out, and lending a general hand to so many of us. The first thing that I thought, when looking over your pics, was, "Man, that is the garage that that guy deserves!" You have an obvious passion for automobiles, and those cars deserve an owner like you. Good luck with the build, and marked as a favorite.

cptsnoopy ( MSG #16, 04-25-2010 01:23 PM
      What Tony said ^^^.

Munching popcorn and enjoying the show.

Thanks for taking the time to post your info Blooz!


motoracer838 ( MSG #17, 04-25-2010 01:48 PM
Originally posted by Bloozberry:

Thanks guys for the interest (BTW Rourke, it's my '29 model A five window you noticed... it's out on the 5-year build-horizon though... the F355 is gettin' done first).

I'd be posting an update right now except that 'someone' said it would be better for the longevity of the thread if I used PIP instead of Photobucket for my pictures. OK, I thought... I'll go along with that... except I keep getting a "Run-Time Error '13' Type Mis-Match" error message every time I try to open PIP. What's up with that? I've reloaded PIP three times now and still get the same thing. Damned software gremlins! Arrrggh.

I've never been able to get pip to work, hell, I've had friends who are computer geeks that couldn't get it to work!!!

I'm using the imagehost over at

The only downside is that it only allows 100k or smaller, and the smallest that my camera takes seems to be about 112k so I have to spend some time resizing. I really wish that would get an upgrade!!!

That's a big project in front of ya' Blooz', good luck with it.

You might be a king, or a little street sweeper,
but sooner or latter you'll dance with the Reaper. Joe

[This message has been edited by motoracer838 (edited 04-25-2010).]

Bloozberry MSG #18, 04-25-2010 03:34 PM
      Thanks for little tips there bowrapennocks... I'll have to make sure I don't make any of those mistakes! And thanks for the encouragement there Dratts, Tony, Charlie and Joe. I'm banking all these positive comments to help keep me going when I'm sweaty and full of fibreglass dust later this summer.

[This message has been edited by Bloozberry (edited 04-25-2010).]

Bloozberry MSG #19, 04-26-2010 09:00 PM
      It wasn’t very long after I got my engines that I could hear the lower mileage one calling out “Pick me! Pick me!”. But like any engine builder knows, it’s a good idea to run a few tests to make sure a used engine has the potential to be anything more than an anchor. I like to turn the engine over with a breaker bar at least two full crank revolutions to be sure there aren’t any bent or broken valvetrain parts. If there’s no obvious grinding, seizing, or blockages, then a compression test is in order to get an idea how well the valve and pistons are sealing. At first I was hopeful, it spun the needed 720* and I got 170 psi plus or minus 5 psi on all eight cylinders. That’s right in the range for good static compression for a Northstar. So far so good. Maybe I would avoid the nightmares of some of the other PFF members.

Next up, I cleaned the outside of the engine off so that I wouldn’t contaminate the insides with the crud from the outside. Then I took the valve covers off, and apart from the valvetrain being a little discolored from hot oil, there was no sludge which indicated that the engine probably saw at least semi-regular oil changes. Another thing I learned from AJxtcman was to look for a fine metallic deposit built up on the inside of the valve covers in the area of the sprockets. I forget what the source of it is, but in any case it’s not a good sign if you have it. Mine didn’t… whew!

What it did have though was worn out exhaust cams. This was my first clue that I’d been “had” by the eBay seller. 100K kms doesn’t make flat spots on the nose of your cam lobes. (I could’ve sworn I took close-up pictures of those so I’ll post them later when I find them). Closer inspection of the cam followers also revealed that some of them had the tell-tale wear circles in the middle where the case-hardening had worn through to the softer underlying metal. Cha-ching!… I could hear the cash register at my local machine shop ringing already.

I had decided from the get-go that I was going to do the Timesert repair whether it needed it or not, so I went ahead, removed the heads and dropped them off at my favorite cylinder head shop (that’s all he does) for an in depth inspection and rebuild estimate... keeping my fingers crossed.

skuzzbomer MSG #20, 04-26-2010 10:43 PM
      This is interesting.... following along.

darkhorizon MSG #21, 04-27-2010 04:34 PM
      Northstar rebuild.... YIKES!

Bloozberry MSG #22, 04-27-2010 05:21 PM
      I finally found the pictures of the cam lobes and followers in my digital "shoebox". First though, here’s a close up of the hot oil varnished cams. It’s hard to see anything problematic from this photo, although you’ll notice here how several cam-bearing cap bolts have been removed because I got curious after finding one of them loose!

Now I doubt this is a common problem with Northstars, because I would’ve probably read about it given the volumes of info I researched before diving into this, but it is something you should check if planning on using a warmed-over Caddy engine. The one cap bolt was loose because it was broken(!) where the threaded portion met the shank, its weakest point. From the fracture site, the failure mode was obviously tensile loading and not shear, in other words, it broke after it was torqued and not during the tightening of the bolt. I'm guessing that someone didn’t have the torque specs for the bolts or didn’t use a torque wrench to tighten the caps at some point in the engine’s history. In any case, this one was torqued beyond the bolt’s yield point but not quite enough to break it. The loading of the bearing caps from operating forces on the cam were enough to tip the scales on it and break it in tension.

Now have a look at the picture. The bolt on the left is an unused one, the one on the right is the broken one (duh), and the one in the middle is what four other cam-bearing cap bolts looked like on that head after I removed them. See anything a little off? The eagle-eyed among you will notice the “necking” or narrowing of the bolt diameter where the threads meet the shank… exactly where the other one broke. Someone clearly used the “it feels tight enough” approach on these caps. I couldn’t be certain of the condition of the remaining bolts, so I turfed them all.

Here’s the picture of the exhaust cam lobe I promised earlier. All the lobes on both exhaust cams were like this. Clearly worn beyond reuse without reconditioning or replacement.

And here’s what worn cam lobes do to cam followers. The one in the background is from an intake cam so it’s better, but at this stage there was no point in keeping any of the followers.

And here’s what the exhaust valves looked like. Beyond grinding. Kaput. Cha-ching! More cash register sounds at my machine shop. By the way, this was supposed to be the low mileage engine. When I removed the valve covers off the high mileage engine, they looked about the same for wear and tear. But that’s OK because I probably would’ve replaced most of this stuff on spec anyways. No point in rebuilding an engine if you’re just going to throw the old parts back in it.

pmbrunelle ( MSG #23, 04-27-2010 05:29 PM
      That's really a lot of cha-ching! Cha-ching times 32 valves and times 4 cams.

Does the other engine have useable cams, tappets, valves? Did you disassemble that one?

Bloozberry MSG #24, 04-27-2010 05:39 PM
      I didn't disassemble the heads on the other engine to the same degree, but I knew that engine had 250K kms on it. Even if it looked better after taking it apart, I would've replaced the moving parts anyways. 250K kms is just too much to just transplant into a car and hope for the best.

White Spyder ( MSG #25, 04-27-2010 08:17 PM
      One day......when I hit the lottery..........

Fiero Owner MSG #26, 04-27-2010 08:51 PM
      Very interesting. Will be keeping an eye on this. Nice to see a project like this close to home too.

dratts ( MSG #27, 04-27-2010 08:52 PM
      My first thought was look around for another set of heads. Then I thought "I wonder what the rest of the engine is like." I hope it doesn't turn into a huge build and lots of dollars. I agree, I would pull any engine apart to check the cams valves bearings and crank, and to install time serts, but at the point you are I think it might be cheaper to source a good engine over a rebuild. Just an opinion. From what some of the storys I've heard you can throw money at these engines just like they're boats.

Bloozberry MSG #28, 04-27-2010 08:54 PM
      Hey! Hantsport! Right on. Never noticed you were so close there Fiero Owner.

Bloozberry MSG #29, 04-27-2010 09:48 PM
Originally posted by dratts:

I hope it doesn't turn into a huge build and lots of dollars.

Thanks for your advice dratts... but I think if you want a reliable Northstar in the long term, there's no cheap way to do it. You either spend your money up front and buy a late model engine (and try to figure out the cam phasing), or buy a cheap early engine and spend your money rebuilding it. You have to expect (as I did) that a 10 to 15 year old engine is going to be worn close to the end of it's useful first life. One way or the other, you really really have to want one to be able to justify a N* financially because there are several engines out there that are cheaper and more powerful. Realistically, I think you have to set aside $5000-$6000 for this engine, in Canada anyways. More if you haven't got the space, time, skills or tools to do it yourself.

dratts ( MSG #30, 04-27-2010 11:51 PM
      Well I shouldn't be giving "advice". If your posts didn't convince me that you probably know a lot more than me, your shop would. Still I remember when cadillac dealers didn't fix these engines, they just replaced them. There was a time when you could get a brand new N* for $2500 from an outfit I think was called speedway motors or something like that, but that was a while back. Anyway have fun it's gonna be a great engine.

pontiackid86 ( MSG #31, 04-27-2010 11:54 PM
      Thats quite a garage you have there blooze.

ltlfrari ( MSG #32, 04-28-2010 08:05 AM
Originally posted by pontiackid86:

Thats quite a garage you have there blooze.

Yeah, but this is his house...

OK, I admit it, I'm just jealous of that garage really.
Great thread by the way, looking forward to reading (and learning) more.

Bloozberry MSG #33, 04-28-2010 08:15 AM
      LMAO ltlfrari! No better way to start off a day than with a good laugh.

darkhorizon MSG #34, 04-28-2010 11:01 AM
      What happens if you just get a regular 300hp northstar from a junkyard, put it in, and run it till it dies?

It is rare that I see a rebuild motor last longer than a OEM one.

dratts ( MSG #35, 04-28-2010 11:02 AM
      I thought that the unabombers shack was in a museum. I love all the pictures. Everything looks so clean and neat. I have a tendency to get spread all over the place.

[This message has been edited by dratts (edited 04-28-2010).]

Bloozberry MSG #36, 04-28-2010 12:22 PM
Originally posted by darkhorizon:

What happens if you just get a regular 300hp northstar from a junkyard, put it in, and run it till it dies?

There's nothing wrong with doing what you suggest, but unlike some engine swappers, my goal isn't only about injecting HP. I find that a car with questionable reliability is hard to go anywhere with and have fun. Crawling under the car on the side of a freeway in the rain never appealed to me! My goals are to have a car I won't have second thoughts about taking over long distances, and for it to be a show quality ride. Spending 100 hours polishing a worn out N* engine doesn't make sense in my case.

pmbrunelle ( MSG #37, 04-28-2010 09:00 PM
Originally posted by darkhorizon:
It is rare that I see a rebuild motor last longer than a OEM one.

"Rebuild" means many different things to different people.

Foe example, some people will knurl their valve guides and call them good as new, rather than press in new ones... (like the moronic previous owner of my car).

You've probably seen mostly half-assed rebuilds, which is probably more common than good ones.

Bloozberry MSG #38, 04-28-2010 10:14 PM
      Very true pmbrunelle. I've seen some "rebuilt" engines that are little more than a tune up...

Anyways, next up in the disassembly phase was to remove the oil pump, which mounts to the front of the crankshaft on the Northstar. Since it was on the list of things to be replaced regardless of its condition, I couldn’t help but take it apart and examine it.

It’s a gerotor-style pump which uses a nine toothed pump gear (or inner rotor) in a ten-toothed gear housing (or outer rotor). As the crank turns counter clockwise in the image below, the inner rotor is keyed to the crank through two flats on the shaft. Since the two rotor's teeth mesh at the bottom, both rotors turn with the crank. As they do so, the space between the teeth of the inner and outer rotor increases towards the top from the 4 o’clock to the 1 o’clock postions, creating a vacuum. The vacuum pulls oil into the pump through the circular port on right hand side of the pump housing. The channel or manifold leading up from the inlet port narrows in diameter as it swirls up to the top of the pump where it meets a dead end and oil is forced between the teeth. The oil is carried around through to the 10 o'clock position where a new manifold opens up. As the rotor continues to turn, the area between the teeth decreases from the 10 o’clock to the 7 o’clock position, pumping the oil into the outlet manifold and through the outlet port.

If you look carefully, the outlet manifold branches the right where the pressurized oil acts on a pressure regulating piston that you can see through a circular hole at the bottom. As higher oil pressure in the outlet manifold moves the piston further into the bore, it uncovers the circular hole which has an interconnecting passage in the other pump case half that redirects the surplus oil pressure to the inlet port area.

Things to look for if keeping an old pump:
a. check the mating surfaces of the teeth for deep scratches or uneven wear;
b. check the sides of the rotors and their mating surfaces on the pump housings for scoring;
c. check the OD of the outer rotor for scoring; and
d. check to make sure the pressure regulating piston is free to move fully into it’s bore;

Bloozberry MSG #39, 04-29-2010 09:00 PM
      Darkhorizon mentioned it, but I’m sure there are lots of other people who would rather just drop in a used N* and run it until it dies rather than taking it apart. But here’s another reason (and there’s more to come…) why it may not last very long and you’ll find yourself dropping the cradle sooner rather than later. After the oil pump was off, I was able to get to the primary timing chain, crank and secondary sprockets. Have a look at how much the spring loaded chain tensioner on the LH side of the chain is extended.

At first I thought it was due to the chain being stretched, but after I removed the tensioner, I found another reason. The cushion block on the tensioner was eaten through nearly 75% of its thickness from the chain passing over it. It’s the kind of thing that might last another 20K miles, or finish chewing through it after 5K. And you just know when that happens it’ll be catastrophic because it’ll relax the chain tension, cause the chain to jump the sprocket, and all hell will break loose when the pistons start hitting the valves. It’s important to note that this is all hidden wear that you won’t be able to see without some major disassembly. And remember, this was on an engine with a "claimed" 100K kms. To borrow a phrase (well, almost) from Forest Gump... "used engines are like a box of chocolates... "

This is what the sprocket assembly looks like when it’s removed from the engine. The upper sprocket bolts onto a bearing assembly situated where the cam would be on an overhead valve (cam-in-block) engine.

Here’s the bearing assembly the upper sprocket rotates on… note that it gets fed oil from passages cast in the block.

Next up was to remove the four steel head-alignment dowels on the deck surface. They’re swaged in the holes very tightly and are impossible to remove without ruining them. At first I thought they’d come out with a little gentle persuasion, but that gave way to more draconian measures. I’ve seen someone here on PFF remove them by welding a steel rod across the tops and twisting them out that way, but I found an easier method. I used Vise-grips to twist them out but found out that unless you push something into the hollow dowel, the Vise-grips will just deform it and slip rather suddenly. An extension for a 3/8” drive socket wrench fits just right. The extension prevents the dowel from collapsing and from there it was a simple matter of twisting and pulling at the same time. It still took a couple minutes per dowel though.

Here’s what they looked like after they came out. Definitely not reusable, and after a quick call to the local dealership, I found out that they wanted $17(!) for each one! And, to top things off, they are discontinued. There were still a few sets here and there across the good ol’ US of A, but I’m certain that shipping, brokerage fees, and taxes would have nearly doubled the price of these puppies. Luckily I have a friend with a metal lathe who turned some new ones for me for $20 labor.

[This message has been edited by Bloozberry (edited 05-03-2010).]

Bloozberry MSG #40, 05-03-2010 09:13 AM
      The next step on the tear-down was “The Big Decision”… Do I go the whole nine yards and pull the pistons, separate the case halves and renew everything? Or just listen to reason and leave the lower rotating assembly together... after all, the compression test results I did at the start were good. I had also read several horror stories of hone jobs gone amok here on PFF. In the end, a combination of the problems I’d found to date, the slightly out of round cylinders, and plain ol’ curiosity “made” me go the distance and commit to opening it (and my wallet) up.

One of the interesting things about the Northstar, is that the windage tray, an oil manifold plate, and the lower case half are all held in place with the main crank bearing cap bolts.

To gain access to the connecting rod cap bolts, you must remove the main bearing cap bolts (all 20 of them) and remove the, pick-up tube...

…the windage tray, and the oil metering plate...

I finally had access to the connecting rod bolts, which I numbered with my stamps like a good boy before taking them apart.

Here’s where being skeptical of the condition of the engine paid off big time… after I had removed the rod bolts and caps, and while I was pushing the pistons downward out of the bores, something went clinkity-clink on the floor when pistons 2, 4 AND 6 cleared the block. Unfortunately it wasn’t just a couple broken rings.

The amazing part is that even with these broken ring lands, the compression was still at 170 psi at cranking speeds. Well, that and the fact that the pieces had stayed in place and hadn’t scored the cylinder walls at all. After having exchanged posts here on PFF with a few of you, and consulting my machine shop, the consensus was that this was probably caused by detonation. It didn’t appear as though the engine was run for any length of time, or at all, after this damage occured since there was no secondary damage… well, except to my wallet... cha-ching! Have you ever priced out new Caddy pistons?

Lambo nut MSG #41, 05-03-2010 11:00 AM
      I'm watching you Blooz!
I've never been into one of these yet. Looks very interesting. That chain tensioner reminds me of the ones on a 2.3/2.4 Quad four. If it goes, look out.
And great idea on the extension in the dowel trick. Nice!


dratts ( MSG #42, 05-03-2010 12:38 PM
      If I was going to buy new pistons I would be looking at lower compression so that I could add more boost. As it is I plan to limit my boost to 5 lbs.

88GTS ( MSG #43, 05-03-2010 07:50 PM
      Do you have a writeup of your N* build?

Originally posted by dratts:

If I was going to buy new pistons I would be looking at lower compression so that I could add more boost. As it is I plan to limit my boost to 5 lbs.

dratts ( MSG #44, 05-03-2010 08:02 PM
      I mostly have a collection of other peoples stuff. PBJs turbo set up, J Strickers wiring and intake, Ryans 7730. My N* fiero was built by a NC caddy mechanic, and the 355 body manufactured and factory installed by John Watson of Air Dynamics. Blooz is the expert here. We just have common interests.

[This message has been edited by dratts (edited 05-10-2010).]

Bloozberry MSG #45, 05-03-2010 08:54 PM
Originally posted by dratts:

If I was going to buy new pistons I would be looking at lower compression so that I could add more boost. As it is I plan to limit my boost to 5 lbs.

I may be wrong, but I think you'd have to have custom pistons made, or pistons from something else turned down. As far as I know it's only been two years now that anyone even makes stock oversized pistons for the N*. I'll get into that later in my thread, but I only found two company's that made them oversized. They're not cheap either... $80 a piece. Will's thread here about halfway down starts getting into what he did for custom pistons. If you have the time his whole thread is a good read.

Zac88GT ( MSG #46, 05-03-2010 11:06 PM
      Silvolite pistons are a lot cheaper than $80 each, and they make them in +.25mm and +.5mm oversizes

328 mera ( MSG #47, 05-04-2010 08:47 AM
      nice thread

dratts ( MSG #48, 05-04-2010 10:44 AM
      I was on the chrfab forum yesterday and there was an old for sale posting of a N* shortblock with custom rods and pistons for a boosted motor. It was going for $2500. That might be cheaper than rebuilding yours. Especially if you are thinking of boost. (Don't know if you are, but don't we all occasionally)

Bloozberry MSG #49, 05-04-2010 11:43 AM
      Thanks for the comments Lambo nut, Zac and 328 mera.

dratts: I'm actually a fair bit further along than my thread. My engine is complete at this stage, so the money's already spent. (I got the impression reading other people's threads that it's wise to start a thread only after you've got a fair bit of work done.) I dont' regret having taken it apart at all since my curiosity wouldn't have been satisfied any other way! All said and done, I only spent CDN$5000 to get the engine where I wanted it, which I don't consider to be out of the ordinary for a Northstar rebuild up here.

dratts ( MSG #50, 05-04-2010 02:21 PM
      I know I keep butting in here cause you totally have my interest. I called about the chrfab forum engine and the phone # is no longer in service. I was interested for myself even though I own two used N*s. I know that I couldn't build one for any where that price.

motoracer838 ( MSG #51, 05-04-2010 06:45 PM
      Blooz, man that engine definantly falls into the "rode hard and put away wet" catigory.

Starting a thread after you've got a good start is a good idea, but is no garanty life won't get in the way, my N'star build has gotten so derailed that I won't even bump the thread anymore 'till I can actually work on the car again (maybe latter this year).

keep us updated. Joe

Bloozberry MSG #52, 05-04-2010 09:49 PM
      So now you’ve seen all the bad news about this particular engine, there were no more surprises waiting for me (whew!). To summarize for those not wanting to read the whole thread to date, the exhaust cams, cam followers, valves, and timing chain tensioner were worn out, as well, three pistons had broken ring lands. If that’s not enough hidden damage to make anyone think twice about just slapping a used Northstar into their car, then nothing will.

The last couple steps before my favorite part (the rebuild), were to remove the lower case half, and remove the crank. Removing the lower case half was actually a lot easier than I thought it would be. Cadillac machined several thin slots along the parting line to let you stick a screwdriver in between and pry the lower half off. The orange lines down the length of the block on either side are formed neoprene-like case half seals. GM found that they didn't seal very well so the first iteration of a fix was to employ an anaerobic sealant (one that doesn't need air to cure) on the orange seal and in between the case halves. That's the dark brownish-black stuff you see along side the orange seals. It's actually brittle and flakes off. Now GM recommends not using the orange seal at all and filling the groove with a new engine case sealant (AC Delco 88901148). It's a light grey silicone-like sealer that comes in a short caulking gun tube. More on that later.

This is the top side of the lower case half (this side mates with the block). You can see how the baked-on oil left a coating of varnish on the inside of the engine. It makes for some pretty cool pictures with neat colors, but the chemical cleaning would soon take care of that.

This is the underside of the lower case half. This is the side that mates with the oil manifold plate. You can see the reason for the oil manifold plate if you look carefully. There are grooves machined around the main crank bearing bolt holes in the foreground that interconnect with the ones in the background. Oil to the main bearings is pumped in these grooves, around the bolts, and up to the main bearings. The oil manifold plate turns these machined grooves into sealed channels. The thin darker lines are just old sealant traces to separate the various passages from leaking and losing pressure.

So here’s the crank once it was lifted out of the upper block half. It needed the main bearings to be turned down 0.25 mm (0.010") to get rid of some light scoring, but the connecting rod journals only needed a polishing. For those of you who aren’t familiar with newer engines, the machined disk in the middle of the crank that has the square saw-teeth is the rotating portion of the crank position sensor. Two stationary magnetic probes bolted to the side of the the engine “read” the position of the teeth as they pass by and send the information to the PCM for spark control, misfire detection, etc.

Here’s the upper case half (upside-down). Notice that the crank thrust bearing is located on the number three main bearing web. What concerns me somewhat is that the thrust bearing is very thin, and only has a thrust surface on the bearing half that fits in the top half of the case. If you scroll two pictures, you’ll notice that the #3 bearing in the lower case-half doesn’t mirror the bearing half in the upper case. It’s missing the thrust flange. I suppose that’s perfectly fine for an automatic, which doesn’t see much axial loading of the crank, but with a manual transmission there’s considerably more every time you push in the clutch. I hope this doesn’t cause problems in the future.

Lastly, here’s the top view of the upper case-half. It’s amazing how light-weight this thing is… one hand to move it around, no problem. Looking in the bores, it’s clear that the original cylinder honing was glazed-over in the one axis and worn in the other. Next stop: the machine shop for measuring and machining.

katatak MSG #53, 05-04-2010 11:36 PM
      Great thread Blooz! Thanks for sharing all you wisdom with us. Sure gives me a new "light" on the N*.


Zac88GT ( MSG #54, 05-05-2010 11:06 AM
      What engine management system are you going to be using? If you're going to use the 7730 you can ditch the knock sensor in the "lifter valley" as the one it uses threads into a boss on the back side of the motor.

Bloozberry MSG #55, 05-05-2010 12:17 PM
      I'm still on the fence with that one. I'm waiting for the latest possible moment to decide in case something new comes along. As it stands, I'd like to stay OBD2 and will soon check out Wester's Garage's claim that for $500 they can recode a stock Caddy PCM. But thanks for the info.

fieroguru MSG #56, 05-05-2010 12:47 PM
Originally posted by Bloozberry:

I'm still on the fence with that one. I'm waiting for the latest possible moment to decide in case something new comes along. As it stands, I'd like to stay OBD2 and will soon check out Wester's Garage's claim that for $500 they can recode a stock Caddy PCM. But thanks for the info.

I didn't have much luck with Westers on my Ramjet engine. They advertized they could reflash the MPFI controller for the crate engine and I asked about and purchased a 7730 prom for my Ramjet... all I got was a base TPI tune that didn't even come with the correct vortec head timing tables... total disappointment. But at the time I wasn't up to speed on tuning to know what they gave me... just knew it didn't work as well as it should.

bubbajoexxx ( MSG #57, 05-05-2010 01:14 PM
      the proper way to remove dowels is fill them with grease then use a piece of steel rod that fits snug into the dowel then
drive it in with a hammer and the grease will hydraulic the dowel right out

Bloozberry MSG #58, 05-05-2010 02:49 PM
      ...and if that doesn't work, it'll squirt you in the eye with a jet of high pressure grease. But seriously, there's no way my dowels would've come out that way. They were an extremely tight interference fit.

[This message has been edited by Bloozberry (edited 05-06-2010).]

88GTS ( MSG #59, 05-05-2010 02:49 PM
Originally posted by Bloozberry:

I'm still on the fence with that one. I'm waiting for the latest possible moment to decide in case something new comes along. As it stands, I'd like to stay OBD2 and will soon check out Wester's Garage's claim that for $500 they can recode a stock Caddy PCM. But thanks for the info.

Here are the some of the available Northstar Engine Management options:

1. CHRFab Holley Commander 950

2. Ryan Hess 1227730 ECM

3. AJxtcman LS1 PCM on a Northstar

4. Northstar OBDII PCS tuned by Webster’s

My personal perceptions and comments on these options are:
1. The CHRFab Holley works, but is crude compared to OEM computers.
2. Ryan Hess ECM has also been proven, but I personally don’t like 80’s technology batch fire ECMs.
3. AJ’s LS1 PCM from the Shelby Aurora 4.0l project has a lot of potential, even for boosted applications, but AJ became quiet in 2009 and I haven’t seen a completed implementation yet.
4. The Webster’s tuned OBDII Northstar PCS came up recently, but again I haven’t seen the final word that it’s working yet. Don’t know if manual transmission or boost will be possible.
Anyone with comments or updates on these options?

Bloozberry MSG #60, 05-05-2010 02:50 PM
Originally posted by fieroguru:

... total disappointment. But at the time I wasn't up to speed on tuning to know what they gave me... just knew it didn't work as well as it should.

Good to know... thanks Fieroguru.

Newbfiero ( MSG #61, 05-05-2010 05:16 PM
      Looking good berry Nice work


fieroguru MSG #62, 05-05-2010 06:53 PM
      Might want to check with Ryan @ Sinister Performance. He found the GM program for the Aurora/LS1 ecm that AJxtcman was using and might be able to assist.

pmbrunelle ( MSG #63, 05-05-2010 10:18 PM
      There is the MegaSquirt option...

The latest edition, MegaSquirt-3 is quite capable:

Bloozberry MSG #64, 05-05-2010 10:25 PM
      All great info guys... thanks. I have some research to do.

(A "+" for those of you I haven't already rated)

[This message has been edited by Bloozberry (edited 05-05-2010).]

mcaanda ( MSG #65, 05-05-2010 11:02 PM
      MEFI 4B will run the N* as well. That is currently what I have for mine, as it is the 2002 style.


1986 Fiero GT ( MSG #66, 05-05-2010 11:53 PM
Originally posted by mcaanda:

MEFI 4B will run the N* as well. That is currently what I have for mine, as it is the 2002 style.


Jebus...I see what you were saying about that little guy being a costly bugger. $1,300 and you're not even into a harness yet. I still think I'm going to try my luck with a Shelby Series-1 09354896 PCM from Lyndon here shortly. Otherwise, if it weren't so damn expensive, that MEFI would be right behind it. I just love it because it's so tiny. About the size of two packs of smokes, I'm told.

joshua riedl MSG #67, 05-06-2010 06:47 AM
      I've done buisness with westers. I wouldn't consider them an option.

Bloozberry MSG #68, 05-06-2010 03:01 PM
      OK, so I lied. The next stop wasn’t actually the machine shop… although “machining” work was done. At this stage I decided that if I was going to polish the engine block, now would be a good time so that the chemical cleaning later on would also take care of the grinding and polishing growlies. I started with the oil pan knowing that if it turned out to be too tedious a task to carry on with the whole block, that at least some of it might show, albeit only me and the local garage techie who does the annual inspections would ever know. I started by sanding the big casting lines off it, then got progressively finer with the sand paper until I stopped at 400 grit. That took the better part of 12 hours to do. Here it is part way through around the 220 grit phase.

Then I broke out the polishing compound and my 8” bench-mounted buffer and had-at-it for another 3.5 hours. I found that the oil pan isn’t made of the highest quality aluminium and there are swirls of different colors here and there. But that’s OK because at 120 km/h only the bugs at road level will ever see it… just before they get sucked into the vortex left behind by my rear bumper. I find photographing polished aluminium always disappointing; it never looks anywhere near as nice as it does in real life. I loosely assembled the engine block back together so that I could work on it at a comfortable work height on the engine stand. This is what it looked like with the pan done and halfway through the block sanding process. All said and done, the oil pan took 15.5 hours while the block took 25... sure makes the winter pass by quickly, and if you're a thief, it's a good way to get rid of your fingerprints too.

The next messy task was taken straight out of a page from Will’s Northstar build thread, and I quote:

“When the Northstar was being designed, GM found that holes in the main bearing bulkheads to allow each bay to exchange air with its neighbors were practically a necessity. Because of the Northstar's lower crank case design, each main bearing bulkhead comes down almost to, if not touching the surface of the oil, essentially sealing off each bay from its neighbors, dramatically increasing pumping losses. In testing otherwise identical prototype engines, it was found that engines without windows gave up something like 30+ HP to engines with windows.”

He goes on to explain more about this so check it out here if you want the full scoop: In summary, there’s two different sets of windows; one small U-shaped set on each side of each main crank bearing web, and another much larger circular set through the block where the cam would otherwise be on a cam-in-block engine design. The bottom line is that these window passages have sharp edges that don’t optimize the flow of air through them. A simple hotrodding trick to squeeze a few more ponies (more like hooves) out of a Northstar is to radius the sharp edges to enable better flow. While I didn’t go quite as whole-hog about it as Will, here’s the results of my effort. I found that a high speed cutting bit in my air die grinder made quick work of this… in fact I had to “hold-back”.

These are the larger windows. They’re a little awkward to do because the adjacent webbing keeps getting in your way.

Lastly, in my search for any other little improvements, I found casting flash in all of the oil passages around the main bearing bolts. It wasn’t serious, but clearly an impediment to the oil flow up to the main bearings. Here’s a general picture to orient you with respect to where I found this problem.

And here’s a close up view of the casting flash. This passage was the worst one but all of them had some to one degree or another.

A one-second twirl of a little dremel router bit took care of the offending metal. This is before I cleaned it up with a bit of sandpaper, but you get the idea.

mcaanda ( MSG #69, 05-07-2010 05:10 PM
Originally posted by 1986 Fiero GT:
Jebus...I see what you were saying about that little guy being a costly bugger. $1,300 and you're not even into a harness yet. I still think I'm going to try my luck with a Shelby Series-1 09354896 PCM from Lyndon here shortly. Otherwise, if it weren't so damn expensive, that MEFI would be right behind it. I just love it because it's so tiny. About the size of two packs of smokes, I'm told.

I picked mine up for much less than that new, and UNLOCKED which is a huge deal. Most people that you are going to find that sell you the, what I call the muffy, are going to lock it. I had a buddy that had the program / cord to interface with it as well and picked that from him so that I have access to the whole kit and caboodle. I bought the plugs to make the harness, as I didn't know where I wanted to put it and I didn't want to risk having to rip it apart after paying to have it completed.

It is infact about the size of some smokes, which as we all know we should not know what their dimensions are...

Originally posted by joshua riedl:
I've done buisness with westers. I wouldn't consider them an option.

Please elaborate, as I know there are a few here that are seriously considering spending more that the cost of a super sized happy meal with this shop, myself included.

Blooze - sorry for the thread jack, and GREAT thread - I've always wondered what was inside these things but have been too afraid to open it up for fear of what it would cost to put it back together.

joshua riedl MSG #70, 05-07-2010 05:58 PM
      My setup was obd1. Running a 3900 with a 3.4tdc computer. He knew ahead of time and agreed to do the work. He basically deleted the egr and evap and sent it back for $300. We exchanged emails for a while and as politely as I could tried telling him it was running way too rich and has 28lb injectors, and like a lot of people doing the same thing for too long had an attitude. Anyway, the money was a waste and the support was non existant. If there are more opinions on the matter I will be glad to PM but this is a very interesting thread and don't want to take up any more space here. Great build!

Bloozberry MSG #71, 05-07-2010 07:15 PM
Originally posted by mcaanda:
Blooze - sorry for the thread jack

Originally posted by joshua riedl:
... don't want to take up any more space here.

It's all good. I need this info as much as anyone else. At least if you post in here I won't have to go looking for it!

ptboy55 ( MSG #72, 05-07-2010 07:47 PM
      Great work Blooz...!!! Im following, your a patient perfectionist with an eye for detail, all the polishing looks fantastic..!! Good, clear pics with descriptions, really interesting..!!


1986 Fiero GT ( MSG #73, 05-07-2010 10:19 PM
Originally posted by mcaanda:

Please elaborate, as I know there are a few here that are seriously considering spending more that the cost of a super sized happy meal with this shop, myself included.

...and me. I still haven't bought anything from him yet, so we'll see.

Any more leads on another unlocked MEFI-4B, haha? There's nothing on eBay and everybody on forums wants like a grand. No thanks.

Bloozberry MSG #74, 05-09-2010 06:05 PM
      While I was waiting on new head bolt inserts, I decided to run the block out to my favorite machine shop for cylinder honing and to have it checked out generally for squareness and trueness. This place doesn’t look like much from the outside, but it’s a whole different story on the inside. The place is called A&J Armstrong Machine Ltd and the line up of trailers hauling Pro Street, NASCAR, Top Fuelers… you name it, parked outside on any given day is amazing. He gets business from across the US and Canada daily. To walk in and see the tens of millions of dollars worth of CAD, CAM, & CNC machines whirling turning and doing their thing is out of this world.

Anyways, with all the talk here on PFF about how important it is to find a machine shop that can do a proper bore and hone on a Northstar, I knew he’d be able to satisfy my need. He measured the cylinders up and found that to bring them back into round he’d need to over-bore by 0.25 mm (or 0.010”). In this case though, it isn’t really bored, but rather just subjected to an extensive hone job. I had told him of the especially hard cylinder liners and that only aluminum oxide stones were going to cut the biscuit. Well, forget the silicon carbide stones… forget the aluminum oxide stones… he dug out the 280 grit diamond hones for my engine. His machine is fully automated too, continuously measuring, honing, and truing at the same time by cyclically varying the stone pressures to render the cylinder round, while the operator just stands by and watches. Here’s the block sitting in the bed of the honing machine after doing one bank.

And here’s what a typical cylinder looked like up-close after it was done (albeit a little out of focus).

At this point, I opted not to get the block chemically cleaned yet since the machine shop couldn’t guarantee that all my hard work polishing the block wouldn’t be tarnished or slightly etched for that matter. But that was OK since I had a back-up plan… and besides, I still needed to do more dirty work… the long dreaded head bolt inserts!

For head bolt inserts I was trying to save whatever money I could by dropping in on the local dealership and sweet-talking them and showing them pictures of my project before springing the question of potentially “borrowing” their Timesert tool kit. (In case anyone wasn’t aware, the Caddy Timesert kit is made by Kent Moore (p/n J-42385-500) and retails for $770!!!) In exchange, I would buy the actual inserts from the dealership at $7 each X 20 inserts for a total of $140 they wouldn’t otherwise make off me that day. I had one foot out of the Service Dept door with the kit under my arm and on my way to the parts counter when the service manager stopped me in my tracks. Dough! So close. He said they couldn’t lend me the kit at all, fearing it would set a “dangerous precedent”, but he would see about getting me a cut-rate if I let the shop do the work for me. Uh-huh. The “great deal” turned out to be a half-hour labour per hole X 20 holes X $70 an hour, plus $140 of inserts, plus taxes… at, you guessed it, just shy of $1000, IF all went well. Just then, the Kent Moore kit suddenly sounded like a steal.

According to another PFF’er here who’s a Caddy technician (AJxtcman) about 50% of the blocks get junked during Timeserting because of porosity. The factory procedure calls for initially drilling and tapping for a fine thread insert, but then if too much porosity is found, a larger insert with more aggressive threads can be substituted after re-drilling and re-tapping. But even then, there’s a distinct possibility that the larger insert won’t solve the porosity issue in the vicinity of the head bolt.

Anyways, it was about at that time I PM’d several PFF’ers who had done Timeserts themselves seeking anyone who would lend or sell me their tool kit. While nobody stepped up (and I don’t blame them, but I had to try), IXSLR8 (Dave, a PFF’er) put me on to Norm Huhn ( who’s developed his own insert kit that’s marketed as being superior to the Timesert kit. His inserts have an even larger diameter and coarser thread than the over-sized Timesert kit, giving his inserts greater load spreading capacity and holding strength. The best thing? His entire kit, including 21 solid inserts and the optional bore-alignment jig, was only $500 delivered to my door after taxes. Here’s what the kit looks like (I know, I know... $500... doesn't look like it goes very far... but this is a Northstar! Everything is more expensive.)

The jig is bolted to one head bolt hole using an old head bolt, and is swivelled around to drill and tap any of the adjacent holes. There are separate collars and a guide pin that slides through the jig to accurately locate the jig before drilling and tapping since both tools have different diameters.

The instructions say that because of the depth of the holes, the soft nature of the aluminium, and the aggressive pitch of the drill bit, you have to drill without using a lot of pressure and you have to pull the bit out and clean the flutes three to four times before hitting the bottom of each hole. If you don’t, the shavings accumulate and gall-up the hole and can cause you problems when tapping. I found this to be good advice. The other thing to be aware of is that it takes a drill with a 1/2" chuck, not the run-of-the-mill 3/8" chuck.

Here’s the nature of the shavings that came out… the bit really bites into the block and I found that if I placed any more than a light pressure on the bit, it would bite hard into the block and twist the drill right out of my hands. Notice the tip of the bit… Norm even thought about removing the cutting edge from the tip to prevent you from going any further down into the block than the original hole. As an added precaution, I stuck a piece of masking tape on the bit to mark the maximum depth of the hole.

Bloozberry MSG #75, 05-10-2010 07:55 PM
      After drilling out the factory threads, the next step was to tap the new holes for the inserts. Norm’s kit also included the tapping oil and the Locktite to secure the inserts in place.

Here are the two taps he provided with his kit. Notice that the top one is more tapered at the end than the other. This is the tap that’s run through first. It’s tapered to make each cutting thread take a progressively larger bite out of the material you’re tapping instead of trying to do it all at once. The bottom tap is called just that… a bottom tap. It’s used to finish up the last few threads in the bottom of the hole that the tapered tap can’t do.

To start the tap squarely in the hole, it’s necessary to use the alignment jig again with a different collar inserted in it to accommodate the larger diameter of the tap. Tapping the holes is much like drilling the holes except that you have to back out the tap more often and blow out the chips to prevent them from galling your newly cut threads. I found that with the engine on the stand, it was easier to rotate the engine upside-down and then blow the chips out with compressed air than trying to blow them out with the engine right side up.

Once you’re done tapping each hole, you have to inspect the new threads to be sure that you didn’t come across any porosity that would lead you to reconsider using the block or getting a new one. Porosity will show up as several threads with chunks missing here and there. Luckily, all my holes tapped well.

It’s a pain-staking process to do all 20 holes and you can’t be in a rush. There’s a learning curve that goes with it too. In reviewing my build notes, I see that it took me 4.5 hours to set up the alignment jig and drill and tap the first 10 holes. With experience behind me, I was able to do the other cylinder bank in 2.5 hours, and from there, it took a final half hour to apply Locktite and screw all those inserts in. If you weren’t counting, that’s 7.5 hours in total! Here’s the pile of chips left on the floor after I was done all the drilling and tapping.

Here’s a close-up of Norm’s new threaded inserts. They’re gigantic compared to a Helicoil, and they’re solid too… not a wound spring-like insert. Also, unlike the Timesert inserts which expand as you’re threading them in and cinch themselves to the block mechanically, Norm’s inserts are held in place only with Locktite… presumably making them easier to remove if ever the need arose. The T-handle is the tool to thread them into the new holes.

Before you actually apply the Locktite, you have to thread all the inserts into the block and make a final measurement to be sure they seat at a specified depth. Then remove them all a final time (or re-tap any hole that wasn’t quite deep enough… it happened on one hole for me) and re-install with the thread locker.

Finally, here’s what the insert looks like fully threaded in and locked in place. Pretty deep down in there eh?

Enjoying the slide show so far?

mcaanda ( MSG #76, 05-10-2010 08:18 PM
Originally posted by Bloozberry:
Enjoying the slide show so far?

Oh yea -

Isolde MSG #77, 05-10-2010 08:24 PM
Originally posted by Bloozberry:

Luckily, my wife has owned her own automotive upholstery business since '93. The interior is the only thing that I don't need to worry about!

that's a helpful tidbit. Nothing like that around here, so I'll have to order out anyway.

olejoedad ( MSG #78, 05-10-2010 08:40 PM
      Great writeup Blooze!

It's in My Favorites!


Hudini ( MSG #79, 05-10-2010 09:03 PM
      Good stuff. I'm watching it as well.


dratts ( MSG #80, 05-10-2010 10:12 PM
      From what I have read I was leaning towards this kit too. I've heard that some cadillac dealers prefer this kit to time serts too.

IXSLR8 ( MSG #81, 05-11-2010 01:05 AM
      Looks good. That's the way I did my block as well. And it sure does leave a shavings mess.

Your kit is an improved later version than mine. Mine didn't come with the fancy alignment jig. I found that predrilling the block holes with a 1/2 inch bit made things easier to drill with Norms bits. I also used ARP (VW) studs instead of GM's stretch bolts. I like norms kit because it holds great and you can use GM head bolts or aftermarket studs. I've taken the heads off twice and they held fine under each re-torque.

A new kit has also been developed by a fellow named Jake in Ontario, Canada. His kit is a one piece stud: He's on the site and is not in favor of the inserts of course.

Both kits seem to work extremely well compared to GM's approved time serts. I think its good insurance to do Norm's inserts or Jake's studs to your block regardless if you have a head sealing issue or not.

You might want to consider using Cometic head gaskets (provided you have the 94-99 N*). They will not deteriorate like the GM graphite or Felpro gaskets under the shrinking and expansion of the heat cycles in the water jacket areas. I have them on my N* and they seal nicely. Expensive motor isn't it!

Bloozberry MSG #82, 05-11-2010 12:14 PM
      Thanks for the comments mccanda, Isolde, Joe & Hugh.

Dave: the alignment jig was extra... it retails for $95 separately but if you buy it with the basic kit, the total comes to $395 for both so there's a savings to be had. I think it was worth the extra money to get the drill and taps lined up properly.

Bloozberry MSG #83, 05-12-2010 10:21 PM
      At this point with all the machining, polishing and tweaking done, the engine was finally ready for a good wash... I was getting tired of all that burnt oil-varnish ruining my photos. I took the block to a different machine shop here that specializes in rebuilding cylinder heads, which I knew from experience could wash the block in a high-pressure hot water and detergent machine that wouldn’t ruin my polished exterior. The results were great and the block came out looking better than brand new. Over the course of the next few photos you’ll see the difference.

One thing I decided I wasn’t going to do was polish anything that wouldn’t be seen, like the intake valley (or the lifter valley if it were a pushrod engine). After the wash, the valley was super clean but still quite pitted so I wanted to protect it from future corrosion as much as possible. The dreaded white powder starts in the little pits and grows outward so the idea is to seal off the pits with paint to keep water and other contaminants out. Here's the bare valley:

I masked off the cylinders and bought some Duplicolor Chrome paint… this stuff is amazing… looks great and dries fast. I think you’ll agree. It does smudge if oil contacts it once it's dry though, so if anyone reading this plans on spraying their entire engine with it, it will need to be clearcoated to keep the sheen.

With that little loose end tidied up, I could turn the engine over on the stand and start working on building up the lower end. The first thing was to measure the main bearing clearances so in-went the bearings. This is #3. You’ll notice it’s the thrust bearing with the side wings. I wear gloves when I handle bearings because finger grease is acidic enough to etch the finish on them if you’re not careful.

Here’s a pic of all the bearings in place (notice the clean innards?). Like any other engine, they go in the block dry. I lubed up the surfaces that contact the crank with a thin layer of motor oil before laying in the crank, but nothing thick like assembly lube at this point since I didn't want to throw off measuring the clearances.

Next up was laying the OEM neoprene case-half seals and a piece of green Plastigauge on each of the main crank journals. The whole thing had to come apart again to read the Plastigauge, so no sealant was used on the case-half seals at this point. In retrospect I could have left the seals out at this point, but I figured they couldn’t do any harm. Later, I would discard these seals altogether and replace them with a new engine sealant that GM recommends instead.

The lower bearing halves were installed in the lower case half, and the lower case half was then installed carefully onto the upper case half. There are four tight fitting guide pins that make installing the lower case half difficult without a rubber mallet.

Because the main bearing cap bolts pass through the windage tray and the oil manifold, these parts must be assembled onto the lower case half as well before finally installing the bolts. Here’s the oil manifold sitting there awaiting the windage tray installation.

And here’s the windage tray in position and the main bolts (all 20 of them) being set in place. Unlike the connecting rod cap bolts, these are not TTY (Torque To Yield) and can be reused.

[This message has been edited by Bloozberry (edited 05-12-2010).]

IXSLR8 ( MSG #84, 05-12-2010 11:11 PM
      Nice. I like that chrome paint! Nice to see shiney, shiney.

katatak MSG #85, 05-12-2010 11:45 PM
      Amazing work Blooz!

Will ( MSG #86, 05-13-2010 08:48 AM
Originally posted by Bloozberry:

After drilling out the factory threads, the next step was to tap the new holes for the inserts. Norm’s kit also included the tapping oil and the Locktite to secure the inserts in place.

Be sure you use an appropriate solvent to clean all the tapping oil out first.

I'd suggest "maximum strength retaining compound" (don't know the number right off) as opposed to regular red Loctite.

Will ( MSG #87, 05-13-2010 08:54 AM
Originally posted by IXSLR8:
Both kits seem to work extremely well compared to GM's approved time serts. I think its good insurance to do Norm's inserts or Jake's studs to your block regardless if you have a head sealing issue or not.

You might want to consider using Cometic head gaskets (provided you have the 94-99 N*). They will not deteriorate like the GM graphite or Felpro gaskets under the shrinking and expansion of the heat cycles in the water jacket areas. I have them on my N* and they seal nicely. Expensive motor isn't it!

The Y2K engines use the same head gasket. I think it was used through '04 or '05.

Unless your had a problem with losing bolt tension or head gasket seal due to relaxation, creep or corrosion of the original threads in the block, or you are going to run 30 psi of boost, timeserts are quite sufficient.

The problems dealerships have with them are that the engines that need inserts are so badly neglected that they've deteriorated so much that they need bigger inserts than the timeserts.

IE, if you don't have a detectable porosity or corrosion problem already, you will almost certainly not need anything more than timeserts. Even at that, you only need timeserts for durability of the threads after multiple torque cycles.

Will ( MSG #88, 05-13-2010 09:03 AM
Originally posted by Bloozberry:
Finally, here’s what the insert looks like fully threaded in and locked in place. Pretty deep down in there eh?

Enjoying the slide show so far?

Deep set headbolt threads in the outer wall of an open-deck block keep the cylinder wall loaded in compression under all circumstances and help the cylinder keep a more consistent shape. This helps ring seal and therefore both power and economy. This was (I think) the first time GM used this configuration (although Honduh may have used it earlier in the B-series).

Will ( MSG #89, 05-13-2010 09:10 AM
Originally posted by Bloozberry:
And here’s the windage tray in position and the main bolts (all 20 of them) being set in place. Unlike the connecting rod cap bolts, these are not TTY (Torque To Yield) and can be reused.

The bottom end of the Northstar is extremely robust. I believe that Alan Johnson of CHRF uses stock main bolts in all of his engines at any power level (including 2000 HP Methanol burners).

BTW, I'd torque the main bolts first, THEN tighten the smaller bolts that help seal the oil manifold.

[This message has been edited by Will (edited 05-13-2010).]

Bloozberry MSG #90, 05-13-2010 12:17 PM
      Thanks for the feedback IXSLR8 and Katatak!

As for Will... thanks too for your comments... I was wondering how long it would take before you chimed in! I'll address your comments one at a time:

a. The red Loctite I used was supplied by Norm in his kit, I too forget the number, but I have no reason to believe it he would include it in the kit if it wasn't strong enough... (keeps fingers crossed).

b. I know your comment was directed at IXSLR8, but the point I was making about Timeserts is that they are just too expensive. I don't think anybody questions their effectiveness on engines that meet the necessary minimum requirements, but for the cost of the the tool kit, it's no surprise there are equally good alternatives showing up at 40% -50% cheaper.

c. Interesting theory for the deep headbolt threads. I had just assumed that they were made deep to enable the use of longer steel bolts that would stretch more easily than shorter ones and come closer to matching the rate of expansion of the aluminium block and heads.

d. I'm not sure what difference it would make to torque the main bearing bolts first rather than the oil manifold bolts or vice-versa. The oil manifold bolts only retain the manifold to the lower case-half, whereas the main bolts secure the lower case-half to the upper case-half. Perhaps you meant that you'd torque the main bolts before the case-half perimeter bolts. That makes more sense to me, and is also the order which the manual calls for them to be done. In my picture, you can see one perimeter bolt, but I had only just tightened them finger tight.

Will ( MSG #91, 05-13-2010 01:02 PM
      Large bolted interfaces should be tightened down from the center outward. Thus my suggestion regarding the main bolts.

Did you check ebay for a used Time Sert kit? I will agree that the kit itself is expensive. I did my main bolt holes on a mill and thus only needed the insert installation mandrel... which was something like $150. Absurd.

A 3" steel bolt will expand with the coefficient of thermal expansion of steel, the same as a 6" bolt. There are many reasons to use longer bolts.

Bloozberry MSG #92, 05-14-2010 08:07 PM
      The perimeter bolts I mentioned above are a series of smaller 8mm diameter bolts that secure the lower case-half to the upper case-half next to the seals. Here’s a picture of where the are.

Before the perimeter bolts are tightened, the main crank bearing bolts have to be torqued to spec. The instructions call for a nominal 18 lbft to be applied initially in a particular sequence, then followed-up by turning each bolt an additional 65 degrees. To do this accurately you need an angle gauge on your ratchet wrench. For those who’ve never used one, they’re quite simple… they just attach between the wrench and the socket. There’s a little adjustable arm that sticks out to one side that you must butt up against a steady surface like the side of the block, then you zero the gauge to zero by spinning the face up with wherever the needle is. The last thing you do is turn the wrench, which spins the needle until you reach the desired number of degrees.. The little arm keeps the dial face from spinning along with the needle. It’s really quite simple actually. Lastly, the perimeter bolts get torqued to 89 lb-in.

Once again, this is all just to check the main bearing clearances with the Plastigauge, so it’s all got to come apart after waiting about two minutes for it to take a final “set”. The Plastigauge gets squeezed between the bearing surface and the crank journal leaving a line of varying width depending on how tight the clearances are. Here’s what the lines looked like on the lower case half bearing shells.

I took my measurements from the marks left on the crank journal. There’s a little scale on the packaging for the Plastigauge that allows you to measure the clearance in accordance with the width of the squished gauge. The spec calls for 0.0006” – 0.020” (yes… that’s six ten-thousandths) whereas mine measured from 0.0010” to 0.0015” so I was happy.

Once you’re done, you can’t forget to clean the Plastigauge off of the journals and the bearings. I find WD40 on a soft cloth does a good job of dissolving it since it gets stuck on there pretty good. You don’t want to use a fingernail on the bearing surface, that’s for sure. Next up is the final crank installation so a good healthy dose of assembly lube on the bearing surfaces is in order… I’ve used the Clevite and the Permatex assembly lube with equal success… this stuff would make a Vampire think about going for a tall cool one.

A final cleaning of the crank journals and Voila!… the crank finds it’s permanent home. A quick spin to lube up the journals all the way 'round and I was ready for the crank end-play measurement.

Crank end-play or float is the amount of fore and aft movement of the crank in the block along the axis of the crank. On a manual transmission it's especially important since everytime you press in on the clutch, it shifts the crankshaft forward along it's axis with a fair bit of pressure. Too much movement and you begin to throw the connecting rods off of their intended plane of movement. The #3 main bearing with the thrust surfaces (shown earlier) is what determines the amount of crank end play.
The way I measured this was by sticking a magnetic dial gauge to one of the crank’s counterweights, with the gauge plunger on the stationary bearing web. Then I pushed the crank as far backwards as possible with a small pry bar, zeroed the gauge, then pushed the crank as far forward as it would go and took the measurement. The spec calls for between 0.002” to 0.019” and mine was 0.008”.

With everything in order and within specs, the lower case half was re-installed, along with the oil manifold plate, windage tray, main bearing bolts and perimeter bolts for what was supposed to be the last time… ahhh… ignorance is bliss.

IXSLR8 ( MSG #93, 05-14-2010 09:18 PM
      Not sure how many of you N* owners frequent the site.

Here's an interesting thread on head gasket failures, GM timeserting and the use of other inserts such as Norms. I'm not making a particular statement but rather showing a link where you can find more information on inserts, head gasket failure and related info from a fix perspective:


dratts ( MSG #94, 05-14-2010 11:14 PM
      With no practical experience I can only theorize. I suspect that norms are better than serts. I would think that even better would be studs. Especially if removing the heads a few times. Can the rwd head gaskets be installed on a fwd?

Will ( MSG #95, 05-15-2010 02:14 PM
Originally posted by Bloozberry:

Before the perimeter bolts are tightened, the main crank bearing bolts have to be torqued to spec. The instructions call for a nominal 18 lbft to be applied initially in a particular sequence, then followed-up by turning each bolt an additional 65 degrees. To do this accurately you need an angle gauge on your ratchet wrench. For those who’ve never used one, they’re quite simple… they just attach between the wrench and the socket. There’s a little adjustable arm that sticks out to one side that you must butt up against a steady surface like the side of the block, then you zero the gauge to zero by spinning the face up with wherever the needle is. The last thing you do is turn the wrench, which spins the needle until you reach the desired number of degrees.. The little arm keeps the dial face from spinning along with the needle. It’s really quite simple actually. Lastly, the perimeter bolts get torqued to 89 lb-in.

Be sure to go back and RE-torque the sequence to 18 ftlbs BEFORE applying the 65 degrees. The first bolts in the sequence WILL relax as you tighten down the bolts around them.

Bloozberry MSG #96, 05-15-2010 04:30 PM
      I forgot to mention that Will... thanks! This is very true whenever torquing anything with a torque wrench.. always go back and and retorque all of the fasteners a second time to pick up the slack on the first fasteners created by the last ones. Even though this isn't mentioned in the assembly manual, it's common sense. In my case, I think I put another 30* or so on the first few main bolts before the torque wrench "clicked" at 18 lbft the second time around. If I hadn't rechecked, then clearly the first few main bolts would have been under torqued by 30* when all was said and done.

Bloozberry MSG #97, 05-17-2010 09:35 PM
      With the lower case-half installed, I could finally move on to installing the sparkly new pistons. Or could I? Within minutes of having torqued the main bearing bolts for the second time, it dawned on me that there was no way I was going to be able to install the connecting rod caps and bolts with the lower half of the engine installed. There just isn’t any room… especially with that windage tray in the way. Rats! I got ahead of myself.

Before removing the lower end again, I decided I’d turn the engine upright (something you can’t do with the lower case-half off without the crank falling out!) and measure up my compression ring gaps. If you’ve never rebuilt an engine before, when you measure the ring end gaps you have to ensure they’re level in the cylinder or they’ll throw off the measurement. The best way to do this is to slip a ring into the cylinder and push it down an inch or two with an upside down piston. It’s easy to make sure the piston is level since there are all kinds of ring lands to line up with the deck surface.

Once the ring is in level, pull out the piston and measure the ring gap with a feeler gauge. You have to do this with all 32 rings (1 top ring, 1 middle ring, and two oil scraper rings per cylinder) and make sure you dedicate each ring to the cylinder that it was measured in. Not all cylinders are exactly the same diameter, and not all rings are exactly the same size, so to file as few ring gaps as possible, I measure all the rings starting with the lower scraper rings first, then swap around tightest and loosest rings until I get the end gaps to match as close as possible between all of them. The oil scraper ring end gaps on a Northstar are allowed to be 0.010” to 0.030”. Once I was finished moving them around for the best fit, mine were from 0.010” to 0.013”… not bad at all. Then I move on and do the same for the two compression rings. By mixing them up I was able to avoid any ring gap filing and therefore maintained the nice, even, factory square edges.

Next up is to install them, starting with the lower oil scraper ring, the spacer, upper oil scraper, lower compression, and then upper compression ring. You have to install them in this order because the rings get installed from the topside of the piston and you can’t stretch a lower ring over top of an upper ring if it were installed before the lower ring… it just doesn’t work. The oil scraper rings are easily installed with your fingers…

…but the two compression rings are best installed using a ring expander.

I bought a master engine rebuild kit that basically comes with everything you need to rebuild an engine. It’s the cheapest possible way because to buy the parts individually you’d pay easily 1.5 to 2 times as much for the same parts. I ended up buying my kit from a company called EngineTech because they were one of the two companies that offered 0.25mm oversized pistons that I could find. There were choices between hypereutectic and coated pistons from other companies, but as far as my budget was concerned, I thought it best to spend the money on other things.

I was happy with the quality of the parts from EngineTech except for the piston wrist pins. They weren’t consistently the same length, nor were they consistently chamfered at both ends. Here’s an example of two pins from the same kit. To be honest, I’m not sure I would have noticed except that when I went to install the retaining clips, 5 of the wrist pins were too long. I ended up having to shorten and/or chamfer all 8 pins to one degree or another.

Once that bit of business was taken care of, I was able to assemble the connecting rods to their respective pistons… (note the ugly busted knuckle… the result of losing a fight with rounded bolt on a customer’s car)

… and install the spring clips to retain the wrist pins… (I know, I have an ugly thumbnail too… from flipping the nail on another customer’s car… ouch!). You can see from this photo why too long or improperly chamfered wrist pins cause a problem. You can get one spring clip in place, but you just can’t seat the second one.

Finally, here’s a couple shots of the completed rods and pistons ready to be installed in the block… well, once the lower case-half was removed again.

[This message has been edited by Bloozberry (edited 05-18-2010).]

Tony Kania MSG #98, 05-18-2010 01:14 AM
      A beginner could damn near build his first engine with the information, and pics that you provide in this thread. And a free bump.

bamman ( MSG #99, 05-18-2010 03:20 AM
      Do I know you, I have a 4.9 in my 88 fiero and I live in Brooklyn. I would have met you at the Berwick car show.

bamman ( MSG #100, 05-18-2010 03:34 AM
      No need to reply to the post above from me. We have met. This looks like a great project for you, great workmanship you have. I still think about the go-cart. Someday I will make plans to visit you at the "old farm" when cruising the valley. My fiero is painted black and is a fifty footer. Bye for now.

Bloozberry MSG #101, 05-18-2010 08:26 AM
      Hey Bamman, PM sent.

Bloozberry MSG #102, 05-19-2010 07:44 PM
      One thing I forgot to mention in my last post is that it’s a good idea to measure the side clearance of the top two piston rings too. You just slip a feeler gauge between the piston ring and the ring land on the piston itself. The clearances are pretty tight for this measurement: 0.0016” to 0.0037”. It’s hard to find feeler gauges less than 0.0020” thick although a more expensive set I bought for this engine had a 0.0015” feeler. I could fit the 0.0020” in all of mine but not the next size up 0.0025”, so all was good.

So I turned the block upside down again, removed the lower case-half, and began installing the pistons and connecting rods to measure connecting rod bearing clearances. The first thing to do is to make sure the rings are well lubricated. I get an old margarine container, put an inch or two of oil in the bottom, and dip the whole piston top in it. It’s messy, but effective. Now's the time to lube them up since there’s no need to take the pistons out again after checking the bearing measurements.

