OK, I want to begin this by saying that the people at Spec were great, Jeremy in particular. We spent a lot of time on the phone deciding which unit would work for our race car application and what all I needed to use.

My setup is a Northstar with 300° cams from CHRFab, 36# injectors, and I'm running the 7730 ECM with Ryan Hess' programming. Alan at CHRF says that it should conservatively be a 400 hp motor with a proper tune. He's dyno'd several in sand rails with about the same setup as mine and made over 425. We'll see when we get it on the dyno. It also will not idle with these cams below about 1300 rpm unless it's very, very lean, so I'm idling at about 1500 rpm or a bit less.

I bought the steel flywheel from CHRF and when it came in I checked dimensions with it compared to a stock flywheel on a duke block and also a stock flywheel on my 2.8L dummy block. I don't recall the actual dimensions but the CHRF flywheel stood out further from the back of the mating surface where the block mates to the transmission .289". This was measured by laying a straightedge across the flywheel and using calipers to get the dimensions from between the straightedge and the block face. Now when I ordered the flywheel Alan told me that it would work with any stock dimension Fiero Clutch, but that seemed like a lot of variance to me.

I called Spec and talked to Jeremy and we decided on a solid hub stage 4 clutch and pressure plate and got it on the way. Because the Northstar flexplate bolts weren't long enough, I ordered a set of 12.9 grade bolts from AAA Metric in Denver and got them on the way. The were socket headed allen capscrews.

The flywheel got here first and I called Alan telling him I was concerned about how deep the flywheel was sitting into the bellhousing. He told me he had several running in the Fieros. (His flywheels, BTW, are made by McLeod). The clutch arrived and I started to bolt things up.

The first thing I noticed was that if I installed the clutch as indicated by the stickers on the pressure plate, two things happened. First, the nose of the clutch hub rested on the flywheel and I could put .060" feeler gauges between the disk and the flywheel. Second, after a lot of measuring, there would be about .300" of the splines in the disc that were not being used by the input shaft of the transmission.

If I turned the disc around, the clearance issue with the crank went away, but now I was about .060 tight against the transmission snout with the hub and that obviously wasn't going to work. I called Spec and talked to Jeremy again and he pulled another disc off the shelf and we decided that somebody on the production floor (again!!) put the stickers on the wrong side of the disc. He was not amused after the last thread he participated in here on the forum and the law was laid down to the production guys to make damn sure the stickers went on the correct sides. All that aside, he told me that as much as they physically can, the try to keep their clutches to stock dimensions, +/- .030", so anything else that was stock dimensioned should bolt right in.

I called Alan again and told him of all the issues, and he then told me that to make it work, I'd have to use the McLeod Clutch and pressure plate if I was having these issues. To be honest, I was getting a lot more support and help from Spec than I was CHRF, so I decided to see if they had a flywheel on the shelf. They did have an aluminum one there and even ate 1/2 the next day air to get it to me the following day, so about $400 lighter and I was putting my clutch in.

I checked the dimensions on the Spec flywheel as soon as it got here and it was within .020" of the two stock setups I have been measuring, so I put the disk in backwards, according to their markings, and everything slipped together normally.

We get the motor in the cradle and everything in the car, then did some tuning to get it to at LEAST idle, and when we had the car on the hoist the clutch felt fine and I had about 1.1" of travel at the slave. We get ready to load the car on the trailer to leave after pushing it off the hoist and.....................NO CLUTCH DISENGAGEMENT!! To say I was not amused is the understatement of the year. I played with it that night (cancelling our hotel reservations for the night) and gave up about midnight.

All of the normal things were checked like air in the clutch hydraulics, slave throw, bent clutch arm (already been replaced with steel), etc., etc. Everything seemed OK. I decided to sleep on it.

