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LS4 / F40 swap - fieroguru by fieroguru
Started on: 12-13-2010 01:34 PM
Replies: 1757 (138166 views)
Last post by: fieroguru on 09-16-2021 08:54 PM
fieroguru
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Report this Post03-09-2021 06:10 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Just roughing in the general concept digitally... several aspects of this will still change some - like I don't know for sure that my caliper will clear the arm (it is flipped 180 from stock 88 position) and the upper bracket is just a block right now and its exact geometry isn't figured out at the moment.

[This message has been edited by fieroguru (edited 03-09-2021).]

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Report this Post03-09-2021 12:23 PM Click Here to See the Profile for qwikgtaClick Here to Email qwikgtaSend a Private Message to qwikgtaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Will:


What's this part from?


I was looking for "ball joint extensions" and those popped up. They seem to be used by the import crowd for lowing or correcting a lowered suspension
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Report this Post03-09-2021 12:38 PM Click Here to See the Profile for qwikgtaClick Here to Email qwikgtaSend a Private Message to qwikgtaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:
As with anything, there are hundreds of possible solutions. Where things differ are the constraints people put on their solution. Since I am an 88 only guy, I want my solution to use as many stock 88 suspension pickup points on the cradle as possible.


No I get it, I love that your an 88 guy, your vision and capability will allow all of us to benefit. I was only offering up my observation and a possible solution. As you have said, others have already used different parts, or modified Fiero parts to make this work. I've only recently looked into the 87 stuff after picking up this 87 GT, the 84-87 stuff is new to me having owned 88's for so long. Looking forward to seeing how your new parts evolve.

Rob
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Report this Post03-21-2021 06:05 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Fought the plasma table for about 4 hrs today... the cut program would randomly lock up mid cut... ended up being a bad USB connection.

Eventually I was able to cut out the wheel bearing flange for the C5 wheel bearing as well as the complimentary brake bracket for my 13" rotors and 88 calipers.



I am always looking for stuff and going down rabbit holes so it seems... I came across this wheel flange and bearing. It is a solid flange, so redrilling it for 2 other patterns would not be any issue. The bearing is larger than the opening in the 88 front knuckle, but not by much. If the 88 front knuckle is cast steel vs. cast iron, then this becomes a real possibility to weld on the needed bearings supports and make this one work.




I also had the opportunity to pick up one of these:

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Report this Post03-22-2021 09:32 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:
I am always looking for stuff and going down rabbit holes so it seems... I came across this wheel flange and bearing. It is a solid flange, so redrilling it for 2 other patterns would not be any issue. The bearing is larger than the opening in the 88 front knuckle, but not by much. If the 88 front knuckle is cast steel vs. cast iron, then this becomes a real possibility to weld on the needed bearings supports and make this one work.





What's the application?

If you're looking at things like that, then BMW's system of having a fixed spindle with a similar sealed DRACBB pressed into the hub would work. The spindle would just bolt onto the '88 knuckle where the factory hub bolts on.
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Report this Post04-02-2021 11:26 PM Click Here to See the Profile for qwikgtaClick Here to Email qwikgtaSend a Private Message to qwikgtaEdit/Delete MessageReply w/QuoteDirect Link to This Post
I know its not the same thing, but when I saw this I thought of your design.

https://www.elephantracing....stable-spring-plate/




Rob

[This message has been edited by qwikgta (edited 04-03-2021).]

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Report this Post04-04-2021 02:25 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
I also went ahead and purchased the Race Traction Control setup and waiting for it to arrive from oversees. It should help keep the Fiero pointed in the direction of travel.


Picked up a set of 97-02 C5 rear axles for the CV and fitment to the C5 wheel bearing.


Been doing a lot of pondering the custom rear suspension and basically exploring dual paths. The 3 link setup similar to the C3 or making a dropped rear upright that accepts the stock 88 lateral & trailing links, the C5 wheel bearing and a 92-92 Camaro strut (still available in fully adjustable rebound and compression). Both paths will use the same basic method for housing/supporting the wheel bearing and connecting it to either the tailing arm or dropped knuckle. Here is what I have so far for enclosing the wheel bearing and creating some good attachment points for either solution. I do need to shorten the spaces a little more so the bolt heads will fully clear the CV.