To compress the piston rings so the pistons will slide into the cylinders, I use a locking band-style ring-compressor instead of the pliers-style. I couldn’t take any pictures at this stage because it took too many hands to install the pistons with the block upside down, and besides, I was full of engine oil! For those who’ve never done it, here’s a picture of me installing a Fiero 2.8L piston in a block that’s right side up. The ring compressor just squeezes the rings flush with the piston OD so that they don't hang up on the deck when pushing the pistons in. The compressor has to be held up tight against the block deck or else the super thin oil scraper rings slip out of the crack and expand prematurely preventing you from going deeper. It's not bad right side up, but rather frustrating to do up side down on the N*.

Of course the Northstar pistons and connecting rods are uni-directional so they must go on in a particular orientation. Here’s a picture of some virgin Plastigauge on the rod journal prior to bolting on the caps.

Before sticking the connecting rod cap on, there’s an important thing to remember when rebuilding a Northstar. The connecting rod bolts are Torque to Yield (TTY), meaning that they get torqued so much that they are irreversibly stretched the first time you torque them, and then if you remove them, they’re no good anymore. They’re also $17.14 each times 16 of them equals $300 after taxes, so you don’t want to use up your new ones to check your bearing clearances or it’ll be a costly mistake. I reused the old bolts to check the bearing clearances. Once again, you install the rod bolts, torque them to a nominal 18 lbft, click on the angle gauge, set it to zero…

… and torque the crap out of it until you reach a whopping 110* more twist on the bolts. It not only sounds like a lot, it feels like a lot. You can only do two at a time since you can’t turn the crank without smearing the Plastigauge, and you’d never get the other caps on without turning the crank.

So two by two you torque the caps, remove the caps, check the rod bearing clearances, clean off the Plastigauge, reinstall the caps using your new rod bolts, and torque them up a final time. Then you move onto the next pair of rods. Here's more squished Plastigauge.

Here’s a pic of the rod bolts (GM p/n 12552947). I thought I’d include it because of the strange threads. It’s only the fine threads at the end of the bolt that engage the connecting rod, so I’m not exactly sure of the reasoning for the coarser threads halfway down. Just bizarre enough to make you think long and hard about going to the hardware store and buying some generic rod bolts at a quarter of the cost.

With the pistons installed, the next step was to retrieve the heads from the machine shop! Yay! In preparation for this, I knew I needed new cylinder head alignment dowels as previously mentioned, so I took a trip to a buddy of mine’s who has a lathe. Within an hour or so, he had a new set of four nicely turned for me for $25 instead of $75 from the dealership.

A few quick hammer taps and I was ready for the heads.

pmbrunelle ( MSG #103, 05-19-2010 10:09 PM
Originally posted by Bloozberry:
I reused the old bolts to check the bearing clearances. Once again, you install the rod bolts, torque them to a nominal 18 lbft, click on the angle gauge, set it to zero…

… and torque the crap out of it until you reach a whopping 110* more twist on the bolts. It not only sounds like a lot, it feels like a lot. You can only do two at a time since you can’t turn the crank without smearing the Plastigauge, and you’d never get the other caps on without turning the crank.

Sounds like the rod bolts really were torqued to yield.

Erik ( MSG #104, 05-20-2010 03:02 AM
      I wonder if the strange threads are part of the TTY feature ..

Bloozberry MSG #105, 05-20-2010 07:29 AM
      You're probably right there Erik. The bolt would be at it's smallest cross section in the bottom of the coarse threads, so that would be the weakest point.

Bloozberry MSG #106, 05-21-2010 09:01 PM
      Hmmmm… I keep getting ahead of myself. Before I could turn the engine upright and install the alignment dowels, I had to bolt the lower case-half on again. This time, luckily, I had done a little more reading here on PFF about sealing the case halves properly. I mentioned before that the original way was just using the orange neoprene seals. I guess GM found that they didn’t work very well so at some point a few years back they recommended following up with some anaerobic sealant in the seal grooves, then installing the seal, and then more anaerobic sealant before joining the two halves together. Most Northstar rebuilds on PFF to date have used this method with good success.

I, on the other hand, had downloaded and was following AJxtcman’s instructions for reassembling my engine. In it, GM calls for a particular sealant which I tried to buy but was told that the part number had been superseded to AC Delco p/n 88901148. The instructions make no mention of the neoprene seals at all, instead, they say to fill the machined grooves that the seal sat in with this new engine sealer. So I did.

The sealant costs $17 and comes in a 1/3 length caulking-gun tube and has enough sealant to do about 90% of what you need… it’s like they know and they do it on purpose. It’s kind of a grayish putty-like silicone and blends in reasonably well with the color of the aluminum. Once you fill the grooves you have a maximum of 20 mins before it skins over and becomes useless. It’s plenty of time. So once the lower case-half was gooped up, I flipped it over and onto the block. Next came the oil manifold plate.

GM recommends replacing the oil manifold plate and I now know why. It takes more time than it’s worth to clean the OEM silicone out of the serpentine grooves. Once it was done though, it got the same treatment as the lower case-half… AC Delco engine sealant in all the grooves with enough to stick up about 3mm above the surface of the plate.

With the oil manifold plate installed, next came the windage tray (again), and finally all the main bearing bolts for the last time (**crosses fingers**). One thing to be watchful of once everything is torqued back into spec is that the engine sealant doesn’t ooze into the oil drain-back tubes on the side of the block and plug or restrict them. The oil drain-back tubes carry oil from the heads down through the upper case-half, lower case-half, oil manifold plate and finally into the oil pan. All of these mating surfaces except the heads have engine sealant applied to them so you’ve got to reach down with a thin bladed screwdriver or dentist’s tool into each tube after every step and clean up any sealant that squeezes in them. Here’s one of the tube holes I’m talking about. I had to clean sealant out of about three tubes.

Another frustrating thing about the ’97 block is that the oil manifold plate doesn’t come with a replaceable oil pick-up tube seal. Some earlier-year blocks do, but GM probably decided that since you should replace the manifold plate, then there was no purpose to making a replaceable pick-up tube seal. Before I ruined mine digging it out, I read the list of contents of my master rebuild kit and it included the seal, so I went ahead and tore the old one out of the plate. Only after I had done that did I actually look for the seal only to find an O-ring that didn’t fit. The later blocks use a molded-in-place neoprene-like seal. To make a long story short, I ended up using more engine sealant around the pick-up tube and sticking it in place. This is an area where you can’t afford to have leaks because the oil pump would much rather suck air in through that leaky joint than try to suck that thick oil up from the pan.

Here’s the pick-up tube bolted in place. Notice too if you’re building your own Northstar that one of the main bearing bolts is actually a stud… that one goes on one of the #3 bearing caps so you can bolt the oil tube to it later. Finally I treated the oil pan with the same engine sealant and tossed out the orange neoprene seal. The oil pan bolts get torqued on is a particular sequence just like everything else. OK, now I was ready for the heads.

Fierofreak00 ( MSG #107, 05-26-2010 07:34 AM
      I'm going thru withdrawls....and need an update, this is a great thread! -Jason

AJxtcman ( MSG #108, 05-26-2010 08:58 PM
Originally posted by 88GTS:

Here are the some of the available Northstar Engine Management options:

1. CHRFab Holley Commander 950

2. Ryan Hess 1227730 ECM

3. AJxtcman LS1 PCM on a Northstar

4. Northstar OBDII PCS tuned by Webster’s

My personal perceptions and comments on these options are:
1. The CHRFab Holley works, but is crude compared to OEM computers.
2. Ryan Hess ECM has also been proven, but I personally don’t like 80’s technology batch fire ECMs.
3. AJ’s LS1 PCM from the Shelby Aurora 4.0l project has a lot of potential, even for boosted applications, but AJ became quiet in 2009 and I haven’t seen a completed implementation yet.
4. The Webster’s tuned OBDII Northstar PCS came up recently, but again I haven’t seen the final word that it’s working yet. Don’t know if manual transmission or boost will be possible.
Anyone with comments or updates on these options?

I gave Westers the information that got him started in the Northstar Tuning world. It is kind of funny after all of the arguing with some members and now some of them recommend Westers

Bloozberry MSG #109, 05-26-2010 10:52 PM
      I’m baaaack (and this post should put me on page four! Edit: but it didn't!) Life has a habit of catching up to you when you start a build thread. I’ve been busy piecing a ’67 Pontiac GTO convertible back together after the owner had it totally stripped of every part you can imagine for painting (interior, wiring, glass, trim, bumpers, ...the works) then brought it here for reassembling.

Thanks for the feedback Fierofreak, this hit is for you. AJ, glad to see you chime in too. I’d love to use your LS1 tune on my Northstar but I’ve been on the fence about it for the same reasons as many others… I’m just not sure if the development was ever completed. It would be great if you could post an update. It would be nice to see some testimonials from people who are running your tune too.

Anyways, to continue my story… once I saw the condition of the cams, the cam followers and the valves, I knew the heads would have to be completely rebuilt to satisfy my obsessive need for things to be just right. Normally I would farm out the machining and reassemble the heads myself, but the machinist at this specialty-heads shop around the corner convinced me he would machine them as though they were his own, and only charge a nominal fee to reassemble them. So I entrusted him.

He started saving me money from the get-go. After he measured up the cam wear, he decided that the intake cams were perfectly good with almost no measurable wear. The exhaust cams were a different story though, but I already knew that. I can’t recall the exact pricing for new exhaust cams, but it was enough to make my eyes nearly pop out of my head. Something like $600 each. Luckily there’s a place in Moncton, New Brunswick that can weld up, regrind, and re-harden the cams using a process called Parkerizing. (It’s a trade-name for a method of protecting a steel surface from corrosion and increasing its resistance to wear by immersing it in a solution of manganese or zinc acid with phosphate.)… and all this for the lowly sum of $210 for each cam. Needless to say I didn’t need much convincing.

He cleaned the bare heads, bead-blasted them, planed them, re-cut the valve seats, and put in all new intake and exhaust valve guides, new valves, new cam followers, and reconditioned cams for about $1400. Not cheap by any stretch, but not bad for a N*. I think you’ll agree they look like new too. God I love the look of those 32 valves! (insert Tim-the-Toolman grunt here)

A thing of automotive beauty... I'm restraining myself from posting the twenty-something photos I took of just the heads from different angles.

I almost didn’t want to put the heads on the engine and hide all those shiny mechanical parts, but my wife didn’t agree they’d make great coffee table conversation pieces. I kept them tightly wrapped up in clear plastic bags for months showing anyone and everyone who walked through my shop, but the time finally came to install them. Despite all the recommendations from everyone to use cometic gaskets, I bought the Fel-Pro Permadry head gasket set (part number HS26150PT-1) at $250 for the set. I can’t offer any other explanation than cost for my choice. At some point the piggy bank just says “No”. Here they are installed on the deck surfaces just waiting to be sandwiched by the heads.

And this is the crowning moment when the first head was finally put in place… Yay! Not surprisingly, the heads are actually quite light and easily handled by one person despite their size.

And here’s the double-crown look. From this point of view, without the intake, it’s clear how the double overhead cam heads make the engine so much wider than say, a SBC. I know the Northstars fit in a stock Fiero engine bay, but it’s kind of nice knowing that I’ll have an extra three inches of depth due to the frame stretch on mine.

In my next post I’ll go over torquing the heads down and what to look for to prevent foreign object damage from the by-products of the headbolts.

[This message has been edited by Bloozberry (edited 05-26-2010).]

dratts ( MSG #110, 05-26-2010 11:32 PM
      I'll never be able to afford what you are doing to your engine, but I would like to make an album of all your great pictures and I'm learning a lot from your build. Much appreciation!

Fierofreak00 ( MSG #111, 05-27-2010 07:05 AM
      Ahhhh sweet serenity, that's much better.... but, it's only going to last a day or two so get to work! -Jason

Bloozberry MSG #112, 05-30-2010 03:47 PM
      With the heads in place, the next step was getting them torqued on. There’s some good discussion here on PFF about whether the head bolts are reusable or not since the GM service manual states that they must be replaced without really explaining why. The consensus is that they are theoretically reusable since they aren’t torqued beyond their yield point (ie TTY). But from a practical standpoint, they should be replaced because of the specialized coating on the threads. Apparently it is a one-time-use coating that cannot be reapplied to the threads outside of having the highly specialized machine processes at your disposal. One other thing to point out here, is that if you haven’t drilled out your OEM threads in the block and replaced them with inserts, GM makes it pretty clear that you MUST clean the coating left over from the old head bolts out of the threads in the block before using new bolts.

So armed with this information, I took my 20 perfectly good used head bolts and set them in my bin of used-big-bolts-in-case-I-ever-need-that-particular-odd-size-ever-again. It’s amazing how many bolts are collecting dust in there. And off to the internet I went to order two boxes of ten Fel Pro head bolts (p/n ES-72186) at $42.50 each box. Here’s what they look like:

Notice there’s not only a coating on the threads, but also on the underside of the head too. Presumably it’s there to give an accurate torque reading, but then again these bolts are tightened with a specific number of degrees of rotation so there’s not much need to reduce the friction under the head. It's possible that it's a sealant to keep engine oil from creeping down the bolt holes and affecting the coating on the threads, but I'm just speculating. One thing it does do is give you a hard time after you’ve finished torquing the bolts. The rubberized orange sealant squeezes out as the underside of the bolt comes in contact with the cylinder head, and then gets pinched off by further tightening. So you end up with these little strands of orange sealant dropping off into the cylinder head. I wasn’t impressed since it took about half an hour using tweezers to pick out the pieces after I was done.

Here’s a quick pic of me using the angle meter again while torquing the head bolts on. For these, you start by applying 22 lbft of torque with a torque wrench to all twenty bolts in a particular sequence and then recheck them a second time. Next you rotate all twenty head bolts in sequence a further 60* one after the other, then go around again for another 60*, and then a final 60*. It takes a bit of time to set up the meter each time and you really don’t want to be in a rush or be disturbed while doing this and lose track of where you are in the sequence. It’s best if you lock yourself in your garage and let no one disturb you until it’s done.

Here’s a topside view of the heads once they were installed. The orangey-yellow stain on the intake cam and the white stain on the exhaust cam are factory paint markings probably to enable the assembly line worker to differentiate between the two at a glance.

And here’s a close up of the cams. Notice that the cam journals ride directly on the casting, without bearings per se. If you’ve been following my thread since the beginning, you’ll remember that I had to replace a number of the cam bearing cap bolts due to them having been over-tightened at some point in their previous lives and therefore significantly stretched beyond their yield point… two of them to the point of fracture. Luckily I was able to steal a couple from my spare-parts engine.

A picture is worth a thousand words, so here’s a close up of one of the intake ports just dying to have something accidentally fall into it. It’s a good idea to mask off the intake decks until you’re ready to install the intake.

darkhorizon MSG #113, 06-01-2010 10:36 AM
      In a-typical PFF fashion this project is coming together quite quickly and is looking really interesting!

This is going to be a purely n/a build right?

Bloozberry MSG #114, 06-01-2010 12:59 PM
      Yes Darkhorizon... it's going to be normally aspirated. I figure trying to get this thing to run nicely on either a reprogrammed LS1 or a Caddy PCM is going to be challenging enough!

darkhorizon MSG #115, 06-01-2010 01:33 PM
Originally posted by Bloozberry:

Yes Darkhorizon... it's going to be normally aspirated. I figure trying to get this thing to run nicely on either a reprogrammed LS1 or a Caddy PCM is going to be challenging enough!

Its not so bad, just pick up a TC2 for about $700 and you will have it dialed in in no time. I considered stepping in behind AJ and finishing where he has sorta faltered at as far as the plug and play northstar market is concerned. I am a bit confused why Ryan at GMtuners has yet to offer anything (although I think he would be your best bet for getting a economical mail-order tune). I just do not have a northstar to play with to justify getting a TC2 (I would probably need 2 northstars to justify doing 1).

Boost on a LS1 pcm is possibly the easiest thing you could do. It is just a matter of getting a maf sensor that mind the boost (pretty much any gm maf will work great, some are better than others)

I bet if you begged HPT enough, they would plug in the northstar bits to their software as well.

Bloozberry MSG #116, 06-01-2010 06:49 PM
      Thanks for the info Darkhorizon... I'll be looking at management systems soon enough so this will help.

Back to business: At this point, rather than carry on with the installation of the timing chains and sprockets, I decided to take a different tack and rebuild the starter. If any of you aren’t familiar with the Northstar starter, it’s located under the intake manifold in the Vee formed by the cylinders. It’s a crazy location at first glance, but on the other hand it leaves more room on the exterior of the engine block to route things like the exhaust system, axles, and mounts. I kind of like the ingenuity behind the decision to stick it in an otherwise empty space.

Of course this just means that it would be silly to stick the old one back in without rebuilding it. Mine looked OK from the outside, but it was a different story once I opened it up (another reason not to just install a N* without taking a good hard look at it). Here’s a breakdown of the major parts from top left: brush carrier, armature, magnet housing, gearbox, and at the bottom of the image is the solenoid.

Here’s a close up of the housing for the starter brushes. Note how much dust there is from the wear of the four brushes. I would imagine that at some point in time that all that electrically conductive dust would cause problems. The entire four-brush assembly is held in the housing with only two screws making it easy to take out and clean. Once removed, all I did was spray some electrical component cleaner on the brush assembly and in the housing to rinse it all out.

The brushes were nowhere near worn out, so there was no need to replace them. Notice in the picture below that there are holes in the rectangular brush guides that allow you to stick in a small diameter rod to hold the brushes in the retracted position. This allows you to slip the commutator end of the armature back in between the brushes later on.

Here’s the commutator/armature assembly before I attacked it with the wire wheel on the bench grinder. (The commutator is the part on the left and the armature is on the right.) Mine had obviously been penetrated by moisture and sat in the same position for some time as the armature had a build-up of rust on one side. If you use a wire wheel to clean one up, you have to be careful not to grind away any of the insulating varnish on the copper wires of the armature coils. There was also a lot of ground-in brush dust between the individual sections of the commutator so I took an Exacto knife and cleaned out the grooves.

Here’s what it looked like after it was cleaned up. Once it was spic and span, I mated the brush assembly to the commutator end of the armature and pulled out the little brush retaining pins I had made out of some piano wire. The brushes snap into place since they’re spring loaded.

With that bit of business taken care of, I could reinstall the guts of the motor assembly back into the freshly refinished brush housing. The brush housing has a small Oilite bushing in the end that the shaft of the armature slips into.

Once the rubber plug for the main wire lead is lined up with the notch in the housing, the brush assembly can be screwed to the housing from the outside. At this point you have to be careful not to turn the assembly upside down since the armature will fall out. If that happens you have to remove the brush assembly again and retract the brushes with the pins and start over again.

[This message has been edited by Bloozberry (edited 06-01-2010).]

Will ( MSG #117, 06-02-2010 01:43 AM
Originally posted by Bloozberry:
Back to business: At this point, rather than carry on with the installation of the timing chains and sprockets, I decided to take a different tack and rebuild the starter. If any of you aren’t familiar with the Northstar starter, it’s located under the intake manifold in the Vee formed by the cylinders. It’s a crazy location at first glance, but on the other hand it leaves more room on the exterior of the engine block to route things like the exhaust system, axles, and mounts. I kind of like the ingenuity behind the decision to stick it in an otherwise empty space.

With the engine in the car, it takes about 10 minutes to get to the starter. Under normal circumstances, the starter will also be CLEAN. The Northstar has the easiest starter replacement of any engine swapped into a Fiero. Don't even have to lift the car.

Erik ( MSG #118, 06-02-2010 02:11 AM
Originally posted by Will:

With the engine in the car, it takes about 10 minutes to get to the starter. Under normal circumstances, the starter will also be CLEAN. The Northstar has the easiest starter replacement of any engine swapped into a Fiero. Don't even have to lift the car.

Nice thing about the N* starter is you can swap the motor to the later small form factor 60 dgree v6 starters and vice versa ..since I have tons of them I am good to go for the forseeable future

doublec4 ( MSG #119, 06-02-2010 10:09 AM
      Very thorough and complete write up! Awesome work!

Will ( MSG #120, 06-02-2010 01:15 PM
Originally posted by Erik:

Nice thing about the N* starter is you can swap the motor to the later small form factor 60 dgree v6 starters and vice versa ..since I have tons of them I am good to go for the forseeable future

Not unless you change the drive housing... The Northstar starter is mounted via axial bolts, while the V6 starter is mounted via perpendicular bolts.

Edit: N/M, you meant swap the Northstar drive housing onto the V6 starter.

[This message has been edited by Will (edited 06-02-2010).]

17Car MSG #121, 06-02-2010 06:54 PM
      Looking good, nice to see some progress on the project.
You have more guts (and money) than I do to rebuild a Northstar. Seeing how complex it is makes me wonder if I should have went with a 3800, I'll feel different when my swap is done.
Did you consider a set of CHRFabs cams? I believe that they are only about $500 for a set. Beats $700 a piece and it's an upgrade, but I will be interested in how your refurbished cams hold up.
Edit: Hooray! I own my first page ever!

Bloozberry MSG #122, 06-03-2010 07:36 PM
      Thanks for the comments Will, Erik, DoubleC, and 17Car. It's always more encouraging to continue the thread when you get a little feedback!

So for tonight's show, the next step was to clean up the magnet housing… here’s what it looked like before. It’s interesting to note that the magnets are fully sealed in a metal casing. Not sure why, but it’s a notch above the rest, as far as field magnets go. I wire wheeled the outside on my bench grinder and used steel wool on the inside to clean up the rusty stains. Then I spent ten minutes getting the wire wheel bristles that broke off and the steel wool lint off the magnets! With the power of these magnets, I could probably have used the wire wheel without wearing goggles!

Once it was cleaned up and painted to match what I expect to be the body color of the car (at this point anyways), I was able to install it on the armature assembly. Two things: 1. nobody except me and whoever reads this post will ever know that it was painted to match the car, but what can I say… it makes for a pretty picture…

And 2. I learned the hard way that you simply can’t slide the magnet housing towards the armature and expect the armature to stay put. About two seconds after the above photo was taken, the armature whipped out of the brushes and stuck itself to the magnet housing. Of course that meant starting all over again removing the brush assembly and retracting them to be able to slip in the commutator again. But I’m a quick learner so the next time I went to install the magnet housing, I held the armature firmly in place so it wouldn’t get sucked out of the brushes housing.

On to the gearbox half of the starter: The gearbox is separated from the motor with a plate that’s supposed to keep the grease off the motor. Mine was kinda rusty looking so I took it off and sandblasted and refinished it. Here’s what it looked like with the motor half removed.

With the cover removed (it’s just held in place by a tab), you can pull three little planetary gears out, and retract the entire gearbox’s guts from the housing with a little persuasion. In this case, the sun gear is part of the armature shaft, which meshes with the three sun gears that spin on pegs that are welded to gearbox’s input shaft. This gears down the RPM of the motor and multiplies the output torque. The gearbox stator is kept from moving by having big plastic teeth or splines that engage the ID of the housing. That’s the part that needs a little coaxing to get the guts out. The other major assembly in the gearbox is the solenoid fork which acts just like a clutch fork. Here’s what the major parts look like once cleaned up:

With the innards removed, I was able to examine the needle bearing in the starter snout and decided it needed to be cleaned and re-greased. I used varsol to desolve to old grease and spun it dry with shop air then used a Q-Tip to re-grease the needles. Here’s a close-up of the little guy after I cleaned it but before I decided to remove it and grease it properly.

To remove and reinstall it, I used a small arbor press which made things easy, but I'm sure you could used a punch and hammer judiciously. In this picture I’m pressing it back in after cleaning and re-lubing it.

I promise to wrap up the starter rebuild in the next post, so for those of you itching for me to get back to the engine, the suffering is almost over!

fierogt28 MSG #123, 06-04-2010 07:50 PM
      Blooze, I've been following your swap. Nice to see the detailed info and pics.

I love seeing cleanness in work even if its going into a fiero. That's what makes it more interesting.

Hopefully, I'll get to see you swap someday, once I get around to NB in the next couple of years with 3 weeks

Bloozberry MSG #124, 06-05-2010 08:08 PM
      Thanks Fierogt28. I had one of my customers tell me one day that "cleanliness is next to Godliness when it comes to building engines" and that sort of stuck with me. It's all about perceptions. It's also so much more satisfying to go to a car show and pop your decklid to a clean engine bay. Sure it takes alot more time but I think it's worth it. By the way, what's up with the line "even if it's going into a Fiero"? No disparaging remarks about Fieros are allowed here!

Anyways... cleaning and re-greasing the gearbox was pretty straightforward. The main component of the gearbox is the starter pinion assembly. The big black plastic part, as mentioned earlier, is locked to the gearbox housing but the portion in the right hand side of this picture is the part that whips out and engages the flywheel. Here I’m greasing the splines that the pinion travels on. The manufacturers of different car maintenance products are starting to get wise… make things like grease in pretty colors and even the women might take an interest in auto repair! (...apologies to the women of PFF)

Next I greased up the backside of the pinion bearing that the actuating fork contacts, and installed the fork. The fork doesn’t stay there on it’s own, it has a little yoke that gets captured by the gearbox housing once it all gets put back together.

I greased up the pinion journal that will marry up with the needle bearing in the gearbox snout too.

Then installed the three little planetary gears in the plastic housing and lubed them up good. At this point the pinion assembly was ready to be installed back into the gearbox housing.

It took a little persuasion to get the black plastic planetary gear housing to seat properly, and once it was into place, I realized why. The little yoke that the fork pivots on was binding up so I had to pull it all out again and take a little more care in aligning the yoke into it’s recess. If you take one of these apart, make sure before you close it all up that the little lever that the solenoid is connected to can actually pivot freely to slide the pinion gear back and forth.

A little grease on the solenoid pushrod and it was installed using three little screws…

… then the gearbox grease shield…

… and finally the starter gearbox was ready to be mated to the starter motor.

Ta-dah! One rebuilt Northstar starter. Tiny little bumble-bee-of-a-thing eh? I hooked it up to a spare shop battery and made sure it worked by cycling it about twenty times… I don’t want to have to deal with it again for a very long time.

Finally, here it is mounted in place in the cylinder valley. The cables for it and the knock sensor run under the intake manifold and emerge up near the pulley end of the engine (oops, I almost said “front end of the engine”).

katatak MSG #125, 06-05-2010 09:14 PM
      Seems a shame to do all that nice work to the starter just to cover it up with the intake! Nice work Blooz.

fierogt28 MSG #126, 06-06-2010 02:15 AM
      Blooze, what I meant was 99% of the folks that I see that own a fiero don't have a clean engine bay. They probably don't care because they aren't worth much; but that's to them. If anything, I want cleanness and new components through-out. I don't like doing a half ass job. But what your doing is exactly what I'd want, or do.

I'd like to see the car once your done. Sounds like an interesting swap and the 6-speed mated to it.

Bloozberry MSG #127, 06-06-2010 07:19 AM
      That's OK Fierogt28, I was just pulling your leg.

dratts ( MSG #128, 06-06-2010 09:33 AM
      Any idea how moisture got in there? Most exterior starters don't get that rusty.

Bloozberry MSG #129, 06-06-2010 12:22 PM
      ... haven't a clue... although the engine came from a big wreckers yard in Ontario called Schram's Auto Recycling (... rhymes with Scam...) and may have been pulled from the donor car a long time ago and sat outside. It's one thing to be stored outside under a hood and quite another to be left open to the rain and snow. But I'm just speculating. But Dratts, you live in California... isn't there a song about how it never rains over there? And I bet the only salt you've ever seen is next to the pepper!

dratts ( MSG #130, 06-06-2010 12:51 PM
      That would be my guess too. Again thanks for all the info and pictures. Are you keeping track of the cost of your engine rebuild? I'm pretty much not in Ca. anymore. I still have an island by Antioch, but I spend most of my time in Coeur d' alene Idaho with my Murciealago replica. The N* 355 isn't getting as much of my attention until I finish the Murci. The Murci is registered and draws a ton of attention when I drive it, but needs a lot of work.

Bloozberry MSG #131, 06-08-2010 10:02 PM
      Mercy me... a Murci? Have you posted images of it here yet on PFF? What's it got for an engine? As for total engine costs I keep a detailed record of all my expenses to help the insurance appraiser come up with a replacement value for the car, should the need ever arise. The engine, engine parts, and machining to date (not including flywheel, and PCM tune) have cost me about $5150. Really not bad at all.

OK, so with the starter out of the way, I moved on to the valve timing components. It was a lot more intimidating and time consuming to read through the process than it was actually doing it. Once all the parts were cleaned up and inspected, I opted to keep all of the original timing components except the primary chain tensioner. If you've been following from the beginning, you'll remember why. So here now are the components that form the primary timing chain assembly from top left to bottom right: crank sprocket, intermediate sprocket set journal assembly, intermediate sprocket set, chain, tensioner, and guide.

The first step is bolting on the intermediate sprocket journal assembly. It’s a no-brainer. Interestingly though, it gets fed pressurized oil from a hole in the back-side, and directs the oil to the sprocket set via rifle-drilled holes in the journal surface. Three bolts hold it in place.

Next up is to install the crank sprocket, intermediate sprocket set and the chain all in one shot. Before you do that though, you have to align a pair of dots on the two sprocket sets so that the dot on the crank sprocket is pointing straight up and the dot on the intermediate sprockets is straight down. Again, it’s not rocket science or brain surgery. Both sprocket sets just slip right onto their respective shafts without any fuss. (The intermediate sprocket set is actually machined from a solid piece so you don't have to worry about aligning them to each other).

There’s a fair bit of slack in the chain at this point, so you want to make sure that the chain is tight on the side that gets the guide, and loose on the side that gets the tensioner. Here’s me installing the guide and torquing it to 18 lbft.

The last component to be installed is the tensioner. When you remove the tensioner on the teardown phase, it springs to its fully extended position. To reinstall it, you have to rotate a little spring loaded lever on the side of the tensioner, push the piston back into the block, and stick a peg in the hole in the little lever. The peg keeps the piston from shooting back out. Here’s a picture showing how much travel there is in these little suckers. (These are actually secondary timing chain tensioners, but the primary tensioner is similar, as you'll see in the next photos.)

So here’s the brand new primary tensioner being installed. Again, just two bolts tightened to 18 lbft.

And finally, once you make certain that the little dots on the two sprockets are perfectly aligned, you pull the peg and let the tensioner take up the slack in the chain. Too easy. The cam chains on the other hand are a little more work. That's next.

Bloozberry MSG #132, 06-10-2010 10:18 PM
      Here are the main components of the secondary timing chain system from top to bottom: replaceable upper chain guide shoe; upper chain guide; lower chain guide; chain; and tensioner.

The first step is to install the shoe on the metal upper chain guide and slip the guide through the top opening of the chain case (this is the guide that will have the tensioner pushing its backside).

On the front (or left, or even) cylinder bank, this guide is mounted above the chain and is secured in place with one pivot bolt that’s reachable through one of the holes that’s been bored and tapped in the front of the chain case like this:

The lower chain guide on this bank is made of plastic and it goes in through the top like the upper one, except it has two bolts that secure it in place.

Once that’s done, you slip the chain through the top of the case as well, feeding between the two guides, and hang it over the ends of the cams like so:

Even though the Northstar wasn’t used in any longitudinal applications at the time this ’97 was built, GM still called the different banks LEFT and RIGHT. So for the Fiero application, the left bank is the front bank, which are also the even numbered cylinders. You need to know this when you go to stick on the cam sprockets, which are next. The intake and exhaust sprockets on the left (front) bank are identical but they go on in different orientations. Here you can see that the locating pin on the camshaft slips into either of two slots depending on which cam it’s destined for (ie left intake cam (LI) or left exhaust cam (LE).

Before you can slip them on though, you’ve got to rotate the camshafts so the pin on the end of them is at 90* to the valve cover mounting surface. Because the cams are under a fair bit of tension from the valve springs, GM had the fore-thought to cast a hex onto the cams so you can turn them with a wrench… that was handy.

Next you slip the chain around the inner of the two primary sprockets down below, then slip the chain onto the exhaust cam sprocket in such a way that when the sprocket is installed on the exhaust cam, that there's no slack on the chain segment lying across the plastic lower guide. The chain should fit just right so if there’s any slack, double check that the dots on the primary sprocket set are perfectly aligned, and that the exhaust camshaft pin is at exactly 90* and turn either one as necessary.

Once that’s done, then slip the intake cam sprocket onto the chain so that when it’s installed on the intake cam, that there’s no slack on the chain segment between the intake and exhaust sprockets. To do this, you may need to reposition one or both cams a little using the wrench because if either cam pin isn’t perfectly at 90* you’ll find it impossible to install the chain without it sagging between the sprockets.

At this point, all the slack in the chain should be on the chain segment between the intake sprocket and the primary sprocket down below. That’s because the chain tensioner is what will eventually tighten up that segment… but not yet.

The next step is to install the rear/right/odd bank chain set. It’s similar but not exactly the same as the front/left/even bank

[This message has been edited by Bloozberry (edited 07-13-2010).]

Tony Kania MSG #133, 06-11-2010 12:51 AM
      As I said earlier, just amazing!

Originally posted by Bloozberry:

Mercy me... a Murci? Have you posted images of it here yet on PFF? What's it got for an engine? As for total engine costs I keep a detailed record of all my expenses to help the insurance appraiser come up with a replacement value for the car, should the need ever arise. The engine, engine parts, and machining to date (not including flywheel, and PCM tune) have cost me about $5150. Really not bad at all.


I have witnessed said Murci. I will let the owner explain her, but what a car! She definately has curb appeal. The lines are really proportionate, and not at all boxey or out of place. I have pics, but will post only if Dratts says it is cool. Oh, please let me post them?

And Dratts, I will be at FieroKing's tomorrow. Maybe it won't snow this time?

EDIT: As to not take up Blooze's space, I will post a thread in the General section. I have some very appealing pics of your car.

[This message has been edited by Tony Kania (edited 06-11-2010).]

dratts ( MSG #134, 06-11-2010 11:23 AM
      Hey Tony, Sure, post away. It's got a 350 tbi vortec in it for now. It's at midtown motors ruight now getting a new interior. I'd post more but I don't want to distract from bloozes fantastic story. I'm learning more than I'll ever need to know about N*s but it's always nice to know what's under your hood.

cptsnoopy ( MSG #135, 06-11-2010 06:32 PM
      Blooz makes it look so easy I am surprised we don't have a rash of N* rebuild/installs being posted...


Bloozberry MSG #136, 06-12-2010 09:37 PM
      Tony, thanks for posting those pics of Dratts car... that is one awesome looking ride. Dratts, that thing looks all Italian, but with that 350 TBI in it I'll bet it sounds all Detroit! Nothing one of your Northstar engines couldn't solve though. Charlie and I will walk you through it.

Anyways, I must admit when I went to install the rear bank timing chain parts, I started to doubt myself. In my head, I imagined the installation would be the mirror image of the front bank’s set-up, but came across my first hurdle when I went to install the upper guide. It wouldn’t fit no matter how I turned, squeezed, or willed it into place.

But then it struck me… if the chain guides were installed as the mirror image of the front bank (ie with both tensioned guides at the top) then the front bank would work properly but the rear would have the crank’s power being applied to the slackened segment of the chain. That wouldn't work well... remember the chain is only pulled, not pushed by the crank. So for the whole thing to work properly, the rear bank’s hardware would have to be installed as though it were removed from the front bank, lock, stock and barrel, and simply rotated around the crank's axis like the hands of a clock. (I have no idea whether that makes sense to anyone except me, but at least all the pieces fit!)

So once the upper and lower guides were in, the next step was installing the cam sprockets, as before. Except that one of the rear (right) bank sprockets has a pin on it that none of the others do. It pays to notice the little things because no mention of this is made in the Service Manual. The pin is part of the camshaft position sensor circuit. The sensor gets installed on the side of the head where the exhaust cam is (at least that's where the hole is!), so it became pretty obvious which sprocket had to go where.

The rest of the installation is similar to the front bank. Once the chain is sorted out and the slack is on the proper side of each sprocket, the tensioners for both sides are installed and the little release pins are pulled. Notice the big “LB” for Left Bank (or lost bonehead).

To keep the road grime out, the access holes for the chain guide bolts are then plugged with threaded plastic bungs. They have an o-ring on the backside that seals up tight against the cylinder head.

So when it’s all said and done, this is what it’s supposed to look like. Each chain has a stationary guide (on the powered leg of the chain) and a pivoting guide with a tensioner holding it tight against the return-leg of the chain. It looks busy, but it's really quite simple. Personally, I had expected it to be somewhat confusing to set up the timing chains after reading about the process and having seen other people’s threads, but it turned out to be straight-forward.

stickpony MSG #137, 06-12-2010 11:23 PM
Originally posted by 17Car:

Looking good, nice to see some progress on the project.
You have more guts (and money) than I do to rebuild a Northstar. Seeing how complex it is makes me wonder if I should have went with a 3800, I'll feel different when my swap is done.
Did you consider a set of CHRFabs cams? I believe that they are only about $500 for a set. Beats $700 a piece and it's an upgrade, but I will be interested in how your refurbished cams hold up.
Edit: Hooray! I own my first page ever!

agreed... its much cheaper to get a crate engine off ebay these days than rebuild an N*... i understand his angle though, as building it yourself is peace of mind, since you KNOW it will be done right, as long as one knows what one is doing

Bloozberry MSG #138, 06-17-2010 09:07 PM
      I’m back after a short break working on a ’67 GTO convertible… almost done. So after the chains were in place, I installed the camshaft position sensor in the hole next to the rear head exhaust cam sprocket. It senses the passing of the little metal pin on that sprocket for timing purposes. Like all of the the M6 bolts, the sensor hold down bolt goes on with 89 in-lb of torque. The difference with this little guy however is that it goes right through to the innards of the chain case so it needs a little dab of RTV on the threads to keep it from leaking.

The last thing before the chain case can be buttoned up is the oil pump. I ordered a new one on spec as cheap insurance even though the old one looked OK. They're a pretty robust pump. I was surprised that the new pump came with a drive sleeve, because I can’t see why this part would need to be replaced. I used the new one anyways… it just slips onto the crankshaft.

To get the new pump on, you simply line up the flats on the drive sleeve with the mating flats on the pump rotor. It too just slips on. Surprisingly, there are no O-rings or other seals between the inlet and outlet ports of the pump, and the mating surfaces of the block.

To hold the pump in place there are three screws that must be tightened in a particular sequence and then turned an extra 35*, and you’re done.

Before the chain case cover can go on, there’s a couple things you have to do. The first is to replace the front crank seal in the cover. Getting the old one out was a cinch… I just used my arbor press and pressed it from the front side, out through the back side. If you haven’t got a press, then a few carefully placed hammer blows with a punch would do the trick.

Getting the new one in wasn’t as easy. No matter what I did, the seal always seemed to get started cockeyed. I worked at it for fifteen minutes trying to get it to start all the way around to no avail. It’s as if the seal was a smidgen too large for the hole. So I decided to use my Dremel with a small sanding drum and chamfered the edges of the hole in the cover. Once that was done, the seal pressed straight in.

The second thing to do before the cover goes on is to use a straight razor and slice off any engine sealant that oozed out or is protruding from the case-half split line at the front of the engine. Then you’ve got to place another dab of fresh sealant in the same two spots.

The third thing is to put a new cover gasket in place. It’s got two holes that line up with corresponding alignment pins so there’s no need to try to hold everything in place. The new seal came with the master engine rebuild kit. It’s made of a hard composite material that’s got an orange neoprene-like seal impregnated in it on both sides.

Finally the cover gets put in place… forever sealing up the beautiful mechanical artwork underneath. My cover was a little pitted so rather than filling the pits with body filler, I sandblasted it, primed it, and sprayed it with a Tremclad silver paint that gives a “hammered” look to it once dry. I didn’t want to waste too much time on a part that will not be seen.

The cover gets torqued on (you guessed it) to 89 in-lbs starting at the bolt I’m torquing in this picture, and going around successively to the next bolt in a clockwise direction until you’ve done all fifteen. Then, if you’re smart, you go over them one more time. The service manual states that a thread locking compound must be used on these so I used the high temp red Locktite left over from my head bolt inserts.

aaronkoch ( MSG #139, 06-18-2010 12:17 AM
      Man, in that last pic you really get an idea for how MASSIVE those engines are.. Just insanely big. (physical dimensions wise)

Nashco ( MSG #140, 06-18-2010 08:32 AM
Originally posted by Bloozberry:
I didn’t want to waste too much time on a part that will not be seen.

Given the amount of time you put into that starter, that's kind of funny that you'd say this about the timing cover. Maybe the starter taught you a lesson?

Thanks for the documentation, I enjoy reading/seeing it!


Bloozberry MSG #141, 06-18-2010 12:12 PM
      Hey! You're not supposed to notice little deviations like that... just read the story and go with the flow. (Actually, I rebuilt the starter for peace of mind... I didn't fill the scratches on it with body filler either!)

ALJR ( MSG #142, 06-30-2010 11:37 AM
      On vacation?

LitebulbwithaFiero ( MSG #143, 06-30-2010 02:37 PM
      The Northstar looks familiar to the engine I tore down and put back together in school. Mine was a V6 with the one piece main caps and had dual overhead cams. But I think it was a Ford. I don't know about the N*, but the V6 had it where only one of the intake valves per cylinder where getting air for the lower RPMS. It had a set of butterflies in the lower intake manifold that would open to let air get to the second set of intake valves, which I think was controlled by the computer with an electronic solenoid.

Bloozberry MSG #144, 06-30-2010 05:54 PM
      I finally moved that '67 GTO I've been working on out of the shop and will get back to the 'Blooze-Zone' after the long weekend. More to come soon. Thanks for the interest!

Litebulb... you were probably working on a Taurus SHO engine... made by Yamaha. That was a nice powerplant while it lasted.

Bloozberry MSG #145, 07-12-2010 09:01 PM
      So much for intermission… it’s back to work! I’ve been toiling over what to do with my valve covers. On the one hand I’d like to shave off all the little bosses on the “ugly” cover, pretty it up with some stick-on grooved caps (like some I’ve seen here on PFF but forget whodunit), and paint them lipstick red, or fly-yellow since the car will eventually be yellow. Orrrrrrrr… spring for a pair of those obscenely expensive cast, ball milled and polished CHRFab beauties. Maybe some of you could give me ideas on what you’ve done?

While I sit on the fence with regards to the valve covers, I’ve pretty much made up my mind that I’m not going to use the Caddy beauty cover. I may design something later to cover up the intake plenum, but for now I’ve decided to make the plenum as appealing as possible. To that end, I made a few inquiries last week here on PFF about replacing the really busy looking plastic fuel rail with the very sano-looking stainless rail. The stainless rails were installed as a result of a recall in the USA for ’95 to ’97 cars but not in Canada… so it looks like I’ll have to buy one. Here’s the stock plenum in all its complexity.

I started the dismantling process by removing the connectors on the injectors. If you’ve never done it before, they’re the same as on the Fiero V6’s… you need to take a small screwdriver to a little spring clip that wraps halfway around injector.

Then with a little twist, stretch the end of the clip off the plastic tooth that captures it like this.

Its easier to remove the fuel rail itself once you’ve removed the electrical connectors since the wires are partly in the way. Here I’m pressing the plastic release lever on the fuel injector rail to be able to remove it from the plenum.

I found that the injector o-rings were stuck in the plenum so a gentle pry with a screwdriver broke the tight seal and got things moving.

Because the plastic fuel rail is quite rigid, I had to release all four injectors on each side, working them up a little at a time before being able to lift the whole rail up and off the plenum.

So here’s the old rail. I’ll need to remove and have the injectors cleaned to get them ready for the stainless rail. To further clean up the top of the engine, I’m working out an idea to hide the injector harness under the plenum and have the connectors come up through an access hole I’ll drill for each pair through the plenum mounting area.

To finish stripping the plenum of hardware so I could clean it properly and assess just how many brackets and bosses I could shave off, I removed the throttle body adapter:

…and this spring-loaded trap door at the rear of the plenum. I would imagine this is a pressure valve in the event of a backfire. I could be wrong. It’s easily removed with a simple twist and a pull.

Here’s what the inside of the plenum looks like. All the runners open into the common central part of the plenum at the bottom. They curl around a total of about 270* of which the first 180* are circular, and the last 90* gradually straighten out into a flat run into the intake port. You can see from mine that there’s a fair bit of oil and carbon deposits in there. I’ll explore different ways to clean out the runners without trying to melt the PVC plastic that they’re made of! Hot soapy water in the pressure washer comes instantly to mind, but I’m open to suggestions.

katatak MSG #146, 07-12-2010 11:17 PM
      Hey Blooz,

Just a tip for you. If you push on the center of the "clip" - push it toward the injector, you can pull the injector plug off - no need to pop one end of the clip out of the connector.


Will ( MSG #147, 07-13-2010 12:00 AM
      Ditto on the injector connectors.

You'll also have to take the FPR apart and reinstall it in the stainless rail. It has little bitty parts, so be careful.

[This message has been edited by Will (edited 07-13-2010).]

IXSLR8 ( MSG #148, 07-13-2010 01:43 AM
      I took my plastic intake plenum to an engine rebuilder for cleaning and they couldn't clean the carbon out. They tried the hot tank, everything. The shine came off but not the carbon particles. I've also read that they are supposed to be replaced instead of cleaned because of the inaccessible areas that can't be cleaned that hold carbon deposits.

Bloozberry MSG #149, 07-13-2010 08:01 AM
      Katatak: "Whale oil beef hooked!" (say it with a Newfoundland accent... "Well I'll be f___"). All these years I've been painstakingly unclipping those rotten injectors with a screwdriver. Thanks for the tip!

Will: Really? The pictures of the stainless fuel rails I've seen all seemed to have the FPR installed on them. Here's one for an Aurora on ebay that's supposedly new. Is that just the mounting boss on the rail and not the FPR itself?

IXSLR8: I had read that the plenum's were to be replaced rather than cleaned in the service manual too. But I have a hard time believing anyone would do that. I haven't priced them out but I don't imagine they're cheap! Other than to make profit, for the life of me I can't understand GM philosophy (scratches head). If even the hot tank can't remove the carbon deposits, then I don't think we have to worry about them accidentally falling off into the engine, and I can't imagine there ever being enough deposits to choke off a runner. All I want to do is to get rid of the excess oil just pooled there in the bottom.

aaronkoch ( MSG #150, 07-13-2010 02:13 PM

Can't you just pinch the wire retainer in with your thumb? On all of mine, I just push in on the wire retainer, and it spreads out at the back, allowing you to just pinch & pull, and the connector slides right off.. Or maybe these are different than the 3800's... Sure look the same though.

Edit: Looks like somebody beat me to it.. oh well.

17Car MSG #151, 07-13-2010 05:48 PM
      This thread is due for the Construction Zone!
I know you don't like the stock beauty cover, but I believe that the 93-94 engines came with a magnesium one that can be polished. There was a member on here who had one, looked realy good.
I have yet to find one though.

cptsnoopy ( MSG #152, 07-13-2010 11:56 PM
Originally posted by 17Car:

This thread is due for the Construction Zone!

I second the motion!


IXSLR8 ( MSG #153, 07-14-2010 01:06 AM
      LOL! Yes. I didn't replace my intake either. Just used it after I couldn't get it all cleaned up as stated. The pools of oil is a natural N* attribute. I've had it off after it was cleaned and spotted the oil in there again...even with the heads all redone. If you delete your EGR system, its not supposed to carbon up any further. I deleted mine.

The fuel pressure regulator is a plug and play type set-up. You just take the clip out of the rail housing and pull the regulator. you can clean it up carefully as Will mentioned. Look for "O" rings and small fuel screen. The nice thing about the regulator is that its adjustable. You can counterclockwise and clockwise the screw and get more fuel pressure. Sort of an alternative for larger injectors for the mild cams. I'm getting ready to set mine at 65lbs.

Will ( MSG #154, 07-15-2010 05:37 AM
Originally posted by Bloozberry:
Will: Really? The pictures of the stainless fuel rails I've seen all seemed to have the FPR installed on them. Here's one for an Aurora on ebay that's supposedly new. Is that just the mounting boss on the rail and not the FPR itself?

Maybe it's different by application, but I ordered the part number for the correct connection locations (via Russ' thread on the matter) and the FPR pot was empty. Moving it over wasn't hard, but as I said there are small parts.

cptsnoopy ( MSG #155, 07-15-2010 12:00 PM
      When I got my stainless fuel rail from the local GM dealership it was without the FPR. The good news (for me anyways) is that the new FPR was inexpensive. I think it was around $20. I could have used an older one but I found some info around that suggests that these FPR's have a tendency to fail and let fuel into the vacuum line. I don't know what a new one will cost where you are so cost may be a factor.


IMSA GT ( MSG #156, 07-15-2010 07:07 PM
      Time for the Construction Zone

Bloozberry MSG #157, 07-16-2010 09:33 PM
      Hey! A new home in the Construction Zone! I like the company in here!

Anyways, before giving the plenum a bath, I figured I’d get some of the messy work done and over with, so I decided to give this porcupine a shave & haircut. Here’s what I’m talking about:

Notice all the fuel rail mounting brackets molded into the sides of the plenum? Here’s what they look like close up. They’re no longer needed when the stainless rail gets installed.

At first it seemed like it would be an easy, quick and dirty task. I started out using a hand hacksaw to be able to control the cutting more easily, but found that the blade wandered a lot. The plenum runners weave in and out a bit too so you can't get a straight line of sight with the saw. I had to cut with the blade bent in a U shape which makes controlling it much more difficult.

Here’s the first “ear” lopped off. Notice how the plastic rail mount gets thicker towards the bottom of the runner as the angle between the runner and the mounting boss gets shallower. This is where the greatest work ended up taking place.

At first I thought I’d be able to use a grinding stone on my die grinder to make quick work out of smoothing off the left-over plastic, but from this photo you can see what happened within the first couple seconds of trying that idea. The stone just heated up the plastic and made it stick to the stone like Bubblicious on a summer sidewalk.

Next I tried a hand file but found that to be waaaaayyyy tooooo sloooow. And you can forget about sandpaper too… the PVC plastic just gums it up after a dozen or so passes. My breakthrough came when I tried a set of high speed multi-fluted dies. I tried one out on the spark plug wire clips molded into the top of the plenum and it worked like a charm. It chops instead of grinds so it doesn’t heat up the plastic and it was very easily controlled at high speed.

Here’s what the first boss looked like once it was lopped off and roughly smoothed. One of the things I found as I was shaping the lowest part of each fuel rail boss is that the mold line for the plenum must run under the bosses. If you look carefully, you’ll notice that the runner carries on in a nice smooth line under the first web (from top) that crosses the runner. But as it gets to the solid bottom part of the boss, the outside runner wall takes a bit of a step. GM obviously wasn’t expecting anyone to shave the bosses off so whether the mold halves lined up perfectly under them or not probably wasn’t a big concern. Oh well… nothing a little body filler can’t cure.

The other tough part was shaving one of the two vertical webs of each boss because it starts on the base of one runner, crosses over the valley between the adjacent runner and carries on part-way up that adjacent runner at a very shallow angle. If you look at the forth image in this post you’ll see what I mean. It’s the vertical web on the left side of the boss pictured that's a headache. Anyways, getting the tool to follow that eccentric path without slipping and nicking either runner is pretty difficult. More Bondo!

Here’s a couple shots of the intake plenum with all the unnecessary brackets shaved off, and with only two or three little nicks. Bring on the aftershave and the Kleenex bits! Next stop… the hot tub.

katatak MSG #158, 07-17-2010 12:07 PM
Originally posted by Bloozberry:

Katatak: "Whale oil beef hooked!" (say it with a Newfoundland accent... "Well I'll be f___"). All these years I've been painstakingly unclipping those rotten injectors with a screwdriver. Thanks for the tip!

Will: Really? The pictures of the stainless fuel rails I've seen all seemed to have the FPR installed on them. Here's one for an Aurora on ebay that's supposedly new. Is that just the mounting boss on the rail and not the FPR itself?

IXSLR8: I had read that the plenum's were to be replaced rather than cleaned in the service manual too. But I have a hard time believing anyone would do that. I haven't priced them out but I don't imagine they're cheap! Other than to make profit, for the life of me I can't understand GM philosophy (scratches head). If even the hot tank can't remove the carbon deposits, then I don't think we have to worry about them accidentally falling off into the engine, and I can't imagine there ever being enough deposits to choke off a runner. All I want to do is to get rid of the excess oil just pooled there in the bottom.

I feel your pain - took me 4 years to learn that - by mistake I might add.

Looking great Blooz - Welcome to the construction zone!


[This message has been edited by katatak (edited 07-17-2010).]

fieroguru MSG #159, 07-17-2010 12:20 PM
      Great job on decluttering the top side of the intake... it will look sharp and really set your swap apart.

bamman ( MSG #160, 07-22-2010 12:38 AM
      Thanks for all the up-dates. I can't see my self changing the 4.9, unless I win the lotto. But I think it is great that you are sharing for all those that will go the Northstar route.

NiNeFiVeFoUrOh ( MSG #161, 07-22-2010 04:18 PM
      Nice build up.

I am currently doing basically the exact same thing with a few exceptions.

I have a couple of suggestions for you that you might want to try.

I sent my TB and intake to a company called VmaxMotorsports, they specialize in LS1 stuff mainly, but they port the plastic style intakes for LS1's. When I noticed this, I contacted Pete at Vmax and asked him if he would do a Northstar intake (since they're very similar to the LS1 type). He said he had done a few and would be glad to do mine. Along with that, I sent in my TB and he opened it up for me.

He told me that the LS1s typically see 15-20whp from these mods combined on a stock motor. I know our gains may not be as generous, but as a Northstar modder, it's great to get anything, even if it costs a little bit more for us. From the TB alone after flowbenching it, Pete told me that gained 17.2 cfm over stock. I don't know how much the intake gained, because mine was soaked in carbon and oil build up like yours, but I'm sure it'll be a decent amount. (BTW, I haven't tried cleaning it yet, but I don't think "soap and water and a pressure washer" will be adequate, that stuff is thick and hard to clean! I'm going to try using this thing a friend of mine has called "VAT", it's some really strong chemicals used to clean parts with in a 5 gallon sized jug... it shouldn't hurt the plastic, but hopefully will clean up the majority of the buildup inside of the intake).

It cost me $430ish? plus shipping to get these mods done. The application is a 4.6 being swapped into a 95 Aurora. Among other things going in the motor (very similar build to yours) will be CHRFAB 272 cams, Wiseco .020 over pistons, Eagle rods, and worked heads. Planning on tuning with Westers.

I decided to go with the lighter lower end parts (the Wiseco Pistons and Eagle rods) because according to my math, there is a 2-3 pound weight difference, maybe this will make a noticeable difference in the performance of the motor (it better!).

I'd like to get this intake/TB setup on a stock 4.0 Aurora and dyno it, to see what the actual gains are.
I really dig that gasket job on the Oil manifold on your motor... where did you come across that technique? I've been racking my brains to try and figure out what to do when I get to that point. If you have a write up on it or anything specific I'd love to see it.

Bloozberry MSG #162, 07-23-2010 09:55 PM
      Thanks for the comments katatak, fieroguru, and bamman. Bamman swung by my place about two weeks ago with his 4.9 powered black coupe... sure sounded nice! I'm not sure I would change that engine even if I won the lotto... your car's a real sleeper.

As for NiNeFiVeFoUrOh (wouldn't it be easier just to write 9540?), that's one nice lookin' TB. US $430.00 works out to about 600 clams up here in Canada after shipping, duty, taxes, and exchange... a bit rich for my already swelled budget! You'll have to post your results once you get your car running. It will be interesting to see how that porting affected overall performance.

You asked about the oil manifold sealant procedure I used. I don't have any other write up other than what's in this thread. But there's no black magic involved... I just couldn't see myself spending the money on a new oil manifold plate when it isn't a wear item. GM probably recommends replacing it because it isn't worth the time and effort for a dealership technician paid at $65/hour to dig out the old sealant. It's a time consuming process that took me a couple hours. Then, I figured the oil manifold plate sees the same harsh conditions as the insides of the case halves, so the case-half sealant should be good enough for the oil manifold too. The part number for the sealant in the US is different than it is here in Canada. For you, the sealant is GM part number 12378521. Just be sure to completely fill and slightly overfill the oil manifold seal grooves with a continuous bead of it, ensuring the sealant is higher than the rail surface by about 3 mm (0.118 in). Be sure to stick it together before 20 mins are up too, or it won't seal properly.

As for a quick update: I finally managed to clean out the insides of the plenum by first dropping it off at my favorite machine shop to get it hot-tanked. They assured me that the solution they used would not melt my plenum, but only after they double-checked with the manufacturer of the chemicals! Once the oil residue was removed, I lightly bead-blasted the interior of the runners and the insides of the main central part of the plenum with very fine glass beads. It worked like magic, removing every bit of carbon as far as the eye could see. I used a lower air pressure around 80 psi and the beads just bounced off the plastic manifold without so much as even discoloring it. Lastly, I blew it out really good with shop air. Next, I block sanded the entire intake plenum then ran lots of water through it to ensure it was clean. Today, I dropped it off at the paint shop for final smoothing and color. I'll update with pictures as they become available from the shop. Any guesses what color I picked?

motoracer838 ( MSG #163, 07-24-2010 01:19 PM
Originally posted by Bloozberry:

Hey! A new home in the Construction Zone! I like the company in here!

Anyways, before giving the plenum a bath, I figured I’d get some of the messy work done and over with, so I decided to give this porcupine a shave & haircut. Here’s what I’m talking about:

As always, nice work. I hadn't even thought of cleaning up the manifold, and running w/out the cover. After seeing yours, I might have to rethink what I'm doing. I moved my coils to the bulkhead and trimmed the cover to revers it.

Cheers Beers n Gearz. Joe

[This message has been edited by motoracer838 (edited 07-24-2010).]

Bloozberry MSG #164, 07-24-2010 02:10 PM
      Thanks Joe! Actually, I thought I had an original idea shaving the plenum, but it turns out after reviewing some earlier threads that WAWAZAT came up with the idea before me in this thread on page 2 near the bottom: Goes to show that there aren't too many truely original ideas out there.

17Car MSG #165, 07-24-2010 09:30 PM
      motoracer838, I did the exact same thing, only I painted my cover to match the valve covers. Which side did you move your coil pack to? I put mine where the air filter canister used to be.

motoracer838 ( MSG #166, 07-24-2010 10:20 PM
Originally posted by 17Car:

motoracer838, I did the exact same thing, only I painted my cover to match the valve covers. Which side did you move your coil pack to? I put mine where the air filter canister used to be.

I put mine on the bulkhead between the engine compartment and trunk.


Bloozberry MSG #167, 08-01-2010 12:30 PM
      Before getting ahead of myself only to find that I needed to backtrack and redo things all over again, I headed out to my favorite paint shop to get their opinion on the best way to fill the nicks and imperfections in the plenum. The good news was that the plenum isn’t made of Bakelite… apparently this is a notoriously difficult material to get paint to adhere to. I believe the plenum’s made of ABS plastic… the same stuff your in-home drain pipes are made of.

The paint shop recommended one of two courses of action: 1. do it the cheap way... epoxy prime it first then apply a polyester filler to the primer to ensure good adhesion, or 2. do it the proper (read:expensive) way with a special flexible epoxy filler directly on the plastic. I already knew that applying a polyester filler directly to the runners wasn't going to work since I tried it on one only to find I couldn’t feather it effectively. So I opted for choice number 2. The body shop owner, who knows what this is for, also convinced me that if I tried to do this at home it would take five or six hours to smooth out whereas his much more experienced body guy could do it in two. So with instructions to lightly sandblast the whole shemozzle to rough it up a bit and bring it back to them for prep and paint, off I went.

As mentioned earlier, I used about 80 psi pressure and crushed glass to bead-blast it, and when I saw how well that worked, I opted to turn the blaster onto the insides as well. It worked like magic to remove the leftover carbon deposits in the runners and central part of the plenum. The important thing to remember is to get the plenum hot-tanked first to remove any residual oil. That way when you sandblast the insides it’s bone-dry and the sand won’t stick to it. As a final step, I ran hot water through it to rinse out any glass dust, blew it out with shop air, and let it complete drying in the sun.

I dropped it off at the paint shop with instructions of my own for them to take a few pictures of it while undergoing the transformation. Here it is with the body filler applied. It’s the same stuff they use to fill the flexible bumper covers on cars. Apparently there are around three different levels of flexibility of the stuff… they used the stiffest.

Luckily they quoted me a cost of $300 to do this work and stuck with it. It sounds like a lot of money (and it is) but, I wanted it flawless since it’s the main point of focus when you open the decklid. The body man who I know to be very experienced and also a perfectionist, said it took him 5 hours, not two, to properly shape the filler to the contours of the runners. They had originally thought it would take about two hours. Here it is with the sanding underway.

With it fully shaped, the next step was the application of an epoxy primer. Here you can really see how much cleaner the lines of the plenum are.

I had searched for just the right color when I saw a late model Mazda in “True Red”. The color code is A4A. Here’s the plenum with the flat looking basecoat sprayed on. Notice the air drier in the background… the body shop is a fully modernized water-borne paint facility.