About 4:30 am I woke up with a plan to make a tool, simple really, to manually measure the clutch throw. I came out to the shop and got a piece of 1/2" aluminum, band sawed it about 1" wide and 6" long, drilled a hole in the center. I found a piece of 7/16" all thread and cut it long enough to go through the hole with a nut welded on the back side to put a ratchet on, put a nut on the back side, and started turning until all the freeplay is out of the clutch. Since it was 7/16" - 20 thread, I knew that every 20 revolutions was 1". At 20 turns, everything was still solid. At 30 turns it was still solid. At 45 turns, if I pushed the car by hand, it would move with a "ratcheting" sound coming from inside the bellhousing. Not good. Didn't know what it was, but it was all going to have to come apart again.

At 7:00 am the car went back on the hoist and at 8:30 my hired hand showed up. Chris came over from Hays and by 10:30 the cradle was on the dolly and the engine/trans on the hoist. Another 15 minutes or so and the transmission was off. We worked slowly now, looking for anything. Took the pressure plate off and the clutch disc and examined them carefully.

I found some marks on the rivets on the clutch hub and some matching marks on the heads of the allen headed capscrews that I used for flywheel bolts. What was happening was that when the disc was against the flywheel, the rivets were dogging themselves to the bolt heads, making it a solid unit. I had to release the clutch almost twice as far as it should have gone to get enough clearance for the rivets to "pop" over the capscrews.

Believe it or not, I was ecstatic. We had actually FOUND the problem and had a chance to fix it without wasting a lot of time shipping in parts. I called our Fastenal stores and they thought they had bolts that would work. I wanted some with the thin heads that get used on flywheels a lot, but all the had was normal heads. They didn't have any 12.9 but they did have 10.9 and the stock Northstar flywheel bolts are actually 8.8.

We made a beeline for the shop and bolted everything up, measuring carefully. I had .070" clearance between the rivets and the bolt heads now, but didn't know if that was enough when the disc would wear. I called Jeremy up at Spec and asked him what the minimum clearance should be. He asked how much I had. I told him it didn't matter how much I had, how much did I need? He said that when that disc wears .040" closer to the flywheel, the clutch will be shot, so how much did I have? I told him .070" and he told me to put it together and run it.

We talked for several more minutes and I strongly suggested with the clearance issues involved, that they include flywheel bolts with the flywheels. He said he would recommend it to bean counters and hopefully they would be included with future flywheels.

We put it together and this time, using my tool, when we had the engine in the cradle, we verified that we got clutch disengagement. It disengaged with 14 turns on the tool, so that's about .700" of travel. Put everything back together, fired the car, and checked for proper clutch operation and everything was fine. We had it in and running before 4:00 pm and buttoned up and on the trailer by 6:00 pm.

I'm not sure if Alan will take the flywheel back. It has never been run, but there's loctite on the threads (which we can clean out with a tap) and a few minor surface scratches. Hopefully I can get some credit for it, I guess we'll find out. He agreed to accept it and look at it.

The moral to the story is two fold. First, if you're doing a swap, get all your parts (clutch, flywheel, pressure plate) from the same place. Only they know the dimensions they built them to before you ever get them in your hot little hands and once you have them, it can be a PITA to get things straightened out. Second, measure everything, check everything, and most important, before it all goes back in the car, make damn sure the clutch will release. If you don't, you might suffer the same aggravations I did.

John Stricker

I have great respect for Alan (CHRF) but even though he says he has sold flywheels to Fiero owners, his flywheel HAS to have .100 removed from the friction face to work in the Fiero. it doesn't matter what clutch you use, if it's made for a Fiero application it will not work with the stock CHRF flywheel. I have one in my own Northstar Fiero, and I know of what I speak . I'm quite satisfied with my CHRF flywheel, but it WOULD NOT WORK WITHOUT TRIMMING THE FACE .100 . I've told Alan this myself, but he still doesn't seem to understand.

Glad you got your car up and running John. good job !!!