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Report this Post04-06-2021 03:48 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
Going to C7 bearings lets you step up to 33 spline outer CVs, which were also used with a large number of GM FWD cars. Parts are more widely available and as a side effect, you get a choice between 5x115 and 5x4.75" bearings.
The C7 bearings are plug/play for C5 bearings, except for integral ABS sensor. The C7 bearings do not have built in ABS.

Either way, you can ultimately play with a set of these:
https://www.driveshaftshop....-porsche-930-cv-2210

or

https://www.driveshaftshop....108mm-porsche-930-cv

[This message has been edited by Will (edited 04-06-2021).]

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Report this Post04-06-2021 06:21 PM Click Here to See the Profile for TrintenSend a Private Message to TrintenEdit/Delete MessageReply w/QuoteDirect Link to This Post
Question on this topic, as I'll be getting custom length axles from the drive shaft shop with C5 CVs on it... what is the difference/improvement of having a "Porsche style" inner and outer CV? I haven't had great luck in finding information on this that made sense.
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Report this Post04-18-2021 09:02 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Been playing around with some rear knuckle designs...
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Report this Post04-24-2021 08:25 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Trinten:

Question on this topic, as I'll be getting custom length axles from the drive shaft shop with C5 CVs on it... what is the difference/improvement of having a "Porsche style" inner and outer CV? I haven't had great luck in finding information on this that made sense.


It's a strong and available CV joint. It's also very strong for the package size. I think the designers grew it too large to fit into the same 94mm six bolt circle, so they made the bolt circle uneven to be three clusters of two in order to have space to put the legs of a larger tripod.
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Report this Post04-25-2021 01:19 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Been playing around with the strut version with some 16ga. It is basically a 1 1/2" dropped knuckle with the C5 wheel bearing and setup for my 13" rotors, but I only adjusted the strut attachment point by 3/4" to keep clearance between the base of the strut and the CV.






I have also been playing around with the rear arm solution as well:


[This message has been edited by fieroguru (edited 04-25-2021).]

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Report this Post04-27-2021 09:17 PM Click Here to See the Profile for qwikgtaClick Here to Email qwikgtaSend a Private Message to qwikgtaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Please, take my money!!! if you ever decide to make those strut spindles, i'll take 2 sets. Not worried about the price.

Rob
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Report this Post05-02-2021 06:18 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Nothing to see here... just a puny 5.3 with some factory cast iron manifolds killing any power potential... that is what I want everyone to think with my stealth turbo install (and kept the factory truck)!











With the engine back in the Fiero, I can finish up the exhaust to the tips and see if I can use my cutout at the end of a Helmholtz tube. I can also work on the cold side as well as play some more with the rear suspension/knuckles.

Seeing the engine back in the engine bay always helps keep me motivated!

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Report this Post05-02-2021 11:16 PM Click Here to See the Profile for Bob2112Send a Private Message to Bob2112Edit/Delete MessageReply w/QuoteDirect Link to This Post
Looks so great - can't wait to see this one done.
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Report this Post05-23-2021 12:05 AM Click Here to See the Profile for Rickady88GTClick Here to Email Rickady88GTSend a Private Message to Rickady88GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I came up with a functional solution to the fuel rail mounts. At least I think they will work for me. Let me know if you came up with a solution. I can post a picture or two of my solution.

[This message has been edited by Rickady88GT (edited 05-23-2021).]

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Report this Post05-24-2021 08:10 PM Click Here to See the Profile for FrankedSend a Private Message to FrankedEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hey Paul, would you consider selling that cradle in a weld it yourself kit form?
I'll buy one today!!
Frank
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Report this Post05-26-2021 07:18 PM Click Here to See the Profile for BreakkoutSend a Private Message to BreakkoutEdit/Delete MessageReply w/QuoteDirect Link to This Post
Just started really considering a fiero project a d went on the webz and see this.. I'm scared
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Report this Post05-26-2021 08:20 PM Click Here to See the Profile for TrintenSend a Private Message to TrintenEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Breakkout:

Just started really considering a fiero project a d went on the webz and see this.. I'm scared


Many Fiero projects, including engine/transmission swaps, do not go to FieroGuru level. Out of the literal thousands of members on here, and likely hundreds of documented swaps, I can only (off-hand) think of 5.... 6? People that put this much work (or money for other people to do this much work) into their swaps.