And finally, with the clear coat. This thing looks like a whole bunch of Rolling Stones lips all puckered up and ready for a big wet kiss… something the painter thought I would give him when he saw how happy I was at the way it turned out.

katatak MSG #168, 08-01-2010 01:05 PM
      That manifold is beautiful Blooz - very nice!

cptsnoopy ( MSG #169, 08-01-2010 06:12 PM
      Very nice WOW factor!


motoracer838 ( MSG #170, 08-01-2010 06:17 PM
      I don't think you'll get that kind of deal from your body shop again, that looks fantastic.


Bloozberry MSG #171, 08-04-2010 07:47 PM
      Thanks Pat, Charlie, and Joe. I figure whatever he lost on the plenum, he knows he'll be more than able to make up for it when it comes time to paint the whole car! There's no such thing as a free lunch.

Anyways, with the plenum back in my hands, I did one final clean out of the innards to make absolutely sure there was no body filler dust or wads of masking tape hiding in there just waiting to get sucked into a cylinder on first crank. Here’s how much nicer the insides looked with all that carbon and those oil puddles now a thing of the past. The openings of each intake runner are at the bottom.

Before I could install the plenum on the block, I had to finish up the wiring to the starter and the knock sensor since they're in the valley underneath the plenum. I cleaned up the eyelets and replaced the corrugated plastic wire loom since it was fairly brittle from 15 years of soaking up the heat in that little cave.

New intake runner seals were included in the FelPro Cylinder Head Seal Kit. They’re just an ABS-type plastic with neoprene-like injected seals around the base of each runner.

They clip onto the plenum at either end like so. Good thing I verified what each of the little moldings were on the plenum before I shaved it! Actually it probably wouldn’t have made much difference since the mounting bolts locate them anyway.

A quick inspection of the plenum mounting bolts revealed that the long ones had old thread sealant on them. This got me curious so I inspected the ten holes in the heads and found that none of them appeared to breach into the water jacket, but clearly GM didn’t want to take chances. In this picture you can see that the four bolt holes closest to the transmission could easily need thread sealant to prevent leaks. I added some RTV to the bolt threads just to be sure I wouldn’t have problems later.

Ahhhh… finally time to install the lips… uhhh… I mean plenum. It just lowers straight down onto the intake port “shelf” of the two heads.

The plenum is held in place with six shorter bolts, and four longer studs that sandwich plastic stand-offs to the intake. The stand-offs are there to mount the beauty cover, but in my case, they'll only be needed to mount the new stainless fuel rail at the correct height. All the bolts get torqued to 89 in-lbs starting with the bolts closest to the middle and progressively working your way outboard.

Here’s me installing the freshly cleaned backfire protection valve (at least that’s what I call it ). If you remove your vavle, lubricate the large O-ring before you reinstall it. The valve just gets stuck in the hole at about a 45 degree angle to engage a set of tabs into mating slots, and then rotated so that the valve is at the bottom and locked in place.

Here it is snug in it’s hole, hopefully never to be needed.

fieroman22 ( MSG #172, 08-04-2010 09:55 PM
      def WOW factor, must agree. been watching too much agt, hulu..... no cable for now

doublec4 ( MSG #173, 08-04-2010 10:05 PM
      Looks damn pretty!

17Car MSG #174, 08-08-2010 04:54 PM
      One word. Beautiful.

AJxtcman ( MSG #175, 08-10-2010 09:16 PM
      That intake looks great. Nice job

I did mine up a couple of years ago

I did the sight sheild also. I don't think I will ever use it

katatak MSG #176, 08-25-2010 09:27 PM
      Blooz......Any updates? Everything OK?


cptsnoopy ( MSG #177, 08-25-2010 09:39 PM
      Lol! I was thinking the same thing. Must be that school just started and the family is getting priority...


Bloozberry MSG #178, 08-26-2010 07:16 PM
      I knew the pokes were coming. I've been off the build thread radar lately since I've been doing transmission and suspension stuff for a change in pace, but I don't want to post stuff out of order in the thread. I did order a pair of CHRFab's polished double bump cam covers... still waiting on them though. It was tough shelling out $650 clams but I think I would have regretted spending any money or time trying make the stock covers look good.

The rules for the construction zone say you're not supposed to post fluff, but here goes anyways. I'm also doing a few renos to the inside of my car storage building. I store 85 classic & prestige cars for local people over the winter months... kinda like a grown-up candy store here in the winter. I drool a lot! 16,000 sq ft of cool cars.

I also volunteer at the local military aviation museum (I know... blah blah blah...) but thought some of you might like to see what I'm rebuilding over there too. It's one of the first UAVs (unmanned aerial vehicles) that Canada bought for use in Afghanistan back in 2000 or so. They weren't that great, but they look neat! Now if I could only find a way to hook up that infrared camera turret to the 355 without drawing too much attention...

Intermission is over... stay tuned fo more F355 stuff soon.

Tony Kania MSG #179, 08-26-2010 07:54 PM
      Aviation! Not sure if any of us would be interested?! Oh yeah! I would bookmark a thread such as that from you.

Your engine looks amazing. I want to lick it.

Bloozberry MSG #180, 08-26-2010 08:10 PM
      LOL. I'm tempted, but I'm afraid my wife might walk in and not understand!

Bloozberry MSG #181, 09-06-2010 09:43 PM
      I finally managed to find some time to work on the Blooze-mobile over the past couple days. My objective was to get the throttle body taken apart, cleaned, polished, and rebuilt. I consider it a success story, but I’m getting ahead of myself. So for starters, Here’s a picture of what the TB/MAF looked like when I removed it from the intake manifold several months ago. Pretty rough looking, but I saw it as an easy challenge compared to what I had to do to the engine block to get it shiney.

And here’s what lurked behind the throttle plate… there was enough carbon built-up to choke off an industrial incinerator in that thing. Clearly oil was getting into the combustion chambers and leaving a mess in the intake via the PCV and IAC port.

This is the other half of the TB which I call the TB adaptor since it bolts between the TB and the plenum. It was pretty crudded up with carbon too. Little did these Pigpens know that no matter how baked on their carbon or how corroded their exteriors were, they’d stand little chance of resisting the cleaning they were about to get.

After stripping them down of all the sensitive doo-dads like IAC, TPS, throttle plate, and various seals, they were ready for the glass-beading booth. Here’s the TB ready for some deep cleaning.

Once they were bead-blasted, I spent about 6 hours sanding them smooth again (at least as smooth as I had the patience for!) and polishing them with various buffers. There’s lots of nooks and crannies on the TB so it’s impossible to get them all, even with a Dremel. But before I unveil the masterpiece, I first wrapped it up in masking tape and hit all the exposed steel with some primer and then a coat of semi-gloss black Tremclad.

And now, the moment of truth… drum roll puh-leeeease… and draw the curtain! Ta-dah!

OK maybe a little too much drama, but at least it’s a lot better than it looked. With the dirty work done, the rebuilding phase could start. If you ever take one of these TB’s apart and get stuck not remembering which way the throttle plate goes back in, it’s easy. Just make sure the numbers stamped into it are facing upright and toward the MAF.

Once in place, the throttle plate gets secured by two tiny screws that are Locktited into place… they’re the last thing you want to have vibrate loose because they’ll only head in one direction if they ever come out!

katatak MSG #182, 09-07-2010 11:24 PM
      I love clean and shiny parts!

Bloozberry MSG #183, 09-08-2010 08:43 PM
      You and me too there Katatak!

Anyways, here’s the polished adapter:

A new gasket came with the master rebuild kit so I used it… no sealant required just apply it dry.

Then I installed the two halves together and torqued them as per specs. Here’s where I got ahead of myself (again) and caused some unnecessary work. Before you attach the two halves together, you’re supposed to attach the throttle body adapter to the intake plenum and then the throttle body to the adapter. The reason is quite simple: the throttle body covers up the screws that are used to attach the adapter to the plenum. I forgot about this little detail so I kept building up both halves of the TB as shown in the next few pictures. Just don’t follow this sequence if you’re doing this yourself. (Come to think of it, this’ll teach anybody who just looks at the pictures a little lesson!).

Next was the throttle position sensor (TPS). You can’t go wrong with this one… the throttle shaft is D shaped so the sensor will only go on in one orientation. It’s held on with two little screws.

Then the idle air control (IAC) valve was installed. There’s no special instructions for the Northstar IAC unlike the Fiero one where you have to retract the plunger etc. Just put it in the hole and tighten the two little screws.

So here’s where I had to undo the part about installing the two halves together. In order to be able to install the TB adapter to the plenum, it has to be done before the TB is mounted onto it. Here you’ll see the new O-ring that also came with the master rebuild kit. It gets installed in the plastic plenum opening.

And finally the TB gets screwed onto the adapter (again). I used Locktite on all the screws to keep them from ever backing out on their own. And causing air leaks.

Here’s what the thing looks like once it’s installed.

Next up… I got a surprise in the mail yesterday… but all I’ll say for now is that they’re nice and shiney!

Jefrysuko MSG #184, 09-09-2010 12:46 AM
Originally posted by Bloozberry:

Show us the after picture.

After that extra gasket material started bothering you because some wise guy on a message forum pointed it out and you decided to trim it off that is.

cptsnoopy ( MSG #185, 09-09-2010 03:00 AM
Originally posted by Bloozberry:Next up… I got a surprise in the mail yesterday… but all I’ll say for now is that they’re nice and shiney!

Hmmm, I wonder what that might be...? Hint, Curly recently had some pictures posted of these and yes, they are very shiny!
Of course you were nice enough to let the cat out of the bag a while ago...
Originally posted by Bloozberry:I did order a pair of CHRFab's polished double bump cam covers... still waiting on them though. It was tough shelling out $650 clams but I think I would have regretted spending any money or time trying make the stock covers look good.

Very nice job cleaning up the TB! (I spent a lot of dough just to avoid having to do that... )


Bloozberry MSG #186, 09-09-2010 07:53 AM
Originally posted by cptsnoopy:

Of course you were nice enough to let the cat out of the bag a while ago...


Bloozberry MSG #187, 09-10-2010 10:15 PM
      In case anyone reading this has had their heads stuck in the sand, the '93-'97 Northstar (and perhaps later years too), came with only one nice looking valve cover... the one that's seen front and foremost when you open the hood of a Caddy. This is what the pretty one looks like once it's sandblasted and ready for paint:

The problem with installing a Northstar in a Fiero engine bay is that the pretty valve cover is up against the back of the seats, exposing the ugly sister to show all her warts in plain view when the decklid is open.

I seriously considered spending upwards of a hundred hours shaving warts, sanding the pebble finish, and polishing these two fraternal twins into something befitting of a Ferrari's engine bay, but I just couldn't picture any amount of plastic surgery that would cut the biscuit. So, I broke down and phoned CHRFab three weeks ago. A couple days ago I got a parcel-delivery notice in the mailbox. I like parcels (even if this one came with an additional invoice that I owed $107 in federal and provincial taxes before the post office would hand it over). I was surprised at how heavy the box was... secretly I was hoping that they accidentally sent me two pairs of valve covers, but that was not to be. I was happy when I opened the box nonetheless.

These are things of beauty... of course they should be for the price! They're fairly substantial castings too. I know others have posted pictures of them before, but here's a few more for the record. What you don't see because of the glare, is my smiley face reflected in the polished aluminum. And if fingers could smile, all ten of mine would be flashing their pearly whites too, happy that I spared them the labor.

As beautiful as they are, in my next post, I'll cover a few things about them that left me wanting a little more given the premium price tag.

(Edit: PS... Thanks for pointing out that extra gasket material on the TB there Jefrysuko! It's history!)

[This message has been edited by Bloozberry (edited 09-10-2010).]

cptsnoopy ( MSG #188, 09-11-2010 02:11 AM
      I am surprised I am not blocked from your thread for being the party pooper. I was just letting you know that I actually do read it. (but mostly I look at the pictures! )

Gorgeous!, they look like they will go very well with the rest of the parts you have meticulously polished up.


motoracer838 ( MSG #189, 09-11-2010 09:33 AM
Originally posted by Bloozberry:

As beautiful as they are, in my next post, I'll cover a few things about them that left me wanting a little more given the premium price tag.

(Edit: PS... Thanks for pointing out that extra gasket material on the TB there Jefrysuko! It's history!)

You mean, like how to put oil in the engine???

I love those valve covers, but for the price you'd think that you wouldn't have to cut them up just to get oil in them and add a pvc valve.


Bloozberry MSG #190, 09-14-2010 02:09 PM
      So like I said, here are my observations on the cam covers. To be fair, I should note that I decided to accept them the way they are and I haven’t contacted CHRFab about any of these issues. The reason I’m posting this info is so that anybody else ordering a set of these may know what work may lie ahead of them, or to be sure they address these issues directly before ordering.

My initial awe at these masterpieces was tempered somewhat after examining them more closely. As motoracer838 pointed out, the first thing is that there are no ports for crankcase venting nor oil filling, but this was not a surprise since CHRFab states on their website that vents aren’t drilled so you can configure the covers as you like. For oil filling, they suggest either ponying up another $50 at time of order and they’ll weld an aluminum oil fill bung anywhere you like. If that doesn’t suit your fancy, then they suggest filling the engine using any of the four removable plastic plugs on the fronts of the heads. To keep the appearance as clean as possible, that’s what I think I’ll do.

So problem #1: Something that took me a little by surprise was that the insides of the new cam covers don’t have provisions for screwing the PCV baffles into place. Here’s what I’m talking about on the OEM covers:

I’ll have to do a bit of research but I seem to remember having read in an older thread where oil ingestion into the intake can be caused by improper sealing of the oil baffles under the stock cam covers. Clearly if sealing is an issue, then not having the baffles at all must present a real problem.

Problem #2 was that there is a dark spot on the rear cam cover… the cover that’s seen in a Fiero. It appears as though there must’ve been a casting void that was later filled by welding, and then an attempt to polish it out. The filling was well done, but there’s an undeniable blemish. You can see the area I'm talking about in the last two pictures of my last post in the bottom valve cover at the bottom right corner on the sprocket hump. Here's a close up look:

Problem #3 was that there were polisher marks in the finish of both cam covers… not from incomplete buffing, but from accidental slips with the buffing wheel. If you’re not familiar with polishing techniques, then the issue is that portions of them were polished in one direction and other portions were polished at 90* to the first part. This isn’t necessarily a no-no as long as the different portions aren’t in the same plane. The trouble happens when you slip with the buffer and contact an area that’s already been polished in one direction, with the buffing wheel at 90* to that part. It leaves buffing marks clear as day across the previously polished area. Although I was unable to take pictures of this effectively, I had to spend at least an hour re-buffing both cam covers because their buffer accidentally touched areas that had already been buffed in a different direction. For anyone without the tools or skills to rebuff them, this would have been cause of great disappointment.

On a related note, the spark plug holes in the covers were full of buffing compound. To me, this is just sloppy. I did not expect to have to clean the cam covers.

Problem #4 involved more casting issues. When I turned the cam covers upside down, I noticed that the groove for the cam cover gasket was cast and not machined into the parent material. This isn’t necessarily a problem in itself, but again, the casting wasn’t perfect. There was a fair bit of very granular casting flash in the bottoms of the gasket grooves which would have prevented me from installing the gaskets properly and would have caused leaks. Here’s a picture of what I’m talking about:

To correct this I had to take a die grinder with a special bit and carve out the excess aluminum from the grooves. Once again, for the average Joe without the right tools, this may have presented itself as a major hurdle. It was certainly a disappointment regardless of experience and skill.

Problem #5. On the Northstar engine one of the intake cams protrudes through the cam cover so that a small pulley can be attached to drive the water pump. In addition, there are supposed to be three tapped holes to be able to secure the seal that prevents oil from leaking around the cam where it sticks out of the cover. Neither the camshaft hole nor the seal mounting holes were bored. I returned to the website where I bought the covers and could not find where it was stated that these had to be machined by the buyer. Have a look at the stock cover:

And the cover as delivered (note that the marks for determing the location of the hole were made by me):

One final problem was that the cam cover, even once modified for the water pump drive shaft, would not fit on the engine. The covers are significantly heavier castings than the stock covers and the extra thickness around one of the cover’s mounting holes simply would not clear one of the camshaft bearing caps. This meant that I had to shave some material off the inside of the cam cover to get the necessary clearance. Not much… but enough that it could drive you crazy after all the other little issues to deal with.

Next post I’ll show you how I measured and made the holes in the right spots for the water pump drive shaft and oil seal.

cptsnoopy ( MSG #191, 09-14-2010 04:13 PM
      Wow, did not see that coming...


motoracer838 ( MSG #192, 09-14-2010 09:43 PM
Originally posted by cptsnoopy:

Wow, did not see that coming...


What he said!!!

The known problems are bad enough, but I think I'd be calling Alan about the other issues, that's wayyyy too much to expect the coustomer to take care of given what the things cost to start with!!!


Bloozberry MSG #193, 09-16-2010 09:18 PM
      As I mentioned in my last post, the front cam cover needs to have a hole drilled through it to accommodate the intake cam on that side, which sticks out and serves as the water pump drive. My new CHRFab cam cover didn’t have the necessary hole so here’s how I went about getting it in the right place. It’s important for it to be accurate because the oil seal must be centered on the shaft or else it will leak.

The first step was to measure the location of the center of the hole on the OEM cam cover and transfer it onto the new cam cover as accurately as possible. It’s not rocket science, but there’s a monkey wrench thrown in for good measure. The OEM cover doesn’t sit flat on the workbench because of a gasket flange that protrudes below the bottom, part way around. So it wobbles as you try to measure the height of the hole. Anyways, it’s not super critical at this stage as you’ll soon see, so I drilled a pilot hole once I was satisfied.

Once the pilot hole was drilled, I worked my way up to a ½” bit and then ground the hole to about 5/8” using a die grinder. I then installed the neoprene gasket, test fitted the cam cover and torqued the cam cover bolts to spec (89 in-lb). You need the gasket since it compresses to about 1/16” thick. This showed me that my original hole was off center by about 1/8” height-wise but at least I could now measure exactly where the hole had to be. To do this, I left the cam cover on and slid a large washer with a ½” ID and 1” OD onto the shaft and traced the outline onto the cover. Once the cover was removed again, I was able to grind the hole to 7/8” diameter (same as OEM), concentric to the correct center. Here’s what it looked like, torqued down, after getting the hole in the right location:

The next step is to locate the three oil seal mounting holes in the correct location so that the seal is perfectly centered on the shaft. The easiest way to do that is to install the seal on the shaft and mark the location of the holes:

Remove the cam cover again and then drill and tap them to about ½” deep. Drill size: 1/8” diameter; tap size: M4 x 0.7. Even at that depth, the holes don’t penetrate through the material of the cover so no sealant is required, however thread locker is used on the screws.

Here’s the final installation. Like I said, it’s not rocket science, but getting that seal on so it’s perfectly centered on the shaft is important.

Finally, here are a couple shots of the covers installed on my engine. They certainly dress up the engine enough to look the part! Hopefully it’ll perform as nice as it looks.

Too bad it won't be installed longitudinally like this... it would look cool that way.

While I was taking a few photos, my 328 poster cropped up on the wall in the background, so I couldn’t help underscoring it with the top of the engine… too bad it’s not an F355.

Bloozberry MSG #194, 09-17-2010 10:02 PM
      At last I only have a few “accessories” to clean up and install before I finally get to business other than the engine. I still have to order up a stainless fuel rail, and sort out some PCV venting, clean, modify and install the pulley system up front, install the oil filter mount and the water pump/log. I’ll start with these last two, first.

Depending whether your Northstar donor car originally had the towing package or not, your engine either has an oil filter mount with integral oil cooler ports or not. Of the two engines I bought one had the provisions for the cooler and the other didn’t. Since I’ll be running an unconventional radiator set-up, I decided to use the oil filter mount with the cooler ports to give me additional cooling capacity. I cleaned it up and installed it, but it just looked out of place and was screaming “Polish me!”

So off it came and two hours later it was ready to be installed again.

I got two new o-rings in my rebuild kit so I stuck them on before tightening the mounting bolts to 18 lbft. The oil pressure sender also gets installed into yet another port on the filter mount. It’s a pipe fitting thread so don’t forget to use some RTV.

Next came a task I was not looking forward to. Polishing the water pump/log. For those who aren’t familiar with the N* configuration, the water pump is pressed into a huge aluminum water manifold that bridges the two cylinder banks at the back of the engine. It’s so long that many people refer to it as the water log. Here’s what it looks like off the engine.

Up close you can see that it’s a rather rough sand casting with lots of raised, mismatched seams, manufacturing stamps and cast-in time, date, and part number stamps. Luckily not a lot of it is seen, but enough that if I didn’t polish it, it would look like I got lazy.

Today I started the polishing process by smoothing the water log out as much as possible. To accomplish this I broke out a handful of rotary sanding disks, flapper wheels, and grinding stones. It’s a messy job requiring safety glasses and a mask because the aluminum dust will end up in every one of your bodily orifices if they’re not covered… (yet another reason not to use a grinding wheel in the buff!) J At the stage shown in this picture I’ve used mostly a 3” and a 1” diameter 60 grit flapper wheel to get the pebble finish smooth and to remove the casting lines. Next up will be a special scrubby-type material buffing wheel to minimize the sanding marks, and then hand sanding… ugh.

rourke_87_T-Top ( MSG #195, 09-21-2010 05:47 AM
      That Nylon intake looks really nice painted red, I didn't think it could be painted. You have been making a lot of progress on the engine, it's looking really good with all that elbow grease. I added to my favourites .

doublec4 ( MSG #196, 09-21-2010 10:17 AM
      This has to be one of the most detailed and well documented build threads around! Looks great!

motoracer838 ( MSG #197, 09-22-2010 08:08 PM
      Arrgh, oh man how I hate polishing!!! you sir have more patience than I, it looks awesome.


Icelander ( MSG #198, 09-23-2010 12:06 AM
      Is that water log a single unit with the pump? If you have to replace the pump, will you have to polish another log?

[This message has been edited by Icelander (edited 09-23-2010).]

cptsnoopy ( MSG #199, 09-23-2010 12:21 AM
      The pump can be replaced separately.


Bloozberry MSG #200, 09-24-2010 09:04 PM
      Thanks Rourke, Doublec4, and Motorracer... I'm addicted to positive feedback! For Icelander, there's no way in hell I would have started polishing that log if it had to be replaced along with the water pump! I can just see the look on some rebuilder's face when he got my core in for remanufacturing. I think they would have mounted it on a plaque and made it the employee of the month award or something. I'm half tempted to mount it on a plaque in memory of my long lost fingerprints! Thanks for chiming in there Charlie too.

On a side note, I got diverted from polishing the log a bit when I torqued the oil filter mount onto the side of the block. The specs say it goes on with 18 lbft but as I was tightening them, I heard two snaps! Both bolts pulled the threads right out of the block. I'm still messing around with helicoils because I accidentally drilled and tapped one hole a little crooked, so the filter mount won't seat properly before the bolts bind up. So far, drilling larger holes in the filter mount hasn't corrected the misalignment enough to solve the problem. Arghhh!

Well I finally managed to finish sanding and buffing the water log. There were a lot tricky spots on it that needed special attention and special tools. I’ve found that to get into the ½” concave radii, the best tool is a tightly wound roll of sandpaper about a ½ ” in diameter and 3” long that’s made especially for porting cylinder heads and such. You screw it on a special needle-like mandrel that fits in your ¼” shank die grinder. As the outer layers are worn off, the inner layers are exposed, so one little roll lasts pretty long. Works fast and does an excellent job in those tough-to-get-at corners. In all, I spent 12.5 hours from start to finish on this piece, and I'll be the first to admit it’s not perfect, but then again if you've ever looked into the bay of a N* Fiero, there isn't much of it that's going to be seen. So before anyone asks the obvious question, my compulsive obsessiveness made me do it.

Here’s a close-up of the combination thermostat housing / water pump inlet. I personally don’t know how anybody makes any money polishing metal for others.

To install it on the water log, you need a specially shaped neoprene-like seal. Mine came with the master rebuild kit, and it’s a good thing, since the old seal needed to be removed from the groove to clean up a little oxidation and antifreeze deposits. It crumbled when I tried to take it out.

Once the new seal is in place, the housing is installed with just four 6mm bolts. They get torqued to 89 lb-in and don’t need any sealer on the threads since they don’t break into the water jacket of the pump. For the water log and it’s accessories, I decided to buy all new stainless steel socket head bolts. I take the belt sander to the fine ridges on the OD of the bolt head to get rid of them and then polish them on the buffing wheel. They look ten times better than the old steel hex head bolts and they’ll stay that way for eternity too! The nice thing about stainless is that it should minimze the galvanic interaction between the steel and the aluminum.

Next up is the thermostat itself. Interestingly, this T-stat has a small vent hole drilled though the shroud already… almost like they knew it would be a challenge to bleed the air out of this monster.

Finally, the thermostat neck gets bolted on with a couple 6mm bolts torqued to 89 lb-in as well. No additional seal or gasket is required because the thermostat comes with a rubber o-ring around its outside edge.

Here’s the pump end of the water log all built up. The eagle-eyed among you will notice that I’ve installed the dog bone mount. I'm hoping to be able to use it. The one bolt that you can see for the mount is actually a hollow bolt that taps into the water jacket so it needs RTV on the threads. The coolant hose coming from the throttle body heater connects up to that bolt.

Gokart Mozart MSG #201, 09-25-2010 08:18 AM
I've always liked the look of polished metal over chrome.

Originally posted by Bloozberry:
It’s a messy job requiring safety glasses and a mask because the aluminum dust will end up in every one of your bodily orifices if they’re not covered… (yet another reason not to use a grinding wheel in the buff!)

I won't ask if you've tried that...

topcat ( MSG #202, 09-25-2010 09:08 AM
      This by far ranks in the top 5 of my favorite threads of all time. The level of detail you put into the project is inspiring and makes me want to tear my engine apart to detail it. Have you given any thought on how to keep the polished aluminim clean and shiney? I had aluminum wheels that were a bear to keep polished and took a lot of work.

Fiero Thomas ( MSG #203, 09-25-2010 10:40 AM
      This is the first time that I have read over this thread and you are doing an amazing job. Your car is going to be a work of art when finished if you keep up doing this the way you are going. I will follow this thread. I think I need to get some caddy manuals on my site now as well.;

Bloozberry MSG #204, 09-25-2010 10:09 PM
      Thanks Gokart for stealing page 6... so far, I only own page 1 and I'm the one doing all the work!

Thanks for the compliments there too Topcat and Thomas. For Topcat, there's no magic formula to keeping the aluminum nice and shiny that I've found so far. The corrosion forms in the pits, so sanding and polishing takes care of a good deal of the problem. The quality of the aluminum also makes a big difference though. I've polished the intake plenum on my TPI small block only once and over 14 years it's never oxidized. On the other hand, I polished my 2.8L plenum on my '86 and had a tough time keeping it looking good. Last year before storing it for the winter, I repolished it and tried spraying it down with WD40 to get a protective film on it. It worked great but it left me with a different mess to clean up in the spring, though it's far easier to wipe off the WD40 than to try to clean off oxidation. I may try using car polish (carnuba wax) in an attempt to keep the pieces from tarnishing on the N*. The polish should fill in any voids preventing moisture from getting into the tiny surface imperfections. I'm keeping my fingers crossed that the engine block is made of the same alloy as my TPI plenum, but so far it looks like it's not.

Fiero Thomas: I think Caddy service manuals would be a great addition to your site. AJxtcman has already scanned in a lot of the engine inspection procedure in this thread here: and much of the rebuild manual in this thread here: Both are archived now so they're not as easily found as when they were active threads. They may save you some time if you're serious about adding Northstar info on your site.

Anyhow, to finish up the water log I still needed to install the EGR valve since I plan (at least at the moment) to run OBD2. I figure emissions testing isn't going to get any slacker in the future so I may as well keep the pollution provisions intact. The first thing is to install a new gasket.

Next, the EGR valve itself. It's strictly an electrically controlled valve as opposed to the electro-pneumatic valve on the Fiero. It's a straight forward two bolter, torqued to 89 lb-in. No vacuum lines to contend with, just a single four pin connector. The water log has an integral channel drilled through completely separate from the water circuit to route the exhaust gases from one side of the engine to the other. Flex lines similar to the Fiero V6's EGR tube connect the exhaust system and the throttle body to the water log.

Here's what the EGR valve installed on the water log looks like:

And finally, the completed polished water log with everything on it... well, it's missing the water pump belt tensioner, but I'm still working on polishing that little piece.

Icelander ( MSG #205, 09-26-2010 01:55 AM
Originally posted by Bloozberry:

So before anyone asks the obvious question, my compulsive obsessiveness made me do it.

We need to get you the t-shirt that says:
"I have CDO. It's just like OCD but the letters are in the proper order."

Fantastic work! Maybe someday my Ecotec will look as pretty.

[This message has been edited by Icelander (edited 09-26-2010).]

Bloozberry MSG #206, 09-26-2010 08:08 AM
      LOL. "Hi. My name is Dave and I have obsessive compulsive disorder. It's been 8 hours and ten minutes since someone pointed out an error I made, and even though it's bugging the hell out of me, I've so far refrained from editing my post."

Gokart Mozart MSG #207, 09-26-2010 03:19 PM
      [QUOTE]Originally posted by Bloozberry:

Thanks Gokart for stealing page 6... so far, I only own page 1 and I'm the one doing all the work!

No prob! I'll give you the chance to steal my thread when I start working on mine.

Fiero38SC ( MSG #208, 09-27-2010 11:59 AM
Originally posted by topcat:
Have you given any thought on how to keep the polished aluminim clean and shiney? I had aluminum wheels that were a bear to keep polished and took a lot of work.

Someone told me WD-40. Spray it and wipe off the excess.

And that person is OCD also, so it must be true.

Bloozberry MSG #209, 09-30-2010 09:48 PM
      A few odds and sods for this post: I bead blasted the harmonic damper to get it nice and clean for paint when I noticed something interesting:

Anyone recognize the symbol? It sure looks like the Briggs and Stratton logo to me. I wonder why that would be stamped into the damper. Hmmmm… are there any 32 valve lawn mowers out there that I’m not aware of? Anyways, once it was nice and clean I sprayed it with some Tremclad red oxide primer, then a coat of gloss white, and finished with a coat of John Deere yellow. I use the white undercoat to really make the yellow pop out. I plan on painting all of the pulleys and idlers yellow to match the current plan for the exterior of the car. And no… before anyone asks, it’s not going to be John Deere yellow, but it’s not far from it. The John Deere paint is just a great inexpensive way to get a nice bright yellow on the accessories. I find that the Tremclad yellow is very orangy.

While working on the water pump pulleys I found yet another reason to go over your junkyard engine with a fine tooth comb before just plopping it into your car and hoping for the best. This is the water pump belt tensioner:

Apart from a little corrosion, it doesn’t look all that bad, except that the tensioning pivot point was seized and the pulley was coming apart. I’m pretty sure in no time it would have ate up the little water pump belt. And since it’s not in an easy place to inspect once it’s installed in the Fiero, it could easily lead to an overheated engine. It’s up against the front wall and is hidden with a small sheet metal belt guard to protect probing fingers:

The pulley core and outer ridges are made of steel with a plastic coating. The two middle ridges on the pulley are entirely plastic. No biggie right? Just remove the pulley and order up a new one. Except that GM doesn’t sell the pulley and the tensioner separately… of course not! And the cost… are you holding onto your socks? A whopping $197. Unbelievable. Good thing I have my second engine to rob parts like this off of. If you need one and can afford it, it’s part number 12555153.

Surely I would have better luck with the cam-mounted pulley right. Strike two! The middle ridges looked like a mouse had munched on them for breakfast, lunch, supper, and a bedtime snack. Aside from that explanation, I have a hard time understanding how this would happen. Again, the dealership wanted five times more money than the part could possibly be worth… $69.25. It’s GM part number 03535846. Spare engine, to the rescue!

After spending a couple hours bead-blasting, sanding, polishing and painting various parts of the water pump tensioner, here’s how it turned out… like a little jewel.

And here’s the cam pulley along with a shot of the mini serpentine belt (GM p/n 12588412 for a mere $19.97)

Erik ( MSG #210, 10-01-2010 01:26 AM
      going to have to wear sunglasses to look at your engine

Bloozberry MSG #211, 10-03-2010 09:51 PM
      Thanks for the suggestion Erik… I haven’t had this thing out in the sun yet. It’s bright enough to look at just in the darkness of the cave I call my workshop. (insert smiley face with shades)

So on with the water log/pump installation: The first thing to do is install the cam pulley. It’s fairly straight forward… just slip it on the end of the cam shaft with the snout pointing outward, and use any old 8mm X 1.25 bolt in the end of the shaft to draw it into place. When it’s seated correctly, the end of the shaft is flush with the end of the snout.

The next step involves having some RTV handy since some of the water log mounting bolts penetrate into the water jacket. I was curious to which ones needed the RTV and decided to shine a light into the four mounting holes on the engine block and the four in the cylinder heads to see. I was surprised to find that only two of them did, so I imagine GM specified RTV on all of the bolts to make things easy on the assembly line. The two that needed it on my block are the ones highlighted in green, the red ones were fine, but I applied RTV to all the bolt threads just in case:

Apart from the boltholes, the way the water passages seal up against the block and heads is with a metal gasket that has a neoprene-like seal embedded on both sides. It’s a little tricky to get all four seals on the log and get it up to the block without the seals falling all off since nothing captures them. The trick is to slide all eight mounting bolts through the log and hang the seals on them.

Another complication is that you must hang the little water pump belt off the cam pulley and make sure as you raise the log up to the engine, that you slip the water pump pulley into the belt loop. If you don’t do this, you’ll soon find out that there isn’t enough room between the snout of the pump pulley and the block to install the belt. I know this first hand. Needless to say, lifting this contraption up to the block took two hands so there aren’t any pictures of it going into place. Here it is though, in the process of being torqued down. All eight get torqued to 18 lbft.

Next up is the little water pump belt tensioner. In this series of three photos, the first is mounting the tensioner to the log with two long, small diameter studs. (Notice the space between the tensioner pulley and the cam pulley at this point).

This photo shows how you "lever" the tensioner pulley against the force of the tensioner spring towards the cam pulley, by using a ¼” drive socket-wrench in the handy-dandy little ¼” square hole on the back side of the tensioner arm. Notice how much closer the tensioner pulley is to the cam pulley?

With the arm fully retracted there’s enough slack to slip the belt on the tensioner pulley, and from there it’s just a matter of releasing the pressure on the tensioner. It’s easy to get the belt on crooked as I found. I had to re-take this picture after coming back to the office, downloading the photos, and seeing that the belt wasn’t properly seated on the cam pulley. Good thing I noticed before trying to start this puppy up! This is with the pulley on properly.

Finally to keep those probing fingers safe from whirling belts and pulleys, here’s the little pulley guard that mounts to the free end of the two tensioner mounting studs mentioned earlier.

Kento ( MSG #212, 10-04-2010 07:20 PM
Originally posted by Bloozberry:
for Topcat, there's no magic formula to keeping the aluminum nice and shiny that I've found so far. The corrosion forms in the pits, so sanding and polishing takes care of a good deal of the problem. The quality of the aluminum also makes a big difference though. I've polished the intake plenum on my TPI small block only once and over 14 years it's never oxidized. On the other hand, I polished my 2.8L plenum on my '86 and had a tough time keeping it looking good. Last year before storing it for the winter, I repolished it and tried spraying it down with WD40 to get a protective film on it. It worked great but it left me with a different mess to clean up in the spring, though it's far easier to wipe off the WD40 than to try to clean off oxidation. I may try using car polish (carnuba wax) in an attempt to keep the pieces from tarnishing on the N*. The polish should fill in any voids preventing moisture from getting into the tiny surface imperfections. I'm keeping my fingers crossed that the engine block is made of the same alloy as my TPI plenum, but so far it looks like it's not.

There is only 1 way to keep polished Aluminum look good after your done and have the part powder coated clear afterward. That will seal in the finish and not let it oxidize. But you run the risk of any oil embedded in the part coming out afterward causing a nice blemish. I am yet brave enough to PC clear any polished aluminum parts yet.

Bloozberry MSG #213, 10-04-2010 09:22 PM
      I forgot to mention a big milestone I reached in the last post in terms of engine rebuilding. I finally moved the engine from the stand to a floor dolly. Yay! It had to be done in order to install the water log, since the engine stand gets in the way. I also couldn’t install the rear crank seal with the engine on the stand either.

I didn’t get any pictures of the rear crank seal by itself, but the seal is quite innovative in that it’s actually a combination metal sleeve and a typical elastomeric axial shaft seal with a garter spring. The metal sleeve gets driven onto the crankshaft flange with an interference fit, renewing the journal surface on the flange that the old seal rode on by covering it up. The new seal is sized for the diameter of the sleeve, not the diameter of the crank flange. The sleeve and the seal are inseparable since the sleeve is formed with small flanges on both ends at the factory once the seal is slid on. It’s great because your new seal isn’t riding on the old worn surface. The trouble is that to get the sleeve pressed onto the crankshaft, you need to buy, rent, or make a special tool. Stealing an idea from PFF’er WAWUZAT, I made a tool from a piece of 4” PVC drainage pipe and some 1/8” cold rolled steel plate. I cut a piece of the PVC pipe about 2” in length:

The PVC pipe is exactly the right diameter to contact the outer sleeve flange of the seal assembly. So, to be able to apply even pressure to the pipe while installing the sleeve, I used the Caddy flex plate spacer to trace the outline of four of the eight crankshaft bolt holes onto a 4” X 4” piece of steel plate:

Then, by using the metal plate on top of the pipe, along with an assortment of bolts and washers, the sleeve and seal assembly can be pressed onto the end of the crankshaft squarely and under control by tightening the four bolts. The instruction that comes with the seal state that it must be installed dry, so don’t use lubricants here. You must be careful not to bottom out the bolts as you draw the seal into place because the holes in the crankshaft flange go completely through the flange. Immediately behind the crank flange is the rear bearing cap, so if you’re not careful and end up side loading the cap, you’ll warp it. To prevent this, I kept removing the bolts and adding more washers under the heads as the seal inched into place.

You know you’ve seated the seal/sleeve to the proper depth once it’s past the end of the crank flange by about 1/16”. Here’s a close up of the final product:

For the clutch/flywheel stack, I plan on using the Caddy flex plate as the starter ring gear, with a spacer sandwiched between the flex plate and a dual mass flywheel. The thickness of the spacer will be determined once I’ve bought the rest of the parts like the pressure plate, friction disk, and flywheel, none of which I have at the moment. But that didn’t stop me from prettying up the flex plate in the meantime.

I bead-blasted it…

Then shot it with a white undercoat, and finally some more of that John Deere yellow paint.

Then I temporarily installed it to get it out of the way. For good measure, I made two marks on it in line with the case half as a reference point for #1 TDC just in case the cranks turns a little while installing the front end pulleys and belt later on.

Next up: the front end hardware (or I guess that'd be the RH hardware on a Fiero). I’ve done a fair bit of research in older threads about belt routing and found some interesting stuff on relocating the serpentine belt tensioner to where the old power steering pump was up on top of the engine in the middle. So far though, all the threads I’ve seen use AC, something I don't plan to run since my car wasn't orignally equipped with it. I’ll ask here and also start a new thread in Tech asking the same question since it’ll probably get a wider audience there: Has anyone got an example of how they routed the belt on a N* without the AC compressor?

[This message has been edited by Bloozberry (edited 10-04-2010).]

Gokart Mozart MSG #214, 10-05-2010 07:55 PM
Originally posted by Bloozberry:
Has anyone got an example of how they routed the belt on a N* without the AC compressor?

If this looks like yours, the ac is the bottom right. You should be able to just get a shorter belt. Use a piece of string and follow the route to get the length.

Bloozberry MSG #215, 10-05-2010 09:46 PM
      Thanks Gokart Mozart, but I also want to ditch the power steering pump too, I guess I should've been more clear. Referring to the diagram you posted, I want to relocate the tensioner (like many others have) to where the PS pump is (at the top), and eliminate the AC compressor. I know it's not rocket science, I'm just wondering if anyone else has done this that is willing to share a picture.

Edit: On second thought, I guess I'll just relocate the stock stationary idler to where the PS pump is (maybe even convert the pump into the idler similar to what IXSLR8 did), leave the tensioner in the stock location, and ditch the AC. So going clockwise from the top of the engine, the belt would come off the new idler, around the alternator, to the crank, then to the tensioner in the stock location, and back up to the new idler. That settles it. I'm good to go.

[This message has been edited by Bloozberry (edited 10-05-2010).]

Jefrysuko MSG #216, 10-05-2010 10:48 PM
      You only need to drive the alternator correct?

Could you get rid of everything but the alternator and then relocate the tensioner to the A/C location pushing up on the bottom of the belt?

It would look alot cleaner with the belt not being routed up to the top.

Bloozberry MSG #217, 10-06-2010 07:46 AM
      Thanks for the idea Jef. I'll see if it's feasible... the only potential problem I see is that since the alternator pulley is quite small in diameter, having the tensioner pushing up on the lower belt may place it too close to the upper side of the belt for comfort.

(Edit: BTW, +'s for both of you Gokart and Jef)

[This message has been edited by Bloozberry (edited 10-06-2010).]

Gokart Mozart MSG #218, 10-06-2010 10:13 AM
      What about moving the alternator to the bottom, where the ac was? You can make a standard slot adjuster, eliminating the tensioner.

[This message has been edited by Gokart Mozart (edited 10-06-2010).]

88GTS ( MSG #219, 10-06-2010 12:13 PM
      Or leave the alternator and use the aircon mounting hole for a custom bracket to support a tensioner. This way you will have low maintenance, but more important, have a short belt that is tucked away out of site. I would hate to see your beautiful engine spoiled by an ugly pulley and belt loops at the top.

cptsnoopy ( MSG #220, 10-06-2010 02:10 PM
      I don't know if anyone has looked at this but it may work. Not the optimal angles for either the tensioner or the alt but not too far off. The lower bolt on the alt pivot mount would probably require modification as it protrudes into the belt approximately 1/16". Please ignore the top idler and the ac compressor.


88GTS ( MSG #221, 10-06-2010 02:51 PM

I think your proposal will work. What you want is maximum belt contact on the traction pulley surfaces (crank & alternator) and minimum traction on the idler and tensioner pulleys and you have almost 180 degrees on the alternator.

A slightly modification to your layout is what Russ did on his (see 1/2 way down) -


[This message has been edited by 88GTS (edited 10-06-2010).]

Bloozberry MSG #222, 10-10-2010 07:21 PM
      Well, I’m pretty sure I’m going to route the serpentine belt in accordance with Charlie's (cptsnoopy’s) suggestion, but I’m only going to commit to it once I get all the parts polished and can test it out. So that means only one thing… more painting and polishing!

On the painting side of things, here are a few engine brackets that needed refinishing… some I know I need, others, not so sure but I was on a roll with the sandblaster. I just hope I don’t change my mind on the color of the car over the next year or so (although some of you probably do!)

Next up was the serpentine belt tensioner since I knew I’d be using it regardless of the belt routing. So off came the pulley, where it got treated to a varsol bath, and the rest of the tensioner got thrown into the sandblaster. Once good and clean, the tensioner got the rough-medium-fine flapper wheel treatment, some extra fine hand sanding, and finally a good buffing on the wheel. While that was going on, the pulley got undercoated white, then sprayed with some color. Here’s the finished product… better than new!

Again, I’m unsure whether I’ll be able to make use of the stock dogbone mounts on the engine itself, but my plan is to use them if at all possible. I’d rather have the dog bone(s) on the forward firewall where they’re less obvious than on the trunk wall like most people have them. I won’t know if I’ll have the space or not for another week or so when I test fit the engine but in the meantime I figured I’d schnazz up the RH one to help motivate me to use it no matter what the obstacles. Here’s the “before” picture:

And here’s that “after” picture. Since my engine bay is deeper by 3” due to the chassis stretch, I have good reason to believe that I’ll be able to adopt my front dogbone idea into my car. On this bracket, it simply wasn’t possible for me to get the pebble finish of the sand casting off the recessed areas. I couldn’t figure out how to polish in those areas either so I left them rough, and painted them instead. I think it adds a finishing touch to an otherwise difficult piece to polish.

My heart kind of sank as I reached into the tickle trunk to see what my next task would be and pulled out two more aluminum brackets. Arghhhh… will the polishing ever end? It turns out that the Northstar alternator is held in place with not one, but two brackets. Here’s what one of them looked like in a typical crusty finish.

A bunch of elbow grease, a lot of patience, some buffing compound up my nose, a couple hours, and here’s what the two brackets came out looking like... this is the rear one:

And this is the front one:

With those done, I could finally install them…

…and move onto the last piece needed to complete the front serpentine belt system… the 140A alternator. That should be easy right? Except good ol’ Murphy (from the Law society) has taken up residence at my place for some time now and made his presence felt again. I figured I would just be able to take the alternator apart, polish the case, and stick it back together again. That was wishful thinking...

cptsnoopy ( MSG #223, 10-10-2010 09:10 PM
      WOW! (again... )

Those before and after pics are amazing...! I can see why it took a couple of days to post again, you had your work cut out for you.


doublec4 ( MSG #224, 10-11-2010 02:57 AM
      polishing OCD!

Tony Kania MSG #225, 10-11-2010 10:42 AM
      Exactly DoubleC4! The guys in my area think that I have issues? Blooz is full blown looney. But I love it!

[This message has been edited by Tony Kania (edited 10-11-2010).]

Bloozberry MSG #226, 10-11-2010 12:00 PM
      LOL. You guys crack me up. I think you guys are suffering from "polish-envy".

[This message has been edited by Bloozberry (edited 10-11-2010).]

cptsnoopy ( MSG #227, 10-11-2010 04:23 PM
Originally posted by Bloozberry:

LOL. You guys crack me up. I think you guys are suffering from "polish-envy".

yep, I won't be able to open my trunk now...


Gokart Mozart MSG #228, 10-12-2010 11:40 AM

[This message has been edited by Gokart Mozart (edited 10-15-2010).]

Fierobsessed ( MSG #229, 10-13-2010 03:24 AM
Originally posted by Bloozberry:

Anyone recognize the symbol? It sure looks like the Briggs and Stratton logo to me.

Most GM harmonic balancers are Briggs and Stratton. You can also find the same logo on the 3800's balance shaft.

From the early days of GM till... I think '67 GM's Keys were Briggs and Stratton as well. If you see the Hexagonal head on a classic cars keys, thats a B&S ignition key.

Now, on with the show. The engine is looking absolutely beautiful. I am very impressed with your workmanship. Doin' us proud.

Bloozberry MSG #230, 10-14-2010 04:30 PM
      I wanted to polish the alternator case so that meant taking it apart. (I know for many of you rebuilding an alternator may be uninteresting, but if this helps one person in the future, then it was worth it. The rest of you can scroll on by!) There are only four screws that hold the case halves together, and once they’re out, the alternator literally comes apart in four major sections excluding the fan and pulley. To get the armature/rotor to let go of the bearing in the front case halve, I had to press it off with my arbor press.

Here are the major parts clockwise from the top left: fan, pulley, field windings, rear case half, front case half, and rotor/armature:

Because I don’t have a rebuild manual for this specific alternator, I took a close up picture of the layout of the electronics in the rear case half to make putting it back together a little easier. Good thing I did too because I needed to refer to it several times.

I removed all the components so I could clean, sandblast, sand and polish the rear case without worrying about ruining something. Once the case was polished, I cleaned the individual parts of the voltage regulator, rectifier, and heat sinks and reinstalled them. To be honest, I haven’t a clue which part is which so I won’t even pretend. Here’s the part with the heat sinks. There are two sets and they snap onto a plastic insulator mount of sorts:

Once they’re back together, they can be set back into the rear case.

Next in the order of reassembly comes this doo-hickey… again, for now it just gets set into place:

And here’s where my problem started. As I was taking apart the alternator and inspecting the various pieces, I noticed that the armature where the brushes ride was worn asymmetrically. When I removed the brush assembly, this is what I found:

That’s when I almost cried because I wasn’t aware that you could buy the brushes separately, and a rebuilt alternator is $230! After a few calls to the dealership (I don’t know why I bother) and some local parts stores, I learned that for $5.77 I could have new brushes the next day! Yay! I got these from NAPA:

Installing the new brushes was pretty straight-forward, but for anyone who hasn’t done this sort of thing before, you basically insert the brushes into a holder, then slip a small diameter pin (I used part of a bicycle spoke) through a couple holes in the holder and the brushes to keep them from springing out. Here’s one side that’s done and the other just waiting to be pinned in place:

One of the brushes was originally soldered onto a tang that protrudes out of the solid state box, so I did the same with the new brush too. Here you can also see how the pin keeps both brushes tucked inside the holder until you’re ready to release them.

And with that, I’m off for the weekend flying to Ottawa to catch Roger Waters perform Pink Floyd’s The Wall. Yes… this should be awesome.

dratts ( MSG #231, 10-14-2010 07:14 PM
      What fun! That is one of the movies that I recorded on vhs and watched at least 6 times. I guess you won't see the incredible animation at a concert, but todays kids being used to digital animation are probably not impressed anyway. Now I'm envious of you for that too!!

BtotheB ( MSG #232, 10-15-2010 10:35 AM
      Great thread, been following for a while now and am impressed at the time you're spending on this.

I'll be at the Roger Waters show on Sunday too, should be fun!


Bloozberry MSG #233, 10-18-2010 08:29 PM
      I’m back… and feeling comfortably numb. What a show, simply awesome. I looked for a Fiero in the parking lot (all 30,000 cars) but didn't see yours there BtotheB! As for Dratts... I can't remember how many times I've seen the movie, each time figuring out a little more of the meaning behind it all. My brothers and I rented it again and watched it as a primer on Sat night... I still like the girl with the pink pants! BTW, the graphics were first-rate during the show... turning a 250' wide white wall into the world's largest HD wide screen TV.

But back to business… I popped out the needle bearing when I took the case apart, cleaned it with varsol, blew it dry with air, inspected it, and decided to re-use it after suitably greasing it back up with clean synthetic grease.

I used my arbor press to squeeze it back into the rear case and then focused on installing the remaining electronics. Here is everything installed in its proper place. When I installed the brush assembly, I had to remove the pin, hold the brushes in place with one finger, and reinsert the pin through a little hole in the back face of the rear case made just for this purpose. I actually got a little ahead of myself in this picture. If you note the two nuts between the 12 and 1 o’clock positions on top of the copper strips, and a similar nut at the 3 o’clock position, well, the three eyelets from the field windings are supposed to go on those studs before the nuts go on, so I had to take them off.

Here are the field windings being installed. Not visible in this photo are the three wires with eyelets on them that attach to the three studs mentioned above. The windings themselves are countersunk into the rear housing by about 3/16”. Notice a trend in the color?

Once the field windings are in, the armature/commutator assembly needed a little attention. Here’s what it looked like before the make-over:

And after:

Once ready, it just gets lowered into place with the end of the shaft seating in the needle bearing that was installed earlier. At this stage, don’t forget to reinstall a thick spacer washer on the free-end of the rotor shaft. It serves as a thrust washer against the inside of the front housing.

Next up is the front housing which needs to be clocked in the proper orientation with respect to the rear housing if you want the electrical connections to be accessible once it’s installed on the engine. When looking at the front of the alternator, place the thickest of the two ears on the front housing at the 3 o’clock position, then line up the large lug for the positive battery lead on the rear housing at approximately the 1 o’clock position.

Then reinstall the four housing screws and torque them to 60 in-lbs.

With the two halves back together again, it’s time to pull the pin out of the back of the alternator to release the brushes, like so:

The last step is to reinstall the front end components in this order: thin spacer, fan assembly, thick spacer, pulley, washer, then nut. I used my impact wrench set on medium to tighten the nut.

And voila! A far cry from what it looked like before.

dratts ( MSG #234, 10-19-2010 08:08 PM
      Regarding the girl in the pink pants. I'm pretty sure I know the one you are talking about and it's been a while since I watched it. In fact it's on vhs and I don't even have a vhs anymore. She was a groupie right?

Bloozberry MSG #235, 10-19-2010 09:35 PM
      How can you not remember the girl in the pink leather pants?!! In the movie, she's the one who says "Wanna take a baaaath?" Now do you remember her?

mattwa ( MSG #236, 10-21-2010 12:50 AM
      Looking good! I love all the shiny metal. Quick question, do you clear coat the aluminum pieces after you polish them, so they don't corrode again?

Bloozberry MSG #237, 10-21-2010 08:11 AM
      Thanks Mattwa. There's a couple of considerations when deciding what to do to keep the aluminum shiny. The most important is polishing the part as best as you can. That means sanding out all of the little pits in the surface since that's where the corrosion starts. The next thing is being able to tell whether the part is aluminum or "pot metal" (aka white metal) which is just a blend of all kinds of scrap alloys melted together and cast in a very porous state. Sometimes it's hard to tell which is which, but usually the aluminum is denser and just "feels" like a better quality part. For aluminum, corrosion isn't usually a problem if the parts stay dry. I'm using a coat of a good quality paste car wax on these parts. This fills in any of the pores to seal them off. For the pot metal parts, there isn't much other than a coating of WD40 that keeps them shiny. The metal is just so porous that even when you sand it, you break into tiny cavities that are everywhere under the surface.

Clear coating may work for aluminum but it won't work very well for pot metal because of the porosity. It's very hard to get the polishing compound out of the tiny pores in the surface, so the clearcoat "fish-eyes" when you try to apply it. The other problems with clearcoating though, are that the moment gasoline touches it, it turns yellow, and anywhere that a bolt must be tightened down over-top of the clearcoat, it breaks through the protective coating and the corrosion starts from there.

Polished parts need regular maintenance, but if you're starting off with quality aluminum rather than pot metal, you'll have way less work to do to keep it shiny.

(Edited for spelling)

[This message has been edited by Bloozberry (edited 10-21-2010).]

Kento ( MSG #238, 10-21-2010 11:11 AM
Originally posted by Bloozberry:

Clear coating may work for aluminum but it won't work very well for pot metal becasue of the porousness. It's very hard to get the polishing compound out of the tiny pores in the surface, so the clearcoat "fish-eyes" when you try to apply it. The other problems with clearcoating though is that the moment gas touches it, it turns yellow, and anywhere that a bolt must be tightened down over-top of the clearcoat, it breaks through the protective coating and the corrosion starts from there.

Polished parts need regular maintenance, but if you're starting off with quality aluminum rather than pot metal, you'll have way less work to do to keep it shiny.

You can powder coat the parts with a clear and it will protect the "shiney "

Bloozberry MSG #239, 10-22-2010 09:03 PM
      With all the front mounted accessories finally polished and/or painted, it was time to install them so I could take a few measurements for my new serpentine belt. When I started to wrap the stock belt around the pulleys to do this, I realized that the stationary idler pulley would need to be changed out for one with grooves. I’ll need to go scour the scrap yards one of these days if the rain and freezing-cold wind ever stop. Here’s everything installed, at least temporarily, with the wrong idler pulley.

A couple weeks ago I started surfing eBay for a stainless steel fuel rail and came up with one from an Oldsmobile Aurora for $50 including the injectors, pressure regulator, MAP, and harness. I probably could have gotten it for cheaper but I decided to use the “Buy it Now” button since I figured it was a good deal as is. It arrived a couple days ago and except for the electrical connector having been cut off, it was in good condition. I don’t need the connector since I already have one from the old plastic Northstar rail.

I wanted the Aurora rail because the fuel connections are on the forward bank of the engine rather than on the aft bank in the stock Northstar configuration. Both are still at the transmission end, which means having to lead the lines over to the passenger side of the engine bay but at least with the Aurora rail I won’t have to lead the fuel lines forward since they’ll already be on the correct side of the engine.

The Aurora rail has it’s own set of challenges though. It can’t be installed directly on the Northstar without removing the dog-bone mount at the transmission end of the engine since the fuel rail interferes with it. The ends of the rail also have an up-turn so I will cut off the ends to kill two birds with one stone. I haven’t decided how I will couple the rail to the car’s fuel lines yet but I recall a post where someone was able to use some AN fittings from Russell. More on that once I do some more research.

Since I wasn’t entirely sure the Aurora rail had the same fuel pressure regulator or that it was set at the same pressure as the Northstar, I swapped them around. To remove it from the rail it’s a simple matter of pulling off a retaining clip with your fingers (this one is on the old plastic rail)...

…and pulling up on the little regulator. It’s a good thing I decided to swap them over because the inside of the regulator on the Aurora rail was partly rusty and very gnarly-looking. If you do this yourself, be aware that there’s a large o-ring on the regulator OD, then there’s a very fine plastic fuel filter, and deeper inside the housing part of the rail, there’s another tiny o-ring that seals against the little tube at the bottom of the regulator. Sometimes the filter stays inside the housing, but the tiny o-ring almost always stays inside it.

I haven’t decided yet whether to replace the injectors or try to get them cleaned. Where I live, I haven’t yet found a shop that can clean them unless they’re installed in the car, which makes the whole process moot if I have to drive there first only to burn up a piston and some valves. I may have to break down and buy some new ones for peace of mind. PFF’er Will mentioned that there are inexpensive Ford pieces that are direct replacements. Regardless, here’s how you take them off the fuel rail… first, you have to pry off a stiff little metal clip at the top of each injector…

…and then you have to pull pretty hard on the injector to get it to let go of the rail. I’d say about half of the time the upper injector o-ring stayed in the rail rather than come out with it, so have a good look to be sure you have them all out. After they were pulled out of both rails I noticed that the injector part number is the same for both the Aurora and the Northstar rails. I would have figured the Aurora injectors would be different because of the smaller displacement, so they must compensate with shorter pulse widths instead.

elitopr MSG #240, 10-22-2010 10:27 PM
      nice job!!!!!!!!!!! keep doing that way

cptsnoopy ( MSG #241, 10-23-2010 12:15 AM
      Interesting, my Aurora fuel rail was mostly straight. Straight enough that I decided to leave the stock quick connect fittings on and run it as is. I bought it and the pr new so I did not have to worry about it being gummed up. The regulators should be nearly, if not, the same. I know that Russ found some slight difference in the ones he had and my new one but not enough for me to be concerned. The engine looks awesome. I did not think about the idler being on the other side of the belt... When I bought my PS delete pulley I just went to the local auto parts store and bought a Dayco brand. Hopefully it'll last a while. Good luck getting the "perfect" length belt.


Bloozberry MSG #242, 11-01-2010 03:34 PM
      OK, it's been a week since I last posted up some progress, so let's play a game. Can anyone spot what I've been up to?

[This message has been edited by Bloozberry (edited 11-01-2010).]

topcat ( MSG #243, 11-01-2010 03:53 PM
      I see you got the fuel rail polished and installed.

Looks good -

Bloozberry MSG #244, 11-01-2010 04:49 PM
      True... but that's not it.

FieroDev MSG #245, 11-01-2010 05:12 PM
      wiring by chance?

Bloozberry MSG #246, 11-01-2010 05:37 PM
      You'll have to be more specific.

topcat ( MSG #247, 11-01-2010 05:47 PM
      I saw the labled wires coming from the fuel log area, but I am not familiar with the N* engine, so I am clueless what those wires are for.

Erik ( MSG #248, 11-01-2010 05:50 PM
      the injector wiring is inside tubing

Jefrysuko MSG #249, 11-01-2010 07:34 PM
      And you installed the dipstick!

Bloozberry MSG #250, 11-01-2010 07:38 PM
      Bingo, Jefrysuko figured it out! Just kidding... Erik was right. I kinda figured it would take someone with a Northstar to spot the difference. I wanted to finish off the "cleaned-up" manifold look by hiding the wire harness to the injectors. My first thoughts were to run them underneath the intake in the valley between the cylinders, but that would've meant having to drill additional holes in the plastic somewhere to get them on the right side of the manifold again. The space is there to do it, but I wasn't keen on removing some of the webbing under the manifold to accomplish it that way.

So, on to door number 2: stainless tubing. I figured by mimicking the contour of the fuel rail with a second stainless tube, it would fool most people into thinking it's part of the stock fuel system, like a return line or something. The fuel rail is 1/2" OD, so I didn't want to go any larger than that if possible, so I played around with some carbon steel tubing just to see if I could bend it with the right radii, and if all 19 wires would be able to fit into that tight little tunnel. That's where the first hurdle was. The steel tubing had 3/32" wall thickness and was just too tight to fit them all in. After about a week's worth of looking everywhere (on-line, locally, nationally, etc) I finally found a source for some stainless tubing 1/2" OD with 0.065" wall thickness for about $1.25 a foot! Considering that the only other places I could find 1/2" OD stainless was at a medical supplies store for over $170 for a 4' length, I figure I lucked-in.