Russ544

quote Originally posted by Russ544: I have great respect for Alan (CHRF) but even though he says he has sold flywheels to Fiero owners, his flywheel HAS to have .100 removed from the friction face to work in the Fiero. it doesn't matter what clutch you use, if it's made for a Fiero application it will not work with the stock CHRF flywheel. I have one in my own Northstar Fiero, and I know of what I speak . I'm quite satisfied with my CHRF flywheel, but it WOULD NOT WORK WITHOUT TRIMMING THE FACE .100 . I've told Alan this myself, but he still doesn't seem to understand. Glad you got your car up and running John. good job !!! Russ544

I thought you mentioned that before, Russ, and is one reason I checked it. (if not you, then somebody else ran into it, Will maybe??) FWIW, for about the same price Alan charges for the steel flywheel, the guys at Spec will sell you an aluminum one. In my case, I wanted one for faster revving, but may not be the best in all applications.

I was pleasantly surprised at how nice and even the solid disc stage 4 engages. I wouldn't hestitate in a moment to use it in a street car now that I've driven it. If it don't have the springs in the hub, they can't break and come out.

John Stricker

edited to add:

I would not have been satisfied unless I could have taken at least .180 off the flywheel and I was going to run into issues with the disc hub hitting the flywheel even worse than the spec and/or more issues with the rivets dogging to the flywheel bolts if I did that. I also wasn't comfortable with taking that much material off the flywheel at all, that's a chunk of metal to remove.

[This message has been edited by jstricker (edited 08-14-2008).]

thats why I am also using a solid hub ..no springs to worry about ..I have to get my headers finished before I can get mine running and I still have to get the proper flywheel bolts with thin heads ..not sure where to get them though. Does CHRF have them? I am running a spec aluminum flywheel

quote Originally posted by Erik: thats why I am also using a solid hub ..no springs to worry about ..I have to get my headers finished before I can get mine running and I still have to get the proper flywheel bolts with thin heads ..not sure where to get them though. Does CHRF have them? I am running a spec aluminum flywheel

AAA Metric Supply in Denver If they don't have it, you don't need it. Just don't get the allen headed capscrews or you could have the same issues I did, Erik. They can get you either 12.9 or 10.9. If they can get you the shallow head flywheel bolts you can use their conical washers (that would be good). If you have to use normal thickness bolt heads then you'd better just loctite them and leave the washers off. The clearances are that close. IIRC mine were 25mm long?? I'd have to go back and look to be sure. That time is all a blur to me now.......

John Stricker

quote Originally posted by jstricker: Because the Northstar flexplate bolts weren't long enough, I ordered a set of 12.9 grade bolts from AAA Metric in Denver and got them on the way. The were socket headed allen capscrews.

Haha... As soon as I read that, I knew this was coming:

quote I found some marks on the rivets on the clutch hub and some matching marks on the heads of the allen headed capscrews that I used for flywheel bolts. What was happening was that when the disc was against the flywheel, the rivets were dogging themselves to the bolt heads, making it a solid unit. I had to release the clutch almost twice as far as it should have gone to get enough clearance for the rivets to "pop" over the capscrews.

I've had similar experiences with Getrag ring gear bolts (12.9's with VERY specific length and head thickness requirements/limitations)

quote The flywheel got here first and I called Alan telling him I was concerned about how deep the flywheel was sitting into the bellhousing. He told me he had several running in the Fieros. (His flywheels, BTW, are made by McLeod). The clutch arrived and I started to bolt things up.

I take the things that Alan says with a grain of salt. His primary market is hot rodders and sand rail builders who are so used to whipping up everything from scratch that they probably don't even notice having to modify anything as long as it's close when it comes out of the box. He also started in the RWD market, which uses MUCH thicker flywheels. It's probably easy to get that number wrong. He also doesn't seem to be too worried about products he doesn't sell many of, which includes ANYTHING to do with Fieros.

It's great that you figured it out. Let us know how bad this puppy ends up being!

Have Russ build you a throttle/cylinder intake so the engine will idle.

[This message has been edited by Will (edited 08-15-2008).]