So the first step was to bend it and mock up some stainless legs to hold it at the right height on the manifold. Interstingly, the fuel rail doesn't have two 90* bends in it. It actually is angled along the bottom of the U to follow the angle of the intake runner:

I kind of knew that two legs wouldn't be enough, and was right, so I fabbed up another leg and welded it on to keep the whole thing from teeter-tottering.

Next, with it temporarily installed on the manifold, I marked where the wires would need to come out of the tube to mate with the injectors themselves, and then drilled, and chamfered the holes to keep the edges from chaffing the insulation.

The hardest part was actually threading the wires for the injectors through the tube. At first I thought they'd all just slip inside and everything would be hunky-dorey. Not so. There's enough room inside the tube, but only just enough so the last four wires get really tight. Then I tried fisching them through with extra-tough strings like in the photo below, but there was no way to adequately fasten the end of each pair of injector wires to the string without the string pulling off towards the end. Lastly (and successfully), I threaded one sacrificial spare wire as a fische through each small hole until it emerged from the end of the tube, then soldered each pair of injector wires to it's respective fiche wire to hold it securely, and was finally able to pull each pair through... but not before a lot of silicone spray lube was used up and a lot of swear-words for the last three MAP sensor wires. I then tested each wire end-to-end for continuity just in case I broke any wires internally, and checked each wire to make sure it wasn't shorting to the tube either, but all was good.

Here's a close up of how the wires and connectors protrude out of the tube. I'll still need to squeeze a dab of silicone sealant into each of the small holes to act as both a sealant and a grommet to protect from the steel edges.

And here's a view of the whole harness tube ready to install on the manifold:

Here's how it mates up with the fuel rail to look like it's an integral part of the design. I opted to weld the little legs of the harness tube in such a way that they pick up different fasteners than the fuel rail does since to do otherwise, it would've been difficult to tighten the fuel rail fasteners with the harness tube in the way.

Finally, here's another angle of the whole schemozzle temporarily installed on the manifold as I wait for my good injectors to make their way back to me from a cleaning and rebuilding somewhere in the good ol' US of A. Nice and clean with no wires showing, eh?

Erik ( MSG #251, 11-02-2010 01:39 AM

[This message has been edited by Erik (edited 11-03-2010).]

Erik ( MSG #252, 11-02-2010 01:46 AM
      That"s badass really cleans up the look! I might just do that on my ITB setup thanks for the great idea. Your engine is the best looking one on the forum.

bowrapennocks MSG #253, 11-02-2010 09:18 AM
      A most incredible build. Keep up the great work. I just bought an F40 6SP and just started planning my swap. I have decided on which engine yet. I look forward to how you address clutch/pp, flywheel and axles. Keep going I just can't wait.


aeffertz ( MSG #254, 11-02-2010 02:39 PM
      That injector wiring is very impressive!

BlackGT Codde ( MSG #255, 11-05-2010 07:21 PM
      you my good friend are a REAL technician.
the entire industry has gone the route of parts changing. i think there can still be a market for real mechanic/tech work and doing it right.
following and extremely interested. love the work.
i work at a gm dealer and have never seen anyone even try to use ingenuity like yours.
best of luck to you.
oh and gm reccomends mobil 1 in all the updated northstars with the 305hp rating... ever notice that?

Custom2M4 ( MSG #256, 11-06-2010 10:02 PM
Originally posted by cptsnoopy:


This is how I ran my belt, but I ran it under the idler pully, not over it, without a tensioner.

neverendingproject ( MSG #257, 11-07-2010 06:06 AM
      I love what you've done cleaning up the engine and making it truly show quality. The wiring looks great, keep up the good work.

Bloozberry MSG #258, 11-07-2010 08:25 PM
Originally posted by Erik:

Your engine is the best looking one on the forum.

I think most people would agree that your Northstar with the ITB’s is going to be the best looking engine on Pennocks! That thing just screams exotica.

Originally posted by bowrapennocks:

I look forward to how you address clutch/pp, flywheel and axles. Keep going I just can't wait.

This is my last post on accessories and I’ll move onto the transmission and axles next.

Originally posted by BlackGT Codde:

gm reccomends mobil 1 in all the updated northstars

Thanks for the compliments and for the tip. I was planning on using synthetic oil in this engine after the initial break-in.

As for aeffertz and neverendingproject (NEP for short!), I appreciate your kind words. For Custom2M4, read on... I'd like to know what belt you used.

So then, just to finish off last week’s series of pictures, here’s how I terminated the injector harness wires sticking out of the stainless tube. I had originally thought I’d be able to unplug the connector pins from the back of the connector and fiche them along with the wires through the tube, but there just wasn’t enough room. I made a quick schematic before cutting it off knowing that I’d be in for an hour or so of splicing and soldering it back on the loose wires.

With that done, I waited for the next nice day (it’s been raining for a week now) before heading out to one of the local junkyards in search of a 3.5” idler pulley with grooves to replace the Caddy smooth idler. I think I looked under the hood of every car on the lot before finally finding a ’95 Ford Contour with a 16 valve Zetek engine that had just what I was looking for. The pulley came off of the Contour’s tensioner, not to be confused with the Contour’s idler, which was smooth.

It was in great shape but clearly the wrong color so once I got it home, I pressed the center bearing out of it, bead-blasted, primed, and painted the pulley. Here’s the Caddy idler on the left and the Ford is on the right.

The two pulleys are remarkably similar dimensionally except that the Contour pulley has a much smaller bearing, both ID and OD. The photo below shows the Contour pulley and the Caddy mounting bolt and spacer. The spacer locates the pulley the correct distance away from the block to line up the grooves with the other pulleys. The problem is that the Contour pulley won’t fit on the Caddy bolt and spacer because the Contour’s bearing ID is too small.

To correct this minor problem, I used the poor-man’s lathe and machined the collars on the Caddy bolt and spacer down from 0.662” to 0.590”, which made a nice fit inside the Contour’s bearing.

The next issue was the diameter of the Caddy bolt and spacer’s integral washers. They were too big and when installed, contacted the part of the pulley that needed to rotate, so I chucked them up in my drill press again and machined them down from 1.420” to 1.340”. Here’s a picture of the two pieces where only the spacer (the lower part) is machined down in both areas as compared to the bolt which is still the original size:

Here’s another view of the discarded Caddy idler on the left with an unmodified spacer from my spare engine above it, and the Ford tensioner pulley on the right with the modified spacer above it. It’s hard to see the differences in the bearing inside diameters but if you look at the spacers carefully, it’s clear. One last tidbit before the Ford pulley would line up properly is that the bearing must be pressed into the pulley so that it’s flush with the back side of the pulley’s center bore. This provides the correct offset.

Finding a correctly sized belt was a lot easier than I expected, it just took a lot of sweat to figure out that I actually had the right one. I temporarily installed all of the belt drive system on the engine and carefully measured the planned route of the belt using the original Caddy belt, which is waaaay too long. I calculated that the new belt would need to be an odd-ball 40.5” long... oh great (sigh). I crossed my fingers and called the local auto parts store and luckily they had a six-rib Dayco at exactly 40.5” (part number 5060405). For good measure, I also brought home a Goodyear Gatorback that was 40” (part number 4060400).

After routing the 40.5” belt the way I had originally intended, the tensioner was up against it’s stops (vrtually useless) and the belt wasn’t especially tight. So next I tried the 40” belt and worked like a dog at installing it for what seemed like an hour without any luck… it was just too tight to get on the pulleys no matter how I tried. It’s hard to believe that a half inch one way or the other could result in too much slack or not enough. So then I tried Custom2M4’s idea of reverting back to the stock Caddy smooth idler from my spare engine and running the belt under the idler and ditching the tensioner (I really really wanted to use the tensioner after having spent countless hours polishing it though!) But, neither belt was long enough to reach in that configuration either. I don’t know what belt Custom2M4 used, but the 40.5” was too short and the next size up (46” I believe) was clearly going to be too long.

Finally, I retried my original idea with the 40” belt, only this time I changed the order which I installed things, and it worked. Here’s the trick for anyone duplicating my configuration: First, have only the crank pulley and alternator pulley installed, and slip the belt on those two. Next, slide the modified Caddy idler bolt part way through the Contour pulley and screw the spacer partly on the backside. Then place the idler pulley under the belt and reef up on it as hard as you can to align the bolt with the hole on the block, while a second person screws the bolt. At this point the belt is quite tight and it’s no wonder there wasn’t enough slack to pull the belt over the ridges on the idler when I tried it the first time with the idler already installed. Lastly, to get the tensioner on, there’s only one way. It’s held in place by one bolt but it has an integral pin on the backside that mates with a hole in the block to keep it from spinning on the one bolt. To get the tensioner on, don’t stick the pin in the hole and try to lever the bolt to line up with it’s hole, instead, screw the center bolt into the block part way first. Then, using a ½” ratchet wrench in the square hole on the tensioner arm, rotate the entire tensioner about the center bolt’s axis until the pin lines up with it’s mating hole in the block. At this point the tensioner will be under a lot of tension so you may need someone else to finish tightening the center bolt, drawing the pin into it’s hole at the same time. Here’s the final belt routing:

The Contour’s pulley comes within 1/8” of the Caddy alternator fan (arrow B), but it should be enough clearance not to make contact. The only other issue is with one of the bolts that hold the dog bone bracket to the block (arrow A). I’ll have to replace that bolt with a pan-head bolt to get the necessary clearance… right now it’s touching the belt.

Finally, once I had cycled the tensioner arm a couple times using a ratchet in the square hole, the tensioner settled into a nice spot exactly within the range it was designed to operate in. The picture below shows the little pointer on the stationary part of the tensioner hub pointing at the small raised square that indicates the center of the tensioner arm’s travel. And what you don’t see, is the smile on my face knowing that the engine is basically done .


To solve the interefence between the belt and one of the bolts pictured above, I considered advice from Bubbajoe to buy an allen-keyed socket head bolt and countersink it into the aluminium dogbone mount. Once I had a closer look though, there simply wasn't enough material thickness to the mount to do this. Instead, I used a low profile panhead bolt and gained the needed clearance.

[This message has been edited by Bloozberry (edited 11-14-2010).]

cptsnoopy ( MSG #259, 11-08-2010 01:21 AM
      Just freakin gorgeous! Thanks for sharing.


dratts ( MSG #260, 11-08-2010 10:08 AM
      Are you going to put that engine in your car where it will get all dirty?

bubbajoexxx ( MSG #261, 11-08-2010 05:44 PM
      (arrow A). I’ll have to replace that bolt with a pan-head bolt to get the necessary clearance… right now it’s touching the belt.

replace that bolt with an allen head cap screw and counter sink the bolt head

Bloozberry MSG #262, 11-11-2010 08:00 PM
      Thanks Charlie. As for Dratts... I think this car is going to be a fair-weather baby... and we have clean roads in Nova Scotia (well... until harvest time that is.) Bubbajoe, that is a great idea. I'll post an updated photo when I get around to doing just what you said.

And now… for the transmission. Most people reading this thread are well aware of the incredible deals that were to be had starting about a year ago on Pontiac G6 transmissions, but for those tuning in for the first time, here’s a brief summary. In 2006, Pontiac offered a new higher-powered version of the G6 sport sedan called the GTP. The GTP had a 240 horsepower 3.9 L V6 with variable valve timing which came standard with a four-speed automatic transmission, but for no cost, a six-speed manual transmission was available. The transmissions fabricated by GME in Germany are known as the F40 (RPO code MT2) and came with the following gear ratios: 3.77 / 2.04 / 1.32 / 0.95 / 0.76 / 0.62 / Rev 3.54 with an axle ratio of 3.55 which gave a final drive raito (in top gear) of 2.51:1. The torque capacity was officially rated at 295 lbft.

These transmissions however were superseded in 2007 with ones having slightly different ratios and a few improvements to counter noise complaints, resulting in a surplus of F40’s. Sometime in 2008 these surplus transmissions started appearing for retail sale through a number of online sites for approximately $400 - $500, an incredible deal considering they were brand new, and worth between $4000 - $5000 in 2007. I bought mine from a company in Michigan called Schram Auto Parts for a grand total of $666 including shipping, duties and taxes.

The nice thing about the F40 and the Cadillac Northstar, as many people know, is that they have nearly compatible bellhousing patterns. The major differences are the starter locations, a slight interference with the Northstar’s rear mounted coolant manifold, and one bolt hole that doesn’t line up with the rest. The F40 and the Northstar have been mated successfully by several people here on PFF and the next couple posts will really only be duplicating what has already been done before. The difference is that I hope to provide a bit more detail on how to go about doing the necessary mods.

So then, the first thing that needed to be done was to sit down with a ruler, a compass, and some cardboard to make a template of the F40’s bellhousing flange. With a mock-up traced out, and using the top two mounting holes, I then transferred the template to the rear of the Northstar. That’s when I first noticed the interference with the water log and carefully trimmed out the triangular piece to the left of the picture. Then I measured the location of the starter snout on the engine in relation to the top two bolt holes and traced it onto the template so I could transfer the starter location back to the F40.

Here are the critical dimensions for anyone doing this in the future. Basically locate the center of starter hole 58mm to the right of the top left bolt as viewed from the bellhousing side of the transmission. Then, drop 55mm down at 90* from the top edge of the bellhousing to locate the center of the starter. Use that point to draw a 70mm diameter circle (35mm radius), which is just large enough to clear the diameter of the starter snout.

Use an exacto knife or something similar to cut out the hole since you’ll need to keep the circle for later. Next, test fit the template on the engine to be sure the starter hole is properly located. Once satisfied I had the hole in the right place (if you look carefully, it took me two tries!), I relocated the template back on the transmission using the two top bolts, and colored the edges of the webs that I could see through the starter hole using a red marker. Notice that the hole isn’t centered on the vertical web of the transmission.

Then, to locate the depth of the starter notch on the horizontal web, I took the 70mm round hole I cut out earlier, drew a line through the center of it, and used it to trace a half circle under the horizontal web, lining it up on the red marks I had made earlier. Finally, to get the right depth of the notch on the vertical web, I just measured 35mm from the machined edge back along the intersection of the two webs and then eyeballed the quarter round shape using that mark and the one made earlier on the vertical web using the template. If you can’t follow what I just wrote, then this picture should help:

The next step was what I thought would be the easy part: cuting out the notch. Ha! That aluminium is hard! I first started with a fluted grinding bit on my die grinder and it worked OK for the first bit but then galled up with semi-molten aluminium.

Next, I tried what I call a Zippy-tool… it’s basically a dremel on steroids that uses special bits that look sort of like drill bits, except they’re made to be used like a router. That thing made the going a little easier, but it still took me close to 1.5 hours to do it right, and not have it looking like some butcher with a sawzall did it. The most difficult part was the vertical web since there isn’t a lot of room to manouvre.

Here are the parts (finally) out of the way:

And here I am test fitting the 70mm circle to be certain I cut enough material away both horizontally and vertically.

Lastly, here is the nicely finished notch once I was satisfied the profile was right and after I cleaned the edges with a 2” sanding drum.

[This message has been edited by Bloozberry (edited 11-11-2010).]

dratts ( MSG #263, 11-11-2010 09:30 PM
      I've seen getrags modified the same way for a N*. Needless to say, this is the neatest job I;ve seen on this modification. Nice job!

Bloozberry MSG #264, 11-14-2010 10:03 PM
      (Just a quick side note here: for those that are interested, I edited an earlier post on this page by adding a photo of how I resolved the interference between the serpentine belt and the head of a bolt.)

Next on the “to-do” list was to cut the triangular wedge out of the bellhousing to clear the water manifold at the back of the engine. I simply traced the outline from the template I made earlier onto the bellhousing. Then, to make a nicer radius at the corner where the two cuts meet, I first drilled a hole. I used a cutoff wheel on my die grinder to make the cuts and it went fairly well:

Here’s the little piece once it was cut out. I later used a file and smoothed out the freshly cut surfaces.

With those two modifications done, it was finally time to test-fit the transmission to the engine! The F40 weighs 123.5 lbs wet, according to literature… (they’re only shipped with a small amount of oil in them) so they’re easy enough for one person to handle. When I slid it on, the two alignment dowels on the engine gave me a little grief, but apart from that, it went on with only a small hitch. There’s an engine sensor of some kind (not sure what it’s for yet) on the side of the engine block, in-line with the triangular cut-out on the transmission. The sensor doesn’t interfere, but a spring-clip holding the sensor wraps around to the bellhousing face that gets in the way. For now, I just bent the clip away. Here’s the assembly.

And a top view. It’s amazing how much of the transmission disappears under the water manifold before finally mating up with the bellhousing face of the block. My next big decision is what to do to refinish the transmission. I’m not polishing it, that’s for sure, and I don’t feel like taking it apart to have it powder coated, so painting it to keep it looking fresh might be the solution… but I’m undecided.

Here’s a close up of the area on the transmission where the triangular notch was cut out to clear the water log. I purposefully made it as tight as possible to avoid the appearance of an aftermarket mod.

Those eagle-eyed among you may have noticed an extra piece of hardware in one of the pictures above. Well here it is:

When I travelled up to Ottawa for the Roger Waters concert a month ago, I took a detour up to Ste Sophie in the Quebec Laurentians. The only used parts dealer on in all of Eastern Canada that listed a Saturn Ion / Chevy Cobalt SS jackshaft was up there. This one is actually from a 2007 Ion. Not including the cost of the detour, it was $108 after taxes.

Zac88GT came up with an ingenious way to mount the jackshaft bearing carrier to the Northstar here about 2/3 of the way down the page: but I decided to do things a little differently. Over the next couple posts I’ll cover what I’m doing, as well as the mods to be able to use as many of the bellhousing bolt holes as possible since some of them aren’t threaded and one doesn’t line up.

War Hammer ( MSG #265, 11-15-2010 01:00 AM
      It is a work of art.

doublec4 ( MSG #266, 11-15-2010 01:01 AM
      Very nice!

Chrome paint the transmission and it should match fairly well I'd think.

aeffertz ( MSG #267, 11-15-2010 08:54 PM
      I think the silver on the trans. looks good as is. What if you painted it with that same, glossy red?

Nashco ( MSG #268, 11-18-2010 12:26 PM
      I vote for leaving the trans as is. If it isn't seeing salt (or much moisture, for that matter) it won't get funky and should be fairly easy to keep clean.


Bloozberry MSG #269, 11-19-2010 10:26 PM
      With the transmission-to-engine installation mocked up, there’s tons of measurements to take for future reference to help determine where on the cradle the powertrain can potentially be installed. The most important one is fore and aft axle alignment in relation to the hubs. Unlike universal joints, CV joints don’t mind running at angles but even so, the idea of placing the transmission output shafts in line with the wheel bearings is to prevent the axle from becoming the limiting factor for suspension travel. With that in mind, I needed to get the jackshaft rigged up so that I would have a much better ability to measure and line up the transmission output shaft in relation to the passenger side hub, which is a long, long way away from the transmission!

I decided to use a jackshaft primarily because I am widening the track width of the car by 3” on each side. Without a jackshaft, this would have meant trying to find a passenger side axle that is about 4” longer than the stock Fiero axle. (The extra inch comes into play because the F40 differential is also shifted 1” further to the driver’s side of the car in relation to the bellhousing surface.) I don’t think I would’ve been able to find any such beast without expensive custom fabrication. Using the jackshaft, it will be easy to find an axle with one set of splines already matched to my needs, and the most it will need is shortening and splines machined on the other end. This will be considerably cheaper than buying a totally new custom-made extra long axle. There are other benefits too.

Here’s the 2007 Saturn Ion jackshaft cleaned up and disassembled. It’s really quite easy to take apart, all you need is a pair of good snap ring pliers and an arbor press to get the bearing out of the carrier, and the bearing off the axle. The bearing is located in the housing on the left hand side of the picture by an integral backstop machined into the housing. To keep the bearing from walking out of the housing on the right side, there’s a ring (the piece to the extreme right of the picutre) that bolts to the housing and sandwiches the bearing against the backstop. (Notice these are SAAB parts!)

I needed to visualize where the jackshaft bearing would be located and what bosses on the engine might be available to hold it in place, since the Ion bearing housing wasn’t lining up with anything. I temporarily installed the jackshaft into the F40. Unlike the Fiero transmissions, there aren’t any snap rings that hold the jackshaft in the transmission, rather, this function is performed by the bearing housing.

After lots of eyeballing, there just didn’t seem to be a good way to fabricate and mount a custom housing because the bearing fell too close to the bosses on the block to make good use of them. Then in a fluke, I installed the OEM automatic transmission bracket on the engine and the light went on.

It still took a little figuring out, but the OEM bracket afforded a nice strong base from which to work with. It also placed the mounting holes for any new bearing housing design in a much more favorable orientation to work with. (BTW, the dullness of the block is due to me having sprayed it with WD40 to keep it from oxidizing.)

The next challenge was to find a way to measure the distance from the holes in the yellow bracket to the centerline of the of the axle in free space. After some thought, I fabricated a preliminary jig out of ¾” plywood that would hold the bearing and that I could then install on the axle. I cut the wooden jig to a 4-1/8” outside diameter because I happened to have a hole saw that big and because it left enough material to be able to pick up the lower hole on the yellow bracket, and still clear the block. It could have been any shape but the hole saw was handy.

To make sure I got the bearing at the right depth on the axle, I installed the inboard snap ring, and then pressed the bearing and preliminary jig into place.

Once the jig was securely butted up against the yellow bracket, I double checked that the jackshaft was also inserted the proper depth into the transmission. To do this, I simply made sure the mark on the shaft from the original car's output seal was more or less in line with the F40's output seal. Then, I traced the location of the lower hole onto the jig from the back side of the yellow bracket.

This then gave me a fairly precise ability to measure where the mounting hole was in relation to the center of the axle, and it allowed me to make a few measurements to determine how thick the final housing would have to be to reach the bracket on the inboard side, and yet still locate the bearing in the correct axial position on the jackshaft. With that information, I was able to work up a shape for a new bearing housing that would mate to the OEM transmission bracket. Here is the preliminary drawing I made.

cptsnoopy ( MSG #270, 11-19-2010 11:39 PM
      If it helps, I found that using the stock fore/aft location on the cradle worked fine for mounting the N*. Not sure if you still have the ability to pull that from your setup or not.


dratts ( MSG #271, 11-20-2010 11:07 AM
      Your IFG body will require a 3" stretch on your wheel base. The easiest way is to stretch the cradle and move the top of the struts back rather than cutting the car in half and rewelding it. The N* requires that you move the front crossbar on the cradle forward 3". I've never heard of it done but why not do the stretch on the cradle behind the front crossbar? That way you kill two birds with one stone. (If you like killing birds with stones) My AD355 body has the rear wheel wells moved forward 3" so that I maintain the stock wheel base. If I were doing it over I would use a stock wheelbase body and stretch the cradle instead. Like everybody says, WHAT A GORGEOUS DRIVETRAIN!!

kikinz24 ( MSG #272, 11-20-2010 03:11 PM
      i will say it looks beautiful so far. everyone i know asks me why my motor is still sitting in the garage andnot running in the car and its beacuse im also taking the time to make everything fit perfet for the best look possible. but your build surpasses mine by far.

Bloozberry MSG #273, 11-23-2010 07:57 PM
      Thanks for your comments kikinz24. I’m starting to feel the same way about my project… the completion date just keeps stretching out there on the horizon.

Speaking of stretching, Dratts, I realize that the wheelbase on my car has to be lengthened 3” to accommodate the body. In fact luckily for me, the previous owner already took care of that and did a remarkably nice job doing it too. Mine was stretched in the customary location just behind the cockpit. I’m not sure your idea of stretching the cradle would work. You would still need to move the strut towers back by an equal amount, which would defeat the purpose and make it a lot harder to do.

Anyways, I’ve got more pictures to share so here we go: Once I had drawn out the shape of the jackshaft bearing mount, I wanted to make one out of some scrap hardwood I had lying around to confirm the dimensions were accurate. I cut out the cardboard version and used it to trace the pattern on a 1” thick piece of wood. Then I used a pair of Forstner drill bits to cut the bearing recesses, and a band saw to cut the outside shape.

I used hardwood so I could drill and tap the mounting holes and actually use them. Then I pressed the bearing into the recess and then the jackshaft into the bearing, and finally test fitted the wooden mount to the engine bracket.

I’m glad I took the time to do this extra step because even though I could get the bearing mount to fit, it forced the axle to be raised an 1/8” higher at the bearing end than it was at the transmission end. By raising the mounting holes 1/8” on the final design, the axle would line up perfectly level.

Oh, and here’s another reason why it was a good idea… can anyone spot the problem?

With the drawing finalized, I took a run out to my favorite machine shop where for $60 they sold me a 7” X 3.75” X 1” block of 6061-T6 aluminum, and machined the holes for the bearing. You gotta like that!

It was nice that there were some finely finished square edges on the block since that made locating the mounting holes a piece of cake. I double and triple-checked my measurements and decided it was time to make some aluminum shavings of my own. If you decide to make something like this yourself, make sure you use a drill press otherwise you’ll surely end up with holes that aren’t parallel.

Then I tapped the two sets of holes for metric threads since everything else on the engine and car would be metric. I tapped the mounting holes for M10 X 1.5 and the little bearing retainer holes for M6 X 1.0 if I recall correctly. I almost ran out of length for the smaller tap while trying to cut the threads all the way through the 1” material.

Once that was done, I transferred the final outline of the bearing mount onto the block of aluminum and test fit the bearing retainer just to make a prettier picture.

Then it was time for this thing to shed some weight! Unlike some of the richer people here on PFF with multi-axis computer numerically controlled milling machines, I had to resort to using my trusty-dusty band saw to make quick work out of getting the rough shape to come out. My machine shop asked how many I was going to make and offered to enter the design in Solidworks for a nominal fee, but I couldn't see a big market for it and besides, I wanted it, like now. As I cut through the solid block of aluminum, I started to feel a little like Michelangelo probably did as he was carving the statue of David out of marble, except I was probably more excited.

Here’s the rough cut bearing mount after surgery. It almost looks like a connecting rod… hmmmmm….

A few more operations to get rid of the scars and it wasn’t long before this thing started to look like it might actually belong on my engine. I used a 50 grit sanding drum initially on the edges, and then traded up for one with 100 grit. The drums lasted surprisingly long, in fact I only went through one of each.

doublec4 ( MSG #274, 11-24-2010 09:39 AM
      Nice solution, I love the ingenuity

aeffertz ( MSG #275, 11-25-2010 05:19 PM
      Cool stuff!

crzyone ( MSG #276, 11-25-2010 06:22 PM
      I have not posted on this forum in a long time but I felt I had to. Excellent thread man! It makes me want to build another Northstar Fiero. I sold mine after I had most of the bugs worked out of the Big Stuff 3 ecu on a 2003 engine. I regret selling it and this thread has me on e-bay looking for an engine to build.

Fiero Thomas ( MSG #277, 11-25-2010 07:31 PM
      This is a work of art 100%

Bloozberry MSG #278, 11-26-2010 01:47 PM
      Thanks guys, I appreciate the feedback… it keeps me motivated! Hey Crzyone, it’s funny what comes around, goes around. You were one of the initial guys with your build thread that inspired me to build a Northstar! I poured over a lot of threads before deciding to take the plunge and yours was one of them.

Back on track here… 6061 aluminum is amazing to polish, as I recently found out. I spent about two hours with some 220 grit followed up with some 320 grit and then hit the polisher with the bearing housing. I think I accidentally stumbled on Romulan cloaking technology! Check it out:

I didn’t want to get sanding and polishing grit in the bearing itself, so I did all the dirty work before pressing it into the housing. Here’s my faithful old arbor press squeezing that sucker into its new home. I apologize for the glare (then again, no I don’t!).

To craft the perfect bearing housing, I would have had to use an aluminum plate 1-3/16” thick. This would’ve given enough backspacing on the housing to mate up with the yellow bracket, and enough material on the front face of the housing for the bearing to be recessed ¼” into the front face. The ¼” is needed so that the countersunk bearing retainer sits correctly. Since the only available plate at the time was 1” thick I decided to make the housing full thickness on the back-side where it meets up with the yellow bracket, which meant that the front face would be 3/16” shallower than ideal. The only impact of having done this is that I’d need some 3/16” spacers for the bearing retainer, so I quickly fabricated some up from some spare 5/8” diameter aluminum rod I had laying around.

And since a picture says a thousand words, here’s where the spacers needed to go to make everything hunky-dorey. (I’ve only partly de-cloaked the housing so you can see what’s going on.)

Here’s the old Saturn Ion bearing housing and my new one, side by side for comparison. I’m glad I didn’t bother trying to polish all the nooks and crannies on the Ion mount, I’d probably still be at it! It’s probably only made of white metal anyways and would have corroded within a couple months.

I roughened up the powder coating on the jackshaft with a Scotchbrite pad, undercoated it with some white paint, then hit it up with John Deere yellow. Once it was dry, I was able to press it into the bearing.

With done, all that was left was to install the assembly into the transmission and bolt it up to the old Caddy transmission snout bracket.

Initially, I found that the axle didn’t turn very freely, so I removed it and elongated the holes in the yellow bracket by about 1/8” closer towards the engine and tried it again. After a bit of adjustment up and down and sideways, I managed to find the sweet spot and tightened it up. In this shot, you can see why the through-hole in the back of the housing needs to be a certain diameter. It has to be large enough to insert a pair of snap ring pliers to remove the ring if necessary.

Finally, here’s the view from the wheel-side of things.

Now it’s time to get busy field-stripping the dilithium reactor, realigning the power tunnel, and fixing the impulse drive on the warp core. Geordi LaForge.... uhhh... I mean... Bloozberry out.

GT-X ( MSG #279, 11-27-2010 10:27 PM
      Amazing work, keep it up!


drive135mph MSG #280, 11-29-2010 11:34 PM
      I love your attention to detail

Erik ( MSG #281, 11-30-2010 05:00 PM
      You're looking a little pale there La Forge ..time for a holodeck vacation

litespd MSG #282, 12-13-2010 10:18 PM
      Time for a bump to keep this on page 1.....

Bloozberry MSG #283, 12-17-2010 03:36 PM
      Thanks for the bump litespd. I know it’s been a while since I posted an update, but I haven’t been sitting on my hands. I’ve been meticulously drawing out the stock ’88 cradle electronically for reference as I plan my own cradle design, plus Christmas shopping, filling out cards, and attending parties have gotten in the way, and most recently we had a 3 day power outage and property damage from 140 km/h (~90 MPH) windstorm. Wild weather!

Anyways, I thought I’d take this chance to make a quick update on fuel injectors. Rather than replacing the OEM injectors with after market ones, I did some research and got some opinions here on PFF about cleaning them instead. There aren’t any shops in Canada that I could find that provide an uninstalled injector cleaning service, so I settled on sending them to an outfit in Oklahoma called Deatschwerks Great company: fast turn around and a full report for $19 per injector. They disassemble, ultrasonically clean them, replace the internal filters, external o-rings, and test the coils, spray patterns, and compare flow rates. Not bad at all. Here’s my report card following cleaning. I can live with the 3.7% difference between the highest and lowest flowing injectors. Once I got them back, I masked the lower halves and painted them, of course, yellow!

Now back to the transmission-to-engine mounting fun. Anybody who’s swapped a Northstar already knows the basic issues with mating one up with a standard GM Metric bellhousing pattern, but for those who aren’t familiar, this post is for you. For starters, here’s the rear view of the N*:

I’ve labeled the six locations for bellhousing bolts to illustrate which ones need massaging for the F40 transmission. The problematic holes are B, E, and F. Unfortunately there’s not much that can be done about mounting hole B. It’s not drilled or tapped on the N* for good reason. There simply isn’t enough depth of material between the bellhousing flange surface and the side wall of cylinder #8. It may be possible to safely drill and tap the location up to 3/8 of an inch deep, but then it wouldn’t serve much purpose, and it would more likely distort the cylinder wall or pull the threads out if any amount of torque were applied. Hole E is simply an unthreaded hole with an alignment dowel pressed into it, so it can’t be used as is to secure the transmission. The hole is waaaay larger than the M12 bolts used to mate the transmission to the engine. Finally, the problem with hole F is that the hole in the transmission bellhousing doesn’t line up with hole in the engine block.

I started by addressing hole F. First, with the transmission mated to the engine, I drew out the dimensions of the two holes in relation to each other. This was an extra step I took so that anybody doing this in the future can design their own coupler with the key dimensions from the drawing. After some research, I decided to follow a similar (though not identical) design that PFF member “buds” used here, about 2/3 of the way down the first page Note that regardless what design you use, there will be a need for some grinding on the engine flange since it covers a small arc of the actual bolt hole on the transmission.

With my drawing in hand, I transferred the dimensions of the larger area I wanted to grind off the engine flange onto the flange itself. This is the view looking rearwards. (I traced the cut-out electronically onto the photo because there were too many reflections to see them properly in the photo.)

Then I used my handy grinding burr to remove the excess material. It ground down surprisingly easily, though I had to stop a few times to clean the bit to keep it from galling.

And here’s the finished product, although I had to make a few minor adjustments later on, which I’ll describe later.

Next I needed to make my adapter. I started out by cutting a 1-3/16” length of 1” diameter steel rod. It goes amazingly fast with the right tools!

Then I fabricated the flat portion out of ¼” steel plate, drilled the 1” diameter arc using a hole saw, and finished by beveling the edges for good welding penetration. Here are the two pieces clamped in the vise ready to be fused into a single piece.

A quick zip-zap with the MIG welder on the inside and outside of the mating surfaces.

… and here’s the finished product once the welds were ground down smooth, and after a quick trip to the lathe to drill the 1/2" diameter hole through the center of the rod. The inside filet is the reason I needed to make a few adjustments to the engine flange notch. To make the adapter sit properly, I needed to grind a beveled edge on the flange.

The moment of truth actually took a few test fittings since I found I hadn’t ground away enough aluminum from the flange even after beveling it. No biggie. To install the adapter, I used an M12 X 1.75 X 70 (12.9) in the lower hole, and an M12 X 1.75 X 35 (12.9) in the upper hole.

Edited to change bolt lengths used.

[This message has been edited by Bloozberry (edited 02-21-2011).]

BMTFIERO ( MSG #284, 12-17-2010 04:50 PM
      I want to thank you again for taking the time for starting and maintaining this thread you have really made my swap a lot easier.

Bloozberry MSG #285, 12-18-2010 01:30 PM
      Next up was to figure something out for hole E. I did a bunch more research here on PFF but couldn't find anyone who had used this hole for a bellhousing bolt. Again, the problem with this hole is that there’s an alignment dowel pressed into it, but the inside diameter is not threaded at all. To make matters worse, the alignment dowel is pressed in very tightly making its removal very difficult. At first I tried the same method I used to remove the cylinder head dowels by shoving a steel rod down into the ID of the dowel to prevent the sides from collapsing as I tried clamping and turning the dowel with Visegrips. It wouldn’t budge and ended up galling up the sides of the dowel. I didn’t think of taking pictures at the time since I didn’t think removing a dowel would be worthy, but I took some afterwards given what I had to do to get it out.

After some measurements I found that the ID of the dowel was just about right to cut some 5/8” threads into it, and I happened to have the 5/8” X 11 tap handy from when I used Norm’s head bolt insert kit. So at first I thought I would just tap the OEM dowel ID, and up-size the bellhousing bolt to 5/8”. But then I realized that wouldn’t provide any clamping force because the dowel isn’t mechanically locked to the engine block except through an interference fit. But it did give me an idea on how to go about removing the dowel, so I tapped the ID anyways. Here it is mocked up with the tap after I actually got it out.

Then, using a spare insert from Norm’s headbolt insert kit (he sends you 21, but you only need 20), I threaded it into the dowel, and then threaded one of the used head bolts into the insert.

Finally, using a slide hammer under the head of the bolt, I was able to pull that sucker out of the block. What a PITA!

Now to make hole E useful, the idea was to fabricate a new alignment dowel that was threaded both on the outside diameter to lock it to the block, and on the inside diameter to allow a standard M12 x 1.75 bellhousing bolt to be used to bolt the tranny to the block. I drew out a schematic of what the new threaded alignment dowel should look like with the appropriate measurements so you don’t have to go through it all yourself:

To make it, I bought an M20 X 2.0 X 60 bolt ($3) and had a friend with a machine shop remove the head, then machine the threads off one end along an 8 mm length to a new OD of 18.5 mm, which is equal to the OD of the OEM dowel. You’ll notice from the picture that it didn’t end up removing the entire depth of the threads, but that doesn’t matter. This will be the end that will stick out of the block. Then he drilled and tapped the core of the new dowel for the M12 X 1.75 bellhousing bolts, and finally cut it to the correct overall length.

Next step was to tap the engine block where the old dowel was. The hole, as mentioned before, is 18.5mm in diameter, so that’s why I went with the 20mm bolt for the new dowel. I bought an M20 X 2.0 end tap ($36) and threaded the engine hole without any problems.

Just be careful if you do this not to over torque the tap as you reach the bottom since you risk stressing the cylinder wall.

The rest was a walk in the park. I just screwed the new threaded alignment dowel into the block (I’ll use thread locker for the final installation later on).

Make sure that the OD threads of the dowel are completely recessed into the block and that the only part protruding is the part that the threads were shaved off:

And install the transmission.

I used the following length M12 X 1.75 bolts in the locations identified in my last post: A = 50mm, B = nothing, C & D = 70mm, E = 30mm, F (top) = 35mm, F (bottom) = 70mm.

Amida ( MSG #286, 12-18-2010 08:15 PM
      Wow! That looks so clean. Nice work.

fierogt28 MSG #287, 12-18-2010 09:10 PM
      Blooze, this is probably one of very few detailed engine swaps here I've ever seen on PFF. I love the fact that you describe / mention / show what is going into the project. Plus the cleanness and show quality that is going into it. I'm not a fan of yellow paint, but that's your taste and preference. The top intake that is painted "fire red" is an awesome color; very hot.

Not just putting a engine and tranny together is the issue here, its all in the detail and recommended torque values indicated. Not many folks respect doing that when doing assembly. You know what I mean, not just torquing the heads down and the rest isn't important.

You do quality job and in the end it pays off, big time !! Plus you got on hell of a nice swap ! :P

Have a good X-mas...

DeLorean00 ( MSG #288, 12-18-2010 10:17 PM
      Wow!! Your work is simply amazing.

What is your background if you don't mind sharing? Fabrication skills like this don't just come out of thin air.

Bloozberry MSG #289, 12-18-2010 10:47 PM
      Thanks for the compliments Amida, fierogt28, and DeLorean00. I sometimes wonder whether I'm overdoing it with too much info and too many pictures of stuff that may be obvious.

Originally posted by DeLorean00:

What is your background if you don't mind sharing?

I'm an ex-military aircraft engineer. I retired six years ago as the senior aircraft maintenance officer at the headquarters level on Canadair Challengers, the Snowbirds aerobatic team aircraft (Tutors), and the now retired T-33's, and F-5's.

17Car MSG #290, 12-19-2010 12:17 AM
      On the contrary, the more pictures the better. Have leaned so much from this thread already.
Have you figured out how to wire up the alternator yet?

DeLorean00 ( MSG #291, 12-19-2010 12:50 AM
      I assumed aircraft. It shows in your work. With aircrafts you have no choice but perfection.

BTW, keep up the detailed log. It reads like a good book. Plus we all can learn a thing or two from someone with your level of experience.

[This message has been edited by DeLorean00 (edited 12-19-2010).]

dratts ( MSG #292, 12-19-2010 09:55 AM
      Ditto! I'll never be able to come close to doing your caliber of work nor can I afford it, but I always await your latest post with great anticipation. I appreciate the work that you do and the effort you put forth to share it. Thganks again

Bloozberry MSG #293, 12-22-2010 08:59 PM
      You guys are what makes keeping this thread fun for me. For 17Car, I haven't started sorting out the electrical issues yet, which I know there will be plenty. I'll probably start that part of the project after the cradle.

The Northstar and F40 at this point are only temporarily mated since the clutch and flywheel aren’t yet installed. I am still contemplating the pros and cons of various flywheel configurations and clutch suppliers, but that didn’t prevent me from progressing in other areas. For starters, the old 2.8L engine and auto tranny had to come out of the chassis. Here it is, albeit a little out of focus, looking a little lost in the engine bay of a “Ferrari”.

The way I remove the engine and cradle from a Fiero is by jacking it from both sides of a 6” X 6” or 4” X 4” post slid under the area just ahead of the front cradle mounting ears. If you choose to do it this way, you must be sure that either the jacks are free to roll forward or the front wheels of the car are free to roll backwards, since the jack pads move fore and aft relative to the body of the jacks as you raise them. Catastrophe awaits those who don’t heed this advice.

Once the car is raised high enough for the plenum to clear the lower passenger side frame rail, I roll the engine out from the wheel well. You don't have to raise the car nearly as high if you pull it out of the wheel well compared to pulling it out from the back of the car because the trunk floor sits considerably lower than the side frame rail.

This car was an automatic, making my conversion a little more involved that it otherwise could’ve been had it started out life as a manual tranny car. It’s a low mileage one though with only 97,400 kms (60,900 miles) since the car has been on jacks since 1999. It still has the (piece of junk) pellet style OEM catalytic converter! I had hoped to use the ’88 cradle for my Northstar as many have done, so I proceeded to separate the 2.8/auto combination from it. This is always a fun time because a little effort produces huge visual results.

Here's the cradle with the engine removed:

I’ll probably rebuild the '88 engine and keep it as a spare, ready to drop in my ’86 GT if it ever needs it. I also have an ’85 parts engine that could be rebuilt but I don’t think I could ever justify the expense. It’s going to be hard enough to justify rebuilding the ’88! The transmission is up for grabs though since I can’t ever see myself using it.

And here’s the shoebox that the Northstar will some day occupy. It should fit with a little more room to spare than most of the Fiero N* conversions since the frame had already been stretched 3” when I bought it (thanks Rick!).

[This message has been edited by Bloozberry (edited 01-08-2011).]

Rickady88GT ( MSG #294, 12-23-2010 01:46 PM
      I like your work You have given me some ideas.
IF, I could give a bit of advice I would recommend starting the engine on the cradle outside of the car before the installation. That way It is SSOOOO much easier to trouble shoot any problems. Just don't run the water pump dry They are enough work just to remove and install once, don't want to have to do it more than needed. It is amazing how easy it is to have one bad wire after doing 100+ splices. I was even able to check for exhaust leaks and water leaks.
I have done this with every swap I have ever done.

[This message has been edited by Rickady88GT (edited 12-24-2010).]

355Fiero MSG #295, 12-23-2010 04:17 PM
      Good job Blooz;

I see you have a 355 kit very similar to my kit that I started out with. Attached rocker, dip in the rear bumper and the rear bumper slopes up toward the rear fender well.

I can email you how to line all that up if you like. I did the same thing on my 355 build as well as separated the rockers and redid the rear bumper to level it out and create more definition in the lower rear bumper area. Not to much work and it really makes a difference in the final look of the car.

I will be done my 308 conversion this January and then it is back to the 355 to finish it off as well.

Keep up the great work and posting pics.


Bloozberry MSG #296, 12-24-2010 10:05 AM
Originally posted by Rickady88GT:

I would recommend starting the engine on the cradle outside of the car before the installation. It is amazing how easy it is to have one bad wire after doing 100+ splices. I have done this with every swap I have ever done.

Hi Rick, thanks for the advice. I hear what you're saying, and I may be tempted to try that once it's mounted to the new cradle, although I find the propsect rather intimidating.

Originally posted by 355Fiero:

I can email you how to line all that up if you like. I did the same thing on my 355 build as well as separated the rockers and redid the rear bumper to level it out and create more definition in the lower rear bumper area.

Great minds think alike there 355Fiero. These are all things I plan on doing to my car as well. I can't stand the rockers being part of the doors, nor what the car looks like when you open the doors with them that way. I don't want to spoil all the surprises on what I'm going to do to my car here in the thread yet, but suffice it to say that the poor IFG body is going to go through a make-over. I'd love to see how you did yours for inspiration, I'll PM you my email address. Merry Christmas!

[This message has been edited by Bloozberry (edited 12-27-2010).]

Bloozberry MSG #297, 12-30-2010 10:17 PM
      With the old engine off the cradle, assessing the cradle’s condition was the next step. I wasn’t prepared for what I’d find, that’s for sure. The cradle was covered in grime and loose scaly rust so the first step was to wash it in varsol and take it outside to sandblast it. From this picture, you can see that I didn’t bother sandblasting the whole thing once I realized the condition of the cradle.

I could see that there was some serious hidden rust in key areas so the first thing I did was cut off the front engine mount shelf to get a better look. It wasn’t at all inspiring. This is the right hand cradle side rail under the mount.

Here are the two mounting points for lateral links on the right hand side. Not much structure left holding the rear mount in place. If you look carefully to the left of the photo, you can see where some one tried to weld up some of the holes with sheet metal.

Here’s the inside view of the left hand cradle side rail. Most of this rust damage wasn’t visible before I started sandblasting. It’s like Swiss cheese! The thing is, that with this level of perforation rust, you just know that the rest of the structure is only a fraction of the original wall thickness, even though you can't tell from the outside.

And this is the rear-most lateral link mount on the LH side rail… it’s barely hanging on! Again, somebody tried to salvage the cradle with a few patch panels but obviously wasn’t aware of the extent of the damage I uncovered by sandblasting.

The front cradle mounts weren’t spared from the rust bug either. This is the left hand one that’s eaten through in a critical area as well… the left-most hole is the trailing link mounting point that takes all of the accelerative and decelerative forces of the rear suspension.

And here’s the rear transmission mounting pocket. I’ve played with the contrast of the picture to highlight the problem. One thing this project has taught me is that the corollary to "Ignorance is bliss", is "Knowledge is bliss for Visa".

bubbajoexxx ( MSG #298, 12-30-2010 10:44 PM
      bad case of road salt termites

Erik ( MSG #299, 12-31-2010 05:34 AM
      Wow that's some bad cancer as it wasn't readily apparent. Now I have to go out and recheck my cradle even though I have already. What state was the car used?

cptsnoopy ( MSG #300, 12-31-2010 06:00 PM
      Wow, sorry to see how bad that is... I am curious to see if you look for a replacement that you will have to modify or just make another using this one as a template?

Other than the above issue,

Happy New Year!


motoracer838 ( MSG #301, 01-01-2011 12:46 AM
      Blooze, that cradle is painful to look at. I just hate it when a project takes a turn like that. Seeing what you've done so far, I think I can guess what you might do about the cradle, but I'll let you suprise us.


[This message has been edited by motoracer838 (edited 01-01-2011).]

Rickady88GT ( MSG #302, 01-01-2011 03:55 AM
      Is the car that bad too?

Bloozberry MSG #303, 01-01-2011 10:30 PM
      Erik, the car was from Ottawa Ontario, lots of salt used on the roads there. Rick, luckily the rest of the car seems really good. There’s a few little spots that’ll need a little attention, but nothing more than some stripping, priming and painting.

Charlie, Motoracer is on the right track. I won’t be needing another ’88 cradle… at least I hope I won’t!

So I’ve been quite busy over the last couple weeks chipping away at some drawings of the ’88 cradle. I figured that before I cut out the front cross member, I should have some decent measurements of the whole thing. I was aware of the cradle drawing in the service manual, but if you’ve ever had a close look at it, there’s really not a lot of information contained on it, only the relative positions of the various mounting holes to one another, but not to any other part of the frame. My initial scope was to plot only enough information to assist me in designing a new cradle, but of course that turned into measurements of just about everything.

So for what it’s worth, here are the fruits of my labor, to be copied at will, I only ask that if you use them, to give credit where it’s due. I can email anyone with larger and greater resolution versions if so desired. Understand that in order to post them, I had to chop up the much larger diagram into it’s different views, so in many cases, if you’re looking for a measurement that isn’t in one view, it will be in another.

Here’s the front view of the cradle:

The top view:

The RH side view (which is nearly identical to the LH side view, so I didn’t bother drawing it out):

And the rear view:

With this work done, I was ready to start mocking up my spare Northstar to the old cradle to get some engine-to-tranny-to-cradle reference measurements.

[This message has been edited by Bloozberry (edited 04-01-2014).]

fieroguru MSG #304, 01-02-2011 12:05 AM
      Those are some pretty detailed drawings... I just imported the PDF of the service manual dwg into AutoCAD, scaled it to some known dimensions, and then outlined it... but then found out that the service manual drawing isn't square.

I would love a copy to add to my drawings. Please email it to

Once you start building a new cradle, I recommend you lower the bottom of the cradle about 1" and push the side rails further out (not as much material inboard of the lateral links) to gain more clearance for the F40. Doing so will allow you to mount the engine/tranny as low as possible without the cradle rail getting in the way or the oil pan sticking below the bottom of the cradle.

I guess since you are doing a 355 with a wider stance, you could just build the extra width into the cradle as well.

[This message has been edited by fieroguru (edited 01-02-2011).]

Bloozberry MSG #305, 01-02-2011 01:48 PM
      Fieroguru, these are all excellent ideas. I'm still in the brainstorming phase of what to incorporate into my new cradle. Moving the frame rails outboard was one of the top priorities to make more room for the powertrain. And although I've already bought Held's 6" track width control arms, I may still choose to move the control arm mounting points outboard another inch too. That will open up a larger variety of wheel options given the rather limited offsets available for some of the nicer wheels I've been eyeing. There's no point in using spacers if I can design them out of the equation!

I'm not sure I understand your rationale for lowering the bottom of the cradle though.

Another major consideration is raising the control arm mounting points since I will accomplish getting the wheels at the right height in the wells by a combination of adjustable coil-overs, and raising the strut tower mounts. With no other mods, this of course would angle my control arms upwards and alter the dynamic camber change. So raising the mounts should restore the stock geometry while raising the wheels into the wells. But then I want to research anti-squat, and a host of other issues too, so more grey-matter needs to be exercised.

BTW, I sent you and BMTFiero the source file for the cradle drawings via your email accounts.

fieroguru MSG #306, 01-02-2011 07:28 PM
      Thanks for the drawings. When I get an afternoon or two, I might put them into AutoCad.

As for lowering the bottom of the cradle, this allows you to lower the drivetrain to lower the CG and give you more clearance to the decklid hinge boxes, but doing so puts the axles at an upward angle as they go to the wheels. In the end it is a matter of personal preference.

Raising the front mount for the lateral link will reduce squating and is farily easy to do. Raising the lateral links at the cradle with the F40 is going to be a challange... not much room to move them, unless you raise the entire drivetrain. Depending on where you place the axle centerline vs. the wheels a large bolt boss will be very close to the front lateral link mount.

I am looking forward to seeing what you come up with for a cradle!

BMTFIERO ( MSG #307, 01-02-2011 11:01 PM
      Thanks Bloozberry,
I got the drawings you sent me I am going to try to convert them to CAD.

FieroWannaBe ( MSG #308, 01-07-2011 11:31 AM
      I wanted to just ask if you have recorded the wall thickness of the cradle. Is it mostly uniform for its members?

Bloozberry MSG #309, 01-08-2011 11:04 AM
      FieroWannaBe: I took measurements from several places on the cradle to determine the original thickness of the metal and I got anywhere between 0.090” to 0.100”. The rustiness probably had an impact on the variability in wall thickness, but this should give you a range to work from.

One last thing I did before cutting off the front cradle crossmember was to mock up the new Held’s rear tubular control links just to make sure they would align as promised. Here’s a sneak peak at what’s coming in the next post:

As most people reading this thread would know, the placement of the Northstar engine with the F40 transmission interferes with the OEM front crossmember, so the crossmember must be moved forward. I welded in a piece of angle iron between the two cradle side rails before doing any cutting to keep the rails properly positioned in relation to each other once the OEM front crossmember is removed.

I used a cut-off wheel in my die grinder to cut through most of the welds holding the OEM crossmember to the side rails, although it was tricky to get the cutting wheel up the rear wall of the crossmember due to the angles. I found that the crossmember was under some stress because it sprang forward about a quarter inch once the final cut was made on the RH side.

On the LH side, there was just no way to get the cutting wheel in the back corner so I resorted to using an open-ended hacksaw to get the rest of it. You have to be patient though because you can only get a couple inches on each stroke before the blade hits the inside opposite wall. This is where it would be nice to have an oxy-acetylene torch… and concrete instead of wooden floors!

With the final cut done, the crossmember just lifted out.

Here’s the offending piece. If only Pontiac would have had the forethought to install a Northstar-friendly cradle, things would have been a little easier! Surely the Northstar was on the drawing table at the time?

And looky-looky what have we here? More rust hiding in a critical area. Such a shame to have more iron ore than steel on an ’88 cradle.

Here’s the overall view of the cradle without the OEM front crossmember. Again, the reason for me doing this even though I don't plan to use the cradle at all, is to be able to properly locate the engine and transmission assembly in relation the OEM cradle mounts, which dictate the location of the axles.

I’m using my spare engine for the mock up purposes so as not to accidentally damage my beauty queen. After setting the ugly sister on the bench, I had been hoping to be able to slip the cradle over top of it to get it in place… no such luck! So I needed the engine hoist again to make it right.

Bloozberry MSG #310, 01-12-2011 11:15 AM
      So then, the next obvious step in the process would be to bolt the transmission to the back of the engine and start designing powertrain mounts. That would be great if the new cradle were going to be similar to the old one, but since I want to make a number of design changes (not all of which are clear in my own head yet), I need to spend more time at the drawing board. My goal is to have the old cradle, the F40, and the Northstar drawn out electronically so I can visualize the interrelationship between things like powertrain placement and planned suspension geometry changes. The electronic format will allow me to cut and paste at will, while minimizing time fabricating parts that don’t fit. Obviously it is going to be a time consuming process to draw multiple scale views of the transmission and engine, so I’ve saved some photos of the suspension upgrade process to keep the thread alive while I'm drawing.

For starters, here’s what the previous owner had in mind to get the wheels out three more inches per side to fill the wheel wells. Yep, three inch spacers:

I don’t have anything against wheel spacers in the rear of a car where steering is not an issue, but moving a front wheel out by three inches makes the center of the tire contact patch walk around a 3” radius rather than pivoting on its center, among many other negative influences. Since I had the money to make it happen, I decided to spring for a better way to space out all the wheels. (BTW, anyone interested in a brand new set of four 3” polished aluminum spacers 5 X 100 on 5 X 100 for $50 each plus shipping, just PM me). This is the HT Motorsports ( tubular rear suspension package, including do-it-yourself adjustable coil-overs, plus new KYB GR2 struts I bought locally. (The eagle-eyed among you will notice that I accidentally included a pair of front suspension parts in this photo too).

Here’s another view of the parts for one side. All kinds of nice new shiny parts! Eric at HT Motorsports will powder-coat your suspension pieces any color you like, although silver is not a common color, so at the time he didn’t keep any in stock. It took an extra week or so delivery-wise before he could fabricate the parts and have them done in my choice of color.

Here’s a few close-up shots of the parts. This is the trailing link compared to the OEM one. The link itself is only marginally longer, but the big difference is in the angle it must meet up with the knuckle:

Here are the lateral links for comparison. The nice part is that all the links came with polyurethane bushings, although recently I discovered that the inside diameter of the sleeves for the bushings had unacceptable variances (Thanks Rodney.)

This piece is an interesting but unfortunate necessity. It’s a strut to knuckle spacer. By moving the knuckle outboard (which incorporates the lower strut mount) the angle of the strut would change significantly if nothing else were done since the strut upper mount is fixed. Two ways to remedy this is to either move the top strut mount outboard as well, or to use a lower strut mount adapter like this. The jury is still out regarding what I will do to solve this problem. I bought the parts, but now I am leaning more heavily towards changing the upper strut mounts for several reasons which I’ll get into later. One of the obvious ones though is to shed the needless unsprung weight of these adapters.

1fatcat MSG #311, 01-14-2011 10:01 AM
      Blooze, your attention to detail is truely amazing! That is going to be one sweet ride! Keep up the great work!

Bloozberry MSG #312, 01-17-2011 07:09 PM
      Thanks 1fatcat. I just noticed that the number of views is now over 15,000! I would never have guessed there would be this much interest.

Anyways, with all the parts on hand to modify my new KYB’s into coilovers, I decided to convert them next. There are lots of threads on how to do this but I figured I’d document the process to buy more time drawing the tranny. Converting them was really quite easy. All it took was a die grinder with a cutoff wheel and a steady hand. The idea was to cut the old spring perch off the strut where it’s been welded on. I cut just above the weld and slowly went deeper until I could just see the underlying strut tube. It almost hurt to take the wheel to these brand new parts.

Once the spring perch was off, it was a simple matter of grinding the weld down flush with the tube body using the bench grinder. I found I had a lot more control doing it this way than with an angle grinder, which others have said they used. I also found that I had to get every last bit of weld off to be able to slide the threaded adjuster tube over top. Here’s the before and after picture of the two struts.

The next step is to slide the threaded adjuster tube over the strut body. It’s a tight fit. It comes to rest on the knuckle flange and would be OK just to leave it like that, but I used a bunch of silicone sealant between the two parts to keep moisture out and to keep the threaded tube from rattling against the strut body. It probably wouldn’t ever make noise given that the spring will always keep tension on it, but there was no harm doing this extra step.

Once that was done, I slipped the springs onto the strut and seated them on the adjustable collar. I was somewhat wet behind the ears with respect to spring rates when it came time to order rear components. On the one hand, I didn’t want a rattle-my-amalgam-fillings-out-of-of-my-teeth ride like my 308 kit, but on the other, I’m planning for only about 4” of ground clearance so it can’t be soft either. Throw on top of that the added weight of the Northstar/F40 and the added leverage of the longer suspension links, I just didn’t feel like I had the ability to choose correctly. So I fed all of my particulars to HT Motorsports and had them recommend what they thought would be the best set up. This was at the time HT was being transferred to the new owner Erik, so I got the “benefit” of the old owner’s experience (Lee, I believe).

Lee suggested 350 in/lb springs in the rear and 325 in/lb in the front, despite my inner voice telling these are going to be way too stiff. He said that if I wasn’t happy with them, and as long as they were still in good condition, he would exchange them. I wonder how many years this offer is valid for… They’re 2.5” diameter X 12” (I believe) in the rear.

Enough about springs… to keep them in place at the top end, it’s a simple matter of sticking on a washer, a shaft bushing, followed up by a polyurethane spring seat, the hat, another shaft bushing, another washer, and the locknut. Tah-da! One adjustable coil-over:

To finish off the assembly, all I needed to do was bolt on the lower strut adapters. They’re heavy suckers though so like I said, I’m going investigate shifting the upper mounts outboard instead of using these.

Here’s what they looked like after they were assembled. I used brand new M16 X 2.0 X 80 (10.9) bolts for them as well as for the ones that will attach the adapters to the tops of the knuckles. The old bolts just didn’t look right all pitted and rusty looking. At $2.50 each, they hardly even register on my cost spreadsheet.

Next up: big brakes… well, rotors anyway.

dhobbs84sc ( MSG #313, 01-17-2011 10:20 PM
Originally posted by Bloozberry:

Thanks 1fatcat. I just noticed that the number of views is now over 15,000! I would never have guessed there would be this much interest.

You deserve the recognition! Amazing job!
Umm.. I think your my dad? Can I come help haha No but really good job!

doublec4 ( MSG #314, 01-17-2011 11:09 PM
      I have KYB's in the rear too, and I went with a 350 lbs-inch spring rate as well.

They're stiff, but not too bad. It's hard to tell how much stiffer it made it, considering I also added poly, and solid cradle mounts at the same time. However, the ride isn't too bad, and I never bottom out which is good news since you're going to have minimal ground clearance. Although you have more leverage on the rear suspension, I would think 350 is a safe bet. Not to mention, I remember reading that anything over 350 isn't recommended for the damping capabilities of the KYB. Otherwise, you might have to go to Koni's.

Looks great as always! Still watching this thread

355Fiero MSG #315, 01-18-2011 03:53 AM

You will still need the lower extensions even after moving the rear shock tower mounts out. I went out as far as I could which essentially used the original outer shock mount holes as the new inner holes and made a new plate on top of the strut tower that stretched the outer mount bolt out. I found that the upper frame rail came into play when turning the strut around so you will still need some extension from the lower solid piece you don't like. I made my own but they are pretty much the same size or maybe a bit narrower but not much. You have a good 4" on each side of the Fiero to extend out with that body you have. It being the same as mine and all......

If you want pics of how I did my strut tower extension, drop me a line and I can send them to you.

Keep it up. It is going to look great when done.


Tony Kania MSG #316, 01-18-2011 12:17 PM
      Dogcreek used 400 # springs on his LS4 build for about a week. The ride was entirely too stiff, and went down to 350 # springs afterward. It is still stiff, but not too much for our aging a$$e$.

Keep up the great work. (We know you will!)


Icelander ( MSG #317, 01-19-2011 11:30 AM
      I ran 250# springs on my '85 2M4 coil-over conversion. I like the ride. I also upgraded from the 13inch steelies to 17inch 45-series tires. The ride got quite a bit harsher after that change but I stick through the corners now much better than before.

[This message has been edited by Icelander (edited 01-19-2011).]

Bloozberry MSG #318, 01-21-2011 08:47 PM
      Thanks son (dhobbs), doublec4, Don, Tony, and Icelander for your input. If Tony says 350 lb spings aren't too stiff for his old creaky butt, then I guess I should be OK, but I hear you there doublec4 and Icelander... springs are only part of the equation. I'll be using polyurethane everything and much shorter tire sidewalls too so it all adds up. For Don, I get what you're saying about moving the tops of the springs too... there gets to be a point where the upper rail is the limiting factor... I hadn't thought that far into it yet. Looks like lower strut adapters might not have been a waste of money afterall! Yay?

OK, back to the thread-building. I lied in my last post. For this story to maintain some semblance of order, the next step has to be about building-up the knuckles. Unfortunately I didn’t take any photos of the knuckles before they underwent a cosmetic surgery, but I’m pretty sure most of you know what a 23 year-old rusty knuckle looks like. Here’s what my ’88 uprights looked like once they spent the day at the “spa” with an exfoliation treatment and some anti-aging "cream":

Because of the different rear suspension links, they’re considerably different than the pre-’88 rear knuckles. One thing GM kept the same on the rear though (luckily) were the wheel bearing assemblies. I bought new SKF units since the old ones had obvious axial and radial play in them. Nice shiny pieces. To help keep the road grime out of the inner bore of the knuckle, there’s a large O-ring that gets sandwiched between the bore and the bearing:

Then it’s a simple matter of placing the bearing on the knuckle and aligning the three retaining bolt holes;

Installing the bearing isn’t rocket science, but since I had the camera out I took a few extra pictures in case someone has never done this before. The bolts that hold the bearing are M12 X 1.75 X 40 and are installed through the road-side of the assembly. Of course the wheel flange would get in the way if it weren't for a machined semi-circle allowing access to one bolt at a time:

Once the first bolt has been snugged-up finger-tight, you have to rotate the flange on the bearing axis until one of other two holes line up, and repeat the process until they’re all finger tight. For the ‘88’s, the three bearing retaining bolts get torqued to 62 lbft.

Next came the caliper adapters. I’m installing the ’88 – ’96 Corvette front 12” brake rotors on the back of my car, but plan to continue using the Fiero calipers for now. Lots of people have done this and it’s an inexpensive way to upgrade. That means though that the calipers have to be moved radially outwards (to accommodate the larger diameter rotors) AND offset slightly inboard to make up for the different offset in the Corvette rotor. That’s where the caliper adapters come in. I bought mine from the now defunct Fiero Addictions. Here’s a close up of one along with the hardware needed to bolt them to the knuckles:

These adapters aren’t marked left or right, or top and bottom, which means you have to orient them so that the caliper ends up being installed a little lower than the OEM location. If the adapters are reversed, the calipers would end up higher up on the knuckle and would interfere with the strut mount.

The reason the calipers are rotated with respect to their stock position is so that they clear the heads of the bolts that attach the adapter to the knuckle. I’ll edit this post and add the bolt specs later, but they get torqued to 74 lbft. Other designs for these adapters have now come out that get around rotating the caliper by using countersunk mounting bolts. I’m sure it’s a good design too, but anyone who’s ever tried to loosen countersunk bolts after years of road use will realize the shortcomings of this idea. The very large contact area under the countersunk bolt heads makes it very hard to loosen them without rounding off the small Allen-key type recesses used to turn them. I've always had bad luck and ended up drilling most of these type of fasteners out after lots of frustration, so I try to avoid them now.

Now the brakes are next.

[This message has been edited by Bloozberry (edited 01-21-2011).]

Bloozberry MSG #319, 01-24-2011 08:26 PM
      The brakes on the ’88 Fieros are different than for all the other years as pretty much everybody reading this knows. The overall diameter stayed the same at 9.7”, but GM finally upgraded the rotors to vented from solid discs. With this upgrade, new calipers were also needed to span the thicker rotor. The new calipers consist of two halves bolted together: one half is cast iron the other is cast aluminum. As mentioned earlier, my new brakes are going to consist of the stock ’88 single piston calipers for now, and vented 12” Corvette rotors. Theoretically, brake performance should improve since the calipers will be acting on the rotors with greater leverage. Practically speaking, I’ll have to wait and see how well it works out and upgrade to multi-piston calipers later if the performance isn’t up to snuff and if the budget allows it.

I didn’t get a good “before” picture of the entire ’88 caliper, so your imagination will need to be put to use again. I did however manage to save a picture of the aluminum half of one of them. Here it is in all its decrepitness:

I bought a couple of caliper rebuild kits, new rubber slider boots from TFS, sandblasted, primed, and painted the cast iron halves, and cleaned up and polished potions of the aluminum caliper halves. When it was all said and done, they came out looking a lot better than they started:

Some of you may frown upon the Ferrari sticker, but I’m not going to spend any time defending them, so don’t waste any bandwidth criticizing. I made them with a sticky-label-making machine and have used them on my 308 kit with great success. They stick like bubblegum to a running shoe on a 112* day… and even better when it’s cold.

With the calipers completed, the next step was to install them on the adapter plates. You need a T55 Torx bit and a torque wrench set to 74 lbft to tighten them:

Here’s how puuuurdy they look once they’ve been attached for good.

And here’s the street side... I find they almost look like four piston calipers... if you squint.

For the rotors, I got lucky when I went to the annual customer appreciation day at the local auto parts supplier. One of the many door prizes included four rotors of your choice… and luckily I happened to know of a car that needed exactly that. I think the owner was hoping that someone with a Geo Metro or a Hyundai Accent would win that prize. Now beggars can’t be choosers, so I did get the rotors but they weren’t exactly what the doctor prescribed. I only needed a little ingenuity and a bunch of time to make them just right. For starters, an old rear bearing assembly, an unused 3” wheel spacer and a drill press were the only bits of machinery I needed… any guesses what was wrong with my rotors?

cptsnoopy ( MSG #320, 01-24-2011 10:49 PM
      Ummmm, needed to have the Fiero bolt pattern drilled?


fierogt28 MSG #321, 01-24-2011 10:55 PM
      Well, probably the inner flange of the rotors wouldn't fit over your wheel spacers (too small). The spacer is too large in diameter for fit on the 88 or Corvette rotor.

Do I win anything...

cptsnoopy ( MSG #322, 01-25-2011 01:25 AM
      After looking again, maybe you decided that smooth rotors just would not look right on a Ferrari so you drilled cool looking cooling holes? I could see where that would take a lot of time...


ArbinShire MSG #323, 01-28-2011 12:52 AM
      After all that work, you're putting on spacers? Spacers that size definitely scream "replica" when viewed....

doublec4 ( MSG #324, 01-28-2011 01:14 AM
      Cross drilled!

Bloozberry MSG #325, 01-28-2011 09:55 PM
      Well, cptsnoopy and doublec4 figured it out. I haven’t a clue what ArbinShire or fierogt28 were thinking. Weren’t you guys paying attention about the part with the HT Motorsports 6" track width tubular control arms? Or when I mentioned the spacers were for sale? I’m starting to think you guys are just looking at the pretty pictures.

Anyways, the Corvette rotors were plain-Jane's and weren't cross-drilled, and they had to be redrilled for the 5 X 100 mm bolt pattern since stock Corvette is 5 X 4.75”. I didn’t trust myself enough to drill the bolt circle so I took the rotors to the machine shop which cost me $20 per rotor. At least I don’t have to worry about them wobbling around off-center like I’m sure they would’ve done had I drilled them! Cross drilling them was something I was sure I could do though. In my opinion, there’s nothing sexier on a big brake package than to have all those little holes in a neat little spiral pattern. I’d never done this before but I figured since the rotors were free I didn’t have much to lose.

The first step was to figure out how the vanes were oriented between the inner and outer rotor faces since I didn’t want to drill into any of them. It turned out they ran radially outwards, not in a spiral like I had hoped. I prefer the look of spiraled holes as opposed to the one that run straight out from the center, but after pondering about it a little, I realized the vane orientation didn’t matter, so I created a little drawing and a template to guide me. (For those of you old enough to remember, I could probably have made use of my old Spirograph to create the template!)

Then I set up the old bearing and spacer in the drill press. The bearing was useful since it turned the rotor into a handy-dandy turntable of sorts, while the 3" spacer kept the rotor from hitting the vise. Once my jig was lined up and leveled, I attached the rotor to the spacer with some lug nuts and was ready to start drawing out my concentric circles. I chucked a marker into the drill, set the correct radius up, lowered the drill just like needle on a vinyl record and spun the rotor. I made 5 concentric rings each 5/16” smaller in radius than the previous one by turning the adjuster cranks on the sliding vise.

Next I used my template to mark where the holes needed to go by lining up the vanes on the template with the vanes on the rotor. One of the benefits of drilling them in the pattern I chose is that the space between each vane only has one hole, except for some of the vanes with the inner and outer-most holes, which have two. By doing it this way, most adjacent holes are separated by a vane, creating an impediment for cracks to propagate from hole to hole. In the few spaces that have two holes, the largest possible distance (greatest material) separates the holes. With the hole locations marked, I started drilling 1/8” pilot holes.

Then I stepped it up by drilling the final diameter. I chose 3/16” after researching typical cross drilled rotors on the internet. At first it seemed a little big, but I like it now.

The final step was to chamfer all the holes to ¼” diameter, more for looks, but also de-burr them and provide greater stress relief. For the previous steps, I drilled right through both layers of the rotor each time, but for the chamfering, I had to do each side separately, obviously.

Here’s a completed rotor. I timed myself in case anyone else thought they might like to try doing this. It took me 2.5 hours to set up the jig and complete the first rotor, then each rotor after that took 1.5 hours. It makes for a long day at the drill press!

For comparison’s sake, I took a few photos of the Corvette rotor with the Grand Am/Beretta rotor (another popular upgrade). The stock Fiero rotors are 9.7”, the Grand Am’s are 10.25”, and of course the Corvette’s are 12”.

Another view of the GA vs Corvette rotor.

For the Corvette rotor to seat concentrically on the Fiero hub, most people know that you need an adapter ring to up-size the lip on the Fiero bearing flange. I got mine at the same time I got the caliper adapters from Fiero Addictions. To install them, it’s a simple matter of slipping it on to the snout and it’s done, but you have to be careful since there is a front and back side to the ring. The back side’s inside diameter is chamfered to accommodate the filet radius where the snout meets the flange.

It should sit nice and snugly against the flange like this… if it doesn’t, then there’s a good chance you have the ring backwards or there some foreign debris between the two.

The last thing to do is slip the rotor on. I’ve found that it can be installed with the caliper already on the knuckle as long as the pads aren’t installed. You have to tip it at a bit of an angle though.

Then to secure it temporarily, I installed a couple lug nuts on a few wheel lugs. Here you can see how the hub centric ring takes up the space between the Fiero hub snout and the larger diameter center hole in the Corvette rotor.

I still need to install the pads, roll springs, and the wire bales, but it’s starting to shape up.

I’m also progressing nicely on my F40 drawings and will soon start working on the N* drawings. I’d like to have them completed before starting the redesign of the cradle. That means I need to stretch out a few more suspension pics to buy time.

doublec4 ( MSG #326, 01-29-2011 12:14 AM
      Shaping up nicely!

Like many others have said, you pay amazing attention to detail, and have great patience when it comes to drilling/polishing/doing it right!

mattwa ( MSG #327, 01-29-2011 04:05 AM
      Awesome! I do have a few questions if you don't mind that pertain to this. First, could I do this to my grand am brake rotors? And second, does cross drilling actually make a noticeable difference, what is the purpose of them exactly?

[This message has been edited by mattwa (edited 01-29-2011).]

fieroguru MSG #328, 01-29-2011 08:05 AM
      Looks good!

I would suggest checking the balance on the rotors once the holes are drilled. The inner portion between the vanes of the rotor is cast and not necessarily uniform thickness and with this variation you could have removed more or less material from hole to hole. Several of the Vette rotors I have used have some balance weights shoved into the vents to balance them and account for this casting variations within the vane sections.

Bloozberry MSG #329, 01-29-2011 08:17 AM
      Thanks doublec4. Matt, you can do this to your GA rotors as well, just be aware that you should inspect the rotors more frequently for cracks that start emanating from the holes. Just Google "cross drilled rotor cracks" images to see what I mean. Some companies now offer dimpled rotors instead of drilling. The dimples are laid out in thte same neat patterns, but they won't initiate any crack sites.

The purpose for cross drilling is mostly cosmetic today, especially on road cars. With older brake pad compounds, the heat generated by braking caused the pad to release high pressure gasses between the rotor and the pad. Without a place to go, these gasses would literally force the pad away from the rotor causing less effective braking. Cross drilling relieved the pressure, but so did modern brake pad materials.

Edit: Good idea fieroguru... I should run them out to the machine shop and get them balanced. I'll post back here with the results.

[This message has been edited by Bloozberry (edited 01-29-2011).]

dhobbs84sc ( MSG #330, 01-30-2011 01:11 AM
      Good Job on the brakes!!

ArbinShire MSG #331, 01-31-2011 12:58 AM
Originally posted by Bloozberry:

Well, cptsnoopy and doublec4 figured it out. I haven’t a clue what ArbinShire or fierogt28 were thinking. Weren’t you guys paying attention about the part with the HT Motorsports 6" track width tubular control arms? Or when I mentioned the spacers were for sale? I’m starting to think you guys are just looking at the pretty pictures.

D'oh! I didn't catch that. +1 for doing it the right way!

Bloozberry MSG #332, 02-07-2011 08:00 PM
      Well I’m running out of rear suspension build-up photos so this will be the last rear suspension post until these parts meet up with the new cradle. I left off the last time ready to install the brake pads so here’s a few pictures covering that aspect. The first one here shows that there are differences between the inboard and outboard pads. The pad on the left is the outboard one and is differentiated from the inboard pad by the lack of the two pegs in the middle of the steel facing seen on the right hand pad. These pegs fit into corresponding dimples in the face of the piston, so the piston must be rotated to have the dimples aligned vertically in order for the inner pad to fit.

When I first tried to install the inboard pad everything was hunky-dorey but when I tried to fit the outer pad into place, there wasn’t enough room even after jimmying the caliper on the sliders to give as much space as possible. At first I thought I’d have to shave the pads down a bit but then got to thinking the piston didn’t look fully retracted. After taking off the e-brake lever and trying to push, rotate, squeeze and use every other possible method of recessing that piston into the caliper some more, I unscrewed the bleeder valve to have a look down the hole. Everything was clean, and by chance, I tried squeezing the piston in further while the bleeder was out and it slid in easily another 3/16”. I discovered that the bleeder valve was screwed far enough into the bore (without the banjo fitting) that it was preventing the piston from retracting fully. Duh!

The extra room was all that was needed to slip both pads in with space to spare. So then came the bail wires, and finally the two roll pins keeping everything together. The roll pins are a press-fit into the aluminum half of the caliper so a couple taps with a small hammer and a punch is all that it takes to seat them.

I decided to build up the rest of the rear suspension off the car so next up was installing the two lateral links. On the ‘88’s, they’re held on to the knuckle with a single M12 X 1.75 X 200 bolt passing through a drilled passage in the lower knuckle. This knuckle hole is notorious for becoming out-of-round and allowing some slop in the bolt, causing problems. Mine were still nice and tight; though I blew them clean with the bead-blaster to clean out the little bit of rust hanging around in them. I ordered new bolts in the smallest order quantity possible for these 12.9 grade bolts (a box of 12) for $100. I actually bought them 220mm long since that way I could cut off 20mm for the rear bolts and use the rest as spares for the hard-to-find pre ’88 front upper control arm pivot bolts as well. I greased them up with anti-seize compound before installing them.

Then slipped the forward adjustable lateral link onto the bolt, then the bolt through the knuckle, and the rear fixed lateral link on the other side.

The nut gets torqued on with 37 lbft first, then turned another 90* for the proper torque. Here I was just getting things snugged up.

After the lateral links, the trailing link was next. At the knuckle it takes an M12 X 1.75 X 65 (9.8) bolt and nut torqued to 44 lbft. The eagle-eyed among you will notice that in this picture, I’m installing the trailing link facing backwards. No biggie, I just swung it around to face the right way in later photos!

Here’s the LH knuckle with all three links attached and again, the eagle-eyed among you will notice that I installed the RH trailing link on the LH knuckle… the telltale sign is that the grease zerk fittings should be on the bottom where they’ll be accessible. I’ll change them around another day.

The last item to be installed was the strut. I’ll probably need to remove them later to install the suspension in the car, so I only installed them loosely for the pretty pictures. It’s held on to the top of the knuckle with huge M16 bolts.

Here’s a close up of all the links attached to the knuckle:

And finally a couple shots of the whole rear suspension for the LH side. I should weigh it, but I’m afraid of what the scale may say!

BtotheB ( MSG #333, 02-08-2011 10:32 AM
      Wow, that's pretty...

Your attention to detail is inspiring! I find myself taking my time more often on my winter projects to get things done right. My skill level is nowhere near yours though, but hopefully my results won't be embarrassing at least.

This is my favourite build thread, partly because of the regular updates! Keep it up..


355Fiero MSG #334, 02-08-2011 11:25 AM

You will want to turn those adapters on the struts over so the strut hangs lower than the knuckle mount. The 355 body kit you have will want the frame quite a bit lower to fill the wheel well properly so having the adapters your way will raise the frame compared to old not lower it. The other way allows for more strut travel compared to your orientation.

Rear setup looks really good.

Keep it up.

Tinkrr MSG #335, 02-08-2011 11:33 AM
      Great work!
One question, will the strut bolts be long enough to acomodate the sway bar bracket?

Bloozberry MSG #336, 02-08-2011 12:48 PM
      Thanks BtotheB (..must be short for "Brad to the Bone" ). Have you got a thread started yet? Canadian winters are perfect for spending long dark days detailing away at things!

For Don: Thanks for pointing out the strut adapters should be turned the other way... I'm not sure I would've clued in on that, but it makes perfect sense. I don't want to have to dial out any more height to the suspension than I'm already having to deal with!

For Tinkrr: The bolt length is another good question since I had overlooked the sway bar until now. I'll check it out later today and report back whether they're long enough or not, and post the details about what dimension bolts are needed. Good eye!

I just knew there were some hawks out there!

Fierobsessed ( MSG #337, 02-09-2011 01:38 PM
      Since you are running poly, I'll recommend that you put a jam nut behind the nut on the long bolt through the knuckle. Many people found that the poly causes the crush nut to work itself loose, even when torqued properly. Even a slight loosening of the nut will cause the toe to move a lot.

Bloozberry MSG #338, 02-13-2011 09:22 PM
      Thanks for the suggestion Fierobsessed. Do you still think jamb nuts are required even with prevailing torque nuts (lock nuts)?

Well Don, I played around with the strut adapters like you suggested and something just doesn’t seem right with them turned the way you suggested. I’m not saying that you aren’t right, but it just doesn’t look like these adapters were made the same as yours… have a look. This is what the adapter looks like on the knuckle with the adapter on the original way I had them:

And this is with the way you suggested. It just looks awkward.

And this is the orientation when installed on the strut the way I originally had it:

…versus the way you suggested:

Beyond the optics of the two orientations, when I tried to install the adapter to the strut the way you suggested, I ran into interference problems. Here’s a picture to show what I mean… I couldn’t get the upper holes to line up enough to get the bolt through:

The interference is between the top of the adapter and the strut body. I would probably have to grind off 3/16” or so off the top of the adapter to rotate it far enough to get the holes to line up. To me, it just doesn’t make sense to install it your way. Installing it the original way I had it won’t raise the car in the rear like you thought. Perhaps one of the photos in my earlier posts gave that illusion, but the adapter will line up straight across, neither raising nor lowering the rear.

So then, on to new things. I’ve finally finished entering the dimensions of the F40 transmission digitally to help me redesign the cradle. Before going through this trouble, I searched far and wide on the internet, at dealerships, machine shops, etc, and made countless calls to GM trying to find someone to release scale three-view drawings of the F40 and the Northstar to no avail. For a while, I thought that I would get something from GM Customer Services, but at the last moment they said they weren’t permitted. Rats!

So here’s the fruit of far more hours of labor than I dare to admit. Each square represents 5mm. I’ll post high resolution drawings of the transmission when I’m finished working up the cradle drawings. It would be nice if Cliff could create a section on the forum for reference drawings like this. Currently I’m working up the rear knuckles, trailing and lateral links too. So here’s the three view… admittedly low rez to get PiP to accept it:

And here are some higher resolution pics of each view separately starting with the end view:

Top view:

And Rear view:

katatak MSG #339, 02-13-2011 09:47 PM
      Truly a work of art Blooz! I wish I had the patience - and talent to get to your level of attentoin to detail. Very nice work you are doing. I am truly amazed. I'm pretty sure I said this somewhere else in the thread but I'll say it again. Thanks for sharing your hard work with the rest of us.


Fierobsessed ( MSG #340, 02-14-2011 12:57 AM
Originally posted by Bloozberry:
Do you still think jamb nuts are required even with prevailing torque nuts (lock nuts)?

Yes, the issue is that even nylock, crush nut or lock nuts CAN be rotated loose, and poly loves to try to spin the underlying washer, causing the nut to free up. A Jam nut will never allow this. Also, if you look at factory bushings, the sleeve in the center has teeth, one side jams into the knuckle to lock the sleeve to the knuckle, the other side locks the washer to the sleeve. So as long as the bolt is torqued properly, the whole assembly acts as one piece. Poly on the other hand, has no teeth on the sleeve, and the bushing has a good amount of friction with the washer. So it's bound to happen from time to time. On my car it manifested itself as heavy toe changes when going on and off throttle. The rear was quite noticeably kicking out when I got on throttle.

fieroguru MSG #341, 02-14-2011 07:32 AM
      If you can install those strut adapter upside down from your original method, you would lower the rear by the distanct between the bolts.

On traditionally lowered 88's, it is pretty easy to bottom out the strut internally... especially with heavier engine swaps. Flipping the upper strut bushing (at the strut tower) helps some by moving the top of the strut shaft up about 1" and your adapters moving the base of the strut down could help even more.

I would love a copy of your F40 drawings if you are giving them out...

Keep up the good work!

355Fiero MSG #342, 02-15-2011 02:18 AM

I see what you mean on the adaptors. I would say I am 100% wrong and you need to put them back the way you had them. I made my own but when I saw the adaptors from others the strut always looked lower. In talking to others, they also said that the adaptors lowered the strut down. The pics you show clearly will not work the way I suggested so my apologies for giving you more work than you already have.......


Bloozberry MSG #343, 02-23-2011 04:59 PM
      Thanks for your kind words there Katatak, and for the advice Fierobsessed, 'Guru, and 355. I am now seriously thinking about redesigning those strut adapters to take advantage of idea to regain some strut travel. That's something I would probably not have thought of on my own.

Well it’s been two weeks since I last posted an update here, but that’s not because I’ve been slacking off. I’ve been busy entering more digital drawings into my computer, saving lots of money not having to heat my shop much this winter.

If you’ve been following along, I realized early on that to design a new cradle for the N*/F40 combination would be silly if I didn’t take advantage of the opportunity to study if improvements were possible as well. The problem with improvements is that you need to have a baseline from which to compare whether your modifications are indeed better or not. It sounds easy, but in reality, none of the Fiero engineering or technical data was released as far as I’m aware, so baseline geometry information remains a mystery to most of us. I hope to fill a little of that black hole by reverse engineering the drawings for the stock configuration as a starting point.

To start the ball rolling, I’ve decided to draw out all of the stock suspension components starting with the ’88 rear. I admit that the accuracy of my drawings is a limiting factor, since most measurements have been taken with calipers, rulers, bubble levels, and squares, not lasers, but they should be good enough to make comparative assessments for most suspension tweaks nonetheless. I also hope to use the drawings later on to create a visual guide to help people determine whether different diameter, width, and offset wheels will interfere with different combinations of coilovers, OEM springs, lowering, etc. (It would be nice if PFF had a repository for such reference material once it's done… hint hint Cliff.) But for now, I have a more selfish goal.

So for starters, here’s the ’88 rear knuckle:

The rear strut assembly proved to be a bear to draw out accurately, but I think I finally have it reasonably precise. The two biggest issues I ran across were the fact that the OEM strut I have to work with, has a worn out top bushing which I only realized much later. This skewed many of my measurements since the top hat was sitting crooked. I thought it was supposed to be like that. The other issue was that since I drew it from the bottom up, I originally assumed that the spring's axis was aligned with that of the struts, only to find that the top hat would not line up with the top of the spring once I got to that point. It turns out the spring is actually offset towards the center of the car on the strut, presumably to give more room for the rear tire. Here’s the finished product in the uninstalled height configuration:

The last thing I drew out was the suspension links. They weren’t difficult, luckily, since by that time my eyes were starting to get tired of focusing two feet away at my computer screen for the last two weeks. These are the lateral links:

And here's the trailing link:

I’ve already combined all of these components onto a master drawing combining the earlier cradle and the F40 tranny drawings. I need to determine a few things yet like the height of the spring at curb weight which means trying to determine the height of the underside of the strut tower mounting surface in relation to some fixed reference point on the cradle. The chassis alignment data in the service manual is lacking in this area. That will be a challenge to measure I think, but I’m determined. More to come.

doublec4 ( MSG #344, 02-23-2011 06:24 PM
      Your meticulous documentation of everything is mind blowing. lol

fieroguru MSG #345, 02-23-2011 07:14 PM

Thanks for taking the time to document the F40 and the 88 suspension bits!

Bloozberry MSG #346, 03-04-2011 01:28 PM
      As always, I appreciate your feedback doublec4 and fieroguru . You guys are doing some amazing stuff in your own respective threads too. It's great to see people stretching or contributing to the envelope of Fiero knowledge 23 years after its demise.

Moving right along, I completed drawing the final suspension components to allow a digital reconstruction of the entire rear suspension system. The last pieces were the wheel bearing assembly (which is identical to all year Fiero's), the brake rotor, the 15" x 7" (ET 30) wheels, and P215/60R/15 tires. I didn't bother drawing out the wheels and tires in great detail nor separately, but chose instead to add them to the master drawings. So for starters, here is the rear wheel bearing assembly (this is SKF part):

And here is the rear rotor ('88 rotors are identical fore and aft):

With these last parts drawn out, I combined all the previously drawn parts onto a single set of drawings depicting the rear suspension system in it's entirety. The precise location of the top of the rear strut wasn't an easy measurement to take, but I cross-referenced the dimensions from my own '88 project car chassis and those taken from an '88 GT stored here for the winter. Here are some sources of info regarding some of the dimensions:

1. the location of the center of Gravity (CofG) of the car in the vertical plane was taken from Road & Track Magazine, Sep 1983, in the article Pontiac Fiero Introduction from the Technical Analysis section. Although this was specifically for the '84 four cylinder car, I assumed the height of the CofG didn't change much, of at all with the introduction of the V6;

2. the horizontal location of the car's CofG was calculated based on the reported front to rear weight distribution (47%:53%) from various magazine sources testing cars with the V6, namely: Road & Track Oct 87, Automobile Magazine March '87, and Car & Driver Feb '86.

3. the ride height of the car (ie ground clearance of the cradle) was a rather fuzzy measurement to take empirically given the variables (tire heights and spring sag to name two.) So I referred to the trusty ’88 service manual but found problems there too. It gives the ride height in a table on page 3-16 but the accuracy of the numbers is contestable, since the ride height doesn’t seem to change despite three different listed tires sizes. There is a 4.5 mm difference in the radius between the tallest tire (215/60/15) and the shortest tire (195/70/14) listed, yet the ride height remains the same according to the manual. To get even more conflicting info, I referred to various magazine articles which stated the ground clearance as anywhere between 5.4” to 6.0”. In the end, I decided to let the ground clearance set itself by drawing the lower lateral links parallel to the ground, and add the P215/60R/15 tires digitally onto the hubs. The dimensions for the installed tires came from two different sources averaged out: the stored ’88 GT with brand new Goodyear Eagle Triple Treads, and my own ’86 GT with 1500 miles on Goodyear Eagle ResponsEdge tires at 32 PSI. Final clearance = 6.25"

I think that’s all that needs to be explained regarding the sources of information contained in the drawings below, but if you have doubts or questions, please don’t hesitate to ask. I would rather have someone point out an error than continue promulgating it. The next step is to determine the key OEM suspension characteristics such as the instantaneous centers, the roll center, percent anti-squat, etc. I’m armed with Herb Adams book Chassis Engineering , the internet, and a bag of Doritos to help refresh me in that department For now though, here's the top view:

The rear view:

And finally the side view:

aaronkoch ( MSG #347, 03-04-2011 04:44 PM
      This makes me love you. No, I mean it. I've been looking for drawings/measurements like this, but am far too lazy/incapable to do them myself. A plus to you, kind sir.

dobey MSG #348, 03-05-2011 02:46 PM
      Wow. Those are some nice drawings indeed.

FieroWannaBe ( MSG #349, 03-05-2011 09:33 PM
      Bloozberry, I had sent you an email a week ago, I am just wondering if you received it. If you didn't, I am hoping you would not mind sharing your hard work with me, I just finished up my degree, giving me much more free-time to take your drawings and create some solid models of your drawings.

Bloozberry MSG #350, 03-06-2011 10:18 AM
      Hey, thanks there aaron and dobey (although I won't believe that you love me aaron until I see a box of chocolates )! Even though drawings aren't as exciting as pretty pictures, I knew some people wouldn't mind a quick detour into the nuts and bolts behind the suspension.

For Fierowannabe: I replied to your email today.

dhobbs84sc ( MSG #351, 03-07-2011 12:35 AM
      Enough drawing and more working!! I wanna see this baby done! Have you ever watched a movie at 30 second incriments over the course of 3 years? THATS WHAT THIS IS LIKE!!
Lol but the drawings are super helpful (not for me, I have an 84, 85 and an 86) I'm amazed by how paitent you are with this. You don't rush or get overanticipated. That is why I check this build everyday for updates. Keep them coming! Even if they are small. Either way your builds are simply amazing.

Nashco ( MSG #352, 03-07-2011 03:56 PM
      As a person who works with CAD every day, I'm really impressed with your drawings. I can't believe you did that all the "old fashioned" way, measuring manually, instead of using a Faro arm or laser scanner or similar. Must have taken a long time, you are extremely patient! Are you doing line drawings or making solids of these? If you can save the CAD files as something in a 3D format (ideally, 2D works if that's all you have), I'll be sure to give them a home on the web for all to use and share. I've been contemplating making a tubular rear cradle on an '88 for Northstar guys as well, so maybe we can join forces and brainpower. You're ahead of me, for sure, but like you said earlier, a few viewpoints can result in better details you wouldn't think of on your own.

Keep up the good work!


FieroWannaBe ( MSG #353, 03-07-2011 11:29 PM
I started on the solid modeling of the cradle, this is going to take the longest to make, there are many profile changes and obscure geometries to model, but I'm getting more familiar with the different solid works features I haven't used much in the newer versions.

Bloozberry MSG #354, 03-09-2011 04:17 PM
      Dhobbs, I know exactly what you mean… I’m getting cabin fever sitting at this computer and am dying to get my hands dirty again.

Nashco: Thanks for the compliment. I wanted to create the drawings in a software package that’s not only available to the masses, but one that everyone operating Windows already has. My drawings were created using Microsoft’s drawing toolbar which can be found under View, then Toolbar menus. I open up an MS Excel file, force the grid lines to squares, then use the drawing tool to create the illustrations. They’re vector drawings so they’re fully scalable and I plan to give everybody access to them eventually. FieroWannabe is one of several who have offered to convert them into 3D as you can see from his latest post. I appreciate your offer to host the source files on your website but I would prefer to have them here directly on PFF somehow. As for providing constructive input, I’m planning on going through the design exercise right here in the thread to get feedback from anyone who’s interested, so you’re more than welcome to join in… I look forward to your contributions!

Well after this post, I think I’ll have finally done all I’m going to do to map out the OEM rear suspension (only the die-hards will stick with my thread after this one). I’ll be the first to admit that I’m no suspension guru and I’m more than a little wet-behind-the-ears when it comes to suspension dynamics, so please don’t be too harsh on me if I get something wrong. My objective here was to learn something new and try to understand what the effects of HT Motorsports extended control arms would be on my car and improve the characteristics if possible.

I bought what I thought would be a great reference book, Herb Adams Chassis Engineering which is highly regarded by many as the “suspension bible”. Rather unfortunately it was a serious letdown for me on several counts. The rear end suspension section was written with its primary focus on live axles and had very limited analysis of independent rear suspensions. With the vast majority of front-wheel drive cars today using Macpherson strut geometry, I expected there would be a great section devoted to them for front suspensions that I’d be able to apply to our unique cars in the rear. Much to my dismay, the only drawing in the book of a strut type suspension is improperly drawn, poorly explained, and incorrectly labeled. Finally, the book is very thin on details regarding how to calculate many of the interesting characteristics of suspension geometry. Instead, the reader is encouraged to buy a suspension software package and let the program do the work. Not exactly what I expected. So most of what I learned recently came from gleaning tidbits of information from many, sometimes contradictory, sources on the internet ( oh yay).

I decided for my most basic analysis of rear suspension geometry, I’d look at five things: swing arm lengths; roll centers; camber changes; toe changes; and anti-squat. Each are discussed separately below, so your own bag of Doritos might come in handy if you plan on sticking with me.

Swing Arms

Understanding swing arms is easy: it’s basically figuring out that the wheels move up and down as though they’re attached to much longer control arms than what they look like. On the ’88 Fiero, which has a Chapman strut rear suspension, the wheels actually move up and down (as viewed from the back) as though they were on levers 7’5” (2.275 meters) long… a far cry from the paltry 1’8” (324mm) long lateral links connected to the knuckle. The first drawing below shows how the virtual swing arm is measured on an '88 Fiero. On a Chapman strut suspension, two lines are drawn: one at right angles to the strut centerline starting at the upper strut bushing (the upper blue line); and the other line through the two pivot points of the lower control arm (the green dashed line), until they intersect way off to the extreme right of the drawing. The intersection is the location of what’s called the lateral Instantaneous Center (IC) for that rear wheel. The length of the swing arm is the distance as projected on the ground from the IC to the centerline of the tire patch. This means that the wheel initially moves through an arc as though it were connected to a lever that pivots at the IC. As you’ll soon see though, the IC moves around as the suspension compresses and extends.

Roll Center
The second thing that can be found once the IC and swing arm are determined, is the rear Roll Center (RC) of the car at ride height. The rear RC is the point about which the center of gravity of the car wants to roll around at the rear. To find the rear RC, all you do is add the red line shown above starting at the center of the tire contact patch and intersecting the IC. Once that’s done, wherever the red line crosses the centerline of the car, that’s where the rear roll center is located. For the Fiero, it’s 74 mm (2.9”) above the ground with the suspension at ride height. According to Herb Adams, “Most successful cars have the roll center height between 1.00 inch below the ground, to 3.00 inches above the ground” so 2.9 inches seems acceptable.

Here’s where it gets a little more complicated, and the drawing a lot more busy. As mentioned earlier, the instant center for the rear of the car changes location since one of the lines used to determine where it’s located, is drawn through the lower control arm. As the lower control arm pivots through its range of movement, the IC and RC will move around with it. To see the effects of that when the ’88 Fiero suspension goes through 3” (76mm) of jounce (blue lines), and 3” (76mm) of rebound (red lines), I replicated the components, rotated them, and added them to the above drawing to create the drawing here:

I know it’s a mess of lines, but it’s a lot simpler if you focus on one color at a time. Starting with the blue jounce lines that angle towards the lower right hand of the drawing and end in arrows, the swing arm length gets so long that I had to calculate its length because the software wouldn’t allow me to make a drawing that large. It went from 2275mm at ride height to 8700mm! Using the same method to find the new roll center as above, the RC drops to below the ground level and further away from the car’s center of gravity by (585mm - 418mm) = 167mm or 6.57” as compared to the location at ride height. A better design would keep the distance between the RC and CG more constant throughout the suspension travel according to Herb Adams. He also says that “reducing the distance between the RC and the CG will reduce roll angle, which leads many racers to want to raise the RC. But a higher RC causes jacking effects and erratic suspension movements”. Instead, “…roll angles can be controlled with stabilizer bars, front and rear, so there isn’t the need for the roll resistance that a high RC gives.” Keeping the RC at a constant height is more important than reducing its distance to the CG.

In rebound (the red lines) on the other hand, the swing arm is reduced fairly significantly causing the roll center to rise up towards the center of gravity by (418mm – 285mm) = 133mm or 5.24”. This would happen in one of two circumstances: either after going over a big bump and the car getting airborne, or on the inside wheel while going around a fast corner. In either case, the wheel is unloaded dramatically and from what I could glean, has little effect on the car’s handling in this extreme case.

Camber Change
The third on the list of basic suspension characteristics is the amount and direction that wheel camber changes as the suspension moves through its range of motion. Camber is the tilting of the wheel vertically as viewed from the front or back of the car. As a vehicle turns a corner, the body rolls toward the outside of the turn and the weight transfer compresses the outboard suspension. If the wheel were to stay perpendicular to the side of the car when it did this, the tire contact patch would tilt away from the pavement onto its outside edge and lose cornering grip. A good suspension design causes the outboard wheel to tilt progressively more inwards at the top to keep the tire contact patch in full contact with the pavement as it compresses. This is called camber gain under jounce. The reverse is true for the inside wheel. Herb Adams book states that one of the main limitations of a Chapman/Macpherson strut suspension is that the design is inherently poor at providing decent camber gain.

To see the effect of suspension compression on camber, once again, the rear view drawing comes in handy, with a few notes to observe: I don’t show the cradle roll angle in either direction for clarity’s sake; and at ride height (black lines), I drew the wheel with zero preset camber, when in reality, the alignment specs call for minus 1 degree:

From the tilting of the wheel centerline you can see the OEM suspension does indeed react the way it should, that is: the wheel gains 1.4 degrees of negative camber under compression and 2.2 degrees positive camber under extension. In Herb Adams example, his car gained 2.7 degrees in negative camber at 3” of compression, and was basically at zero camber gain in extension. For the best traction around a corner, the camber change should come close to matching the angle of body roll to keep the tire perpendicular to the ground. Without a stabilizer bar (anti-roll, swaybar, whatever) to help to keep the body roll angle down, it appears our little cars would suffer rear cornering power loss due to the limited rear camber gain.

Toe Change
The fourth characteristic I wanted to study was the change in rear toe as the rear suspension moved through its arc or travel. Toe is the amount of rotation the wheels take on in the steering axis as viewed from the top of the car. To quote Herb Adams “ Bump and roll steer are really the same thing. What they refer to is the amount and direction that each rear [wheel] might cause the car to steer as it moves through its travel. Even slight changes in the alignment of the rear [wheels] will cause big changes in the direction the car will go. The preferred design characteristics are very little roll steer, and if there is any, it should be in the understeer direction.” For an independent rear suspension “…roll understeer is obtained by having the wheels toe-in as they go up into jounce.”

To visualize what happens on the ’88 Fiero rear end, I used the top view of the suspension drawings I made earlier. To ensure that the rear wheels toed-in on the Fiero under jounce, GM made the forward lateral link shorter than the aft link. The reason this works is because the shorter forward link will cause the front of the knuckle to pull inboard faster than the longer aft link when they are pivotted upwards. I redrew the two lateral links as they would be seen from above, once their angles had been raised to the 3” jounce position (lines in blue). The difference in their effective lengths was only 1.0mm so I needed to calculate the change in toe using basic trigonometry rather than by trying to measure it on the drawing. I grossly exaggerated the change in toe on the drawing to demonstrate the effect of jounce. The actual toe change is about 0.38 degrees toe-in, which seems to meet the requirement stated by Herb Adams above.

Finally, the last characteristic to be studied is anti-squat. Squat is the tendency for the rear of the car to lower as the weight transfers rearward under acceleration. Anti-squat is a suspension characteristic that opposes this tendency, increases rear tire loading, cornering power, and traction available for acceleration. With a live axle, the suspension can be designed to provide 100% anti-squat, but unfortunately for us, the use of an independent rear end limits the amount of anti-squat to around 25%.

Calculating anti-squat for an independent rear end is one area that Herb Adams book didn’t cover very well in my opinion. After a lot of internet searching, I finally found a formula that allowed me to calculate it for a Chapman strut rear end. It involved determining the longitudinal instant center (IC) for the rear suspension by drawing a line (green dashed) through the rear trailing arm angle and extending it forward until it met up with another line (blue) drawn perpendicular to the strut centerline, at the upper strut bushing. Once the IC was located, a third line (red) was drawn between the center of the axle to the IC. The angle of this red line to horizontal (7.85 degrees) was then used in a formula that included the height (H) of the car’s CG and the wheelbase. (I apologize for the small scale of the drawing but PiP has a 1020 pixel limit on the width of pictures) (edited to correct formula and resultant anti-squat value in image below)

From the calculation on the drawing, you can see that the ’88 Fiero appears to have about 66% anti-squat. Interestingly, Herb Adams states that 25% is the practical limit for an IRS. some of you might have already figured out, increasing the angle of the red line would result in even greater anti-squat, so I explored that a little.

The only way to increase the angle of the red line is to shorten the longitudinal swing arm by either increasing the angle of the trailing link, lowering the top of the strut, or some combination of the two. Shortening the strut would give less suspension travel so you would need stiffer springs to prevent the car from bottoming out on the struts. The alternative, ie raising the angle on the trailing links seems more feasible, but the trailing link is the component that transfers the forward accelerative forces to the frame. The more angled the trailing link is to the ground, the larger the vertical component of the acceleration force becomes. At some point, the angled trailing link will cease transferring the accelerative forces forward into the frame and instead cause the wheel to try to walk under it, stressing the lateral links in the process. According to Herb, too short a longitudinal swing arm will also result in rear axle hop during braking, but he doesn’t quantify this in any sense.

Whew! A marathon post with lots of reading. This will separate the comic book readers out from the techies. I give two thumbs up to anyone who got through it all and understood it. As I said, I’m hoping this post stirs up some discussion since now is the time to get the theory right before I start applying the logic to the new design.

(Edited to correct formula in anti-squat diagram above, resulting in an increase in anti-squat from 28% to 66%.)

[This message has been edited by Bloozberry (edited 12-05-2011).]

Zac88GT ( MSG #355, 03-09-2011 07:57 PM
      Wow, great information. It'd be interesting to see the roll center lateral migration under body roll as well, I suspect it's quite high.

cptsnoopy ( MSG #356, 03-09-2011 10:23 PM
      Hey Blooze,

I don't really understand all that stuff very much but your work is helping me get some clue. Thank you!


aaronkoch ( MSG #357, 03-09-2011 11:41 PM
      Looking at your roll center picture, quick question:

So, the lower the C of G of the car, or more precisely, the closer the static roll center is to the CG, the less tendancy the car has to lean when cornering?

In theory, if the roll center was precisely AT the center of gravity, the car would corner perfectly flat without swaybars, right? I know this is really impractical, but a fun mind excercise.. I suppose if you had really tall wheels on a car that was lowered to the point where the CG was UNDER the center of roll, you could theoretically make a car lean INTO a turn. Cool.

dhobbs84sc ( MSG #358, 03-10-2011 04:39 AM
      From what you said, my understanding is, If you increase your anti-squat you have a better chance of lifting the front wheels? And I doubt thats good on daily driving...
But I'm kinda lost lol. 2nd time around I read slower

[This message has been edited by dhobbs84sc (edited 03-10-2011).]

Bloozberry MSG #359, 03-10-2011 10:32 AM
Originally posted by aaronkoch:

So, the lower the C of G of the car, or more precisely, the closer the static roll center is to the CG, the less tendancy the car has to lean when cornering?

Yes that's right Aaron, it would act as though the car were going around a banked oval. Instead of being thrown sideways in the car as you turned the corner, you would instead feel yourself being pushed down into your seat.

Originally posted by dhobbs84sc:

If you increase your anti-squat you have a better chance of lifting the front wheels? And I doubt thats good on daily driving...

No... just the opposite. If you study the simplified drawing below, you'll see how anti-squat works. In the top picture, the torque from the turning wheels applies a lifting force on the end of the long swing arm. In this case, the reactionary force is applied ahead of the CofG of the car so it rotates the car backwards causing squat. In the lower drawing, the reactionary force is appplied behind the CofG and forces the weight to be transferred to the front of the car. 100% anti-squat happens when the reactionary force is applied through the GofG. Since anti-squat is measured as a percent, anything less than 100% means that the force is being applied ahead of the CofG, and anything over 100% means that the force is being applied behind the CofG.

Edit to add definition of 100% anti-squat.

[This message has been edited by Bloozberry (edited 03-10-2011).]

ccfiero350 ( MSG #360, 03-10-2011 03:49 PM
      The drawings are just great, and a lot of man hours. I agree that there should be a repository for just for CAD files some where here in PFF.

One of the best books I have found on suspensions is "Race Car Vehicle Dynamics" by Milliken & Milliken ISBN 1-56091-526-9 , It's published by the Society of Automotive Engineers and you can get it on Amazon.

And it covers tri-link struts like ours.

RCR ( MSG #361, 03-10-2011 07:35 PM
      Blooze...What can I say...Awesome stuff...I have the Herb Adams book and I know what you mean...Not the greatest. A book I would recomend if you can get your hands on it is "Race Car Vehicle Dynamics" by Milliken and Milliken. It's an SAE book. Bill and Doug Milliken invented the science of vehicle dynamics while researching the Corvair issues for GM, then taking the research a step further to dominate CAN AM racing. The history makes it a great read.


Lonster MSG #362, 03-13-2011 09:40 AM
      What are the differences in geometry when changing the lower ball joints (1/2" or 1" drop) on the front suspension when compared to stock? Thought I would ask...

[This message has been edited by Lonster (edited 03-13-2011).]

aeffertz ( MSG #363, 03-17-2011 03:47 PM
      Must be working on something big! Been a few days since an update.


Say, I'm about to tear into one of my alternators and starters to perform a rebuild like you documented in this thread. (Never would've thought about attempting it before I saw your posts!) I was just wondering if you used a special paint for the parts you painted on them?

Thanks and keep up the good work!

[This message has been edited by aeffertz (edited 03-17-2011).]

Bloozberry MSG #364, 03-17-2011 04:02 PM
      Ha! Well you're right about it being something big... it's just not car related Been up to my eyeballs (and nose hairs) in stripping the 200 year old plaster and lat walls from the last room in our house that needed renovation. I'll be back on the project car soon though. (oops my wife just reminded me I'm spending quality time with her while we renovate together... I suppose that's not so bad.)

Bloozberry MSG #365, 03-18-2011 08:36 PM
      Thanks for the reference to the Miliken & Miliken books there ccfiero and RCR. I’ll be ordering it.

As for Lonster, those lowering ball joints on the front-end are going to change the camber curve since the lower, longer arm remains parallel to the ground, but the upper, shorter control arm will ride with a more upward angle at the ball joint end, effectively making it shorter, and pulling the upper end of the knuckle inboard slightly. You’d probably have to counter this increase in static camber by slotting the upper ball joints to move the top of the knuckle outboard again. That would solve the “at-rest” issue, but dynamically you would also get a faster rate of camber change as you compressed the suspension than would otherwise be the case with normal ball joints. That would happen because the upper arm is already part way up it’s arc of movement. At least the camber will change in the correct direction so that’s not bad, but I can’t say if it would perform better or worse than stock. There would be increased bending stresses on the lower control arm where the ball joint is pressed into it. That’s an area that should be monitored for cracks occasionally if you go with the tall joints.

Well, I’m stuck in the middle of some home renos and immediately after that, I’ve got to change a clutch in a customer’s ’88 GT, and do some suspension work on the father-in-law’s MGB. That means I’ve got precious little time to devote to this thread at the moment. So, in the interests of keeping this thread from falling off the front page, I’ve decided to go a little out of sequence and mix things up a bit.

As super-interesting as suspension drawings can be I’m going to buy some time, go out on a limb, and post some front suspension pictures hoping you guys can keep what’s-what straight in your heads. This should buy me enough time to eek in a moment here and there between jobs to work on the 6” increased track-width drawings for the new rear and maybe get on with the cradle fabrication. So without further ado…

For those of you who’ve ever considered buying some of HT Motorsports stuff, these next couple posts are for you. I did a fair bit of research before I bought the increased track-width suspensions fore and aft, and so far, I can tell you I’m not disappointed. I knew that wheel spacers on the front just weren’t going to be in the cards because of the effects they have on everything from increasing scrub radius, to bending stresses on the bearings. Spacers that are up to an inch thick probably don’t change much, but here’s what I had to contend with…

There just wasn’t any way that I was putting 3” spacers on the front. So I removed the wheels and blocked up the car with the lower control arms level to the ground. Then, I placed several different wheels with known widths and offsets in the fender well where I wanted the wheel to sit, and carefully measured the gap from the back of the wheel to the mounting surface on the brake rotor. Here I was using an Audi TT wheel.

This then allowed me to calculate just how long my control arms should be for any given wheel width and offset. I settled on the combination of the longest possible arms and the wheels with the greatest positive offset, namely 3” longer arms, and 7” width front wheels with +48 mm offset. (I can tell you now that there aren’t too many wheel options out there with those dimensions and a 5 X 100 mm bolt circle, so some of you may be able to guess which wheels I’ll be getting

The other thing this test fitting allowed me to do was measure the gap between the top of the tire and the bottom of the fender lip to determine just how much of a drop I would need to fill the wheel wells with the tires. I also played around with some scale drawings I had made to see what the effect of different overall diameter wheels would be in combination with different suspension drops needed to take as much of the guessing out of the equation. Here’s a sample among many I did. The top car is with 16” wheels and 24.5” tall tires without any dropping, and the bottom car is with 18” wheels and 25.25” tall tires, plus a 3” drop IIRC.

To get the right drop and wheel well fill on the front end, I decided to get HT Motorsports 1.5” drop spindles (since that’s the max they currently make), and fine-tune the rest with adjustable coilovers. (At the moment, I expect to buy 225/45/17's for the front since they have a 25" diameter, but this isn't cast in stone yet.) With my HT shopping list in hand, I ordered the front end components and while I waited, removed and took apart the OEM front cross member. Here it is in all its glorious Canadian weathering (less the springs). This is the view from the driver’s seat:

Here’s another view as seen from the front quarter of the car:

I spent a couple hours getting the suspension components off the cross member, running into the usual problems of seized bushing sleeves, and shearing bolts etc, but here is what I was ultimately after since everything else is going to be replaced:

Next stop: the sand blasting booth (the great outdoors), and the painting booth (the great outdoors)… stay tuned.

Fiero2m8 MSG #366, 03-18-2011 10:52 PM
      Very nice work Blooze!
I'll be watching your suspension progress.
I've already decided to cross drill my rear rotors after seeing your posts on the previous page.


ccfiero350 ( MSG #367, 03-22-2011 10:57 AM
      I modeled up the 88 rear suspension based on Bloozberry's terrific drawings and work that I've done previously and have done some motion analysis and made some low rez animations. Next time around I'll set the resolution higher and just wait on the rendering.

If you watch it a few times you can see how the wheel toes in as it travels up and down.

Given this a tri-link stut style, there's not much camber gain, but you can help it out by raising the lower links location on the subframe to keep it negative as long as possible.

I can do one with your long links and see what it looks like.

Bloozberry MSG #368, 03-22-2011 12:57 PM
      Right on! Now that's cool. I give you a big fat "+".

ccfiero350 ( MSG #369, 03-22-2011 03:11 PM
      I'll run the program again with your wide track links, They are +3" each side correct?

Bloozberry MSG #370, 03-22-2011 03:50 PM
      Yep, 3" per side, but remember that the strut remains at the same location and angle... the gap between the newly located knuckle and the bottom of the strut is taken up by a solid spacer that you'll have to model either as part of the lower strut or top of the knuckle.

[This message has been edited by Bloozberry (edited 03-22-2011).]

ccfiero350 ( MSG #371, 03-22-2011 06:44 PM
      Here is the setup, the animations start at ride height, in this instance, the bottom of frame is 5.75" off the ground. Which in most fieros means it's lowered. The wheel/tire combo is 17x9 25mm offset, 255/40/17 tire. I added 3 inches to the fixed length rear toe link and adjusted the others to get a half decent alignment to start with.

I did come across one measurement that looked out of place, the height of the attachment point of the strut piston, is about 5 inches lower then what is on your drawing. If I use your number, my strut does not have enough travel in droop. (Strut is model on a worn out Monroe unit)

As you can see the toe links are at an rising angle to start with, which takes away negative camber as the wheel moves up. For more negative camber gain, the toe links should be angled down at ride height.

It looks like the 3 inch addition acts pretty normal,

Bloozberry MSG #372, 03-22-2011 07:50 PM
      I suspect there's something wrong with the numbers you've used on one of the animations since there should be no difference in the angle of the toe links if the only variable was their length. Did you change tire diameters between the first and second animation? Or change the ride height? Stock ride height IIRC is 6" (plus or minus) as taken at the bottom edge of the cradle. I'm curious why the height of the strut to mount is so much further off too. Must be something we're missing.

ccfiero350 ( MSG #373, 03-22-2011 08:54 PM
      Oh yes, there could be a lot of differences, one of them that crops up is all the links must be constrained as ball joints, and locating the pivot point in a rubber bushing adds a certain amount of guessing, but your right, theoretically the links should be parallel, in real life I've seen them a little like the animation. As for the strut location, what do you measure in a strait line from the center of the hole in the strut tower to the axis of the front toe link on the sub frame? I can match that and try again.

I been using the 5.75" as a chassis height because that was what it was before I took the car apart. I'm not sure if in the real world the bottom surface of the sub frame is actually parrallel to the the ground, isn't there a bit of a rake?

I did change the wheel/tire, the first one was 17x10.5 with a 285/40.

Bloozberry MSG #374, 03-23-2011 08:17 AM
      The distance from the inboard axis of the lateral links to the center of the top strut bushing (which is the effective upper pivot point of the strut), as viewed from the rear of the cradle in a straight line, is 1275 mm (50.2"). You shouldn't use the hole in the strut tower since the bushing is further down by an inch or two.

The cradle bottom, at stock ride height is parallel to the ground... no rake fore or aft.

Tinkrr MSG #375, 03-23-2011 08:47 AM
      By grabing the cursor and slowing down the animation it appears to me in both the side view and the lateral view, that the axle will interfere with the engine cradle when the suspension is in full droop

Bloozberry MSG #376, 03-23-2011 11:15 AM
      It's just the angle the drawings are seen from. You have to keep in mind that on the driver's side, the inboard end of the axle (where it crosses over the dradle side rail) is kept away from the cradle by the CV joint being mounted a fixed distance away from the cradle. The joint allows the outboard end of the axle to droop below the cradle as seen from the side view, but the outboard end of the axle is much further away from the cradle.

On the passenger side, the long axle does get closer to the cradle because the CV joint is much further inboard so there's more relative movement between the axle and the cradle where the axle crosses over the cradle side rail. But again, it clears in the stock configuration and longer lateral links will only improve upon this clearance. In my case, I'm also using a jackshaft to move the passenger side CV joint outboard.

DeLorean00 ( MSG #377, 03-23-2011 05:27 PM
      Whoa whoa whoa!!! There is way too much engineering going on in here. This is a kit car. All you need to know is how to mix bondo and how to use sheet metal screws.


ccfiero350 ( MSG #378, 03-24-2011 08:15 AM
      I'm going to throw an axle and sway bar on it too to see how whole ball-o-wax looks. What is the length of your new longer trailing arm?

ccfiero350 ( MSG #379, 03-24-2011 11:51 AM
      We have discrepancy in dims. I've set the upper strut pivot point (red donut) at 50.2" The shown dim is the from the upper strut pivot to the center of the front lower link hole. I may be wrong, but I don't think the top of the strut is two wheel diameters off the ground.

dratts ( MSG #380, 03-24-2011 02:05 PM
      Check out the f40 flywheel thread in the mall.

Bloozberry MSG #381, 03-24-2011 02:55 PM
Originally posted by ccfiero350:

We have discrepancy in dims.

Yep... for two reasons... the first is that I thought you meant the distance on the diagonal, ie from the outboard axis of the lateral links where they are attached to the knuckle, up to the strut bushing; and second: I accidentally used the wrong scaling factor 20:1 instead of 10:1 when I gave you the 50.2" figure.

So, now that I know you want the distance in "up" plane (the green plane in your last rendering), the 50.2" number should be 595 mm (23.4").

Great 3D drawing by the way. Because there's the potential for miscommunication between us and therefore numerous trial and error drawings, if you don't mind, I'd like to sort out any other iterations of the suspension movements in PM's rather than directly in the thread there ccfiero. That way we won't post misleading or incorrect info. I really do appreciate the work you've done but I'd like to keep the actual build thread as clean as possible.

ccfiero350 ( MSG #382, 03-24-2011 03:48 PM
      Now we are the same page! That number is is more like it.

No problem on the clean thread, but rather use email if we could. I'll send you a 3D pdf you can measure from to the last address you sent me.

Bloozberry MSG #383, 03-27-2011 09:52 PM
      For those of you who found the 3D animations as entertaining as I did, CCFiero's sent me some more of them with the 3" longer control arms for me to look at before he posts them, but I haven't had a chance yet. As cool as they are, I'll still have to go through my own exercise to determine the best possible location of the lateral links height-wise, and cross car width-wise, plus whether I should increase the angle on the trailing links to improve anti-squat, and raise the upper strut mounts to get more travel.

For now, it's back to the front suspension make-over. It’s amazing how a good sandblaster can take a painstaking, backbreaking, four-hour crappy task with a wire wheel on an angle grinder, and turn it into a joy to do. It took me less than half an hour and two $10 bags of crushed glass to strip the old paint and rust out of every pore, nook, and cranny of the front cross member. My compressor just can't handle the bigger jobs, so a friend of mine who owns a top-notch paint shop lets me do the big parts out-back at his shop where he’s got the right set up. Once stripped, I don’t like leaving parts sitting around too long so the shop primed it with an epoxy primer just as soon as it was done. A couple hours later it was home and painted in the final color.

I chose silver because I wanted a different color than the bottom of the car (which will be black), and a light color makes it look less heavy and massive. I know, I know, few people will ever see the bottom of the car, but I want those who do to see right away that this was a ground-up restoration. I find that if everything gets painted black, after a year or two it takes a close look to tell whether it was redone or not. I’d rather it stand out if someone actually takes the time to look under the car.

While I was doing this, a big package arrived in the mail. All the front end parts I ordered from HT were delivered, all nicely packaged up in bubble wrap and foam peanuts (I hate peanuts). Look at all these purdy pieces:

I’ll hone in on each piece separately to give you a better look, and to stretch out the few remaining photos I have before I’ll have to get back to actually working on the car. The most intricate pieces are the drop spindles. There’s a lot of work that went in to these pieces so I can understand the premium price tag better now.

They’ve been ingeniously designed to do away with the OEM ’88 Fiero-specific front bearing assemblies and made to accept the far more common and inexpensive Fiero rear bearing assemblies.

Because the rear bearing assemblies were originally designed for an axle and axle nut to hold the bearing halves together, these bearings are modified with a large bolt as a substitute for the axle. On the left is the modified bearing and on the right, a stock bearing assembly. Note that the large nut has been spot welded to keep it from ever backing off.

Here’s the rear view of the same pair as above. To solve clearance issues with the inside depth of the drop spindle, the head of the large bolt was machined down somewhat.

Finally, here’s what the spindle and bearings look like when assembled as compared to the OEM parts. The 1.5” drop is clearly obvious when you compare the two left-most knuckles in the photo. Notice how much more of the lower ball joint mount extends beyond the diameter of the wheel flange on the new knuckle as compared to the OEM one. (Well, actually, the ball joint mount is in the same location, it’s the spindle that’s been raised making the mount look longer.) That should take care of some of that ugly gap between the top of the tires and the wheel well lip.

doublec4 ( MSG #384, 03-27-2011 09:58 PM
      Those look like some nice pieces! Its a great feeling getting parts in the mail

Still watching this build

Reallybig MSG #385, 03-28-2011 01:55 AM
      If you haven't figured out how, Wierd Al knows a good way to get rid of those peanuts you hate so much at the end of this song.

RCR ( MSG #386, 03-28-2011 07:56 PM
      Looks great Blooze...I'm probably going silver on my front conversion, too, although I may play with some translucent powders.


[This message has been edited by RCR (edited 03-28-2011).]