I got one of the first spec aluminum flywheels made for the N*/Fiero setup. It came with thin head bolts of the correct length. I guess they stopped shipping the bolts with the flywheels since then.

quote Originally posted by jstricker: I would not have been satisfied unless I could have taken at least .180 off the flywheel and I was going to run into issues with the disc hub hitting the flywheel even worse than the spec and/or more issues with the rivets dogging to the flywheel bolts if I did that. I also wasn't comfortable with taking that much material off the flywheel at all, that's a chunk of metal to remove.

You'd be cutting 1/2 the thickness of the ring gear off in order to get .180 removed from the face. I actually don't remember the exact measurments I took when I set mine up, but I do recall that in order to get the exact measurments of the stock fiero it was something like .115 or .120 . whatever it was, it would have meant cutting right up to the edge of the ring gear. there is a slight lip on the flywheel that the ring gear locates on, and that would have been gone with a "full" cut so I settled on .100 . this left a small lip to support the ring gear as well as making the clutch operate correctly. there might be a better way, but it has worked very well for me..... then again, modifing parts is just part of my normal fabrication process. I've never seen a part that was built the way I would build it .

Russ544

quote Originally posted by Will: I take the things that Alan says with a grain of salt. His primary market is hot rodders and sand rail builders who are so used to whipping up everything from scratch that they probably don't even notice having to modify anything as long as it's close when it comes out of the box. He also started in the RWD market, which uses MUCH thicker flywheels. It's probably easy to get that number wrong. He also doesn't seem to be too worried about products he doesn't sell many of, which includes ANYTHING to do with Fieros.

My sentiments exactly, Will. Alan is a sharp guy, but not particularly open to new ideas or thoughts that his products might not be the be all and end all. I'm not saying that he's particularly arrogant in his attitude, in fact he's very pleasant to talk to, it's just that when he comes out with a product after he's developed it, as far as he's concerned it's over.

quote Originally posted by Will: It's great that you figured it out. Let us know how bad this puppy ends up being!

I'm hoping for something over 350 hp at the wheels. If I get close to that, I'll be happy. There is no doubt when it's running that this is no street engine. Whatever the results, I'll post the numbers to the forum and maybe some audio and video of one or two of the pulls. The car is loud. Very loud. Even with a pair of race mufflers. I'll probably have to quiet it down some this winter.

quote Originally posted by Will: Have Russ build you a throttle/cylinder intake so the engine will idle.

I think I can improve the idle quite a bit with tuning yet. My AFR is pretty rich at idle at 12.5:1 and if I kill the fuel pump briefly, it helps the idle a lot (but just for a second or so). I'm going to work on that part of it before it goes on the dyno and if I can ever get Tunerpro to save a valid log file. All do respect to Russ, and I really admire what he's doing (not to mention it's sexy as hell) It's NEVER going to idle below 1,000 rpm, IMHO, because of the 300° cams, but I didn't expect it to. We'll see. (This is half the fun anyway, isn't it??)

John Stricker

quote Originally posted by jstricker: I think I can improve the idle quite a bit with tuning yet. My AFR is pretty rich at idle at 12.5:1 and if I kill the fuel pump briefly, it helps the idle a lot (but just for a second or so). I'm going to work on that part of it before it goes on the dyno and if I can ever get Tunerpro to save a valid log file. All do respect to Russ, and I really admire what he's doing (not to mention it's sexy as hell) It's NEVER going to idle below 1,000 rpm, IMHO, because of the 300° cams, but I didn't expect it to. We'll see. (This is half the fun anyway, isn't it??) John Stricker

Good tuning obviously helps idle a LOT, but a throttle per cylinder setup isolates each cylinder's intake pull from the next cylinder's intake pull. Interaction with the next cylinder's pull is the primary cause of loping at idle. Once that's gone, even big cams can idle.

I'm very curious about what kind of powerband the 300 degree cams are going to give you. I've been considering 288's for my engine. Are you using the stock manifolds or did you build headers?

What class are you racing this car in with what sanctioning body?

We are using the stock rear manifolds on both the front and rear. The primary pipes on that are just a bit (but not enough to matter) longer and it has 2.5" outlets so we could run 2.5" pipes on both sides with true duals. I just ran out of time to try and build any headers for it and this is about the next best thing.