Fiero2m8 MSG #387, 03-31-2011 12:56 AM
Originally posted by Bloozberry:

I chose silver because I wanted a different color than the bottom of the car (which will be black), and a light color makes it look less heavy and massive. I know, I know, few people will ever see the bottom of the car, but I want those who do to see right away that this was a ground-up restoration. I find that if everything gets painted black, after a year or two it takes a close look to tell whether it was redone or not. I’d rather it stand out if someone actually takes the time to look under the car.

Originally posted by RCR:
Looks great Blooze...I'm probably going silver on my front conversion, too, although I may play with some translucent powders.

Some similar tastes here , I wanted a contrast to the black frame too.


cptsnoopy ( MSG #388, 03-31-2011 01:52 AM
      Lol Blooze, watching your thread is seriously threatening my wallet!


Bloozberry MSG #389, 04-05-2011 10:35 PM
      Wow… time flies when you’re busy! I see that my thread is getting closer to the bottom of the first page so I guess it’s time for another update. Thanks guys for your comments. I'm a huge Doors fan Reallybig but I had never seen Wierd Al's take on anything from them. If you see an eBay ad for styrofoam peanuts anytime soon, you can rest assured they're from me! As for Fiero2M8, I've been keeping a close eye on your amazing build too. I feel like my suspension is the Chevette equivalent to your Cadillac version though, so I try not to look too often otherwise I'll either get discouraged, or end up like Cptsnoopy and risk having even more money disappear from my thinning wallet.

Continuing on with the front suspension build-up, the first thing I decided to attach back on the front crossmember was the tidied up steering rack. I checked it over for worn inner tie rods and the rack bushing, but the clearances seemed pretty much like new. So I blasted everything with crushed glass, polished a few highlights on the rack tube, and primed and painted the steel parts. Once it was ready, four simple bolts torqued to 20 lbft hold it to the crossmember:

I think the guys that put in power assisted racks are amazing. It would be cool to do that too, but not on this first go around. I am on some sort of budget. Now those of you thinking ahead might be asking yourselves “How the heck is he going to connect those stock length outer tie rods up to his 3” extended control arms?”

The answer to that is quite simple actually. A 3” tie rod extension tube with male threads on one end and female on the other is all that’s needed. This method keeps the inner and outer tie rod pivot points in the same spatial orientation relative to the upper and lower control arm pivots on the inboard side of things, and the upper and lower ball joints on the outboard side. I just hope that when I go to get this thing inspected (mandatory provincial inspection every two years) that they don’t raise their eyebrows too high when they see this. Maybe I should paint them yellow to blend in a little more.

So next up is installing the lower control arms. Here’s what the old and the new look like side by each. The tubular arms look soooo much cleaner than the stamped steel ones. I just hope they’re as rigid or even more so than the OEM ones.

Notice how the lower shock mount ears extend quite significantly below the arm. This reduces ground clearance somewhat over uneven roads compared to the OEM ones but allows the use of the adjustable shocks. Aren’t they purrrrdy?

Getting these lower arms in the crossmember pockets with the urethane bushings takes a little poly grease and elbow grease. They certainly are a tight fit, which I suppose is better than having them flop around. The two nuts on the pivot bolts get torqued to 37 lbft + 270 degrees. (I’m only mocking things up at this point so I’m leaving things loose for now.)

Next up is the installation of the shocks and springs. Here’s a close up of the my new 325 lb/in front springs vs the old OEM springs. I hope I didn’t make a mistake and order them too stiff. Only time will tell.

Here are the rest of the pieces that make up the coil-over shock. I got the Carerra chromed shocks with my suspension kit, not that anyone will see much of them once they get the adjustable tubes installed. The only thing missing from this photo is the upper spring seat. The springs are considerably smaller in diameter than the stock springs so HT Motorsports provide a heavy duty collar that serves as the new spring seat. I'll post a picture of them later.

In order to keep the threaded adjuster tube from sliding off the end of the shock body, a powerful circ-clip is installed in the lower groove of the shock. Installing those clips nearly had me pitching the whole thing into the pond. It had to be one of the most frustrating aspects of this build so far… no kidding. I bent two pairs of circ-clip pliers, searched half a dozen times for the clips on the floor after they went flying every direction imaginable, pinched my finger tips, you name it… it happened.

Once they were finally on, I could finish building up the coil-overs… which was just a matter of slipping the threaded tubes on and then the springs. This was one of those jobs you'd schedule 5 minutes to do and spend one hour. See what I meant by how little the chrome body of the shock shows? At least I’ll know they’re there.

ccfiero350 ( MSG #390, 04-06-2011 12:52 AM
      Great build!

I added a couple of 3/16" weep holes to my tube arms. That pocket that holds the lower ball joint will fill with water and it needs a way to drain.

aaronkoch ( MSG #391, 04-06-2011 12:52 PM
      Considering the added length of the arm, 325 lbs will probably be fine..

Bloozberry MSG #392, 04-10-2011 08:37 PM
      Thanks for the tip ccfiero… drain holes are now on the list of things to do! Thanks too for your input Aaron. I want the car to ride low, but our secondary roads here in Nova Scotia are pretty pathetic. I think 325 will be a good compromise between being too stiff and bottoming out especially given the added leverage of the longer arms.

Now, on to more pictures. Once I had the springs built up, I tried them on but without any weight on the cross-member the lower control arms were being forced all the way down. Since I’m only mocking things up at this time, I removed the springs and installed just the shocks for now. It’s pretty straightforward, a bolt through the lower control arm mounts and the hemispherical joint at the bottom of the shock, then feed the top of the shock up through the hole in the upper spring pocket on the cross-member. There’s a pair of poly bushings on the top of the shock shaft similar to the ones on the sway bar end links:

I wanted to add this next photo for two reasons. The first is that it shows the stock spring seat in the upper part of the cross-member. With these new springs that are shorter and smaller in diameter than the stock ones, there’s a heavy duty collar that comes with the HT Motorsports parts that adapts the new spring to the OEM upper spring seat. I’ll add a picture of it later since I don’t have one ready right now.

The second reason was to point out the yellow spacers I had to fabricate from steel tubing to center the bottom of the shock on the lower mounting bolt. The space between the mounting ears welded to the lower control arm is way too wide for the width of the heim-joint at the bottom of the shock. It’s a simple fix, but one that I feel should have been included in the kit from HT.

With the shock installed, the next step is adding the upper control arm. Here is a picture of the OEM and 3” longer one for comparison’s sake:

Installing the upper control arm is a breeze, just two bolts through the upper pivot bolt. Getting to that point is a little harder though. HT doesn't provide the upper control arm pivot bolt so you have to re-use your stock one, and that can be a PITA to take off. To remove it from the stock arm, you have to dig/burn/press out the stock rubber bushings from both sides of the control arm before the pivot bolt can be slid out. The usual problems of bushing sleeves seized to the pivot bolt turn what should be a simple ten minute procedure into an hour long drama complete with swearing, flying tools, and either burnt, cut, or pinched skin.

The front-end caster and camber alignment depends on where you tighten the two bolts through the elongated holes in the top of the cross-member though. The nuts that the bolts thread into aren’t captured to the underside of the spring seat unfortunately. Instead they’re welded together onto a thin piece of sheet metal that’s got to be held in place while tightening the bolts. That generally goes OK, but the metal is notorious for twisting out of shape if you ever decide to loosen the bolts.

The next piece of the puzzle is the knuckle assembly. It’s only held onto the spindly little control arms by the upper and lower ball joints and the outer tie rod. In this view you can clearly see the front to rear tilt of the upper control arm. This property of the arm is what determines the amount of anti-dive.

HT designed a generous amount of accessibility to the upper and lower ball joint nuts through large windows cut out of the backside of the tubular uprights:

And here’s the street-side view of the installed knuckle assembly. On the one hand, the whole thing just seems impossibly weak to do the job it does, but on the other,
it looks decidedly race-like… low weight, small visual mass, and a hanging-way-out-there look. Heavy-weight brakes will more than compensate for all that low weight stuff soon enough though.

fierogt28 MSG #393, 04-10-2011 08:57 PM
      Nice job Blooze, very impressive...

Fierobsessed ( MSG #394, 04-10-2011 11:01 PM
      Curious, do the Corvette rotors clear the Lower control arm? It's a known problem on stock 88 cars in the front.

RWDPLZ MSG #395, 04-14-2011 09:55 PM
      The thread was already awesome, and then, the drawings! You are NUTS!

My senior project in high school CAD class was a Fiero, nowhere near the level of detail and accuracy of your drawings.

Bloozberry MSG #396, 04-23-2011 09:06 PM
      Thanks fierogt28 and RWDPLZ (although I'm not so sure calling me nuts was a compliment ) For Fierobsessed, I've checked my lower control arms for interference with the brake rotors and indeed they contact each other, although the condition may only exist at the extreme end of the suspension travel in rebound. I'll have to look more closely at this and post some findings the next time.

For this post, I'm going to finish up the assembly of the front crossmember with the addition of the brakes. As with the rear suspension, I opted for the 12" C4 Corvette rotors and stock '88 Fiero calipers. That meant simply bolting on the Fiero Addictions brake caliper adapter onto the HT knuckle...

... and then bolting the caliper onto the adapter using the stock caliper bolts through the sliders. As with the rear, I discovered that the rotors can be installed and removed from the hub flange with the caliper installed.

Here's the street-side view of installed caliper... I'll go along with this set-up for now and maybe someday I'll beg the Reprovisioning-Fairy for the four piston caliper upgrade.

With the caliper installed, it was a simple matter of slipping on the rotors at a bit of an angle, sticking on a couple lug nuts to hold them square to the hub, and installing the brake pads in the same manner as the rears were done earlier.

I used stainless braided flex lines to complete the look and for the improved pedal feel. The old rubber lines were too short anyways. Here I've installed the springs to complete the mock-up for the picture, but they force the control arms downward to the max rebound position and make it harder to install the crossmember as a unit back into the car. I'll be taking them off to install the front end later.

And finally, here's an inboard shot to complete all the possible angles anyone could possibly want to see. It's kind of colorful, but in my defence I didn't get to choose the color of the ball joint boots or bushings. I would've gone for lime green

doublec4 ( MSG #397, 04-24-2011 12:13 AM
      Looks great as usual! Such a high level of detail into this. I had no doubt it would turn out like that!

88GTS ( MSG #398, 04-24-2011 10:41 AM
      Blooz, your new springs have a smaller diameter than stock - how do they seat at the top?

Originally posted by Bloozberry:

And finally, here's an inboard shot to complete all the possible angles anyone could possibly want to see. It's kind of colorful, but in my defence I didn't get to choose the color of the ball joint boots or bushings. I would've gone for lime green

Tinkrr MSG #399, 04-24-2011 10:55 AM
      I've never seen the dust boots in lime green but they do come in yellow and you seem to have used that a lot. Checkout my left rear inner tie rod.

Bloozberry MSG #400, 04-25-2011 08:49 PM
Originally posted by 88GTS:

Blooz, your new springs have a smaller diameter than stock - how do they seat at the top?

Thanks for pointing that out 88GTS... here's the answer:

When you order the '88 front coilovers from HT Motorsports, they send along a spring adapter that looks like this. The top-side has a ring welded onto it that makes the ID a bit smaller than the bottom side (ignore the flat tab welded on the ID):

The end of the adapter with the smaller ID fits tightly on the OEM spring collar in the crossmember. The adapter is also wedge-shaped so once you've slipped it up through the spring pocket you also have to orient it so the thinner edge of the adapter is towards the inboard-side of the car. That flat tab welded on the ID is on the wider edge of the adapter, so it's got to go towards the road-side.

In the picture below, the HT spring seat isn't perfectly lined up, but you get the picture. Once it's up there, you peen the OEM spring seat collar over to lock the HT adapter to the crossmember. HT also recommends adding a thick bead of silicone between the top surface of their adapter and the crossmember to make any movement between the two pieces as squeakless (is that a word?) as possible. HT does say that peening isn't absolutely necessary since the spring is always in enough compression to hold the adapter in place. I think I'll weld it into place on mine.

I don't have a picture of the springs installed from the bottom side of the crossmember, but here's how the spring seats inside the adpater.

wftb ( MSG #401, 04-25-2011 11:11 PM
      are those the 8" or 10" springs ? the reason i ask is i started out with 8 " springs at 260 lbs (thinking this would be about stock rate ) and quickly found that an 8" spring at 260 lbs just was not going to cut it . too much bottoming out and not enough travel .a trip to the QA-1 website confirmed that to do the same job a shorter spring needs a higher rate .for the front end weight of a fiero with an 8" spring you need about 400 lb rate .with my drop spindles i had room for a 10" spring so i went with a 300 lb rate 10" spring and it has worked really well . i have the same small body carrera shocks as yours .

Bloozberry MSG #402, 04-26-2011 12:11 PM
      Hmmm... interesting. My springs are the shorter 8" ones and are 325 lb/in. Have you got any pictures of what your car looks like from the side with the 10" long springs? How tall are your tires, what's your ground clearance from the bottom of the front crossmember, and what does the space between the top of the tire and the fender lip measure?

wftb ( MSG #403, 04-26-2011 11:35 PM
      i just raised it up a tad to suit the new trolley jack i bought .since i just measured what you asked i need to adjust it some more .its a little high on the drivers side .average height above the tires is 1.75" .there is 6" clearance below the front cross member right now .i am running 205/55 /16 tires on the front .my car is an 86 gt with Held sport suspension kit (not the kit with the custom cross member) and i have street dreams by ross 2" drop spindles .i have ran it quite a bit lower and still had good travel on the springs .since you bought your suspension with drop spindles , you should easily be able to run a 10" spring and get the ride height you want . and you have a big advantage over me because you have the longer control arms you can run the QA-1 HAL shocks .these are much better than the small body shocks .they cant be used with stock length arms so i am stuck with the small bodies .lots of pics of my car on my thread "ecotec swap". i wish my stuff looked as good as yours , everything looks perfect .

Ruffy MSG #404, 05-07-2011 05:34 PM
      I have to say Blooz this thread is the WOW factor! The bad part of it is you get a nice motor that has good compression and open it up just to find some of the pistons were missing parts. Not only that but the build up would turn most of us away and toss the motor! With the level of detail you have put on the motor alone is astonishing to say the least. And then the suspension. In reality you could of bought a newer LS (not LS1 yuck) motor with low to no miles for the price you did the N* for. But then again its in all what you have the love for. Ive built 318 motors over some 360s at times for customers because they like the higher rev.

Couple of questions for you. I spent the last two hours going over your build but didn't read all of it because I was tenting to much and the wife got disturbed lol.

(1) When you had the camshaft redone, is it stock grind or did you have them bump it up a few?
(2) Did you replace the motor cradle or fix the one with a ton of holes in it?
(3) When building the N* were you going for stock 0 miles motor or is there going to be more HP?
(4) Why the N*? There low revving and seem to have issues with head gaskets, not only that but aftermarket parts are hard to come by (not that you are having a hard time because you have them made)

I do have to put this in here take it as good or bad, but that Ferrari kit isn't worthy of what you have done so far! Your work and detail is a loss of words! I personally think you should do a one off body kit of no other to justify the work that has already gone into this incredible machine. Im not saying your kit will be ugly by no means nor is Ferrari ugly (FXX is my top 5 best cars). Also I think we all would love to see what you would do as a one off body seeing how your taste of detail and products/items used is.

I have a new found respect for you Blooz

Robert S Liao

cptsnoopy ( MSG #405, 05-08-2011 03:38 AM
Originally posted by Ruffy:(4) Why the N*? There low revving <snip>
Robert S Liao
6500 seems like a reasonable rev but with a set of springs your good to 7500 which seems almost overboard for a street car. My opinion of course. I am also slightly biased so take that into consideration.

Bloozberry MSG #406, 05-08-2011 09:36 PM
      Thanks Robert for all the compliments. I'll see if I can answer your questions in the order you asked them:

1. Why a Northstar vs an LSx? I guess it's a matter of personal preference... I already have a SBC powered 308 kit, and for me, the LS series engines are just the spiritual successors to the small block. Fifteen years ago when I built my 308 kit, the TPI engine was very cool. Now it's almost boring. This time I wanted something different so that in 10 or 15 years it will still have the Wow Factor, that being the four cam, 32 valve set-up. It's pretty exotic when you stop and think about it.

2. Camshafts: When I had the exhaust cams re-profiled, I stayed with the OEM specs. I did this to limit the number of variables when I finally get around to tuning the PCM. Lots of people here on PFF with much more PCM tuning experience than I have (read: none), have had difficulties getting their Northstars to run flawlessly on custom tunes. I plan to keep my engine as stock as possible until I get it running properly, and then make upgrades one change at a time to limit the adverse effects of multiple simultaneous upgrades.

3. The cradle: I'm working on a new cradle. That's the stage I'm at right now. I've taken a few weeks off from the thread to get the spring cleaning, gardening, car tune ups, and some house renos done. My next posts will cover the new rear suspension in drawings and show why a redesigned cradle will be beneficial, apart from the fact that the old one was rotted through.

4. More HP: As I mentioned before, I plan on wringing out the bugs with the Northstar in stock config. I may create some headers for it, but the rest will be stock for now. Once it's working right, then new cams & valve springs would be my first step to improving HP and redline.

5. Low revving engine: Cptsnoopy answered this one.

6. One-off body: I don't want to sound condescending, but there is a huge difference between building a fiberglass kit car and designing one! I appreciate your confidence in me being able to pull it off, but the reality is that I have very little experience fabricating fiberglass parts. I'm in awe at guys like Whodeanie who can shape and mold parts with an excellent eye for proportion, and outstanding body work skills. If I were to even attempt a one-off body, it would take ten years before the thing ever saw the light of day! I do plan to make many original tweaks to the poor quality IFG fiberglass kit I bought. It'll be a trial-by-fire as I venture into the world of foam molds and bucks, but I think I'll be able to change your mind about the worthiness of the Ferrari kit. Stay tuned!

Terrible Tom ( MSG #407, 05-09-2011 01:39 AM
      To All Pennock's Members:

Let's all volunteer to go up to Blooze's place and deal with this stuff: " I've taken a few weeks off from the thread to get the spring cleaning, gardening, car tune ups, and some house renos done" so he can get back to work on the car!

Seriously, thanks for the great documentation of your super project, Blooze. It's not often one gets a chance to watch an artist at work.


katatak MSG #408, 05-09-2011 07:09 PM
Originally posted by Terrible Tom:

To All Pennock's Members:

Let's all volunteer to go up to Blooze's place and deal with this stuff: " I've taken a few weeks off from the thread to get the spring cleaning, gardening, car tune ups, and some house renos done" so he can get back to work on the car!

Seriously, thanks for the great documentation of your super project, Blooze. It's not often one gets a chance to watch an artist at work.


I'm in - I hate it when I can't get a daily dose of the Blooz build!

Bloozberry MSG #409, 05-09-2011 09:22 PM
      You guys are great! I'm assuming you do know I have a hobby farm right? Because the chicken coop needs mucking out, the horse manure pile needs turning, and someone needs to replace the cedar shingles on the barn. I can't wait 'til you guys get here! BTW, Gene the Rooster (named after Gene Simmons) will decide if he likes you enough for you to stay. He's kinda picky about who he likes... bring him an extra hen if you want to tilt the odds in your favor.

Blue By U MSG #410, 05-10-2011 08:54 AM
      Blooze were are you located?? my wife and I have an RV located in Berwick, we are there every weekend, I would love to come and see the collection!

Bloozberry MSG #411, 05-10-2011 12:34 PM
      Blue By U: PM sent.

Austrian Import ( MSG #412, 05-10-2011 02:17 PM
      Great thread.

Has anybody tried a different suspension geometry, maybe with upper control arms to allow for better camber changes?

Austrian Import ( MSG #413, 05-11-2011 02:15 AM
Originally posted by ccfiero350:

The drawings are just great, and a lot of man hours. I agree that there should be a repository for just for CAD files some where here in PFF.

One of the best books I have found on suspensions is "Race Car Vehicle Dynamics" by Milliken & Milliken ISBN 1-56091-526-9 , It's published by the Society of Automotive Engineers and you can get it on Amazon.

And it covers tri-link struts like ours.

That would be great. Especially if it were a Solidworks, or similar file.

Rickady88GT ( MSG #414, 05-12-2011 02:13 AM
Originally posted by Bloozberry:


That does not look like power steering?

Nice work.

Bloozberry MSG #415, 05-12-2011 07:34 AM
      It's a special Armstrong steering rack... get it... Arm strong?

Rickady88GT ( MSG #416, 05-13-2011 02:55 AM
      How Ironic is that, I used to build tires for Armstrong and Pirelli, and build power steering in a few Fiero's LOL.

aeffertz ( MSG #417, 05-25-2011 01:25 AM

17Car MSG #418, 05-26-2011 09:25 PM
Originally posted by aeffertz:


Blue By U MSG #419, 06-06-2011 11:41 AM
      Blooze, Thanks for the grand tour Saturday! loved seeing the GT, 308 stinger, and 355 in progress, along with all your other toys and goodies!

Ruffy MSG #420, 06-15-2011 09:54 PM
Originally posted by 17Car:



fierogt28 MSG #421, 06-25-2011 09:46 PM
      Any update Blooze on your swap project?? Your kill'in us...

Fiero2m8 MSG #422, 06-27-2011 08:28 PM
Originally posted by Blue By U:

Blooze, Thanks for the grand tour Saturday! loved seeing the GT, 308 stinger, and 355 in progress, along with all your other toys and goodies!

Sorry Blooze, I was in Nova Scotia last week for work and forgot to look you up - next time.

Bloozberry MSG #423, 06-27-2011 08:51 PM
      Thanks guys for all your interest. I'll be back at it soon, other priorities crept up that have demanded my attention for the past couple weeks. For Fiero2M8: Be sure to let me know next time you're in the area...

Hulki U. My-BFF ( MSG #424, 06-27-2011 09:11 PM
      Blooz, the work you do directly matches the level of technical advice you give everyone. You are truly one of the Fiero greats with your craftsmanship. Beautiful work, my friend.

Bloozberry MSG #425, 06-27-2011 10:21 PM
      Thanks Hulki... I've given you a "+" in the past for your contributions to the forum too.

17Car MSG #426, 07-23-2011 09:49 PM
      Monthly Bump!

cptsnoopy ( MSG #427, 08-22-2011 02:46 PM
Originally posted by 17Car:

Monthly Bump!

My turn!

Bloozberry MSG #428, 08-23-2011 12:44 PM
      OKay, okay... I'm finally off my summer of relaxation (yeah right!) and am back with my nose to the grindstone.

Several people have pined about having front suspension drawings done up that are equivalent to the ones I did for the rear suspension. Over the next couple days, I'll be measuring up my '88 front crossmember and entering the data into electronic format to start the process. I'll post the drawing of the front crossmember within a few days, then add the suspension bits from there. Once that's completed, hopefully we'll have the complete picture of the stock '88 Fiero suspension. In an ideal world, that should make it easier to predict what effects modifications will have on handling, but I suspect it's going to be like opening Pandora's Box. Stay tuned!

fierogt28 MSG #429, 08-23-2011 11:33 PM
      Hey Blooze, what's planned for the rear cradle?? Fix the original one, or completely make or fab one up?

I suppose the cradle will be silver...

Have a good end of summer.

Bloozberry MSG #430, 08-24-2011 07:46 AM
      The cradle will be a newly fabricated one, but the final design details will depend on how the planned changes interact with the front suspension. That's why I'm studying the front now.

In a nutshell, the new cradle will have the side rails pushed outboard instead of having them kinked inwards. That will relocate the lateral links further outboard as well, giving more clearance for the link mounts to be moved higher up. As for color... you guessed right... I like how silver gives the illusion of being a lighter, more exotic metal.

5150fauxarri ( MSG #431, 09-01-2011 08:51 PM
      Wow is all I can say! Bloozberry thank you soooooo much for your thread. I have learned an amazing amount of info just from reading your story. As for me I'm in the middle of building an f355 with a n*. Sounds familliar right. My car was started by Bob Nielsen= former publisher of the Fiero News. He had health problems and unfortunately couldnt finish. Its built on an 88 formula. The best part is the N* that he purchaced in 96 from an eldorado that was totalled leaving the dealership. I also only live about 20min door to door from alan at chrfab so help is nearby. He wanted the engine bad since it has no wear and tear. It's has a rebuilt getrag 5spd with centerforce cluch and custom flywheel. Basiclly he was building the car the right way and has all top of the line parts. Anyway I just wanted to say thanks for the inspiration.

Bloozberry MSG #432, 09-02-2011 02:30 PM
      Thanks 5150fauxarri, and welcome to the forum. Sounds like our projects have a lot in common so we may be able to benefit from each other's experience. So is your car running at this time? You should start a thread in Tech Discussion and document as much about your car as possible (with pictures) so that others may be able to glean ideas from your car about things like exhaust routing, engine management, flywheel design, etc.

5150fauxarri ( MSG #433, 09-03-2011 12:52 AM
      Hey Blooz. Unfortunatelly I'm affraid I dont have the time to post everything like you do. On top of that I'm really computer illiterate which is why I don't have a picture next to my name and it took me a week to figure out how to make the right e-mail just to be on this sight. I have 3 kids who take up a lot of my time so I'm lucky just to get out and work on my car let alone write about it. Anyway about the car. My stock subframe was in perfect shape so a new front cross bar was put in place and except the trans mount(still stock possition) the rest was then cut out. The engine has been in and out at least 10 times working on proper fitment but I'm at the point where I'm going to have to weld up my mounts. This monday(labor day here) all my mounts well be done and I will be moving on from there. Anyway I will try to get some computer skills to help out people to learn from my(novice) mistakes.

Bloozberry MSG #434, 09-09-2011 07:08 PM
      Finally some progress to show... (I know, I know, it's been a while). This latest update may disappoint some though since it's not about shiny parts Instead it’s about more drawings… I've finally completed the '88 front cross member drawing, less all the goodies that attach to it. I wished it could have been a quick and dirty affair, but the reality is that it took 48 hours of labor to measure and enter into electronic format. (I must be the world's slowest drafts-person.)

Much of the difficulty comes from trying to establish a reference line or plane from which to measure all other points out there in 3-space. Just when you think you've got some complex curve finally figured out in two views, something goes all hairy in the third view so it's back to the drawing board... literally.

One thing that threw me for a while until I could get it figured out was that there is a measurement error in the '88 Service Manual on page 3J-6 and 3J-8. These pages refer to the underbody frame alignment specs. Although the cross member itself isn’t covered, these pages do provide some information about the mounting points for it, so it was a logical place to get a few initial reference measurements for my drawings. Here’s one of the pages in question (the other page just lists the numbers and includes the same fault):

Unfortunately in figure 5, the vertical measurement for point C* is wrong. After checking and re-checking several times, then consulting with an earlier year service manual (an ’86), it seems that GM just imported these schematics directly from the ’84 – ’87 Service Manual and modified the numbers to suit the '88… but forgot at least one of them. In fact I know this is what they did because the 3D drawing of the space frame on the previous page isn’t that of an ’88 at all in the ’88 SM. Anyway, on with the show.

Here is the overall 3-view drawing of the front cross member (note that the scale is 1 square = 10mm). The red line is an arbitrary vertical plane I chose through the center of the middle section of the cross member to aid in taking measurements. The horizontal reference plane is the top surface of the main central mounting location of the cross member where four bolts pass through it (two per side):

Because of the size limitations for pictures posted in PiP, I chopped up the 3-view drawing into each of the three views separately to get a bit more detail visible. Here’s the Top View, where most of the pertinent measurements for the whole cross member are shown:

Here is the Rear View, plus a sectioned view of the steering rack mount. One important thing to note is that the cross member is completely symmetrical from left to right, with the exception of an alignment pin on the LH side, mid mount location. I found it curious that GM would have only installed a single alignment pin for the whole thing

And lastly, here’s the LH side view of the cross member. The notable feature from this view is the angle of the upper control arm mount, namely 5 degrees. If you’re not sure why this important, it’ll become clearer once I get around to analyzing the front geometry.

Next up: the control arms… stay tuned.

(Edited to update all four crossmember drawings)

[This message has been edited by Bloozberry (edited 11-11-2011).]

fieroguru MSG #435, 09-09-2011 09:10 PM
      Blooze, you rock! I'd give you a + per drawing if I could.

RCR ( MSG #436, 09-11-2011 06:24 PM
      Those are great, Blooze.


Fiero2m8 MSG #437, 09-12-2011 11:29 PM
      Thanks Blooze !
I know it's bass-awkwards but now I have the drawings of what I installed in the Indy

BlackGT Codde ( MSG #438, 09-20-2011 12:08 AM
Originally posted by Bloozberry:

A few odds and sods for this post: I bead blasted the harmonic damper to get it nice and clean for paint when I noticed something interesting:

Anyone recognize the symbol? It sure looks like the Briggs and Stratton logo to me. I wonder why that would be stamped into the damper. Hmmmm… are there any 32 valve lawn mowers out there that I’m not aware of?

um actually yes you hit the nail on the head, general motors, ford (especially the svt and racing development), and chrystler , all use briggs and stratton for a lot of engine building,
as do many other auto manufacturers, your cars are built by the same people who built your lawn mower. if you can believe that.
it is actually true, i have seen this logo and more detail on a ford 5.4 DOHC mustang cobra engine crankshaft. also seen the B&S logo on many pistons here is their home page, (after supposed split)(i believe is still with briggs very strongly)

Bloozberry MSG #439, 09-20-2011 10:09 PM
      <Edit ON>: Where are my manners... thanks for the feedback Fieroguru, RCR (Bob), and Fiero2m8. It's nice to know some people stayed tuned in! For BlackGT Codde: I was thinking either Briggs or Harley Davidson Ever noticed how the two logos are almost the same? <Edit OFF>

Anyways, another quick update: Progress has been a bit slow but here's the upper control arm. The end-view sure is busy! I couldn't really add it to the front cross member just yet because it sits at an angle to the floor as seen both from the side and rear view of the cross member. I know what the angle is from the side view (5 deg) but from the rear view I don't know what it is just yet. I'll need to draw the lower control arm and set it parallel to the ground, then draw both ball joints and the knuckle before the upper control arm angle can be determined. I guess I should have started with the lower control arm eh? (<--- Canadianism).

Hopefully the lower control arm won't take as long... the rainier the weather, the more I stay inside, the faster things get done.

[This message has been edited by Bloozberry (edited 09-20-2011).]

5150fauxarri ( MSG #440, 09-27-2011 10:59 PM
      Ha! The reason my progect goes so slow is since I'm in sunny southern California I'm allways outside (with the honey-do list of corse)!!!!

Bloozberry MSG #441, 09-29-2011 08:00 PM
      Ahhhh yes... the Honey-Do List... every married guy has one longer than his arm.

Speaking of lists, I have a little more progress to report on Blooze-Do List: I finally managed to complete the three-view of the front lower control arm drawing. What a bear this thing is. It has such a convoluted shape on the underside that around Hour 15 of trying to draw it, I realized that for my simple static analysis, I only really need to have a stick drawing with the essential dimensions on it. But then, how interesting would that be? So 20 hours of drafting later, here's the latest in the series of suspension drawings (I wouldn't try to make a set from scratch using my drawings ). The knuckle is next.


Top View zoomed in:

Rear View zoomed in:

Side View zoomed in:

[This message has been edited by Bloozberry (edited 09-29-2011).]

Bloozberry MSG #442, 10-08-2011 10:09 PM
      Only a few more pieces to go and this stock suspension stuff should be over and done with. That will allow me to get on with designing the new rear cradle and hopefully prove the changes will result in improved geometry... at least on paper. But then that's all I'll need to do to satisfy the looming legislation here in Canada which would place strict certification processes on modified suspensions.

Enough of that. I've been slaving away in my spare time getting the front knuckle drawn up. It was a little challenging since there are some interesting angles which complicate getting accurate measurements, but after double and triple checking things using alternate measuring techniques, I'm confident it's very very close. What made matters worse is that I wasn't able to separate the bearing assembly from the knuckle as I did for the rears. I would have had to take the assembly to a shop with a hydraulic press to get them apart. If I had planned to actually use these knuckles and bearings, I would have done that, but since they're only being used for camparison's sake I drew the parts stuck together, like they are. Here's the three-view:

One interesting issue I found is that the P22 parts book lists the RH and LH knuckle part numbers as 10046484 and 10046483 respectively. However cast right into the RH knuckle I used is part number 10048486 with additional castings GM and 84. Are there earlier and later versions of the 88 knuckles?

The next hurdle will be to try to accurately measure the dimensions of the upper and lower ball joints. The center of the pivot point won't be easy to determine with any great accuracy. I tried Googling ball joint dimensions, and schematics, and specifications, and drawings... nothing came up. I did find an obscure thread somewhere where a guy was trying to do the same thing as me for his Honda. He was told by Moog and several other manufacturers that they didn't release that information since it was proprietary. As if we're all going to start making our own backyard ball joints! Hopefully I'll be able to figure out a way without resorting to cutting one of each up. Anyone have any leads for the data or ideas on how to measure it?

(Edited to update drawing)

[This message has been edited by Bloozberry (edited 11-16-2011).]

Zac88GT ( MSG #443, 10-09-2011 03:25 PM
      When I modeled the miata ball joints I'm using for my locost i moved the joint all the way to one side and drew a line down the center of the joint, then moved it to the other side and did the same. I then used the intersection point as the center of rotation. I feel it worked reasonably well but without cutting it apart there's not much else you can do.

[This message has been edited by Zac88GT (edited 10-09-2011).]

Gokart Mozart MSG #444, 10-09-2011 10:27 PM

[This message has been edited by Gokart Mozart (edited 10-09-2011).]

Bloozberry MSG #445, 10-10-2011 09:05 AM
      Thanks Zac and Gokart. For Zac, I used your suggestion and it seemed to have worked relatively well. The upper is now done, I just have to work on the lower one now.

For Gokart Mozart: I looked at the four links you provided but only found the third link helpful. On page 18 there was a cross section schematic of an upper and lower ball joint which helped me to visualize the guts a bit better. Not exactly sure why you posted the other links though.

Gokart Mozart MSG #446, 10-10-2011 11:57 AM
      they had dimensions, thought they might be helpful

5150fauxarri ( MSG #447, 10-12-2011 08:15 PM
      Hey Booz. I dont know if you would be interested or even if you are allready fallowing the build. But under the General Fiero Chat, there is the topic of "My Mera Style 308 Project". The only reason I bring it up is he makes some pretty nice 355 taillights. I've noticed you have the same crappy outer lenses I have and just thought you might be interested. Currently he has posted pictures of the f355 taillights but hasnt put a price on them but Im sure I will be a customer.

Bloozberry MSG #448, 10-12-2011 08:36 PM
      Thanks for the tip 5150fauxarri. But I'm one step ahead of you! A couple months ago I bought a set of new OEM tail lights from Don Ostergard here on PFF who was getting out of an F355 project car.

Bloozberry MSG #449, 10-14-2011 05:02 PM
      This week I worked on the ball joints and the front upper control arm mount. Trying to determine the exact center of the ball joint pivot points was a little daunting at first, but I came up with a measurement method that estimated the location within the precision needed for this analysis. I removed the boots and cleaned the grease from the exposed part of the ball, then swung the stud all the way to one extreme of the permissible movement and measured the lateral and vertical displacement of two fixed points along the centerline of the stud. Then I swung the stud to the other extreme and did the same. These four points described two converging lines that intersected at a point where the pivot center should be. I repeated the measurements several times for each ball joint and then used a bubble level protractor as a back up method, and not surprisingly came up with a very round measurement for both ball joints; 25 mm (or 1 inch) below the lower edge of the where the taper stops on the studs. It makes sense too that a ball joint manufacturer would use common dimensions for these sorts of things rather than some odd number... at least that's what I tell myself trying to rationalize my results!

Here's the upper ball joint. One interesting note is that both ball joints insert into their respective tapered holes in the knuckle right up to the depth where the taper on the stud ends:

And here's the lower ball joint. You'll notice that I didn't include as many measurements simply because not all of them are important, and outside dimensions may differ between manufacturers:

Finally, a simple little drawing of the upper control arm mount.

One last drawing to do before I can start sticking all these pieces together: the steering tie rod.

(Edited to update both ball joint drawings)

[This message has been edited by Bloozberry (edited 11-16-2011).]

5150fauxarri ( MSG #450, 10-14-2011 11:32 PM
      Your work is so nice I would happily take the peices you throw away thats not good enough for you!

Bloozberry MSG #451, 11-11-2011 10:20 PM
      Thanks 5150fauxarri... but I'm a bit of a pack rat when it comes to spare parts. Once this project is done, I'll have 3 roadworthy Fieros to try to maintain!

Well, it's been a while since I posted an update here, but not because I haven't been working my buns off. For starters, as I began piecing the various front suspension component drawings together to create the complete front suspension illustrations, I realized that some pieces weren't fitting exactly right. But I rather expected this since there are so many hundreds of measurements that I was bound to make a mistake or two. Piecing the parts together is sort of like a sanity check... if things don't fit, then there's obviously an error.

For those of you who may be copying some of my drawings to your own computers, you'll want to revisit the four drawings of the front cross member on page 11. I updated the spacing between the lower control arm mounts and tweaked a few other related measurements. Also, I've replaced both ball joint drawings on this page as well since I had forgotten to include the range of movement in the side views.

As for new work, I've drawn up the tie rod recently. There was nothing noteworthy about this drawing (Edit: updated drawing to Version 2):

Now for the part that's taken me eons to get right... the full front suspension illustrations. Just for curiosity's sake, I've been tracking my hours on this build in an Excel spreadsheet since the beginning. (It'll make for some interesting conversation later once it's done, and possibly even help the appraiser determine some value for the time put in it). This next set of drawings has cost me 30 hours to date, and I'm still not finished. I'm posting the side view first as I continue to work on the other two views.

The difficulty so far has been trying to determine the correct angles of the control arms at ride height, and then drawing them at these angles. The earlier 3-view drawings I made of the arms were created at angles that suited the ease of drawing them, not as it turns out, at the actual angles they sit at when the car is at ride height. Here is where having done these in a CAD program would've made things exponentially easier. I can tell you right now that the jounce and rebound drawings later on are going to be stick figures, not illustrations like I did for the rear suspension! (Edit: updated drawing to Version 2)

Anyways, the noteworthy aspects of this side view drawing are that:

1. the tire dimensions were taken from the average between four actual stock-sized, new front tires (P205/60/15) at 32 psi installed on two different '88 GT's, so that's how the rolling circumference was determined;

2. the lower control arm angle was determined by a measurement specified in the '88 service manual on page 3-16. It states that the difference in height between the lower corner of the lower ball joint and the frame rail directly inboard of the joint should be 6.9 mm. Having done this, the upper flat surface of the lower control arm sat at an angle of 7.5 degrees pitched downward towards ball joint end;

3. once the lower control arm was drawn correctly, the knuckle was added after being tilted for 5 degrees of caster; and

4. finally the upper control arm angles could be determined, and the upper arm drawn accordingly.

This side view will be used later on to determine what percentage of anti-dive is built in to the stock '88 suspension. Those of you who are more wiley and ambitious can already figure out this value from the info I've posted here and earlier.

[This message has been edited by Bloozberry (edited 11-19-2011).]

17Car MSG #452, 11-12-2011 01:19 AM
      Amazing work on the drawings, are you using solid-works to draft these?
The dimensions and notation look familiar...

Bloozberry MSG #453, 11-15-2011 10:14 PM
      Thanks 17Car for the comments. I wanted the source drawings to be accessible and modifiable by as many people as possible, even those without CAD software, so I chose the very common drawing software tool that comes with the basic the Microsoft Office Suite. I use Microsoft Excel as the backdrop for the images after having forced the gridlines to squares. The resulting image is a vector drawing (scalable), but is essentially a line drawing that isn't renderable into 3D. That's the drawback to making it available to everyone. I haven't yet posted the source files since I continue to find small errors as I piece the components together. Once I feel they're at a stage where they are as good as I am am prepared to draw them, I will look for a site to host the files for anyone to download.

Now on to a few corrections to earlier drawings For those of you following this thread and downloading the drawings, you'll want to update your files with new pictures of the tie rod above, to which I've added the degrees of motion to the side view (you'll note that it's annotated Version 2). Also, I noticed several errors in the original drawing above titled 1988 Fiero Front Suspension LH Side View so I corrected them and annotated it Version 2 as well. The errors consisted of miscalculated front cradle mounting height and the ground clearance to the bottom of the cradle. As well, I noticed that I hadn't completely drawn the lower profile of the lower control arm which further reduces the overall ground clearance. If I discover any other errors I'll just keep changing the Version number and call attention to the changes in future posts. Likewise, if anyone sees any errors, please do not hesistate to let me know so I can correct them.

Finally a new drawing to add to the collection: the rear view of the front suspension (Edit: updated to version 2 - corrected location of outer tie rod end):

There are a few noteworthy details in this drawing:

1. The '88 front track width (59.7" or 1516.5 mm) was taken from an article in Road & Track (Oct '87). I've found the track width reported in several magazines and books to be erroneously listed as 57.8" including Gary Witzenburg's Fiero, Pontiac's Potent Mid-Engine Sports Car;

2. The camber is set to zero degrees in accordance with the alignment specs.

3. The kingpin angle is 6.0 degrees according to Gary Witzenburg's Fiero, Pontiac's Potent Mid-Engine Sports Car;

4. Neither the upper nor lower A arms are horizontal as viewed from the rear (or front) at ride height. The upper A arm is angled at 6.2 degrees upwards, and the lower A arm is angled at 7.5 degrees downward as measured from the top surface;

5. The scrub radius is an unverified 40 mm as I was unable to find any referenced documentation identifying the actual measurement. It's interesting that it's as large as it is despite the front wheels on the '88 being only 6" wide and having a relatively large 37mm offset;

6. As reported earlier, the center of gravity sits at 19.5" above the ground according to Road & Track (Sept 1983). Admittedly this is for the four cylinder cars, but I am assuming the CofG height most likely did not change significantly with the V6. It's longitudinal location did though;

7. The outer tie rod end is situated about 15mm outboard of the plane defined by the upper and lower ball joints. This results in built-in understeer as the roll angle increases. For there to be no effect, all three would have to align in the same plane; and

8. The shock absorber and the sway bar were left out to simplify the drawing

I think that's all that's pertinent about this drawing for now. Next up is the top view, and then on to some basic geometry analysis.

[This message has been edited by Bloozberry (edited 11-19-2011).]

Jfrost MSG #454, 11-16-2011 12:50 PM
      Just got done reading through your entire build, very impressive! It's seeing builds like these and the attention to detail that got me excited about Fiero's in the first place, and keeps me motivated to work on my car. Keep up the amazing work!

Yellow87FieroGT ( MSG #455, 11-17-2011 04:23 PM
      57.8 for the front track with is correct for 84-87 model years though, correct?

I just want to be clear that isn't a typo as well.



Bloozberry MSG #456, 11-17-2011 04:50 PM
      Thanks JFrost for the kind words.

For Yellow87FieroGT: Yes... the front track on the '84-'87's is 57.8 and the rear track is a bit wider at 58.7 according to many different magazine sources.

Edit for speeling

[This message has been edited by Bloozberry (edited 11-18-2011).]

Yellow87FieroGT ( MSG #457, 11-18-2011 09:37 AM
      ok. Thanks!

Bloozberry MSG #458, 11-19-2011 09:37 PM
      A quick note for those of you saving copies of my drawings: I made an amendment to the drawing above entitled 1988 Fiero Front Suspension Rear View. The latest version (V2) above has the outer tie rod end raised about 5mm higher than Version 1. The reason is because I realized I had not rotated the knuckle to match the built in castor in this view which placed the steering arm on the knuckle lower than it should have been.

Now for the last of the layout drawings, here is the '88 front suspension assembly as viewed from the top:

There aren't many noteworthy aspects to this view except:

1. the difference in control arm lengths is quite apparent;

2. other than a symbolic rack, I didn't include the steering rack and pinion assembly... just too much work for no added value;

3. in the notes, I forgot to mention I left out the sway bar. I'll correct that only if other changes become necessary.

Everything in these three last drawings can pretty much be summed up with the values I've tabulated in the chart below under the heading "Coordinates". The "Static Data" portion of the table contains some measured and some calculated data. All the static data points are directly measured except for the roll center, swing arm length, and anti-dive, which are calculated. I go into how these are calculated in a later post. (Edit: updated chart added).

With the right formulas, this data is all that's needed to calculate the change in caster, camber, tire scrub, toe, front swing arm and side swing arms for any given amount of jounce, rebound, or roll. I know all of this because Herb Adams book tells me so. Too bad Herb doesn't get into the detailed formulas, referring instead to a computer program he uses... great help

[This message has been edited by Bloozberry (edited 12-08-2011).]

Zac88GT ( MSG #459, 11-20-2011 05:06 PM
      Edited to verify results

[This message has been edited by Zac88GT (edited 11-25-2011).]

Bloozberry MSG #460, 11-20-2011 07:39 PM
      As with the front suspension coordinates, I've tabulated the rear suspension coordinates in the same format for anyone to use.

Once again, given the coodinates in the first part of the table, the swing arm, rear roll center height, and anti-squat can be calculated as I've shown on page 9 of this thread for the rear end.

(edited to add updated table)

[This message has been edited by Bloozberry (edited 12-08-2011).]

Zac88GT ( MSG #461, 11-20-2011 08:48 PM
      I used Lotus Suspension Analyzer. I can export a report to Excel with all the data so PM me you're email and I'll send it to you. I'll get to work on the rear suspension, probably won't take very long.

Bloozberry MSG #462, 11-20-2011 09:56 PM
      PM sent. Thanks!

Zac88GT ( MSG #463, 11-20-2011 10:58 PM
      Edited to verify results

[This message has been edited by Zac88GT (edited 11-25-2011).]

Zac88GT ( MSG #464, 11-20-2011 11:14 PM
      There are a couple things to notice right away from these graphs. Under bump the rear toe barely changes but it does toe in slightly, which is good. The front toes in on bump which is undesirable because it accentuates the steering input as the car rolls. Rear camber gain sucks as does rear roll center control.

ricreatr MSG #465, 11-21-2011 08:31 PM
      this feels like a big day in fiero history! thanks guys.

i have a million questions, but i will keep quiet waiting for some smart people to make suggestions for improvements . . .
dont make me wait too long.

Bloozberry MSG #466, 11-22-2011 11:05 AM
      (Edit: Zac88GT used the numbers in the table of coordinates above to input them into Lotus Suspension Analyzer V.5 and generated numerous graphs depicting the change in such things as toe, camber, caster, roll centers, anti-dive and anti-squat etc as the suspension moves into varying degrees of jounce, rebound and roll angles. These graphs were deleted due to several errors found in the data. They will be reposted in a later post once the source of the errors has been found and corrected.)

Thanks again Zac for crunching and graphing the front and rear suspension data. And thanks for your interest ricreatr!

Zac has sent me the data tables for the graphs and I have my work cut out interpreting and double checking everything since not everything is easy to interpret. For example, not all the units of measure are obvious (degrees? mm's?), nor am I certain about the conventions of the scales (what do positive vs negative numbers mean in terms of direction). I found it surprising for example that both the front and rear exhibit toe-out under jounce (assuming negative values in the graphs are toe-out). I expected the rear to toe-in as I'd shown in an earlier drawing. So it's time for some off-line studying...

Anyways, the point of this post is to share my thoughts on where this build thread should go from here. As much as I am super-interested (like ricreatr) to see what the Fiero community comes up with to tweak the stock suspension, I'm just not sure that this build thread is the right place for that discussion. I would like to keep this thread focussed on what I plan to do to to my little car. Afterall, my primary goal in documenting the stock suspension was to ensure I could prove to my provincial registry of motor vehicles that my planned modifcations wouldn't adversely affect the handling of my car. (The car will need to go through an engineering assessment and certification process by the province's PEng before the car will be allowed to roam the streets).

So rather than get side-tracked with discussions on how to improve the front and rear suspensions in here, I'd like to redirect those discussions to the Technical Discussion & Questions section of the site. In retrospect, I should have started a separate thread under TD&Q a long time ago when I started delving into the stock geometry. As it stands now, there's a superb discussion in TD&Q called Redesign a Fiero Suspension for Better Geometry here: That thread has focussed on the rear geometry so far, and probably should be kept that way to keep the thread from being too difficult to follow. So at the risk of reposting stuff that's already in here, perhaps I should kick-off a new thread dedicated to the front suspension.

[This message has been edited by Bloozberry (edited 12-08-2011).]

Zac88GT ( MSG #467, 11-22-2011 03:40 PM
      Negative toe is inwards in that program so your original assumption was correct.

ricreatr MSG #468, 11-25-2011 10:56 AM
      we understand blooz! it is really too much info to have both big projects on the one thread.

zac, if the info gets moved to the other thread, maybe we could talk you into scaling the graphs down small enough to get two side by side, with a graphic in between.
say, , , first graph showing original geometry, small graphic showing what that measurement represents (for the learning impared like me) and the second graph showing the proposed revised geometry.

still reading these posts everyday

Bloozberry MSG #469, 11-25-2011 04:32 PM
      Anyone following this thread should take note that while reviewing the suspension data used to create Zac's curves above, I've found a few important errors in the table of coordinates I posted earlier, specifically the location of the upper and lower ball joint X-Axis coordinates, which had a 4.7 degree impact on the kingpin angle. (Edit: I have now corrected the tables for the front and rear suspension coordinates above, so they now contain correct data).

Also, not quite as significantly, I've asked Zac to review the rolling tire diameters he input into the program since they were around 15 mm taller than I measured empirically with actual loaded tires.

Lastly, I've pointed out in the "Redesign" thread that we need to sort out why there is a discrepancy between my value and the program's calculated rear anti-squat at ride height.

If you see the curves posted by Zac disappear for a short while, it's because we are reconciling the differences between what the Lotus Suspension Program he is using has put out, and my direct observations through the drawings. The curves will be back along with a post indicating they are the latest, corrected ones. Thanks for your patience.

[This message has been edited by Bloozberry (edited 12-08-2011).]

Zac88GT ( MSG #470, 12-03-2011 09:39 PM
      As requested here are the basic suspension views.

Front View

Side View

Top View

Isometric View

Bloozberry MSG #471, 12-06-2011 08:56 PM
      Thanks for reposting the updated 3D views Zac. I finally got to the root of almost all of the discrepancies between the output of Zac’s Lotus program and my drawings. The only discrepancies that now exist are with the front anti-dive and rear anti-squat, but they are very close. I’ll get into more details further below.

So on the topic of rear anti squat (once again) for those making copies of my drawings you'll want to update your files with the new rear anti-squat drawing found near the bottom of page 9. I made a mistake in the original application of the formula that made a big difference. The formula for rear anti squat is:

% Anti Squat = [TAN (A) / (H/L)] X 100

When I first applied this formula on page 9 of this thread, I accidentally used the wrong value for “L”. I thought I read that it was supposed to be the distance between the centerline of the rear wheels and the CofG of the car in the longitudinal plane (X axis). The correct value of “L” is the wheelbase. That changes the rear anti-squat from 28% to 66%… much closer to the 62% that Zac’s Lotus software predicts.

To reconcile the difference, I went over the coordinates one by one (the same ones that are input into the Lotus software), used them to calculate the value of the angle “A” (just as the Lotus software must do), and plugged the rest of the info in to the above formula. There is still a 4% difference in anti squat. Zac wasn’t able to view the equation that the software uses, so there’s no telling how it calculates the anti-squat. I think I’ll use my own value since I know the origins.

OK, on to the stock front anti-dive geometry. Once again, I provided the coordinates of the stock suspension to Zac for input into the Lotus Suspension Analyzer software, and once again we came up with a 5% difference at ride height. I used the formula in the diagram below, which came from Miliken & Miliken. I went through the same process as with the rear suspension and used the coodinates as the basis for the trigonometric calculations for the angle “A”, yet still came up with the discrepancy. Once again, I’ll use my own calculations for anti-dive since I know how it was calculated.

The next drawing shows the location of the lateral swing arm at ride height and the front roll center. At least in this drawing the Lotus output data and my drawings give the same results! The most important part of this drawing is the determination of the roll center height.

Now that the roll center heights for the front and rear suspensions are known, the roll axis is simply a line drawn between the front and rear roll centers (red line), like so:

The roll axis is also shown in the last 3D picture in Zac’s post above. It’s the line that runs down the centerline of the car near the ground.

The next thing I'll cover is a final update to the tables of front and rear suspension linkage coordinates so anyone in the future who finds this thread can plug the numbers into their own suspension analyzer program and modify the numbers to their heart's content. (Edit: this is now done) I'll also repost some of the corrected graphs that Zac posted earlier showing the geometry kinematics, but were since removed due to errors) . I also wanted to present them in a format that I found easier to read than the ones he originally posted.

[This message has been edited by Bloozberry (edited 12-08-2011).]

wftb ( MSG #472, 12-06-2011 11:51 PM
      regarding anti squat on an IRS rear suspension : "the differential torque reaction is not transmitted through the suspension members on an IRS rear suspension.By properly locating the rear suspension members , it is possible to get some anti squat , but a value of about 25 % is the practical limit ." -herb adams

Bloozberry MSG #473, 12-07-2011 10:32 AM
      Yes... I have Herb Adams book too and have spent several hours trying to resolve the apparent discrepancy. In the end, here is how I explained the differences in what he states versus what the Fiero rear suspension does.

There are two separate issues to examine in Herb Adams quote you provided;

1. Herb states "the differential torque reaction is not transmitted through the suspension members on an IRS rear suspension". This is true, and to compensate for this reality, the angle "alpha" in the equation for IRS anti-squat is determined slightly differently than for a live axle. If you look closely at the example in his book on page 75, you'll notice that the vector for the accelerative force starts at the tire contact patch and is angled upwards to pass through the side view instant center on a live rear axle suspension. On the IRS example however, the vector starts much higher up at the center of the wheel rather than at the tire contact patch. With all else equal, this dramatically reduces the angle alpha in the equation for anti-squat, which has the direct effect of reducing the overall % anti-squat. You'll notice on my anti-squat drawing on page 9 of this thread that I drew the red line as it should be for an IRS, from the center of the wheel through to the side view instant center giving an angle alpha equal to 7.85 degrees.

2. Herb's second sentence states: "By properly locating the rear suspension members, it is possible to get some anti squat, but a value of about 25% is the practical limit". The problem with Herb's statement is that I believe he perhaps unintentionally restricted his analysis of anti-squat to a conventional IRS layout like that on the Corvette example he uses. With the Corvette's four ink suspension, it does appear that the practical limit is about 25%, beyond which you would begin to introduce more wheel hop (reading some of the Corvette sites leads you to believe this is a problem with at least the C4's.) On the other hand, the Chapman strut IRS on the Fiero creates a side view instant center significantly higher above the ground than anything remotely practical with a four link IRS. The benefit of this (from the stand point of anti-squat) is that it dramatically raises the angle of the line drawn between the wheel center and the instant center. The angle (alpha) of that line is directly proportional to the amount of anti-squat generated. So the extra height of the instant center caused by the Chapman strut design, effectively compensates for the loss of axle torque reaction, bringing the % anti-squat for an IRS back up to a more comparable level of a live axle.

Bloozberry MSG #474, 01-18-2012 02:27 PM
      Well, it's been a while since I updated the thread, but that's not to say I've been idle behind the scenes. I've been busy mapping out and assessing different permutations and combinations of suspension changes to see what their impact would be relative to the stock configuration, at least theoretically. So on that note, this is an advance warning that this post is going to be dry, and heavy on the graphs and theory.

A couple of disclaimers though:

1. My primary goal is to make the car's stance look good. Then minimize the negative impact to the suspension's performance caused by having gotten the right stance. Actually improving the stock suspension performance is not a primary goal but if I can make it happen, then so much the better (however I've learned that improvements are not easily measured in suspension systems since everything is about compromise); and

2. I am not a suspension expert. I'm learning as I go, so constructive criticism is welcome. If you see something that's wrong, by all means, point it out and I'll correct it.

So then, in keeping with my primary goal to give the car the right stance, I recognized early on the need to:

a. move the wheels outboard to suit the wider body of the F355;
b. lower the car, but maintain a reasonable ground clearance; and
c. fill the wheel wells with the right size wheels.

Each of these simple sounding tasks create their own set of unique challenges and some have negative impacts on performance, which I'll cover. Knowing in advance that there would be some negative impacts, I wanted to have a better idea how to reverse them, so I mapped out the changes to the suspension coordinates at several stages of modification to isolate the causes.

The first step was to map the stock suspension dynamics to form a baseline against which the modifications could be compared. A big thanks goes to Zac88GT who's provided most of the number crunching services using his Lotus Suspension Analyzer 5.0 software. He's been plugging in the hundreds of coordinates I've been feeding him and sending back the numerical results. I then used the data his software cranked out to create the graphs below in MS Excel.

A Word About the Graphs: Zac's program pumps out toe, camber, caster, roll center height, kingpin angles, ackerman angles, wheelbase changes etc etc... you name it, not just for any given bump input, but also for any given roll and/or steering input as well. Unraveling the data would be a full time job so I've decided to post the data generated for bump in this thread, and touch on roll characteristics as necessary. But the rest is available if you have (easy) questions.

I also realize that simply flashing up the graphs isn't going to keep anyone interested for very long. So I'll post a short description of how to interpret each graph separately. That should keep you all awake! I'm open to anyone else's interpretation or additional noteworthy aspects I've missed. I've formatted the graphs to be somewhat more intuitive than the ones cranked out by the Lotus software, by placing jounce and rebound on the vertical axes (as though you were viewing the wheel moving up and down) with +80 mm representing the wheel having moved upwards in jounce, and -80 mm moving downwards in rebound. The suspension characteristic being studied in any given graph is then plotted along the X (horizontal) axis.

Lastly, in an attempt to condense things a bit, I've plotted three suspension configurations on each graph below to show how relocating suspension mounts or using drop springs impacts the baseline curves. In every graph and drawing from this point on, the dark blue lines represent the baseline dynamics of the unmodified suspension. The light purple lines represent the impact of my first goal, which was to increase the track width by 6 inches. And finally, the red lines represent the additional impact of extending the wheel base 3", and lowering the car 2" with shorter springs at all four corners. Even though I don't intend to use drop springs, I wanted to study this option to see what negative impact this has, since most people do accomplish lowering in this manner. I'll divulge my actual plans for lowering the car in my next post... the eagle-eyed among you will notice the blank column in the data tables accompanying the graphs below (my feeble attempt at creating 'suspension suspense'). If you've been reading this thread from the beginning, you'll know that I'm using drop spindles for the front, but my surprise is for the rear.

OK, enough preamble... on with the graphs. I'll start with what's happening at the front end. To help visualize what happens to the suspension geometry when you throw on a pair of drop springs and longer control arms. Here's a before and after drawing.

As mentioned, the dark blue lines represent the stock geometry and the red lines show what happens with drop springs. From the discussion earlier on about how the angles of the control arms govern where the roll center is located, it shouldn't be a surprise that drop springs hurt suspension performance by raising the roll center and limiting the upper range of travel in jounce. But there are a few other surprises about how longer control arms affect performance too. Nothing like a graph to visualize what happens when you start making modifications. The first three graphs depict camber, toe, and caster kinematics. I'll start with camber:

Camber Explained: The first thing to note is that at ride height, the stock camber is set at zero. As you compress the suspension upwards into jounce, it goes negative, and in rebound it goes positive. This means that it tilts inwards at the top as the wheel rises, and tilts outward at the top when the wheel falls below ride height (zero on the vertical axis). From a pure bump perspective, any camber change wouldn't be good thing because it wears the outer and inner edges of your tires faster by tilting the tire at anything other than ride height. Luckily we don't spend too much time in pure jounce or rebound. Camber change is very useful though, when cornering. When cornering around a left turn for example, the car body naturally rolls to the right, causing the suspension on the right side to compress up in jounce, which forces the right wheel to tilt in at the top in relation to the car body. By doing this, the tire stays flatter and in fuller contact with the road, giving more cornering grip. So it's a good thing! On the left side of the car, the suspension extends, tipping the wheel into positive camber which accomplishes the same thing: keeping the tire flat with the ground despite the body's roll. What happens on the left wheel in a left turn is less important though since most of the car's weight transfers off of it giving it less authority over the car's control.

Impact of Modifications on Camber: There isn't much difference between the three configurations shown by the different curves, however the changes are not helpful ones. The longer control arm modification (purple line) predictably dampened the rate of camber change for a given amount of jounce, requiring a greater body roll to achieve the same camber change as stock (blue line). Ideally, the camber change should mimic the amount of body roll in a turn to keep the tire contact patch flat to the ground. Interestingly, the dropped and lengthened suspension (red line) comes closer to mimicking the stock curve where it counts... in jounce. Note though, that on the red curve camber stops changing at +60mm of jounce where an unavoidable problem arises if using drop springs since you run out of shock absorber travel and/or hit the bump stops sooner.

Potential Camber Solutions: Dynamic camber change is created by having the upper and lower control arms different lengths. The shorter the upper control arm is in relation to the lower one, the more rapid the negative camber gain you'll get in jounce. One way to restore the stock camber gain on the longer control arms would be to use the same ratio between the upper and lower control arm lengths as stock, rather than simply adding 3" to both. The stock lower to upper ratio is 1.628:1 whereas the Held control arm ratio is 1.46:1. Shortening the upper control arm would also require moving the upper control arm mounts further outboard to keep the ball joint in the same location though.

Next up, toe: (Graph and text edited to correct confusion resulting from opposite toe polarity conventions between the Lotus software and SAE.)

Toe Explained: Toe is the angle of the road wheel in the steering axis. Often, the wheels of a car are aligned so that when sitting still, they point slightly inwards (toed-in or positive toe (SAE)) or pointed slightly outwards (toed-out or negative toe). There are two reasons why a manufacturer might specify a certain amount of static toe; either to bias it to account for undesirable toe changes in bump, or in the case of the '88 Fiero to account for "manufacturing tolerances... which when compounded requires pre-compensation [in the form of] toe-in [to achieve] parallel rolling of all four wheels."

The '88 Fiero is statically aligned with 0.30 degrees of toe-in per side, but I've chosen not to show this on the graph above since I have assumed that in the dynamic situation where the car is rolling, the wheels will have taken up the manufacturing tolerances and be rolling parallel to each other, eliminating the static toe-in setting. As the suspension compresses or extends though, the toe angle changes in accordance with the curve in the graph. In jounce, the wheels initially toe-in slightly to about 0.10 degrees until the suspension hits 40 mm of jounce. At that point they start straightening out again until 80 mm's of jounce by which time they've returned to the straight-ahead position. In rebound they start off straight ahead but continually point further outwards (or toe-out) through the entire range.

The reason dynamic toe changes are designed into a suspension system is to change the oversteer or understeer characteristics of the car. For example, when cornering around a left turn, the car's body naturally rolls to the right, causing the front suspension on the right side to compress up in jounce, which forces the right wheel to pivot in the direction of the turn even more on the Fiero. This causes the front of the car to oversteer, or turn more than what has been commanded by the steering wheel, at least initially. For a tail-heavy car, this does not help driver confidence, though it helps the initial tip-in into a corner. Past 40 mm's of jounce, toe-in stops increasing and starts decreasing, which to the driver inspires more confidence. But front oversteer or understeer can't be considered in isolation. It is just as important to see what's going on in the rear, which I'll do later on.

Dynamic front toe changes are created by having either the outer tie rod misaligned with an imaginary line drawn between the upper and lower ball joints from the rear view, or the inner tie rod misaligned with an imaginary line drawn between the upper and lower control arm mounts. If you go back to my rear view drawing of the front suspension at the start of this post, you'll see that the outer steering tie rod on the '88 Fiero is outboard of the imaginary line between the upper and lower ball joints. The impact of this is that the tie rod prescribes a larger diameter arc than the control arms when compressed, and therefore pushes outward on the knuckle steering arm. Since the knuckle steering arm is ahead of the knuckle, the knuckle gets pivoted outwards. That is what causes the curve to change direction in jounce.

Impact of Modifications on Toe: Exactly how much bump steer is a good thing and how much is bad? According to Herb Adams book Chassis Engineering, no more than 0.15 degrees of toe-out over 80mm of jounce. (Once again jounce is where it counts since the weight transfers off of the wheel in rebound, giving it less authority on the car's control.)

From the graph, the toe on the stock suspension never achieves a toe-out condition in jounce though it does lose 0.10 degrees of toe-in from 40 to 80 mm's of jounce. To the driver, the loss of toe-in would feel the same as a gain in toe-out in that range. The modified suspension represented by the purple and red lines both show more linear toe performance, though they cause the tires to toe-in ever more through the entire range. From the driver's seat, the modifications will result in greater oversteer and greater bump steer when only one wheel hits a bump. Neither of these characteristics are good changes.

Potential Toe Solutions: There are several possible solutions to rectifying the toe performance if it's found excessive:

a. reduce the static toe to something less than 0.30 degrees toed-in. This would move all the curves to the left by the amount of the reduction. It wouldn't be an effective solution since the wheels would automatically lose 0.30 degrees as soon as the car would be under way and the tolerances taken up. That would leave the wheels toed-out under straight line travel and would wear the tires unevenly. It also wouldn't change the slope of the curves so the front of the car would still gain toe-in in jounce resulting in oversteer.

b. lengthen the tie rod to force a faster transition to toe out (although that would require a new knuckle design to move the steering arm on the knuckle further outboard; or

c. decrease the length of the lower control arm to move the kingpin inclination line further away from the tie rod. That too would necessitate a new knuckle design as well to move the lower ball joint hole further inboard to maintain the correct camber; or

d. as Herb Adams says, lower the outer tie rod end or raise the inner tie rod end, though I don't understand this concept. Anyone with insight on this is welcome to explain how this works; or

e. prevent excessive front body roll by adding or increasing the effectiveness of a front sway bar (anti-roll bar). This was the option exercised by GM on the Fiero. A sway bar allows the wheels to move freely when both are either moving up or down in bump together, but dramatically increases the spring rate when the wheels move in opposite bump directions. By limiting the amount of jounce in roll, the amount of toe-in will also be limited.

On to Caster:

Caster Explained: Caster is defined as the inclination of the steering axis from the side view. In other words if you were to draw a line between the upper and lower ball joints in the side view, the angle the line forms with the ground is the caster angle. If the point on the ground is ahead of the center of the tire contact patch, then caster is said to be positive, whereas it's negative if it's behind the tire contact patch. Positive caster has a stabilizing effect by making it progressively harder to turn the steering wheel as the steering angle increases (when in motion). You can only imagine what it would be like if it got easier! It also is what causes the steering wheel to return to center after making a turn. Negative caster would do the opposite and clearly wouldn't be a safe suspension characteristic. The stock car is set up during alignment to have 5 degrees of positive caster at ride height so that's why the graph shows 5 degrees at 0mm of bump travel. Ideally, the caster angle shouldn't change as the suspension is bumped, so the actual performance of the stock suspension is somewhat undesirable. This characteristic is a by-product of having tilted the upper control arm mounts rearward to gain some anti-dive though, so it is one of the compromises that are made.

Impact of Modifications on Caster: From the caster graph above, the suspension configurations don't change the dynamic caster properties at all. This isn't very surprising since the property that causes a change in caster is the inclination of the upper control arm as viewed from the side. If you recall from earlier drawings, the tilt of the upper control arm was fixed at 5 degrees (down toward the rear) by the control arm mounts welded to the cross member. Since this wasn't changed in either of the two modification stages, caster wasn't affected.

Potential Caster Solutions: Neutralizing caster gain can only be achieved at the expense of diminishing the amount of anti-dive. Since anti-dive is more desirable for a street car than neutralizing caster gain, I don't plan on making any changes to the angle of the upper control arms in the side view.

Next installment: Front anti-dive and a look at what happens at the relationship between the front roll center and the CofG height.

[This message has been edited by Bloozberry (edited 02-07-2012).]

Tomski ( MSG #475, 01-19-2012 08:07 AM
      Blooze, you've turned Fiero into science class

Bloozberry MSG #476, 01-20-2012 03:39 PM
      Thanks Tomski (... at least I think it was supposed to be a compliment ). I know this stuff isn't for everyone and is nowhere near as interesting as glossy pictures, but I figured since I had to go through this exercise, I may as well post it. There might be a few tech geeks out there like me that see a future use for the data from similar graphs, now that the footwork is done. For example, who knows what the effect of installing Rodney's 1" lowering ball joints are? Just how badly do 3" wheel spacers affect steering compared to longer control arms? And when it comes to the drawings, I can see a potential future use to determine the never ending questions about what combinations of wheel dia/width/offset and spring drop is going to clear "my car"?

Enough defending why I'm posting this stuff. I'll get back into glossy pictures soon enough, but for now it's on to Anti-Dive:

Anti-Dive Explained: Anti-dive is a front suspension characteristic that reduces the amount the car will pitch forward under braking. As discussed earlier, it's achieved by tilting the upper front control arm so the aft mount is lower than the forward mount. Anti-dive is calculated using the following formula:

%Anti-Dive = Front Brake Bias (Tan (A) (Wheelbase Length / CofG Height) X 100

Where "A" is the angle between the ground and a line drawn from the center of the tire contact patch up to the side view (or longitudinal) instant center. There's a good drawing depicting this several posts up. Street cars typically are designed to have no more than 20-40% anti-dive according to Herb Adams, since any more tends to bind up suspension under bump. This is understandable since the greater the tilt of the upper control arm in the side view, the less it's track follows the straight up and down movement of the lower control arm, so they begin to fight each other over control of the knuckle once the ball joints hit their limits of travel.

From the formula, anti-dive in bump decreases with a decrease in the roll center height, or the wheelbase, or an increase in the CofG height. The raw data from the Lotus software (not shown) indicates that as the wheel moves up in jounce all of these variables change simultaneously. The roll center and CofG lower at different rates, and the wheelbase elongates despite the center of the front wheels moving backwards (what?), which seems strange until you realize that it's because the rear wheels move backwards even further. What I'm getting at, is that the magnitude of change in anti-dive isn't particularly intuitive (as if any of this stuff is!)

Impact of Modifications on Anti-Dive: From the anti-dive graph below, the stock '88 Fiero has a relatively constant anti-dive between 22.5% to 23% through the entire range of bump travel. This is at the low end of maximum anti-dive normally used in street cars, but is probably fine because of the lack of the engine weight on the front axle. More front weight would need a greater front brake bias which would increase the anti-dive according to the formula.

When the control arms are lengthened 3", the anti-dive performance actually improves marginally in jounce (purple line). On the other hand, lowering the car with a drop spring combined with the longer arms and increasing the wheelbase 76 mm had a detrimental affect on anti-dive (red line), basically the equivalent of shifting the purple curve to the right by 1% to 2% throughout the range of bump.

Potential Anti-Dive Solutions: Even though the graphs make the change in anti-dive appear significant, the scale has to be taken into account. A 2% reduction in anti-dive between the stock and fully dropped and extended suspension is negligible in my opinion. Because I will be using drop spindles rather than drop springs, I suspect the percent change in anti-dive will decrease, but I'll leave that final determination to the Lotus Software, so stay tuned.

Finally, a few (OK, many) words on roll centers:

Roll Center to CofG Explained. This next graph is one which took a bit of development since I didn't find the Lotus Analyzer data very useful without additional massaging. The software produces a table of the height of the front roll center from the ground versus bump (bear in mind that the roll center is constantly changing height not only as a function of the changing angles of the suspension control arms, but also as a result of weight of the car compressing the springs). I didn't find this information particularly revealing by itself, but when combined with information about the height of the center of gravity (CofG), things got more interesting. Here's why: if you accept that the CofG is the point on the vehicle where all mass may be assumed to be located, and consider the vertical distance between the roll center and the CofG as the length of a lever arm between where the wheels actually apply the forces to the chassis; then the greater the vertical distance between the two, the greater the leverage these forces will have on rolling the chassis in a turn. Also, the less the vertical distance between the two points changes, the more predictable the car's behavior will feel to the driver.

The curves above were generated by subtracting the roll center height from the CofG height as the roll center value changed with a progressively greater amount of bump travel. A curve that is vertical would mean that no matter how much the suspension compressed, the distance between the CofG and the roll center would remain constant, and so the roll stiffness would be neutral. If the curve is sloped such that it rises to the right, then that means the distance between the CofG and the roll center increases as the body rolls. This means the roll stiffness decreases, since the same force exerted by the wheels on the chassis would have a growing moment arm the more the body rolls... not a positive characteristic. The more horizontal the line, the worst it is.

The stock configuration seems to be very well designed, keeping the distance between the CofG and the roll center almost constant (+/- 5.5 mm). On the other hand, the 3" longer arms (purple line) do two things, neither of them good: tilt the line to right and shift it to the right at every point as compared to stock (except at -80 mm where it makes no difference). The shifting of the curve is a result of the longer control arms dropping the roll center height by 10 mm at ride height while the CofG height remained steady at 495 mm. The worsening slope is a result of the arms significantly increasing the length of the lateral instantaneous swing arm, which increases the rate at which the roll center moves up and down for any given amount of wheel travel.

The drop spring configuration (red line) shifted the curve to the left (a good thing) but flattened the slope (a bad thing). The shifting of the curve to the left is a combined result of the drop springs having lowered the CofG by 51 mm (2") at zero jounce, while the angled control arms only dropped the roll center by 31 mm compared to the non-dropped but wider suspension. The net result (51 - 31) is 20 mm difference at zero jounce between the purple and red lines. The downfall of this configuration is that the control arms start out angled upwards at zero jounce, giving them less total travel in jounce, and a high rate of change in the roll center height as it compresses.

Potential Roll Center Solutions: As mentioned earlier, the best slope of this particular curve is one that is the most vertical since that results in the driver feeling no change in handling as the car ride height changes. The best location of the curve on the graph is one that places it as far to the left as possible since that decreases the moment arm that rolls the body. There are several ways to accomplish one or both of these criteria:

a. increase the height of the roll center. This would shift the curve to the left (good thing). This could be accomplished by increasing the angle between the two control arms in the rear view. Examples would include shortening the control arms or using Rodney's taller lower ball joints. Unfortunately, either method would result in flattening out the curve in jounce, which is counter-productive. Both would also result in greater camber change. Furthermore, a higher roll center causes jacking effects, which cause an increase in ride height while cornering;

b. decrease the height of the CofG: This would shift the curve to the left (good thing) and can be accomplished by lowering the powertrain and/or the seats, and/or cutting the roof off the car for example. Another very effective means is to use drop spindles (rather than drop springs). If used on stock length control arms, they would maintain the stock slope (blue curve) but simply shift it to the left by the amount of the drop.

The alternative to changing the curves in the graphs is to mask their effect by changing the stiffness of the springs. Stiffer springs prevent the suspension from moving into the upper ranges of travel and therefore limit the amount the body can roll in a turn. The adverse effect of stiffer springs however is that the suspension won't absorb irregularities and bumps in the road as easily and will transfer them to the chassis making a harsher ride in straight line travel.

Sway bars partially solve the problem of a harsher ride by allowing the use of softer springs to absorb road bumps (provided both wheels travel the same direction in bump). Sway bars however work like stiffer springs when the wheels try to travel in opposite bump directions, such as in a turn. Again, the effect is to mask the performance characteristics of the suspension by preventing it from traveling as far into bump as it otherwise would. This is one of the tricks GM used on the '88 Fiero's; softer springs but stiffer sway bars.

EDIT: I've replaced my original analysis of the roll center since Zac pointed out an error in my interpretation of the data, which significantly changes things. Thanks Zac!

[This message has been edited by Bloozberry (edited 01-22-2012).]

Tomski ( MSG #477, 01-21-2012 09:02 AM
      I meant that in a positive way blooze, i'm learning more in this tread than i learned in highschool :P

FieroWannaBe ( MSG #478, 01-23-2012 02:07 PM
Originally posted by Bloozberry:

Roll Center to CofG Explained. This next graph is one which took a bit of development since I didn't find the Lotus Analyzer data very useful without additional massaging. The software produces a table of the height of the front roll center from the ground versus bump (bear in mind that the roll center is constantly changing height not only as a function of the changing angles of the suspension control arms, but also as a result of weight of the car compressing the springs). I didn't find this information particularly revealing by itself, but when combined with information about the height of the center of gravity (CofG), things got more interesting. Here's why: if you accept that the CofG is the point on the vehicle where all mass may be assumed to be located, and consider the vertical distance between the roll center and the CofG as the length of a lever arm between where the wheels actually apply the forces to the chassis; then the greater the vertical distance between the two, the greater the leverage these forces will have on rolling the chassis in a turn. Also, the less the vertical distance between the two points changes, the more predictable the car's behavior will feel to the driver.

The curves above were generated by subtracting the roll center height from the CofG height as the roll center value changed with a progressively greater amount of bump travel. A curve that is vertical would mean that no matter how much the suspension compressed, the distance between the CofG and the roll center would remain constant, and so the roll stiffness would be neutral. If the curve is sloped such that it rises to the right, then that means the distance between the CofG and the roll center increases as the body rolls. This means the roll stiffness decreases, since the same force exerted by the wheels on the chassis would have a growing moment arm the more the body rolls... not a positive characteristic. The more horizontal the line, the worst it is.

The drop spring configuration (red line) shifted the curve to the left (a good thing) but flattened the slope (a bad thing). The shifting of the curve to the left is a combined result of the drop springs having lowered the CofG by 51 mm (2") at zero jounce, while the angled control arms only dropped the roll center by 31 mm compared to the non-dropped but wider suspension. The net result (51 - 31) is 20 mm difference at zero jounce between the purple and red lines. The downfall of this configuration is that the control arms start out angled upwards at zero jounce, giving them less total travel in jounce, and a high rate of change in the roll center height as it compresses.

Potential Roll Center Solutions: As mentioned earlier, the best slope of this particular curve is one that is the most vertical since that results in the driver feeling no change in handling as the car ride height changes. The best location of the curve on the graph is one that places it as far to the left as possible since that decreases the moment arm that rolls the body. There are several ways to accomplish one or both of these criteria:

a. increase the height of the roll center. This would shift the curve to the left (good thing). This could be accomplished by increasing the angle between the two control arms in the rear view. Examples would include shortening the control arms or using Rodney's taller lower ball joints. Unfortunately, either method would result in flattening out the curve in jounce, which is counter-productive. Both would also result in greater camber change. Furthermore, a higher roll center causes jacking effects, which cause an increase in ride height while cornering;

b. decrease the height of the CofG: This would shift the curve to the left (good thing) and can be accomplished by lowering the powertrain and/or the seats, and/or cutting the roof off the car for example. Another very effective means is to use drop spindles (rather than drop springs). If used on stock length control arms, they would maintain the stock slope (blue curve) but simply shift it to the left by the amount of the drop.
EDIT: I've replaced my original analysis of the roll center since Zac pointed out an error in my interpretation of the data, which significantly changes things. Thanks Zac!

One wants the roll center close to the CogG in order to reduce the roll moment induced by lateral load transfer mid corner, A roll center higher than the CofG creates a negative roll moment, and Jacking forces, which make a car's handling not predictable. The front tires in that case will transfer load to the into the suspension and cause the body to rise. This is something battled in Live rear axles frequently. keeping the roll moment constant allows for a predicatble load transfer in roll. A low roll center amplifies lateral acceration forces at the center of gravity in creasing body roll and therefor dynamic outside wheel load transfer. A changing roll center can create a chaging load transfer rate as lateral acceleration increases. BAD for predictablility.
What your chart shows is the single side roll center with vertical suspension movement. In the cornering situation there is much more happening in the suspension that what is shown. since the body is in roll, we need to know at what the roll angle of the body will do to the roll center. using the bump and jounce (x) information and the track width (t), arctan(x/t) will represent the corresponding body roll.
However with the modifications made the roll center height now changes with vertical suspension translation, and there are two roll centers present in the suspension, inner wheel RC(jounce) and outer wheel RC(bump). this is what causes handling that is non linear and very hard to predict. If you could plot RC-CofG VS Roll angle for the Inner and outer supension, a better prediction of turning habits can be seen. How does a transverse roll center difference summize the load transfer on a axle? That question I cant answer for sure right now without a reference, but it isnt indicative of predicable cornering performance. Not only is this complicated, but as wheels are turned roll center axis migrates as the tire center rotates with kingpin inclination, caster, and camber. So midturn, front axles are never straight, and the overall roll angle is induced by lateral acceleration forces (interrelated to steering angle and slip angle) . The system is highly non-linear, the best we can do here is make educated guess, and linearize the system to the best of our abilities through assumptions.

Enough ranting, Is it possible to plot roll center height difference to center of gravity vs roll angle?

[This message has been edited by FieroWannaBe (edited 01-23-2012).]

Zac88GT ( MSG #479, 01-23-2012 07:14 PM
Originally posted by FieroWannaBe:
and there are two roll centers present in the suspension, inner wheel RC(jounce) and outer wheel RC(bump)

I believe you are thinking of instantaneous centers. There are indeed two of these. The roll center is located by the intersection of lines drawn from each instantaneous center through the center of the tire contact patch.

Bloozberry MSG #480, 01-23-2012 07:41 PM
      Thanks for your interest FieroWannaBe.

Originally posted by FieroWannaBe:

What your chart shows is the single side roll center with vertical suspension movement. ...In roll, we need to know what the roll angle of the body will do to the roll center. If you could plot RC-CofG VS Roll angle for the Inner and outer supension, a better prediction of turning habits can be seen.

I prefaced these last couple posts by stating there was much more data than I was planning to show in the thread. I can certainly post the graph you want to see... I'll work on it shortly.

Originally posted by FieroWannaBe:

Not only is this complicated, but as wheels are turned roll center axis migrates as the tire center rotates with kingpin inclination, caster, and camber. So midturn, front axles are never straight, and the overall roll angle is induced by lateral acceleration forces (interrelated to steering angle and slip angle) .

I realize how complicated this subject is, and by no means do I pretend to understand a 10th of it. My ultimate goal here was to see if there was a not-too-complicated way to portray the effects of the changes I plan to make. I knew I needed to map out the suspension coordinates (done), map out some basic kinematics (mostly done, just not all posted yet), and hopefully out of the mess, a few simple conclusions about the effects of the longer wheel base, longer control arms, and a lowered CofG (supported by graphs) would fall in my lap. Theoretically each of these changes should improve performance, but so far, the "falling in my lap" part is still "up in the air". If you or anyone else believes they know how portray these modifications in the best light, then by all means send me a PM with your ideas.

My goal with this thread however is to wrap up an abbreviated suspension analysis within the next three or four posts knowing full well there is much, much more to explore... perhaps in another thread. What I'd like to cover in the next three or four posts is the following: 1. the same graphs as above except with my final front configuration using the longer control arms and longer wheelbase with front drop spindles (rather than drop springs) vs stock; 2. the same graphs as above for the rear suspensio but also include a graph depicting the change in roll axis vs bump, and finally; 3. the effects of the redesigned rear cradle. After that, I really want to concentrate on building the rear cradle and emphasize construction instead of planning.

FieroWannaBe ( MSG #481, 01-24-2012 09:51 AM
Originally posted by Zac88GT:

I believe you are thinking of instantaneous centers. There are indeed two of these. The roll center is located by the intersection of lines drawn from each instantaneous center through the center of the tire contact patch.

Ah your absolutely right there, I was thinking of it as IC's, but there are also two methods used by people for determining RC's, one I feel more correct than others.
1. As you described, Find the IC's of the suspension linkage, and the axis between the center of traction and the corresponing IC. The intersection of both of these axis will located the RC. (most correct) this method shows at what point the body will "pivot" load transfers in lateral acceleration.
2. Another way is the intersection of those IC's to Tire axis with the vertical axis that passes through CofG. for which there are two seperate points. This way can be more revealing of Jacking forces and how the RC's interact with the cars body. But this, I think, shouldnt be called a roll center becuase it isnt the true datum for zero roll moment.
this shows more of what Im talking about, per authors terminology he calls these points Force Application Points.

Vehicle Dynamics isnt an exact science, but applied kinematics and FBD can be vary revealing.
Afterall this is all done, we are still depeding on a street tire for which we dont know much about except overall characteristics, not exacting data.

Originally posted by Bloozberry:

Thanks for your interest FieroWannaBe.

I realize how complicated this subject is, and by no means do I pretend to understand a 10th of it. My ultimate goal here was to see if there was a not-too-complicated way to portray the effects of the changes I plan to make. I knew I needed to map out the suspension coordinates (done), map out some basic kinematics (mostly done, just not all posted yet), and hopefully out of the mess, a few simple conclusions about the effects of the longer wheel base, longer control arms, and a lowered CofG (supported by graphs) would fall in my lap. Theoretically each of these changes should improve performance, but so far, the "falling in my lap" part is still "up in the air". If you or anyone else believes they know how portray these modifications in the best light, then by all means send me a PM with your ideas.

My goal with this thread however is to wrap up an abbreviated suspension analysis within the next three or four posts knowing full well there is much, much more to explore... perhaps in another thread. What I'd like to cover in the next three or four posts is the following: 1. the same graphs as above except with my final front configuration using the longer control arms and longer wheelbase with front drop spindles (rather than drop springs) vs stock; 2. the same graphs as above for the rear suspensio but also include a graph depicting the change in roll axis vs bump, and finally; 3. the effects of the redesigned rear cradle. After that, I really want to concentrate on building the rear cradle and emphasize construction instead of planning.

I understand and appreciate your approach, and the work you have done so far is more than can be said for 99% of all modified road cars and 95% of all race cars. So I appluad you. I wont attempt to side track your process here, I only wanted to suggest a method of analysis for maybe a slightly bigger picture of modification effects. I know there are other threads were in depth indulgence and analysis would be more appropriate. I truely appreciate all your efforts, and then uncharacteristic willingness to share this hard earned insight and information. Im learning myself, Im no expert, jsut trying to provide my understandings and insights.
Keep up the good work.

[This message has been edited by FieroWannaBe (edited 01-24-2012).]

Bloozberry MSG #482, 01-24-2012 03:03 PM
Originally posted by FieroWannaBe:

I won't attempt to side track your process here, I only wanted to suggest a method of analysis for maybe a slightly bigger picture of modification effects.

No need to apologize, in fact your feedback made me realize I was missing an important graph. Although it may not be the specific graph you requested (RC-CGH vs Roll), I do believe it's the one you may have meant. When Zac initally posted some graphs before we realized there were some errors, he included one like the one I think you recommended. The graph below shows how the roll center migrates vertically and laterally across the car for a given roll angle.

There's lots of information on the graph but with the help of the drawing below, it's actually quite intuitive. In bump, the roll center only moves vertically up and down the centerline of the car, but in roll the roll center also moves across the car as well as up and down since the location is a function of what both sets of control arms are doing. Transposing the curves of the above graph onto the rear view of the front suspension, we get this:

Interpreting the curves, it's quite clear that the stock geometry (semi-circular blue line) does an excellent job of keeping the roll center from migrating in both dimensions. That minimizes the change in handling the driver feels as the car rolls (at least for the front suspension... we'll soon see it's not the case for the rear!) The 3" longer control arm configuration (purple line) shows that these arms impact the roll center location in three ways: they drop the roll center, cause it to shift 130 mm (5") to either side of the centerline when rolling left or right 6 degrees, but they also make vertical movement of the roll center nearly zero.

Finally, the full monty configuration (red line) impacts the roll center even more negatively. Once again, the drop springs are the primary cause of the additionally lowered roll center, but the side to side movement of the roll center is even more severely impacted in this config especially considering that the data for this curve only goes to 4 degrees rather than the 6 degrees left to right that the blue and purple lines depict. (The reason for the lack of data past 4 degrees is due to the suspension hitting the bump stops.) At 4 degrees roll, the roll center moves almost 250 mm (9.8") to either side of the centerline, more than a 260% increase over the amount the roll center moves with just the longer conrtol arms (at 4 degrees roll)! This appears to be the most significant impact that the drop springs incur upon performance.

Potential Roll Center Movement Solutions: My understanding is that better lateral control of the roll center with the longer-arms-only-option could be achieved by restoring the stock angles and proportions between the upper and lower arms. Remember that the longer control arms use the same inner mounting points and the same knuckle height as stock, so the effect of the longer arms is to lessen the angle between them by several degrees. To restore the angles, that would mean either raising the lower control arm mounting point by several millimeters or lowering the upper mount several millimeters, or some combination of both. Additionally, the upper control arm would have to be shortened to restore the OEM ratio between the upper and lower arms, which would also necessitate moving the upper control arm mount outboard by an equal amount to maintain the upper ball joint in the extended location. As for improving the drop spring performance (red line), I believe the swap to the drop spindles would bring it in line with the purple line, and then the same modifications to the control arm mounts and ratios would be needed to bring it closer to stock.

[This message has been edited by Bloozberry (edited 02-09-2012).]

motoracer838 ( MSG #483, 01-24-2012 07:39 PM
      Amazing work, now how about getting to work on the car, JK


FieroWannaBe ( MSG #484, 01-25-2012 10:03 AM
Originally posted by Bloozberry:

No need to apologize, in fact your feedback made me realize I was missing an important graph. Although it may not be the specific graph you requested (RC-CGH vs Roll), I do believe it's the one you may have meant. When Zac initally posted some graphs before we realized there were some errors, he included one like the one I think you recommended. The graph below shows how the roll center migrates vertically and laterally across the car for a given roll angle.

Thats exactly the kind of analysis I was imagining, what you have drafted has all the information I was refering to and more. I think this may provide the best insight on how proposed changes will affect handeling performance. Good job and thank you. There are university students who do less work on their Formula race cars. ( I concetrated on hybrid drivetrain performance, so my optimization was a different animal). In order to restore the factory performance I think a good target to shoot for would be to restore the factory IC locations. of course as soon as the suspension moves that IC location is lost (engineers did a good job at constraining migration). Scaling the factory suspension would restore the factory kinematics though. Whatever 3 additional inches is to the a arms as far as a percentage, apply that to all other linkage lengths, not very practical. Its easy to see how analyzing 3 different solutions to track increase and height change, and picking the best of the 3 evils is the necessary/practical approach.

canfirst ( MSG #485, 01-25-2012 01:00 PM
      Bloozberry I wish I could be a fly on the wall in your shop, I would be the smartest fly of all by keeping my eyes on your every move. Also if I lived next door to you I would be looking over your shoulder all the time and never want to go home. Your work is absolutely amazing, your so knowledgeable, and your attention to detail is incredible! You make me proud to be a fellow Canadian (and Fiero owner). Keep up this fantastic thread! I hope all goes well for you and that the final expenses won't be too hard on the wallet. If you recorded the photos with voice-over on CD and sell it on eBay, I would definitely be one of your first customers! I would watch it over, and over, and over, just like Mr. Bean video re-runs even though it's not a comedy (although it could be sort of if you add some #?!@$!? phrases when you find some unexpected surprises) LOL!

Bloozberry MSG #486, 02-01-2012 07:23 PM
      Thanks for the compliments Canfirst! I'm afraid if you were a fly on the wall in my workshop you'd be pretty lonely... and cold. This computer stuff has had me pegged to my office chair for what seems like eons!

After reviewing the info I've posted so far, I realized there's yet another important graph to show what the front end is doing: Camber vs Roll Angle. I must admit I wasted some time trying to figure out how to calculate the roll angle of the car using various amounts of jounce and rebound on opposite sides of the car when it dawned on me that the data was right in front of my face. The Lotus software cranks it out, ready to be charted. Doh!

Once you know how to interpret the info on this graph, it's pretty revealing about the mediocre nature of camber change on our little cars. There's two things to remember that will make using this graph really easy. The first is to ignore the negative signs on the horizontal axis (roll angle)... they're only needed to be able to plot the inside and outside wheel data on the same graph. The second is that the side of the car that the suspension extends will be called the inside tire and the side that compresses is the outside tire, just like in a turn. With those two things in mind, locate the same amount of body roll in both places on the horizontal axis (remember, ignore the negative signs). Then, to find the camber of the inside wheel, simply move down into the lower left hand quadrant of the graph until you hit the curve and read the camber off the vertical axis. For the outside wheel, move up in the upper right hand side of the graph.

The polarity of camber in this graph is important since it follows the normal convention where negative camber means the top of the wheel is tilted in towards the center of the car and positive camber indicates the top of tire is tilted outwards, away from the car. The magnitude of the numbers is the number of degrees the wheel is tilted with respect to the ground though, not the car. The best way to illustrate this is with the little pictogram below which represents the stock suspension rolled 6 degrees:

The convenient thing about measuring camber this way is that it also is a direct measure of the angle between the tire contact patch and the ground. If the tires remained planted square to the ground through the entire range of suspension travel, the curves above would be flat horizontal lines along the x axis. So that means that the two stages of modification both hurt camber gain in roll on the outside tire where it matters most. This also confirms what was found earlier in the camber vs bump graph earlier since the longer control arms dampen the rate that camber changes.

The solutions to improve the rate of camber gain that were discussed earlier also apply here. Aside from improving the rate, one could also improve the camber on the outside tire by setting the static camber at ride height to say, -1 degree on both wheels. This would result in all of the curves above dropping by one degree on the y axis, so at 6 degrees of body roll the outside tire would only be 1.9 degrees from being flat with the ground instead of 2.9 degrees. The downside to this is that the inside tire would be even further away from being flat with the ground (though it doesn't matter as much since the weight will be transferred off this tire), and straight line braking would suffer since the front tires would initially have less contact with the road than if they were at zero degrees camber (thanks for that observation Zac )

Bloozberry MSG #487, 02-07-2012 09:14 PM
      For anyone keeping any copies of the graphs I've been posting, you should be aware that I made changes to the graph and text concerning the front toe vs bump on page 12 of this thread. I needed to make these changes when I discovered that the Lotus software program does not follow SAE convention for the polarity of toe measurements, which screwed things up.

With that out of the way, now it's time for some rear suspension analysis. I'm going to show the results of the same three configurations I used in the front including: OEM stock; a 6" track width increase; and a 6" track width increase combined with a 3" wheelbase stretch and 2" spring drop. To help visualize the differences, here's a before and after drawing showing the stock configuration in blue, and the extended and lowered configuration in red:

Since most of the same concepts apply equally well for the rear as for the front, I won't go into the lengthy explanations about toe, camber, and roll centers unless there are noteworthy differences. For ease in comparing the different graphs front to rear, the graph backdrops are color matched i.e. the two toe graphs are light green, the camber graphs are light blue, etc.

I'll start with the rear toe versus bump graph.

As with the front toe, the stock '88 Fiero rear knuckle is set statically during alignment with some toe-in, 0.15 degrees to be specific. Again, I've chosen to factor this out of the curves above since the toe will neutralize to zero once the car is underway. According to the service manual straightline driving forces will causes manufacturing tolerances to be taken up and reduce the toe to zero. In the stock configuration, it's clear that raising or lowering the suspension causes the wheels to toe-in considerably. This explains the Fiero's tendency to understeer despite the front wheels initially wanting to oversteer slightly. In roll, the outside rear tire toes-in causing the front end of the car to turn less than is commanded by the steering wheel input.

The same happens with the 6" track width increase, only to a much lesser extent so this would tend to neutralize the understeer characteristic compared to the stock car. To increase the rate of toe-in, the front lateral link would need to be shortened and the cradle mount location for it would have to be pushed outboard by an equal amount. This would shorten the arc of the front link and cause it to pull inwards on the front of the knuckle as the jounce increased.

The 2" dropped suspension increases the rate of toe-in considerably causing even greater understeer in roll. In this case, the front lateral link would need to be lengthened somewhat and it's mounting point on the cradle would need to be moved further inboard to reduce the rate.

Rear Camber: There's a lot of discussion on the forum about the poor rear camber characteristics of the Fiero. So just how bad is it? Here are the two most revealing graphs about the rear's performance... one under bump, the other under roll.

Both graphs above show camber after subtracting 1.0 degree of camber as per the stock alignment specs. The effect is to bias the camber in the negative direction to compensate for the poor negative camber gain. The most revealing is the camber vs roll graph which shows that even after the compensating -1.0 degree has been added, there still exists a 3.76 degree difference between the rear wheel's tire contact patch and the road surface at 6 degrees of body roll. This is 0.85 degrees worse than the front tire contact patch.

Were it not for the static alignment spec, these numbers would be 4.76 degrees between the road surface and tire contact patch at 6 degrees body roll, a full 1.85 degrees worse than the front.

The graphs show that the longer control arms improve the negative camber gain slightly but the addition of the drop springs worsen the situation significantly. This is keeping with a commonly known characteristic of strut type suspensions: provided the angle between the lower control arms and the strut as viewed from the rear remains less than 90 degrees, camber gain in jounce will be negative. Shortening the rear springs has the effect of angling the control arms upwards, bringing the angle between them and the strut closer to 90 degrees. The closer to 90 degrees, the slower the negative camber gain, and past 90 degrees the camber gain becomes positive.

Camber Gain Solutions: For a Chapman strut rear suspension, there are several solutions to gaining more negative camber:

a. add even more negative camber to the static alignment, pushing the curves above further to the left, though leaving the rate of change (ie the slope of the curves) unaltered. This would have an overall negative effect by causing uneven wear on the rear tires since most straight line driving would be on the inner edge of the tires. It would also result in a loss of straight line rear traction since the tire contact patches would not be in full contact with the road. Lastly, because the shape of the curves would be unaltered, the new static camber value would correspond to maximum grip at only one specific angle of body roll and be compromised at every other angle.

b. lower the attachment point of the lateral links on the knuckle in a manner similar to what Fieroguru (PFF member) has done here in this thread: which would change the slope of the curves as shown here: . The benefits shown are significantly improved roll center control, and about 1 additional degree of negative camber gain over 75mm of jounce. The disadvantages are a gain in toe-out (negative toe) of about 0.8 degrees over 75 mm jounce which increases oversteer, and the complexity of the necessary metal fabrication.

c. decouple the fixed link between the strut and the upper knuckle making it a pivoting link, and replace the upper knuckle control with an upper control arm. Depending on the design, the designer could theoretically create the ideal amount of camber change throughout the entire range of bump and roll. The difficulties with this approach are the actual design process which must optimize the control arm location and dimensions given the physical constraints of packaging the arm within the available space.

Next up: rear anti-squat and roll center movement.

(Edited to update link to Fieroguru's knuckle adapter)

[This message has been edited by Bloozberry (edited 02-11-2012).]

Bloozberry MSG #488, 02-09-2012 05:43 PM
      Anti-Squat: Rear anti-squat is similar in concept to front anti-dive, where the suspension components can be designed to resist a portion of the rearward weight transfer during acceleration rather than transferring the weight entirely to the springs.

The graph shows that as jounce increases, the percent anti-squat for all three suspension configurations decreases. The longer control arms option (purple line) actually improves the characteristics over the stock suspension everywhere in jounce except for the first 10 mm of compression. The shortened spring version with the extended arms (red line) significantly worsens the anti-dive though. Recalling the anti-squat equation from page 9 of this thread, it's easy to see how dropping the suspension 2" significantly reduces the angle of the trailing link, thereby reducing anti-squat. Here's a quick drawing showing the trailing link angle before (blue lines) and after (red lines) the drop.

Anti-Squat Solutions: In this case the dropped spring longer control arm suspension could be made to perform better by restoring the angle of the trailing link by:

a. raising the cradle mounting point of the trailing link; and/or

b. lowering the mounting point of the trailing link on the knuckle (like Fieroguru's solution pointed out earlier).

A better solution would be to raise all of the suspension link mounts on the cradle by 2" to regain the stock geometry, although the strut upper mount would also have to raised 2" or the lower mount would have to be dropped to regain the full suspension travel.

Perhaps an easier solution would be to raise the entire cradle higher up into the frame of the car if sufficient clearance could be maintained in areas such as the underside of the decklid to engine top, and axle to underside of the lower frame rail. This option would also require strut mount changes to regain full jounce travel.

All of these options would require metal fabrication skills and would be constrained by available space.

Rear Roll Center: Two graphs are used to assess the changing roll center. First up for analysis is the changing distance between the roll center and the CofG in bump. The '88 Fiero rear roll center is controlled by the stock suspension significantly worse than the front.

Since the curves are sloped such that they rise to the right, then the distance between the CofG and the roll center increases as the body rolls. This means the roll stiffness decreases under roll, since the same G forces exerted by the wheels on the chassis would have a growing moment arm the more the body rolls... not a desirable characteristic.

The longer control arm configuration is actually an improvement over stock, lessening the distance between the CofG and the roll center by 43 mm (or 7%) at full jounce. On the other hand, the drop spring modification (red line) significantly worsens the roll moment arm since it increases the distance between the roll center and CofG by at least 115 mm's at every point as compared to stock.

A better appreciation for the instability of the rear roll center can be seen by analyzing the rear roll center location as the body rolls.

Unlike the front suspension graph, it's clear that the stock rear suspension does a poor job controlling the location of the roll center both in height and in lateral movement during roll. A migrating roll center results in inconsistent handling. Recall that the stock front suspension allowed 2.5 mm's of movement vertically and 18.75 mm's laterally over the entire range of suspension travel. The same figures for the stock rear are 470 mm's and 2094 mm's respectively! Here is a more graphic view of how the rear roll center changes:

In his book Chassis Engineering Herb Adams states that the most successful cars have the roll center height between 1 inch above ground to 3 inches below the ground. The Fiero rear end falls considerably outside these limits. The longer control arm configuration (purple line) dampens the rate of movement of the roll center but still allows it to move within a huge range vertically and laterally. An interesting result happens when the longer control arm modification is coupled with the spring drop (red line): the roll center raises rather than lowers as the body rolls. Theoretically, the rising roll center will result in increased jacking forces causing more of the weight transfer to be counteracted by the outside suspension arms rather than being absorbed by the springs.

Potential Roll Center Solutions: As I see it, there are two steps needed to correct the roll center migration problem with the dropped suspension. The first is to find an alternate way to lower the car other than by dropping it on the springs, and the second is to rein in the instantaneous center.

When it comes to lowering the rear suspension, restoring the stock angle of the lateral links is primary. The same solutions used to correct the anti-squat apply here equally well: either raise the control arm link mounts on the cradle, lower the link mounts on the knuckle, and/or raise the entire cradle up into the frame. To restore the stock strut travel, the top strut bushing can be flipped to gain 1", and if using the wider track, the strut to knuckle adapter can be modified to attach the strut to the knuckle lower down.

To rein in the roll center movement, it helps to understand why it moves. Since the roll center location depends on the intersection of two lines, one perpendicular to the strut and the other through the lateral link pivots, the main problem with a strut-type suspension is that the strut angle doesn't move appreciably throughout the range of suspension travel. This leaves the change in angle of the lateral links as the sole variable responsible for the change in roll center as the suspension compresses and extends. In double wishbone style suspensions the upper and lower control arms both change in angle and can be designed to hold the roll center location relatively constant as we saw with the front suspension.

On the Chapman strut suspension, the angle of the lateral links progressively approaches the angle of the line perpendicular to the strut in jounce (blue lines), which sends the instantaneous center diving away towards infinity, taking the roll center on a nose dive. I've posted this next drawing before but include it again here to illustrate the concept (bear in mind that the blue and red lines in these next two drawings don't reflect stock and modified configurations as in the previous ones. Here, red represents full rebound and blue full jounce):

Aside from using stiffer springs and roll bars to limit roll altogether, one way to lessen the roll center movement without constraining the travel is to pre-bias the angle of the strut so it is less vertical. This is another one of the tricks GM used to improve the '88 geometry in comparison to the '84 - '87 cars. This next drawing is only an exaggerated example of how tilting the strut decreases the swing arm length on the stock geometry (the same concept applies to the longer length arms as well though):

Notice how the further tilted strut accomplishes two benefits at once:

a. narrows the IC's vertical and lateral range of movement which also tames the roll center movement as well; and

b. results in greater negative camber gain in jounce or for any given amount of body roll... a characteristic the rear end sorely needs.

I still have to research any negative impacts of decreasing the strut angle, and then determine the angle that optimizes the positive and negative characteristics within the physical constraints. The method of tilting the strut seems easy enough with the increased track width since a strut to knuckle adapter is required anyways. Given that a new strut adapter would need to be built to gain lost jounce travel from lowering the car (as mentioned before), the design could easily be adapted to suit a different strut angle as well.

Finally, one other potential solution to controlling the roll center would be as described in the section discussing camber, that is: decouple the fixed link between the strut and the upper knuckle making it a pivoting link, and replace the upper knuckle control with an upper control arm. This would likely result in the greatest ability to control camber and the roll center, but for reasons discussed earlier, it would likely also be the most complex solution to execute.

fieroguru MSG #489, 02-09-2012 08:21 PM
      More excellent work Blooze! I would like to give you a + for every drawing or suspension curve if I could.

FieroWannaBe ( MSG #490, 02-13-2012 10:36 AM
Originally posted by Bloozberry:

I still have to research any negative impacts of decreasing the strut angle, and then determine the angle that optimizes the positive and negative characteristics within the physical constraints. The method of tilting the strut seems easy enough with the increased track width since a strut to knuckle adapter is required anyways. Given that a new strut adapter would need to be built to gain lost jounce travel from lowering the car (as mentioned before), the design could easily be adapted to suit a different strut angle as well.

If there is sufficient anti squat this had good potential, but if not, under acceleration, the rear of the car will squat, reducing the tires contact patch due to an increased negative camber gained at both wheels, and can limit your available traction, combined with turn-out this can lead to oversteer. Counter this with more anti squat you may not have a problem, until your entering a braking zone. Then the anti-dive, turns to pro-lift as the forces reverse (the body lifting the suspension on deceleration), and there could be a problem with brake hop in the rear, and rear end instability under braking (very bad). The hardest part of the design in finding the perfect balance, and then packaging it.

Pontiac did a decent job on the 88, but the rear geometry still left some development on the table it seems, perhaps due to packaging constraint, it looks as though there could be more done to increase rear stability, and tune out the built in understeer. It does look like a nice track increase can be part of that solution. Good Job.

[This message has been edited by FieroWannaBe (edited 02-13-2012).]

Bloozberry MSG #491, 02-19-2012 10:00 PM
      Thanks for the feedback fieroguru and FieroWannaBe. I appreciate the encouragement since this stuff can be pretty tough to get motivated to work on.

I do have some rewards of my labor to share today though. With the previous discussions focusing on all the problems introduced by modifying the suspension, this post reveals the final solution to resolving the issues with widening, lowering, stretching, and re-shoeing the chassis. Remember, my primary goal was/is to make the car's stance look good, followed by minimizing the negative impact of this stance on performance. So, the three aspects of getting the right front stance involved:

a. moving the wheels outboard to suit the wider body of the F355 using wide track control arms;
b. lowering the car, but maintaining a reasonable ground clearance using a combination of 1.5" drop spindles and a 1/2" spring drop; and
c. filling the front wheel wells with the right size wheels: 215/45/17 tires on 17 X 7 (ET 47) wheels. The somewhat narrow front tires give an approximate ratio of 45% contact patch front / 55% rear in keeping with the weight distribution of the car. The rears will be 18" X 265 mm wide.

Knowing the final configuration allowed me to send the last set of suspension coordinates to Zac88GT for him to run through his Lotus Suspension Analyzer software. Having known from the start that drop spindles are an inherently better solution than simply using drop springs, I was initially quite disappointed when I re-plotted the performance curves and found this combination to be only marginally better than using drop springs. This new case is shown by the orange lines.

I knew there had to be a way to squeeze better performance from this combination, so I decided that the next most logical step would be to shorten the upper control arm to mimic the OEM ratio between it and lower arm. I started by lopping off 29 mm from the upper arms in my drawings, then asked Zac to run a few iterations shortening them even more in 1 mm increments until the best possible performance was achieved. The end result was to shorten the uppers by 35 mm. This of course will entail relocating the upper control arm mounts on the front crossmember 35 mm further outboard, but that appears to be a relatively simple affair after having confirmed the possibility on the actual crossmember.

The static benefits of the new front configuration include a 10.75 % reduction in scrub radius (from 40 mm to 35.7 mm), and an 8% reduction in the CofG height (from 495.5 to 456.5 mm);

Here are the final graphs depicting the kinematics including all of all the earlier configurations, with the final layout in green:

Front Camber vs Bump:

Result: within a whisker of the stock performance in jounce, and improved performance in rebound.

Front Camber vs Roll:

Result: identical performance compared to stock configuration (stock curve hidden by overlap).

Front Toe vs Bump:

Result: improved performance over stock by changing front oversteer in jounce to slight understeer (near neutral steer) up to 50 mm jounce.

Front Caster vs Bump:

Result: identical performance compared to stock configuration.


Result: loss of 1% anti-dive over stock; slight gain in anti-dive stability

Roll Center to CofG Vertical Distance vs Bump:

Result: slightly improved stability and slight improvement in roll couple (1.5% reduction) compared to stock;

Roll Center Location vs Roll

Result: tighter roll center control and lower, improved roll center location compared to stock.

I consider the final configuration to have accomplished my primary goal of getting the stance I was looking for, and was pleasantly surprised that I didn't have to settle for simply minimizing the impact of these modifications. I hope this will be more than enough to satisfy provincial regulators that my new config meets or exceeds the OEM's configuration.

Next up: a break from graphs (altogether now: YAY!), and a return to the workshop to modify the front crossmember and shorten the HT Motorsports upper control arms.

Bloozberry MSG #492, 02-27-2012 07:58 PM
      As promised, this post is about getting the nose to the grinding stone, or more accurately, the grinding wheel to the crossmember. After a quick disassembly of the front suspension, it became a little easier to plan how to modify the upper control arm mount to move it outboard by 35 millimeters. Here's a close up of the area:

My first thoughts were to weld a couple box-like extensions to the existing upper control arm mounts on either side of the shock mount, like this:

This would probably have been the route I would have taken had I not been worried about the unwanted attention the obvious add-on might draw during the engineering certification phase of registration. Then it dawned on me that there might be enough room to simply relocate the OEM mount. The advantage is that it would appear very OEM. The disadvantage is that it would mean having to relocate the shock mount as well. I'm not worried about it affecting performance, just the extra work! So out came the safety goggles and the die grinder equipped with a cutoff wheel.

One thing I can tell you is that those factory welds penetrated very deep into the cross member. Using the cutoff wheel with 120 psi air pressure, it took me nearly 15 minutes of grinding per shock mount to work my way through the steel.

Needless to say, I wasn't looking forward to cutting the 5" long weld seam on the control arm mounts. There are a few obstacles to getting the perfect cutting angle; the first being the non-removable cross member alignment pin on the driver's side. The other obstacle is the return flange along the bottom edge of the crossmember which prevents you from cutting the vertical welds all the way down. The smaller the diameter of your cutting wheel, the closer you can get to the bottom.

These control arm mounts took a solid 1/2 hour to cut off per mount. They are some heavy suckers too. I haven't measured the gauge of the steel but they're at least 1/8" thick. Can you imagine the die pressure needed to stamp one of these out of a flat sheet?

Next, they'll need to be trimmed down in height to account for the rising angle of the cross member in their new location. (The eagle-eyed among you will notice the gloved hand in the last photo. Anyone living in Northern climes will know that you can't use a die grinder bare-handed very long in the winter if your compressor is not in a heated room. It gets soooo cold, it develops a layer of frost on the outside, no joke.)

fieroguru MSG #493, 02-27-2012 08:31 PM
Originally posted by Bloozberry:

The eagle-eyed among you will notice the gloved hand in the last photo. Anyone living in Northern climes will know that you can't use a die grinder bare-handed very long in the winter if your compressor is not in a heated room. It gets soooo cold, it develops a layer of frost on the outside, no joke.

That's why I use an electric hand held grinder with a cut off disk... it gets warmer the longer you use it! I am also spoiled these days, my garage never gets below 50 degrees!

If you need any tabs or brackets off the 88 front crossmember, I have 4 of them on the shelf and one was involved in a roll over (bent lower a-arm mounts).

Bloozberry MSG #494, 03-05-2012 07:00 PM
      I heat my workshop too, but my compressor is in the basement, which I don't heat. Having it down there keeps the noise down but the downside is that the air is ice cold.

I was starting to have regrets about not choosing my first option to extend the UCA mounts rather than relocate the stock ones. It was a ridiculous amount of work to cut them off, and now I was looking at the prospect of trying to modify them so that they would remain at the same overall height, retain the 5 degree slope backwards for anti-dive, but mount them further uphill onto a surface that was sloped 15 degrees sideways. It might sound easy, but when you have a ruler and a level in one hand and a saw in the other, it suddenly becomes a bit more complicated.

The blue lines show the stock location of the UCA and shock mounts, and the red lines show where they need to be, 35 mm further outboard.

When faced with a task I'm not sure how to do, I often find myself cleaning my shop... that's part of the reason why it's taken so long for this update. Once that was done, I started with the easy stuff like knocking down the old OEM welds on the cross member with my angle grinder... anything but address the challenge of modifying the mounts. Turns out it was a good thing. Something that was not at all evident when I drew my earlier drawings of the cross member jumped out at me while grinding.

With the UCA and shock mounts no longer obscuring the OEM design, it was clear that the outboard upper surface of the cross member (which is sloped 15 degrees laterally across the car), is also tilted backwards with a built-in 5 degree slope longitudinally (backwards). The OEM mount straddled both the straight-and-level portion and the sloped-and-tilted portion of the crossmember, so it was designed to account for this strange transition. By moving the UCA mounts outboard 35 mm, this places them entirely on the compound sloped surface, simplifying my life since I need only worry about retaining the original height of the mount, while accounting for the 15 degree lateral slope. The 5 degree longitudinal slope takes care of itself.

Here is a side by side photo of the two UCA mounts with the one on the left being the newly modified one:

So the only two operations that were needed were 1. eliminate the built in 5 degree anti-dive by first making the bottom parallel with the top. Then 2. shorten the overall height of legs since moving it outboard also forces it up the 15 degree slope. (Disregard the long legs at the extreme right and left of the photo, those aren't the legs I'm talking about.) Rather, the legs are the lower horizontal edges. Obviously the outboard leg (foreground) had to be cut shorter than the inboard leg (background) to account for the 15 degree slope of the crossmember. Confused yet?

So with the first mount trimmed just right, I test fitted it to the cross member and measured it for being level in the lateral (cross-car) plane, and for 5 degrees in the longitudinal (fore & aft) plane.

Here's what it looks like without the level:

A bit of tweaking with a file and my angle grinder, it was ready for welding.

Now on to the other side.

[This message has been edited by Bloozberry (edited 03-06-2012).]

fieroguru MSG #495, 03-05-2012 08:25 PM
      Looking good! You are the master of measurement.

Bloozberry MSG #496, 03-08-2012 08:16 PM
      LOL. I'm not so sure about that Fieroguru... once I update the stock cross member drawing, it'll be version 3.

The first control arm mount took me 3 hours to cut off and modify, the second one took 1.5 hours: amazing how experience saves time. Both mounts are now ready to be welded back onto the cross member, but I'm holding off until after the control arms are fully modified. I want to build up the assembly, place the knuckle at zero camber, then weld the mounts so the control arm mounting bolts are centered in the slotted holes in the mounts. I also want to be sure there will be enough room for the shock to pass through much smaller hole in the cross member now that the mount encroaches in that space.

So, on to the control arm shortening! The first step was to make an accurate drawing of the final config for my files, and to help in making the jig to weld it all back together:

Obviously having moved the mounts outboard 35mm meant that the control arms would have to be shortened by the same amount. So I built a small jig just to mark exactly where the fish-mouth cut would have to be, then clamped the first arm into my chop saw to cut as close to the bushing housings as possible. I have to admit I had a moment of doubt as I started the saw... seemed crazy to be chopping up a nice new shiny part. Then I let her rip:

Once all four bushing housings were amputated, I chucked them up in the vise and cleaned off the old welds with the angle grinder. These puppies got HOT.

By the time I was finished the last one, the first one had cooled off enough to hold it to the belt sander for final dressing and preparation for the new welds (the tapped holes are for grease nipples):

The next operation was to build a rigid jig on the drill press table to make the fish-mouth cuts in the correct location, and at the correct angle to ensure the concentricity of the two bushing housings. That first involved finding the centerline of the drill and transferring it to the table. Then I used a thick plate of aluminum to raise the arm off the table so I could cut all the way through the arm without cutting into the table. Then I clamped two guides that would center the 1" tubes of the arm in line with the center of the drill. Finally, I made a steel block with a 1" semi-circle cut out of it to serve as a clamp to hold the arm to the table at the correct depth:

The last thing I needed to do was to set the angle of the entire table to compensate for the slight angles that the control arm legs meet up with the bushing housings. The curved leg meets up at 1 degree, and the straight leg at 5 degrees. Here you can see my angle finder resting on the table.

The bushing housings are 1.5" in diameter, so that's the size of the hole saw needed. Here's what the finished cut looked like:

And here's one arm ready to be mounted in the re-welding jig:

Bloozberry MSG #497, 03-10-2012 07:42 PM
      To re-weld the control arm bushing eyelets back onto the arms, I had to make a small jig out of some 1/4" steel plate, some angle iron, and a piece of exhaust tubing. After tacking the angle iron onto the plate as a back-stop for the bushing eyelets, I transferred the key dimensions of the shortened control arm onto some masking tape stuck to the steel plate. This gave me the exact location for the ball joint in relation to the two pivots. After bringing a short piece of exhaust tubing to a local muffler shop to have them expand it to the correct diameter, I tack-welded it to the sheet metal plate to act as the ball joint alignment pin, like so:

Once the three control arm pieces were clamped in place, I tack welded them together. I couldn't complete the welding right away since the jig didn't allow access to the back side of the arms while clamped in place:

My little Fourney 100A MIG welder is OK for non-critical stuff, but doing this job right called for the help from the local certified welding shop. His Miller 200A MIG made quick work of joining these parts together again, with nicer, deeper welds than the HT arms came with originally.

Once the smoke settled, I cleaned up the burnt off paint with a wire wheel. I had to grind one small nugget from the inside diameter of one bushing eyelet since the weld penetrated right through. No biggie. At least I know it won't come apart on the road!

Lastly, here's an overall view of the shortened arm. A little primer and some new paint and it should look like the new piece it is, only better.

cptsnoopy ( MSG #498, 03-10-2012 08:53 PM
      Substantial and Purdy!


Bloozberry MSG #499, 03-11-2012 08:23 PM
      With the upper arms shortened, I mocked up the entire front suspension again by temporarily clamping the upper control arm mounts onto the cross member in the new location. I wanted to do this for two reasons:

1. verify the final position of the upper control arm mounts and adjust them if necessary since I wanted the arm bolts centered in the mount slots with the knuckle at ride height and zero camber; and

2. cycle the suspension through its range of movement to check for any interference issues.

Part 1 was a piece of cake and everything worked out as planned, but I found when cycling the suspension that there was interference between the shock absorber body and the underside of the UCA mount in the last 1/2" of jounce. This wasn't really a surprise so I had a solution already planned out that I'll get into in my next post. For now, it was time to rejoin the UCA mounts back onto the cross member in their new location (I just love the welding photos):

Once again, I tack welded the mounts in place but for these major structural joints, I went back to the same shop that did the control arm welding to finish the job. Here's a smokin' hot, half completed joint (mmm the smell of burnt powder coating )

And here's the cleaned up final weld:

Next up: addressing the shock absorber problem.

LaFierte MSG #500, 03-12-2012 01:17 PM
      Beautiful welds.

FieroWannaBe ( MSG #501, 03-13-2012 12:42 PM
Originally posted by Bloozberry:
Next up: addressing the shock absorber problem.

I was just going to ask about that...

It's all looking well exectued.

Bloozberry MSG #502, 03-13-2012 09:07 PM
      As I mentioned before, moving the UCA mounts outboard meant that they ended up encroaching on the space where the shock absorber comes through the cross member. The body of my shocks are 42 mm diameter, and thenew, smaller space for it to come up through measured about 45 mm. Not enough room considering how much the shock changes angles as it's compressed and extended by the movement of the lower control arm.

Here's the view from the underside. Notice the OEM spring seat is formed from the edges of the hole in the cross member being formed into a 90 degree lip.

Since the adjustable HT coil-over springs are a different diameter than the OEM springs, the HT kit supplies you with new spring seats that are supposed to be slipped over the OEM seats, and peened into place. But I needed to relocate the spring seat to enlarge the through-way hole for the shock body, so the OEM spring seats had to come out.

A cutoff wheel on the die grinder made short work of that. I followed up the die grinder with the angle grinder (just barely fit) to smooth out the remainder of the old spring seat and bring it flush with the surrounding material. I needed to do this to give a nice level mounting surface for the new HT spring seats later on.

Working from the bottom, there was plenty of room to mark out and enlarge the shock through-way hole in the cross member. I used the HT spring seat as a guide to trace the outline on the underside of the member, and then chucked up a carbide grinding bit to hog out the hole, leaving plenty of material edge-wise to maintain the strength of the area.

Here's a top view photo to show how much further outboard the hole was made. Compared to the first photo in this post, the amount of material removed is obvious.

The next step was to reconnect the front suspension again and make sure the shock would clear with lots of room throughout the entire range of travel. This time everything checked out with room to spare. Considering I had only 1.5 mm clearance all the way around when I started, this pic shows how much additional clearance was gained. The upper shock mount was left off for clarity.

Next up: welding the HT spring seats and the upper shock mounts in their new locations.