The individual throttle bodies could help, you're right. If out of synch, they can also hurt. It's all tuning either way. To be honest, I'm not all that concerned about the idle because the car doesn't sit and idle in traffic and things like that for very long, and it WILL idle, just with a lope and at about 1400 rpm. At the moment.

We built the car primarily for Open Road Racing because it's pretty much a "run what ya brung" kind of deal. We also autocrossed the car before the Northstar in the Prepared class with SCCA, but it will have to go in EM to autocross now. It will probably also need more muffler or they'll run me off. Other than that, track days and just have fun with. To run in SCCA classes it would probably end up in something like GT-2, I would guess, but I haven't looked at the rulebook that closely. (It wouldn't be competitive there).

John Stricker

quote Originally posted by Will: Good tuning obviously helps idle a LOT, but a throttle per cylinder setup isolates each cylinder's intake pull from the next cylinder's intake pull. Interaction with the next cylinder's pull is the primary cause of loping at idle. Once that's gone, even big cams can idle. I'm very curious about what kind of powerband the 300 degree cams are going to give you. I've been considering 288's for my engine. Are you using the stock manifolds or did you build headers? What class are you racing this car in with what sanctioning body?

Good to hear about the stage 4 solid hub clutch. I got one for my Ecotec and was wondering what it may be like.

------------------
yellow 88 GT, not stock
white 88 notchie, 4 banger

quote Originally posted by jstricker: We are using the stock rear manifolds on both the front and rear. The primary pipes on that are just a bit (but not enough to matter) longer and it has 2.5" outlets so we could run 2.5" pipes on both sides with true duals. I just ran out of time to try and build any headers for it and this is about the next best thing. The individual throttle bodies could help, you're right. If out of synch, they can also hurt. It's all tuning either way. To be honest, I'm not all that concerned about the idle because the car doesn't sit and idle in traffic and things like that for very long, and it WILL idle, just with a lope and at about 1400 rpm. At the moment. We built the car primarily for Open Road Racing because it's pretty much a "run what ya brung" kind of deal. We also autocrossed the car before the Northstar in the Prepared class with SCCA, but it will have to go in EM to autocross now. It will probably also need more muffler or they'll run me off. Other than that, track days and just have fun with. To run in SCCA classes it would probably end up in something like GT-2, I would guess, but I haven't looked at the rulebook that closely. (It wouldn't be competitive there). John Stricker

Ok, open road challenges. I've heard of Sonoran and Silver State. That's something I could sink my teeth into. What others are there?

I'm running dual front manifolds to help the packaging, but the 2" outlets are somewhat restrictive.

Will,

The Nevada Open Road Classic is in the spring and it put on by the same people that do Silver States. The Sand Hills Open Road Challenge is in Arnold, NE, and is in August. The Big Bear Open Road Challenge is down at Fort Stockton, TX and is also in the spring but they've been having difficulties getting approval to close the state highways they run on.

I'm involved in getting a new one up and running at Lovelock, NV (about an hour North of Reno) this coming Memorial day. It will have 2 days of open road racing and one or two days of straight line racing out on their airport. It is called the Pershing County Speedweek.

Most or all of these are back west, but there are some straight line runs on the east coast. One that comes to mind is the Maxton Mile in North or South Carolina (I think North, but I can't remember now).

My goal for next year is to win the 100 mph class (or at least place) and run at or near 140 in the 1/2 mile. We can run the mile, now that we have a full cage, but we can't compete with the big boys that run well over 210 mph at that distance. If time and money permits, I'd also like to go to the Big Bear event down in TX, but getting a car ready to run two 24 hours of Lemons races I'm not sure that's going to happen.

John Stricker

quote Originally posted by Will: Ok, open road challenges. I've heard of Sonoran and Silver State. That's something I could sink my teeth into. What others are there? I'm running dual front manifolds to help the packaging, but the 2" outlets are somewhat restrictive.