Bloozberry MSG #503, 03-14-2012 06:16 PM
      The instructions that accompany the HT Motorsports front adjustable coil-overs state that their new spring seats need only be "glued" over top of the OEM spring seats with a 3/4" bead of silicone. They claim that upward spring pressure will keep the seat properly located, and that the silicone will absorb vibrations and prevent squeaking. To be fair, they suggest that you peen the new seat into place, though they say it's not necessary.

I'm not sure I would have prescribed to the gluing philosophy even if I hadn't cut off the OEM spring seat. I'd rather have something as important as the spring seats very firmly attached to the cross member, so I tacked them in place in preparation for final welding. These needed to be welded before the upper shock mounts since I needed access to the spring seats from both the top and bottom for welding, and the shock mounts would have blocked access from above.

The HT seats are actually beveled in one direction, and have a flat bar welded inside them to properly locate the spring since the ID of the seat is slightly larger than the OD of the spring. The tab goes to the outboard side.

Once they were welded in place, I test fitted the springs just to show how they sit inside the seats, rather than outside the seats like the OEM ones.

Finally, the last step before priming and painting was to weld the upper shock mounts in their new location. There wasn't enough room to move them the full 35 mm outboard like the UCA mounts, so I moved them to the furthest outboard point possible; about 25 mm if I recall correctly. I marked the optimal location the last time I had the suspension built up, so it was just a matter of tacking them, then giving them the full blast.

Here's the final outcome. The best thing about it is that it looks totally stock even to the trained eye.

Yarmouth Fiero ( MSG #504, 05-23-2012 09:00 PM

My boys and I are finally starting on our 85 Fiero rebuild. Its been in storage since 1988......10 years before they were even born. We are planning a 355 kit with small block and full suspension and running gear upgrades. I just stumbled on this forum today and saw your project. Very impressive.

We're in Yarmouth btw.

aeffertz ( MSG #505, 05-24-2012 12:03 AM
      This is without a doubt, the most impressive build on this site! Very envious of each and every one of the many skills you have showed us through-out this build.

Keep it up, man!

Bloozberry MSG #506, 05-25-2012 10:37 PM
      Thanks for the kind words aeffertz.

For Yarmouth Fiero: Good to see there is yet another Maritimer that's into Fieros. We are few and far between so we would do best to stick together and trade ideas and info. You say you're "planning" a 355 kit... does that mean you haven't yet bought it? If not, then I highly recommend the AD355 kit over the IFG kit for reasons of quality. You'll save the extra money many times over by avoiding the IFG kit. Anyways, rather than discuss that stuff here, I'll send you a Private Message (PM) so we can exchange contact info.

Back to the thread: It's been far too long since I've posted an update (busy with spring chores) but that doesn't mean I've been neglecting the project car entirely. I've moved on to planning, measuring, and drafting the new rear cradle, which has proven to be an exercise similar to solving one of those Chinese puzzles where a whole bunch of random pieces have to be slid upwards, downwards and sideways one at a time and in a precise sequence in order for all the parts to line up and make a complete picture. More on that coming soon, so stay tuned.

For now, here's a couple photos to wrap up the front end changes... this one is the "before" pic:

And this one is the "after" pic which proves it all went back together without a hitch!

The last thing to do is consider swaybar options, but I'll worry about that later.

Yarmouth Fiero ( MSG #507, 05-26-2012 05:42 AM
      These are awesome shots. Very clean and precise. If I can achieve a fraction of this on our build, my OCD will be quite satisfied.

johnyrottin ( MSG #508, 05-26-2012 06:38 PM
      Blooz, as always your knowledge and attention to detail are spectacular. I can't wait to actually see this and your Pace Car in person!!!

Bloozberry MSG #509, 06-10-2012 10:07 PM
      Thanks Yarmouth Fiero and johnyrottin for your comments... (although I'm not sure what you mean by my "Pace Car" there Johnny).

So now onto the rear end. I must say that the rear is definitely the most challenging portion of the suspension since there are many more variables to deal with than with the front. The same three basic issues confronted me at the back: get the wheels outboard 3" per side, lower the body onto the wheels by about 2", and retain or improve theoretical suspension performance for provincial certification. In addition though, the rear suspension must also accommodate the physical space requirements of the F40 six speed and the Northstar engine... plus take into account the poor design of IFG's F355 body on the Fiero chassis. To the inexperienced, most of these criteria might appear independent from one another but as you'll see they are all interconnected.

So here was the starting point... in fact I don't know what made me think this could ever be made to look right:

I still get panic attacks occasionally wondering if it was a big mistake to buy this half finished kit. I get discouraged when I think about how much easier my life would be if I were to have bought an AD355 kit instead. I suppose I can always do that later if I can't muster up enough magic to make this look right.

A picture says a thousand words, but unfortunately doesn't quantify very much, so I needed to add the cross section of the IFG body on my earlier rear suspension drawings. I didn't get far before I realized I needed a better set of reference points than the cradle way down there, so I measured and drew up the cross section of the strut tower, then I could get more accurate measurements of the fender (in red):

I think I went back and forth to rectify inaccuracies in this drawing a hundred times before I started getting repeatable measurements. Once I was satisfied, I added it to the rear view of the stock Fiero suspension to quantify what needed to be done, and where. I also added the cross section of the stock Fiero rear fender (in blue) on it for reference too.

There's a couple things to note from the above drawing. The first and most obvious is that there is over TWICE the clearance between the top of the stock tire to the bottom of the IFG fender lip. That's 161mm or 6.4"!!! That's an unbelievable gap to try to make up into a reasonable amount.

The second most obvious thing is the stock half-track width falls at least 85mm (3.35") too narrow, so when I ordered the HT 3" suspension links (the max available) I knew that I would also need to choose the offset for my new wheels carefully to make up the difference.

The third thing to note (before you purists point out that your stock wheels don't stick out 14mm beyond the stock fender as shown above) is that I haven't drawn in the 1 degree of camber on the rear wheel in order to make my life easier. The OEM specified one degree tip-in moves the top of the tire inboard by 11 of those 14mm's.

Lastly, if this issue didn't jump out at you when you looked at the above drawing, that's OK because it took me a while to realize the problem too. Notice how the IFG fender is not the lowest hanging part of the chassis above the tire anymore. Rather, the underside of the upper frame rail is. If you disregard the easily bendable lower weld flange of the upper frame rail, the rail is still 28mm below the IFG fender lip. So that means that if I want 76mm (3") of suspension travel before the wheel contacts the rail, the gap between the top of the tire and the fender at rest would be (76 + 28 =) 104 mm! That's 4.1"! Can you say 4X4 Ferarri? Obviously something needs to change.

It's a lot to digest in one post so I'll continue more later.

(Edit: Updated drawing)

[This message has been edited by Bloozberry (edited 07-17-2012).]

355Fiero MSG #510, 06-11-2012 12:30 AM

You can make up a good 2-3" on the upper wheel gap by cutting the fiberglass rear quarters and lowering the wheel well down toward the tire. It also then straigthens out your rear bumper body line which also need leveling. I think the pics I sent you last year should give you a good start to where you need to cut and how you lower the wheel well. Pretty easy easy to do end to end by putting a straight square tube at the top of the rear bumper at the corner and then have it go to the front bumper top corner. This body line should be straight. On these kits, the line is slightly forward sloping whereas on oem 355s the body line is almost level. Nature of the higher Fiero frame you have to deal with. Cut the body panels and push the wheel well down until the top of the bumper and the rear quarter body line are matched up to to bar and screw the panels back in place with spacers. Glass the back end up and then start filling the gaps in on the front side. Doesn't take too much fiberglass mat to bring the upper fender well area back up and then some thin skim coats and you are set again.

Also be aware that this particular body kit also has the driver's side rear wheel well about 1-1.5" closer to the door jamb so there is that to also work into the cutting and pasting.....

Good luck and drop a line for any other info you may need to do the aligning.


Bloozberry MSG #511, 06-27-2012 11:07 AM
      Thanks for that timely reminder to sift through your old pics Don... it opened my eyes to another possibility that I had not yet considered. For those that weren't aware, 355Fiero (Don) bought an IFG kit a few years before me and painfully reworked every single panel in a major way. To say he "tweaked" them would be woefully understated. He sent me nearly 200 photos of how he did it, which have at once inspired and discouraged me. Inspired, because now I know this kit can be made into something great, but discouraged because of all the work that lies ahead! So, thanks Don. (If you want to see what I'm talking about, you'll have to prod him to start a thread showing off how he spent several years turning a pig into a purse.

So to get back on track with rear suspension mods, I decided to take an iterative approach to modifying the baseline drawing in my last post, starting first with cradle and link modifications, then on to new wheels, followed by a spring drop, and finally a fender reshaping. I needed to find a method of keeping track of each successive change I made so I could backtrack in case an earlier modification conflicted with a later one. So I decided to highlight changes in each successive stage in red. Only new changes from one stage of modification to the next are highlighted, not the cumulative changes from the baseline drawing. If that doesn't make sense, it soon will as I describe the next set of drawings.

Stage 1 - Cradle Raising & HT Links.

From my earlier kinematics analysis, I knew that I would achieve most of the needed lowering with a spring drop, and needed either to raise the inboard lateral link mounts relative to the cradle, or to raise the entire cradle up into the chassis to counteract the adverse effects the spring drop has on the lateral and trailing link angles. So with measuring tape in hand, I quickly realized that if I took the raised inboard lateral link mount option, interference with the F40 transmission would limit the amount to about 25 mm, with a 10 mm clearance for power train movement. I abandoned that option when it appeared I could raise the entire cradle a full two inches instead.

Once I had drawn out that scenario and confirmed that a 1" diameter axle wouldn't contact the underside of the lower frame rail at full jounce, I was quite happy with the result. That is, until I took a few height measurements of the newly raised Northstar engine relative to the stationary decklid. Raising the cradle two inches would've put the highest point of the engine 5 mm above the underside of the decklid, not including any room for powertrain movement. That wasn't going to work.

In the end, I worked my way from the top down rather than from the bottom up. I started by choosing a 20mm clearance between the underside of the decklid and the top of the engine, which then automatically determined the relative location of the transmission, which subsequently set the maximum height of the inboard forward lateral link mount allowing for 10 mm of powertrain movement, and automatically set the oil pan level in relation to the cradle bottom. This also established the axle location. With all these interrelated vertical dimensions resolved, that only left room for a 25 mm (1 inch) raising of the cradle. In this side view drawing all of the areas of concern are in red: the transmission to lateral link area, the shortened rear cradle mounts, the lowered front cradle mounts, and the F355 decklid height. Notice that the forward cradle cross member is also in red since it interferes with the Northstar engine, and though it appears to interfere with the transmission it does not:

To keep things a bit less cluttered in the above drawing I left out the strut, so here is the same drawing from the rear view, less the engine, but with the strut detail added:

This view shows that I've added the longer lateral and trailing links, lowered the chassis onto the cradle, added the coil-over strut (which needed to be shortened to accommodate the lowered chassis on the cradle), trimmed the weld flange on the upper frame rail, and changed the angle of the axle due to the location of the transmission. I've also drawn the axle using the G6 inner tripot joint with the Fiero outer CV joint. These are all changes to the baseline rear view drawing posted earlier so they are in red, as well as their effects on various measurements. One thing not clearly shown is that the engine/transmission assembly was centered between the frame rails leaving 35 mm of clearance at either end as measured at the crank centerline. Here's a summary of all the impacts of stage 1 cradle raising and HT links vs stock suspension and cradle:

Strut travel in jounce: reduced 13 mm
Strut angle: 1.25 degrees less vertical than stock
Strut to lateral link angle: 1.25 degrees less than stock
Trailing link angle: unchanged
Lateral link angle: unchanged
Axle angle: 1.6 degrees angled further downward
Engine to F355 decklid clearance: 23mm more than stock 2.8L engine
Oil pan to cradle bottom clearance: 10 mm
Transmission to cradle vertical clearance: 10 mm
Half-track: increased 76 mm
Wheel to F355 fender vertical clearance: (edit) reduced by 25 mm
Wheel to F355 fender horizontal offset: reduced 76 mm from stock
CofG height: dropped from 495.3 to 476 mm in combination with the front suspension changes made earlier (lowered 39 mm)

I won't explain the significance of these impacts since this is only an interim level modification and therefore most will change by the time I get through the next 3 stages. Next up is ditching the stock wheels and tires to see how that changes things.

(Edit to change CofG height in drawings and text to account for front and rear suspension drops)

[This message has been edited by Bloozberry (edited 08-18-2012).]

Yarmouth Fiero ( MSG #512, 06-27-2012 07:47 PM
      Interesting approach by explaining this process in stages. However, to the untrained Fiero builder like myself, it appears a little diabolical as I attempt to see where you are going with this.......... lower the front cradle pivot point, raise the cradle, lower the rear cradle mount but still show 6.25" of ground clearance......... diabolical indeed.
I haven't look at one page for so long since I found my dad's Penthouse when I was 10.

Looking forward to stage 2.

Yarmouth Fiero

Bloozberry MSG #513, 06-27-2012 10:24 PM
Originally posted by Yarmouth Fiero: appears a little diabolical as I attempt to see where you are going with this.......... lower the front cradle pivot point, raise the cradle, lower the rear cradle mount but still show 6.25" of ground clearance......... diabolical indeed.

It might be easier to wrap your head around it if you consider the cradle was held stationary and the chassis was dropped 25 mm by lopping off the top part of the cradle. The ground clearance to the bottom of the cradle remains the same, but the chassis height was lowered in relation to the cradle.

Originally posted by Yarmouth Fiero:
I haven't looked at one page for so long since I found my dad's Penthouse when I was 10.

Only a fellow engineer would admit that.

[This message has been edited by Bloozberry (edited 06-28-2012).]

Yarmouth Fiero ( MSG #514, 06-27-2012 11:02 PM
      Thanks Blooz

That does help with the understanding. I'll keep going over your procedure and attemp to repeat your analysis for my 85 cradle. I think it will be slightly easier with the simpler rear suspension. When its all said and done, I'm hoping the final geometry is still within the realm of the HT wide track system ( AMS).

" Engineers....can't live with them...can't do a thorough suspension analysis without them". unknown.

355Fiero MSG #515, 06-28-2012 12:41 PM

Lookin' good. Question. Is the Fiero cradle normally lower than the rest of the Fiero undercarriage/floor pans? I can't remember and at work so I guess I will have to take a look when I get home. If this works to lower the car down and still keep strut travel, that would be great. One thing about my 355 is that the ground clearance on the engine cradle is brutally low when I get the rear fender wells filled correctly. This might help with the ground clearance on the engine cradle as long as I have room under the floor pans....


Bloozberry MSG #516, 06-28-2012 04:03 PM
Originally posted by 355Fiero:
Is the Fiero cradle normally lower than the rest of the Fiero undercarriage/floor pans? One thing about my 355 is that the ground clearance on the engine cradle is brutally low when I get the rear fender wells filled correctly. This might help with the ground clearance on the engine cradle as long as I have room under the floor pans....

Good point, but after a quick check, this won't solve your problem Don. In the stock config, the bottom of the cradle is essentially at the same level as the lowest parts of the floor pan, so by raising the cradle (ie lowering the chassis) the floor pan will hang lower than the cradle bottom by the amount you raise the cradle. I'll add the floor pan in subsequent drawings because that's what is going to determine the vehicle ground clearance from this point on, not the bottom of the cradle as I've shown.

Originally posted by 355Fiero:
If this works to lower the car down and still keep strut travel, that would be great.

Unfortunately it doesn't work that way... by raising the cradle (ie lowering the chassis) the strut compresses from the top end since you're keeping the knuckle at the same height but you're lowering the strut tower. In my case, to regain some of the lost strut travel, I've switched to coilovers which raises the upper bump stop, and redesigned HT's lower strut adapter, which I'll show in my stage 3 drawing.

[This message has been edited by Bloozberry (edited 06-28-2012).]

355Fiero MSG #517, 06-28-2012 07:18 PM
      OK Thanks Blooz;

That makes sense. So my suggestion then to setup the rear body section on the Fiero tub will be twofold.
The IFG rear section sits on top of the Fiero firewall with the rear window section. The rear clip aligns to that rear window so it sits up off the rear frame. The way the rear clip engine lid lips are shaped, they impact the rear trunk top (rear seal rail if that makes sense) so the rear clip cannot go down easily much further without cutting into the engine lid inner frame and the rear clip and sail panel.

So, from what I understand you are doing with the engine cradle, is to raise the engine cradle to make sure you retain a horizontal rear control arm while lowering the car to the desired road height.

Your method to correct the gap in the wheel well then will be reduced a small amount by the engine cradle lift but the remainder will be by cutting the rear wheel well out of the rear clip and lowering it down to where you want it against the wheel and the alignment of the side body line. In what I did, I went down as far as I could while aligning the body line from rear bumper to front bumper but should have moved the rear bumper down a bit as well to lower the full body line end to end on the car. I had to cut very panel anyway so I guess I should have cut the rear bumper further as well and lowered it a couple inches to give me back those two inches in ground clearance.... (Not sure that makes sense to everyone but I can visualize what I did and how I could have lowered the body lines while retaining ground clearance)

Oh well. I don't get to go over many speed bumps is all..... or maybe I will do some more cuts.......

I am continuing to watch the progress and look forward to seeing how you fill your wheel wells.


pavo_roddy MSG #518, 06-28-2012 07:24 PM
      HI all

Blooze, or anyone else, how much can you widen the Fiero? Like how wide can you make the front tire, say a 17 inch tall rim, how wide can you make that fit and work before having to go with a wider suspension?



edit: 17 inch tall of course

[This message has been edited by pavo_roddy (edited 06-28-2012).]

Bloozberry MSG #519, 06-29-2012 10:31 PM
      Stage 2 - Wheels and Tires

The next order of business was seeing how much difference new wheels and tires would make to the clearance problems. There were six variables to consider : tire diameter, lateral tire placement (depth), tire width, wheel diameter, wheel width, and wheel offset (now I know why there are so many like-new wheels for sale on eBay)

Starting with the tire diameter, I wanted to get a reasonable size to fill the wheel well, but also not be so tall that it would change the rake of the car, causing a need to lower it even more on the springs than otherwise needed. Most people also consider staying with the stock overall tire diameter so as not to throw off the calibration of their speedometers. That was a non-issue for me since I plan to use a GPS calibrated aftermarket speedo. After playing around with the drawings, I decided a tire in the 25" to 25.5" range would be a good compromise between filling the well and not raising the rear too much.

Next I needed to choose the lateral tire placement. I don't like tires that stick out beyond the fenders and besides, I needed to be sure the wheels would tuck in enough under jounce to avoid hitting the fiberglass fender and making a mess. So the goal was to get the new tire to stick out about 11 - 12 mm beyond the lip of the fender with zero wheel camber. That way once the static camber was added, the top of the tire would be flush with the top of the fender opening, as viewed from the top. The math involved is a simple formula using the tire height multiplied by the tangent of the static camber in degrees, ie:

Amount top of tire tucks in = tire height x tan (static camber)
= 643 mm x tan (1.0 degree)
= 643 mm x 0.01745
= 11.2 mm

Two down, four variables to go. Choosing the width of the tire wasn't just a matter of seeing what the maximum width possible was. Instead, to optimize performance (at least theoretically) tire widths should be proportional to the weight distribution to ensure equal tire loading at all four corners. Since the car's weight distribution is approximately 46% front 54% rear, and my front tires are 215's, a 265 mm rear tire gives 45% tire patch up front and 55% out back. Close enough, and it also happens to be the same width as the real F355 too (well... for the back anyways)!

Choosing the wheel diameter was again more than a simple matter of preference. 17 inch wheels with 265mm tires would not clear the top of the knuckle, so 18 inch wheels were the minimum diameter needed. 19 inchers just made too much of a difference with the fronts, which are 17's. So 18 it is. From that decision, the sidewall height automatically fell into my hands since I had already decided the overall tire diameter and width. A 265/35/18 measures 643 mm (or 25.25").

The required rim width was the next thing that needed defining, but the choice of 265 tires narrowed the options. I visited several sites which recommended a minimum of 9.0" and a maximum of 12.0" wide for a 265/35/18. The Goodyear tire site even listed several additional dimensions of the installed tire on a 9.5" wheel, so that's what I chose.

The last variable to choose was the wheel offset, but that was pretty easy since I had already determined how much the tire needed to stick out beyond the fender (before adding camber), that automatically meant the 9.5" wheel would need a 38 mm offset given the amount of sidewall bulge defined in the Goodyear tables.

That's all the data I needed to know to be able to draw the wheel and tire assembly, which I then added to the latest suspension drawing, and here's the result:

The only things drawn in red are things that have changed since the Stage 1 drawing from my last post. The most noteworthy are that the overall ground clearance of the cradle (not the floor pan, Don) was increased by 20 mm, yet the fender gap only closed up 7 mm up top. The reason for the apparent dichotomy is that the new tires have much stiffer sidewalls than the original 215/60/15 tires so the tires are rounder, lifting the chassis up from the bottom more than it closes the gap at the top. Who'da thunk it?

Other notes:

-The rotor was redrawn to reflect the 12" Corvette brakes, which added to the impact the new tire and wheel had on the half track width.

- The CofG was raised about 14 mm due to the taller tires raising the entire rear half of the chassis;

- The vertical clearance of the tire to the fender still remains at an unsightly 130mm (5.1")

Next: Stage 3- Spring Drop.

(Edit: changed CofG in drawing and text to account for combined effects of front and rear suspension drops)

[This message has been edited by Bloozberry (edited 08-18-2012).]

Yarmouth Fiero ( MSG #520, 06-30-2012 06:31 AM
      Hi Blooz

Again, awesome information in your last post. I can hardly wait to run out and buy the entire book when you get published. It would most certainly be a hit.

I have a question regarding your strut offset brackets. They appeared in your last entry but I can't see where you mentioned the offset you chose. You indicated a 6" track wide increase so can I assume that meant a 3" strut offset? Also, the 1.25 deg reduction in strut angle is due to the 25mm cradle pivot point move? Will this require a tapered shim at the top of the strut?

I see the strut offset brackets for sale on the AMS site with various offsets available, but they still talk about a kit to relocate the top of the strut in the strut tower. Why would this be? You have never mentioned it in your thread and it appears you keep the stock location ( albeit a slight change in strut angle). You and I also talked about it during my visit and we seemed to agree it would be an unnecessary change as the location and form of the strut top mount has a unique design. It would seem to make sense to install offset brackets to offset the control arm length increase. Or is there another reason to relocate the top of the strut? Their site mentions moving the top of the strut outboard but that would appear to make the strut interfere with the wheel and tire more.

Your thoughts?

Confused in Yarmouth.

Bloozberry MSG #521, 06-30-2012 12:08 PM
Originally posted by Yarmouth Fiero:

I have a question regarding your strut offset brackets. They appeared in your last entry but I can't see where you mentioned the offset you chose. You indicated a 6" track wide increase so can I assume that meant a 3" strut offset?

Yes... the correct offset adapters are part of the HT track widening package.

Originally posted by Yarmouth Fiero:
Also, the 1.25 deg reduction in strut angle is due to the 25mm cradle pivot point move?

No... the slight change in strut angle occurs because the HT strut adapters seem to be made (either by design or fluke) to give the maximum range of negative camber possible. If you go back to the stock suspension drawing, you'll see that the bolt in the slotted hole at the bottom of the strut is centered in the slot when the camber is zero. In my last drawing with the adpater the bolt hole is all the way to one side of the slot. For me to be able to obtrain the same 16.5 degrees on the strut, the slotted hole would have needed to be slotted even more. As I center the bolt in the slotted hole, the camber goes more negative... which is a good thing because it allows up to about two degrees of neg camber before running out of adjustability. That's better than the other way around.

Originally posted by Yarmouth Fiero:
Will this require a tapered shim at the top of the strut?

Not at this low angle, since the upper strut bushing can handle the slight variance. If you go back several pages where I show the stock suspension metrics using drawings, you'll see that in the stock config the strut moves through an angular change of around 3.5 degrees from full jounce to full rebound. It's the job of the bushing to handle that change. In my next stage of modifications though, you'll see that I do end up using a tapered shim at the top as you suggest, but only because I purposely tilt the strut over even more (as I've hinted at several pages earlier) as a means to control the lateral movement of the roll center somewhat more than stock.

Originally posted by Yarmouth Fiero:
I see the strut offset brackets for sale on the AMS site with various offsets available, but they still talk about a kit to relocate the top of the strut in the strut tower. Why would this be?

I'm not 100% sure what site you're referring to, but it may be to convert pre-88's with an '88 cradle since the strut tops are located closer together in the '88's. If that doesn't explain it, then perhaps you should attach a website link so I can have a better look.

doublec4 ( MSG #522, 07-01-2012 12:38 AM
      Haven't checked back in this thread for a while now... mind = blown.

What an amazing in depth analysis of suspension geometry and the steps taken to improve it.


Bloozberry MSG #523, 07-03-2012 10:32 PM
      Thanks doublec4! But given the drastic measures needed for the rear of this thing, the jury is still out whether the rear suspension is going to be any better than stock.

Stage 3A - 149 MM Cradle Ground Clearance & 24 MM Fender Mod

Well, with 130 mm gap still left between the top of the tire and the fender, it's apparent that a combination of spring drop and fender mods are going to be needed to get a decent looking car out of this. Rather than make two separate stages, one with a spring drop and the other with a fender mod, I decided to analyze two different spring drops in separate stages combined with fiberglass fender mods in both. The first is this one where I lower the car 30 mm and reshape the rear fender by lowering the edge 1" as Don suggested. This combination results in a 5.9" (149mm) ground clearance with the cradle, and decreases the fender gap to 76 mm (3.0") which is still a bit too much for my liking, but it is worth looking at in depth to weigh the pros and cons of appearance vs performance between this stage and the next.

So here is the drawing for now, the Lotus Suspension Analyzer results will follow after the schematics of both stage 3A and 3B, as long as Zac88GT is still out there. :crosses fingers:

In a rather roundabout way, I achieved the 30 mm drop in the chassis by modifing lower strut adapters. This new design drops the entire chassis by 50mm but when combined with a lengthening of the coilovers by 30 mm, the resultant chassis drop is 30mm. You'd think this would result in a 20mm chassis drop, but the angle of the strut comes into play.

One of the more significant impacts resulting from the redesigned lower strut adapter is the regaining of available jounce travel before the strut bottoms out. During the earlier first stage when the cradle was into the chassis, that used up some of the jounce travel at that time. A further shortening of the springs in this stage without the modified lower strut adapters would have reduced the spring travel in jounce to an unacceptable 50 mm (2"). I took advantage of the space between the top of the CV joint boot and the bottom of the strut to extend the strut bottom downwards. I haven't made the adapter yet, so it's only a concept at this stage but as you can see the jounce travel increases significantly to 110 mm. This idea came to me when 355Fiero (Don) thought at one point that I had installed the HT adapters upside down, which would have resulted in a similar looking adapter (though they wouldn't fit correctly that way). That's what's so great about this forum... so many different views coming together in one place.

This new adapter also has the benefit of offsetting the lower end of the strut further outboard, which moves the strut angle further away from vertical. That isn't always a good thing, but on the Fiero, it's a means to reduce the lateral movement of the roll center (that's one of the reasons the '88 has less distance between the strut tops than the earlier cars). Also remember from an earlier post that as the angle between the strut and the lateral links approach 90 degrees during jounce, the camber gain goes from negative to positive, which is a bad thing. Angling the strut by tipping the bottom outboard (or the top inboard) helps keep the relative angle between the strut and the lateral links under 90 degrees. In this case, the new adapter combined with the somewhat neutralizing effect of the angled lateral links results in a strut to lateral link angle of 71.9 degrees which is slightly better than the stock 73.5 degrees.

To accommodate this new strut angle, I've added a 5.9 degree wedge shaped spacer between the top of the strut and the underside of the strut tower. The upper bushing normally takes into account the angular change in the strut through it's bump travel (about 3.5 degrees total) but I consider 6+ degrees enough to warrant the spacer.

The overall 30mm chassis drop causes the axle and lateral links to angle upwards 3.6 and 4.3 degrees respectively, so they're redrawn in red.

I kept the angle of the trailing link constant by raising the forward trailing link mount on the cradle 30 mm's and so that's why the link isn't redrawn in red but the cradle is.

There are other things that happen as you shorten the springs: the half-track width narrows very slightly (1.1mm) and the CofG lowers as well.

Lastly, this drawing depicts a new profile for the rear fender to close the gap above the wheel. As mentioned before, at this stage it's worth actually having some tires and setting the body at the new ride height to see whether a 3" fender gap is way too much or borderline acceptable since the drawings can be misleading. I knew what tires I wanted, so I ordered them, and they're now in. I spent a couple hours playing with ride heights and the camera, so I've decided that while the 3" gap is still too large for my liking, I will analyze the performance data to see how much I lose by stepping up to stage 3B.

(edit: changed CofG height to account for combined effects of front and rear suspension drops)

[This message has been edited by Bloozberry (edited 08-18-2012).]

355Fiero MSG #524, 07-04-2012 02:25 PM

Great analysis on the rear suspension.

When looking at the fender height above the wheel, have a good look at the rear bumper and how the front edge of the rear bumper really raises up compared to the rear section. When lining the straight body line up front to rear as on oem, you will see that the front edge of the rear bumper will have to be lowered by about 1.5"-2" IIRC. Given you are at 3" with a 1" drop in the wheel well, you can probably get another 1/2" or more by leveling out the rear bumper to line up down the body.

You will find you need to adjust the rear bumper down, fender well down, body line in front of fender well and on rear clip down, door cut and just about 3/4" at the rear edge and about 1/2" at the front edge down and then rotate the front bumper rear edge down about 1/2" as well. This will line up the body line and lower your rear wheel well down to a better location to the rear wheel.

I will see if I can find my old pics of the body cut up and pasted back together before fiberglassing everything back together. And then try to figure out the pff upload tool again...

Keep up the posts as these are great to read.


Edit: Finish my sentences and spelling.... and I took your 3/4 side view and added lines to show how the body ends up being cut and pasted back together to make it acceptable. Red line is where the body line should be from end to end and the black lines are where I cut to reposition the panels to get the straight body line. Made a world of difference to the look of the car.

I put the photo on Photobucket as a start to see if it works. (works....)

[This message has been edited by 355Fiero (edited 07-04-2012).]

Yarmouth Fiero ( MSG #525, 07-04-2012 02:58 PM
      Don - Very dramatic cut line on Blooz's photo. Hard to believe there was a plug made at one time and may still be out there waiting for some poor soul to splash resin and glass on it.

Our prayers are with you Blooz

355Fiero MSG #526, 07-04-2012 06:33 PM

I started with the same body and after lots of cutting and pasting all the panels, cutting off and making separate rockers, and rebuilding door panels and the rear bumper, I had a set of panels I was happy enough with. Not as good as some other panels out there but much better than they started with. I am confident Blooz will take as much care and thought into sorting out his panels as he has on the suspension so we are in for a treat of a transformation.....

My, almost, finished product to show it can be done if you are willing to put in the time. Lots of time........

Yarmouth Fiero ( MSG #527, 07-04-2012 07:10 PM
      Even at that stage of completion, the transformation is quite remarkable Don. Like you, I am confident Blooz will work magic on his 355 body.

Do you have any pics with the door open and showing the sills and / or B pillar? Do the door hinge points remain stock?

Bloozberry MSG #528, 07-04-2012 07:34 PM
      Don, I know exactly what you mean and what you went through since I still have all the photos you sent to me including the cut and pasted panel shots on the car you referred to. I've poured over them many times now. I understand the belt line is supposed to be horizontal and not change angle from one panel to the next between the rear bumper, door, and front end. In fact I've had several rows of masking tape stretched down the side of my car for months now, just like the line you drew in the photo above to remind me what lays ahead. One masking tape line is horizontal to the ground, another one bridges the two fender arches, and a third follows the crooked belt line. It's almost comical to see the zig-zagging and divergent lines. It's such a hodge-podge of pieces that I can't help but think IFG had three people working in three different locations form each of the moulds without ever having talked between themselves. I also have a 36" laminated poster on the wall above the car of an actual F355 from a dead-on side view, to remind me what it's supposed to look like. Now that you've reminded me not to overlook the impact of changes that need to be made to the body regardless of anything else I do, I know that the car can be made to look good. I don't worry about that anymore... I have your pictures to prove it

Perhaps to some it seems like I'm still grasping at straws for a solution, but I've posted the three (soon to be four) modification stages not because I'm still scrambling to find an answer, but to show how I arrived at the answer most suitable to me. In particular, I left the spring drop and fender mods for last since these two mods are more flexible in the amount and direction I take with them. More importantly, I don't need to make a decision on these last two attributes to get on with fabricating a new cradle, which is at the top of the priority list. I can take my time analyzing the impact of several different amounts of spring drop at this stage because I'm convinced that I've exhausted all other avenues for lowering (or giving the appearance of lowering) the car with the least negative impact on suspension performance. In fact, I won't likely make a decision regarding the exact amount of spring drop nor fender mods until I have the rear cradle fabricated, the rear suspension components installed, and weight on the wheels. Though it may take longer, I prefer this method over fabricating components through trial and error.

355Fiero MSG #529, 07-04-2012 07:49 PM

Good summary.

This body is, actually, a splash from IFG, not an IFG directly. I found that the front area had been in an accident and another fellow fixed the front bumper and then splashed the panels from there. The front bumper is a bit more level from IFG. I think this is a good example of the results of a splash of a splash of a splash etc.... Like a photocopier, things degrade as you copy a copy.... also, people just not paying attention to the details when copying.....

I looks forward to seeing how you make a new rear cradle.

Yarmouth Fiero;

The door hings stays in the same location as stock Fiero. The front fender rear edges are shaped the way the are to allow for a fully opening door panel without interference. You need to make the rear edge fairly thin though to clear the door panel when it first opens. I can send you some pics to your email of what I did with the doors an rockers to show you the changes. If you go with an AD355 body, you won't need to do these changes as they are already in the panels.

Back to the regularly scheduled program.....


Bloozberry MSG #530, 07-08-2012 10:11 PM
      I snapped a few pictures the other day to give a better appreciation of approximately what stage 3A would look like. Remember, this isn't the look I want, it's just a better visual of what the drawings above are saying: basically a three inch fender gap is too much. First, here are the newly acquired rear meats... Goodyear Eagle F1 Assymetric2's:

And although this next picture doesn't actually have the fender reprofiling I've lowered the chassis on the wheel to show what 76 mm (3") looks like. From the side:

Edit to add:

And from the rear quarter view:

[This message has been edited by Bloozberry (edited 07-08-2012).]

Yarmouth Fiero ( MSG #531, 07-10-2012 06:29 AM
      Hi Blooz

Nice rubber you have chosen. When its all done, what is considered the " ideal look" with regard to wheel and fender clearance? Is a uniform fender gap around the tire desireable? Also, a page back you showed a +/- 76mm suspension travel in your rear suspension analysis. When its all done, what is " normal travel" for the suspension on a car like this? I've been tweeking my chassis additions and I've angled the rear support quite far back to maximize the strength, clear the gas fill plumbing but still give ample room for wheel travel. But once you have selected your ride height, spring rates and such, what do you expect will be normal wheel travel ( assuming I'm driving on typical Nova Scotia roads like you )

Bloozberry MSG #532, 07-17-2012 11:11 AM
      Picking the "ideal" fender gap is obviously subjective, but there are more things to consider than just the looks. I like the fender gap on Don's car in his photos above, so I would consider that pretty close to "ideal looking", but then Don mentioned that to get his car looking that way he finds himself with less than the desired ground clearance. On the other hand, had he raised the cradle up into the car like I'm proposing, the tire to upper frame rail clearance may have become an issue. So the answer is inevitably a compromise between looks, available bump travel, kinematic performance, and ground clearance. Each builder will have his own unique set of priorities.

Changing topics for a minute here, in case you're the type that notices these things, I've changed the title of the Stage 3A modification from 30 MM Spring Drop & 24 MM Fender Mod, to: 149MM Cradle Ground Clearance & 24 MM Lowered Fender Mod. I realized that once I added the modified lower adapter, the length of the spring drop becomes meaningless, so I combined the effects of the spring and adapter into a single more easily understood cradle to ground clearance measurement.

Stage 3B - 125MM Cradle Ground Clearance & 24 MM Lowered Fender Mod

Similar to Stage 3A, this modification uses the modified lower strut adapter to regain jounce travel and tilt the bottom of the strut further outboard. The major change here is that the spring was shortened even more than stage 3A to achieve a tire to fender clearance of about 2" (51mm with zero camber).

Doing so caused several side effects though:

a. it increased the angle of the axle to 7 degrees. Old-schoolers might find this excessive but then the axle isn't terminated with universal joints, but rather constant velocity joints. Automotive CV joints actually require at least 2 degrees of angle to maintain relative motion between the internal components of the tripot joint and provide proper lubrication. Furthermore, typical automotive CV joints can operate at up to about 26 degrees without detrimental effects;

b. the angle of the lateral links increases to about 7.7 degrees. This wields a strut to lateral link angle of approximately 74.2 degrees which is slightly worse than the stock angle of 73.5 degrees. The result is that the camber curve will be slightly less progressive than stock, which is a move in the wrong direction. Regardless, this is considerably better than simply having lowered the stock suspension by 2" as most people do, which would have resulted in an even worse 80.5 degree separation between the strut and the lateral link;

c. the strut angle drops a further 1.1 degrees away from vertical over Step 3A and a full 7 degrees more than stock. This should help limit the lateral movement of the roll center, but will necessitate an upper strut wedge spacer to keep the upper strut bushing within a reasonable amount of deflection;

d. the maximum strut travel in jounce is reduced by 5 mm from stock (93mm) to 88mm. Given the higher rate 350 lb/in springs, this amount of jounce should be adequate to prevent bottoming out on the struts; and

e. the cradle ground clearance is reduced from 6.25" in the stock configuration to 4.9". Unless the floor pan is modified slightly, the floor pan's clearance will be 1" less or 3.9". This means that if the struts are allowed to bottom out, the floor pan will be approximately 1.5" above the ground;

f. the car's center of gravity is reduced by approximately 14 mm over stage 3A and by 22.5 mm over stock.

There are several other side effects of this modification, though these are also impacted slightly by the addition of 1 degree of negative camber to the rear wheel as shown in the above drawing. When the effects of the camber are added to those of the spring drop:

g. the half track increases by 1.6mm. This is a combined effect of the narrowing that results from angling the lateral links upwards, and a widening from the negative camber which pushes out the tire contact patch;

h. the fender gap decreases by 2mm more than the simple 24mm chassis drop due to the tilting of the tire top in negative camber;

i. the outside top edge of the tire gets pulled in so that it is in line with the outside edge of the fender at ride height. This is an area that I will focus on again later when I get the kinematic suspension results back from the Lotus Suspension Analyzer program. Ideally, as the rear suspension compresses beyond the 49mm vertical clearance to the fender, the dynamic camber curve should tuck the tire top in enough to clear the fender horizontally and allow the maximum strut travel (88mm) without the tire contacting the fiberglass. If the software shows that there is insufficient tuck-in, then slightly higher offset wheels or additional fender modifications would be needed; and finally

j. the upper frame rail is modified to gain the additional clearance as shown. Without this modification, the rotating tire would contact the underside of the frame rail limiting wheel travel in jounce to 50mm.

To get an idea what a 2" fender gap will look like, I'll post a few pictures in my next post. Again, this modification step represents the largest suspension angles I'd likely be willing to accept to achieve a good looking fender gap, whereas step 3A illustrates the maximum acceptable fender gap with the least angular impact to the suspension. Neither option explores the possibility of lowering the fiberglass fender more than 24mm, but this is certainly an option as well. My final decision on how to proceed will be made after I show the Lotus Suspension Analyzer data.

(Edit: changed CofG height to account for combined effects of front and rear suspension drops)

[This message has been edited by Bloozberry (edited 08-18-2012).]

Bloozberry MSG #533, 07-17-2012 06:11 PM
      Here are the pictures of the 2" fender gap I promised. Remember, this is just me playing with height of the chassis to illustrate a point, none of the fiberglass fender mods have been done to achieve this look yet. I find that the fender gap in the direct side view always looks like crap without the wheel well liners like in this first pic:

The next two photos give a better impression of what the 2" fender gap should look like:

And the whole car (ignore the masking tape and the front fender gap)

Now that's more like the look I'm after.

fierogt28 MSG #534, 07-17-2012 07:56 PM
      Hey Blooze, those tires are very nice. Can't wait to see them installed on rims
and on the car permenantly. I suppose that will be 2 years from now??

Keep it going Blooze...

Bloozberry MSG #535, 08-28-2012 08:30 PM
      Thanks for the comments there fierogt28! Your guestimate for a completion date is probably pretty accurate. I'm hoping to make great strides this fall and winter as I've cleared my schedule for "me-time".

Well, it's been a while since I last posted an update here... so long in fact that something had to be done to get my thread off the second page of the Construction Zone. The good news is I have more to report than just a simple shameless bump. The bad news is that it looks like I'll be going back to the drawing board.

A few weeks ago, I sent a spreadsheet full of suspension coordinates representing stages 3A and 3B off to Zac88GT. He's been kind enough to run all my data through his Lotus Suspension Analyzer program and send me the results. I plotted the information within a day or so of hearing back from him, but I've been hesitant to post the results because they weren't what I expected, and I had no plan B (more like plan F at this point!).

I won't bother posting all the graphs again since I doubt I will use either Stage 3A or 3B modifications, however I'll summarize the results here. As I began plotting the data, the camber, toe, and anti-squat versus bump were encouraging... both new suspension configurations showed notable improvements over stock performance. The roll couple (Roll Center to CG Vertical Distance) vs bump was pretty much on par with stock performance for stage 3A, but was significantly worse than stock for stage 3B. The camber vs roll angle plots for both were marginally worse than stock as well.

The show stopper for both configurations was the roll center vs chassis roll plots. I'll post these diagrams because a picture is worth a thousand words. In this first plot, the blue line represents the stock movement of the rear roll center as the chassis rolls up to 6 degrees in either direction. The pink and red lines depict options discussed earlier in this thread. The orange and green lines show how much the roll center migrates with stage 3A and 3B modifications respectively:

Clearly roll center movement in both vertical and lateral planes is significantly worse than stock, which is bad enough to begin with. To help visualize the impact of the roll center movement, I superimposed the plots from the stock suspension and stages 3A and 3B over top of a scale drawing of the stage 3B rear suspension below. The squares represent 10 cms (almost 4"). Bear in mind that I stopped connecting the dots for all three plots at 3.5 degrees of roll since the scale of the entire drawing would have been unreadable if I had continued the orange line out to 6 degrees. I did leave the data points on the other two plots to give an idea how they behaved beyond 3.5 degrees, in 1/2 degree increments.

So where to go from here? I know I've said the primary goal was to get the car looking good, with performance a secondary objective, but this is just too much of a deviation to accept without at least studying other alternatives. I've been inspired by Datsum1973 (a PFF member) to look into a short/long arm (SLA) style rear suspension:

(from this thread: ).

I've spent several hours now measuring the rear chassis, studying my previous front and rear drawings, and generally assessing the feasibility of his design. My first impressions are that it looks do-able, so I'll spend the next while brainstorming and posting my thoughts on how his design might be adapted to suit my car, then hopefully Zac will still be around to provide the ever-important number-crunching.

[This message has been edited by Bloozberry (edited 08-28-2012).]

FieroWannaBe ( MSG #536, 08-28-2012 08:43 PM
      I am wondering how much of an improvment FieroGuru's link relocation/camber curve kit will make to the roll center migration. Its worth a try, isnt it?

Bloozberry MSG #537, 08-28-2012 09:04 PM
      Fieroguru got Zac88GT to run the numbers on his relocation kit, so I'll let him post the data if he wants. It's dawned on me that the trouble with the Fiero rear suspension is that the fixed angle of the strut significantly limits roll center control. An upper control arm provides much greater freedom to counter the effects the lateral links have on roll center location.

FieroWannaBe ( MSG #538, 08-28-2012 09:16 PM
      I Absolutely agree with you. I was just wondering how the track width increase and link relocation could help lessen the negative effects.

fieroguru MSG #539, 08-29-2012 06:42 AM
Originally posted by FieroWannaBe:

I am wondering how much of an improvment FieroGuru's link relocation/camber curve kit will make to the roll center migration. Its worth a try, isnt it?

Zac ran the numbers and posted the graphs half way down on this page for a car at stock ride height. The overall benefit depending on ride height of the car.

As you work to lower the chassis a significant amount, the 88 rear suspension (and front suspension for that matter) really starts to work against you unless you start with lowering uprights/knuckles to accomplish the vast majority of the lowering.

fieroguru MSG #540, 08-29-2012 06:47 AM
      Blooze, glad to see you back working on this swap!

Since you are widening the overall track width, have you considered making the rails of the cradle wider? This would lower the overall length of the lateral links and get you further away from interference issues with the transmission and possibly allow the inboard lateral links to be raised further. However, it would be very cool to see you come up with a dual a-arm setup as well!

FieroWannaBe ( MSG #541, 08-29-2012 01:40 PM
Originally posted by fieroguru:

Blooze, glad to see you back working on this swap!

Since you are widening the overall track width, have you considered making the rails of the cradle wider? This would lower the overall length of the lateral links and get you further away from interference issues with the transmission and possibly allow the inboard lateral links to be raised further. However, it would be very cool to see you come up with a dual a-arm setup as well!

On a lowered fiero, the longer links help to lessen the camber gain on compression once the links have passed the horizontal position (but also negatively affect camber loss before they pass the horizontal) since the linkage end travels a larger radius arc. They also lessen the veritcal displacement of the roll center for a given amount wheel travel due to a smaller angular displacment (although the horizontal displacement is greater). Which is why I think combining your relocation brackets can help soften the negative effects of Bloozberry's first proposed solution, but probably not enough to justify it.

Obviously, provided the right coordinates a double wishbone (or a 5-link type like most modern production cars and Datsun1973's solution) a can provide the best selection of geometry kenimatics, and force vectoring.

Bloozberry MSG #542, 08-31-2012 09:22 PM
      Thanks for your observations FieroWannaBe.

For Fieroguru: Earlier on, I did look at making the cradle wider, and shortening and moving the inboard lateral link mounts outboard and upwards, although only superficially. I quickly realized that the F40 overhangs the forward inboard lateral link mount by way too much to ever make enough room for it vertically. The other problem with shortening the lateral links is that it would only exacerbate the angle of the links with respect to the ground, worsening the roll center movement.

One of the things I did to get a warm fuzzy feeling about whether an SLA set up like Datsun1973's might fit, was to overlay the scale drawings of my front control arms onto the rear suspension. My logic here was that since the front geometry works so well, if it could be replicated in the rea, then the rear roll center could potentially be tamed equally well. Here's my first crude attempt to see how the front geometry (in red) would look if it were moved to the rear:

I simply cut and pasted the two front control arms in the exact same orientation they are to each other from my final front suspension configuration, onto the rear Stage 3B rear modification drawing. Even though I don't intend to replace the rear lower lateral links with a control arm, for this exercise, used the front lower control arm simply to locate where the upper rear control would lie. I aligned the front lower control so that the lower ball joint was in line vertically with the hole in the rear knuckle for the lateral links and the inboard pivot was at the same height as the lateral link mounts. The upper control arm then just fell into place.

My first observations are that:

1. the geometry can't be exactly the same as the front since the lateral links are shorter than the lower control arm, and the upper ball joint does not fall conveniently where Datsun1973 has located his upper joint on the knuckle;

2. since the lower lateral links will be shorter, the upper control arm will likely need to be proportionally shorter as well, which will make it easier to package within the available space;

3. the lower frame rail appears to be well located to support the upper control arm pivot, or at least a new structure to support the pivot;

4. with a pushrod set up and shock orientation like Datsun1973's, the strut towers become redundant and could be replaced by a simpler and less intrusive structure tying the upper and lower frame rails together and making more room for the Northstar rear valve cover (not to mention the dead give away the strut towers provide to the actual lineage of the car when the decklid is open.);

The next thing I want to do is draw the rear lower frame rail to see how the front suspension geometry fits in the side and top views... more soon.

Edit: Updated drawing

[This message has been edited by Bloozberry (edited 09-09-2012).]

fieroguru MSG #543, 09-01-2012 08:09 AM
      Since you will have to relocate the lateral link attachment at the upright, why not center the upper ball joint to the center of the upright casting. Then you can drill a hole through it, machine the sides flat and use a rod end or poly bushing on each side. Or shift it inboard 1" so you can have a bracket attach at the stock strut attachment, then come down to the proper area with a cross shaft right inboard of the casting.

Looks like the lateral link attachment would be about 70mm lower (if I can count right on this small net book screen), and I am pretty sure that would fit in your wheels, but the trailing link could be an issue. You might want to consider shortening it and attaching it directly to the front lateral link (but probably want to up-size the tube.

fierogt28 MSG #544, 09-06-2012 06:32 PM
      Blooze, from the pics 3-4 pages are going to change the front ball joints and tie-tod right??

I suspect you just assembled the parts for an example mock-up...

exoticse ( MSG #545, 09-06-2012 11:40 PM

Blooze the car is looking good !

That mock up pic is wicked.

Austrian Import ( MSG #546, 09-07-2012 01:07 AM
      Blooz, could you repost these pictures with your analysis in my suspension redesign thread? - This is very interesting. I was always hoping an SLA would work in the rear and use the lower frame rail.

F355spider ( MSG #547, 09-07-2012 10:05 AM
      Back to the top great work

Bloozberry MSG #548, 09-07-2012 10:48 AM
      I see I have some catching up to do on feedback:

For Fieroguru: You may have a good point, but I'm not sure yet that I'll have to relocate the lateral link attachment at the upright like you suggest. Even if both control arms would need to be angled upwards at ride height as my initial sketch shows, it shouldn't matter much if I can duplicate the control of roll center movement achieved in the front suspension. What I mean is that in the front, no matter what the control arm angles are at, the roll center stays roughly stationary. The challenge will be to define the coordinates of the control arms that not only control the roll center though, but also the camber and toe, given different packaging constraints than the front.

Fierogt28: Good eye. I do have new tie rod ends to install, they're just not painted yet. The lower ball joints are new, but the uppers aren't. They're actually not worn out, but they do detract from the rest of the new parts dont' they? Now that you've pointed that out to the whole world, I feel like I have to get new ones... thanks alot.

exoticse: Thanks for the compliments... it takes an experienced eye to see the potential in a kit car at this stage.

Austrian Import: I would take you up on your offer since the more brainstorming there is, the more likely the best solution will come to the surface. As you likely know though, posting pictures is easy. What takes time is explaining them... more than I can afford at this very early stage. Perhaps once I'm out of the preliminary concept stage I'll have more time. Feel free to download my images from here and repost the ones you think will generate discussion over in your thread though. I always check out new posts in there... afterall, Datsun1973's contribution comes from your thread.

Edit to add: thanks too 355Spider!

Now back to the latest update: It's taken a considerable amount of effort to map out that rear lower frame rail, especially since not all of it is easily accessible for measuring. As usual, I head out to the shop, take a whole slew of measurements and make a hundred little sketches, come back to the office and try to make everything fit. The computer is amazing at simultaneously showing how accurate something can be and at how terrible I am at measuring things. It's no wonder you hear that saying "Measure twice, cut once" so often among people who work with their hands. If I'm lucky, I'll only have a few discrepancies to iron out... wasn't the case this time around. So as one PFF'er states in his signature, "you get what you pay for", consider how much you paid for these drawings before building a new Fiero using these as blueprints!

For now though, just to show that I AM working at it, here are the top and side views of the stretched frame and raised cradle. For the eagle-eyed among you who are curious why I indexed the longitudinal axis in both drawings where I did, well, it's a long story but it boils down to using the rear trunk wall as the index point since it was the closest repeatable measuring point for all other points on the frame rail... and it was the easiest point of reference to use while sitting in the empty engine bay.

I'll superimpose the front suspension geometry over top of them in my next post:

[This message has been edited by Bloozberry (edited 09-07-2012).]

85LAMB ( MSG #549, 09-07-2012 12:18 PM

I have not idea how I miss all the great fabrication you are doing....
You are doing a great job !!!

I had respect for you before, just by reading your comments on the "replica" thread.
But now you are one of the persons I admire must on this forum.

I am sure that if you put as much attention on the body as you do on the mechanichal,
You will have one of the nicest 355.

Keep up the good work

Bloozberry MSG #550, 09-07-2012 04:18 PM
      Thanks 85LAMB... you're very kind. Between myself and Yarmouth Fiero (another PFF'er building an F355) we have some neat stuff brewing in the pot for the bodies.

F355spider ( MSG #551, 09-08-2012 09:41 PM
Originally posted by Bloozberry:

Thanks 85LAMB... you're very kind. Between myself and Yarmouth Fiero (another PFF'er building an F355) we have some neat stuff brewing in the pot for the bodies.

Does Yarmouth have a build thread here? We need more kit car build threads.

fieroguru MSG #552, 09-08-2012 10:17 PM
Originally posted by F355spider:
Does Yarmouth have a build thread here? We need more kit car build threads.

Bloozberry MSG #553, 09-09-2012 09:54 PM
      As promised, here are the two remaining views of the rear frame rail and cradle with the control arms from the front suspension superimposed on them. Again, this is just a crude way to get an idea how well or ill-suited the stock lower frame rail is oriented to locate some mounts for an upper control arm and a pushrod shock. The rear view was posted earlier, so here is the top view with the lower control arm being blue and the top one red:

Once again, I'm not planning to replace the '88 lateral links with a lower control arm. The only reason I left the lower control arm on the diagram was to show the relative positions of the lateral link mounts on the cradle vs where they would need to be to retain an identical geometry with the front. The lower control arm's function is replaced by the two lateral links which are roughly 35 mm shorter than the aft leg of the lower control arm and roughly 65 mm shorter than the forward leg. This view shows clearly that the front geometry cannot be incorporated lock, stock, and barrel onto the rear, but that doesn't mean it's not possible to achieve a similar performance.

Since the lateral links are shorter than the lower control arm, the result would be decreased camber gain in jounce vs the front suspension, if the upper control arm were identical. But this drawing (and the rear view one posted earlier) show that the upper control arm would need to be shortened to bring the ball joint in line with the top of the knuckle. The impact of that change would be to increase the camber gain in jounce... perhaps enough to compensate for the effect of the shorter lateral links.

Here is the side view:

Of course the upper control arm is angled for anti dive when anti-squat is what's needed, so ignore the front to back slope of the upper control arm. The other thing that jumps to mind in this drawing is the amount of caster, indicated by the misalignment of upper and lower ball joints vertically. Caster is needed in the front suspension to make steering more stable, but not needed in the rear so the upper ball joint location could be moved towards the front of the car if it were useful to do so. The only other notable point I can think of about this drawing is that it shows how much room there is rearward for a fore-and-aft oriented coilover similar to Datsun1973's design.

Overall then, the layout and location of the stock rear frame rail appears to be amenable to an SLA-like suspension, only in htis case it would be more like a four(?) link design (is the shock pushrod considered a link?). Certainly worth further development in my opinion, so I'll continue refining these drawings by looking into a suitable upper control arm pivot design or two, and a pushrod shock system. Questions or constructive comments are always welcome.

(Edit: corrected side view drawing to illustrate correct ground clearance)

[This message has been edited by Bloozberry (edited 09-16-2012).]

FieroWannaBe ( MSG #554, 09-10-2012 11:31 AM
      Have you been giving any thought to the Roll Axis Inclination?

From what ive gathered around different sources (Milliken, Smith, Adams, Haney) a anti-roll bar on the rear of a vehicle equiped with an open-defferential is more prone to lossing tractive effort on the inside tire in a turn, and be more akin to oversteering, I havent had the chance to read Olley's book yet, but from the OP in the linked thread, and my quick look at a few more High performance racing setups, the inclination fo the roll axis is to angle it upwards to the rear. I wonder what the effects of the stock 88's is.

Bloozberry MSG #555, 09-10-2012 03:26 PM
      I am aware of the importance of the roll axis inclination, I just don't understand it thoroughly yet. There's more reading in store for me too.

Bloozberry MSG #556, 10-17-2012 10:02 PM
      I've spent the last couple weeks working on and off trying to refine the location of a new upper control arm. I must admit it's taken much more time than I expected mostly because I needed to leave it alone on many occasions to let things sink in, and because I don't have simulation software. I had to try many iterations using a digital stick model approach to narrow down the best coordinates for the new arm. I wanted to make things as easy for myself as possible in the fabrication stage too so I began by setting some design limitations. Though it didn't necessarily make things easy at this stage, I decided to:

a. leave the locations of the lateral and the trailing links intact (following the 6" track width increase);

b. use the upper or lower strut mounting holes on the knuckle to locate the outer pivot point of the new upper control arm;

c. use the 25 mm raised cradle; and

d. leave a 125 mm ground clearance to the bottom of the center of the cradle.

Starting with the rear view, my goal was to locate the coordinates of the inboard pivot point for the new upper control arm, such that the roll center movement and camber gain were improved over the stock configuration. In my head it seemed simple enough to locate a single pivot point, but practically speaking it was anything but.

Initially I just picked a random point near the lower frame rail for the inboard upper control arm pivot, then I rolled the body over 6 degrees and noted what happened to the roll center and the camber of both tires. To keep the impact of jounce out of the equation, I made sure that when I rolled the body I kept the ground clearance as measured at the centerline of the cradle at 125 mm. This may not prove to be what happens in real life but I needed to hold this constant to prevent too many variables from wreaking havoc on my simplistic methodology.

I then changed the location of the inboard pivot point, and repeated the experiment until I got a feel for how the camber and roll center were impacted by various vertical and lateral displacements of the pivot point. I was amazed at how sensitive the camber gain was with only very minor pivot point changes, but I was eventually able to find a location near the bottom outside corner of the lower frame rail that seems to be a good compromise between both roll center movement and camber gain. Whether this pans out when these coordinates get plugged into the Lotus Suspension Analyzer software or not is yet to be seen, but as I said, it's a good start.

Using the best coordinates I found for the uppper control arm, this first drawing shows the static location of the rear roll center being about 92 mm above the ground. If you recall, the static roll center of the modified front suspension is lower at 72.4 mm. The result is a roll axis that is raised slightly at the rear. This is a good characteristic and is what FieroWannaBe was referring to earlier as the roll axis inclination. I won't get into details at this point but suffice to say that this new design is on the right track.

(I apologize in advance for the poor resolution of these drawings, but unfortunately it's a draw back to using PIP.)

This next drawing shows how the same suspension behaves when the body is rolled 6 degrees to the left, as it would be in a high G right hand turn. The most important things to note are that the camber change is almost perfect (excluding the effects of bushing deflection). The outside (LH) wheel counteracts the body roll by tilting the same amount in the opposite direction, which keeps the tire contact patch flat with respect to the ground, giving maximum traction. The inside (RH) wheel comes within 1 degree of countering the body roll angle, which is a significant improvement over stock.

The other important thing to note is that the roll center moved considerably less in this design than my earlier stage 1 or 2 modifications. Here, in a 6 degree roll, the roll center migrates only about 7 mm down and 320 mm outboard as compared to nearly 470 mm down and 2670 mm outboard in my stage 2 design using Chapman struts. Again, I still have to verify that my drawings are correct using the Lotus Software. To do that though, I'll need work on the top and side view drawings to get the additional coordinates in the x-plane.

(Edited to rename both drawings)

[This message has been edited by Bloozberry (edited 10-20-2012).]

FieroWannaBe ( MSG #557, 10-18-2012 10:29 AM
      How interesting. The placement you came up with and Dastun's is incredibly similar.

Great minds think alike.

How nice of Pontiac to put a frame rail right there, a great spot for a upper control arm.

Great work Blooze.

FieroWannaBe ( MSG #558, 10-18-2012 10:45 AM
      This may be of small interest. At a recent SAE chapter meeting, an engineer from the Ford GT project gave a presentation detailing the design process. He had mentioned the design goal was to mimick the Ferrari F360. Using a kinematic test of the ferrari, they designed a suspension to preplicate it, mostly. ( The Ford was finished with a rear camber curve of 0.7 Degrees of camber change per degree of body roll (or something to that effect, IIRC) and 0.5 for the front (this matched the ferrari); and a ride frequency of 1.7Hz in the rear, 1.5Hz in the front, I think this was slighty higher than the ferrari. Those are the numbers I seem to remeber, they may be off, but it was less than unity.

I would be concerned about the foward tractive capability with an overly agressive camber change.

Bloozberry MSG #559, 10-18-2012 02:00 PM
Originally posted by FieroWannaBe:
The Ford was finished with a rear camber curve of 0.7 Degrees of camber change per degree of body roll (or something to that effect, IIRC) and 0.5 for the front (this matched the ferrari); and a ride frequency of 1.7Hz in the rear, 1.5Hz in the front, I think this was slighty higher than the ferrari. ...they may be off, but it was less than unity.

Interesting stuff.