Well I will be the last to say any swap is 'easy', there are swaps that someone who is patient, well organized, and has slightly-more-than-average tools, can do themselves. Don't let the awesomeness that is FieroGuru scare you off! Instead I get inspired... and then ask to buy things from him.
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Report this Post05-30-2021 06:29 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Rickady88GT:
I came up with a functional solution to the fuel rail mounts. At least I think they will work for me. Let me know if you came up with a solution. I can post a picture or two of my solution.


I haven't played with the intake in a while. I took advantage of a black friday sale on this intake last year for $330 with free shipping... The latest update is it will ship in June (yes, backordered for 7 months!). Not sure if I will use it, but it was interesting and figured I could always sell it if I didn't like it.


 
quote
Originally posted by Franked:
Hey Paul, would you consider selling that cradle in a weld it yourself kit form?


Nope. I doubt the cradle will ever make its way to the products I sell - mainly due to time to make it and price point to make it worth my time.
My day job keeps me busy (70hrs/week ave for 2021 so far) and any new product really needs to be something I design, have all the machining and cutting done for me, then I just assemble and sell.

 
quote
Originally posted by Breakkout:
Just started really considering a fiero project a d went on the webz and see this.. I'm scared


Don't get scared off by my swaps... I am a mechanical engineer, machinist and metal fabricator, like to challenge my skills, and have been playing with Fieros about 25 years. I am also a little OCD and want the finished swap to look a certain way. This means I do things that most people think are crazy, and for the most part they are crazy... but it keeps my mind sharp, allows me to refine my skills, as well as build out my fabrication tools/equipment.

A lot has changed since I pioneered the LS4/F40 swap 10 years ago and had the 2nd running LS4/F40 8 years ago. The number of completed swaps is likely pushing 20+ at this point and I have assisted 75+ people with their LS4/F40 swaps as well as about 10+ LS4 based swaps in atypical applications (jeeps, rock crawlers, sand rails. etc).

One of my early customers has branched out into doing LS4/F40 swaps, so most parts for the swap are becoming more readily available. It is a fun swap, but definitely not an inexpensive one.

 
quote
Originally posted by Trinten:
Many Fiero projects, including engine/transmission swaps, do not go to FieroGuru level. Out of the literal thousands of members on here, and likely hundreds of documented swaps, I can only (off-hand) think of 5.... 6? People that put this much work (or money for other people to do this much work) into their swaps.

Well I will be the last to say any swap is 'easy', there are swaps that someone who is patient, well organized, and has slightly-more-than-average tools, can do themselves. Don't let the awesomeness that is FieroGuru scare you off! Instead I get inspired... and then ask to buy things from him.


Thanks Vince!
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Report this Post06-27-2021 03:37 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Just got back from our first family vacation since 2014... definitely needed that...

During the "relax" portions of the vacation, I was in research mode... Since I am going down the route of building new uprights, based on C5 wheel bearings for strength/obsolescence issues, I was struggling with keeping the 88 Fiero calipers. While I have plenty of spares and like their appearance and lightness, there will be a day that they will be much harder to get. So while I am doing a complete clean sheet design, I might as well base it off an OEM caliper from 2010+.

Truth be told, I have been on the hunt for an ideal caliper to replace the 88 Fiero Calipers for several years. I wanted something OEM, visually appealing, multi-piston, and as close to the stock 88 piston area as possible. Here are just a few I have played with.


For comparison, Stock 88 Fiero:


Ideal Brembo: Newer than 2010, 4 piston, 110% larger piston area, and lighter than the 88 Fiero caliper! I think this is the one!


I learned several years back when I picked up the RX7 caliper that my 13" brake rotors won't work with the quad piston calipers as the hat is much too large to clear the piston bores on the outboard side. The Ideal Brembo has the same issue.



Knowing I had to get back on the hunt for another rotor, I detailed out the specs for a lot more rotors (file now has 375+ rotor part #s and critical dimensions). I haven't spent much time looking for a rotor as I haven't drawn out the Ideal Brembo in CAD to know the ideal rotor depth and diameter, but I once I have that, I can sort the spreadsheet and start narrowing down the process. I would like the new rotor to have an OEM drum brake parking brake setup so I can use the same caliper front/rear.

Some older updates:

My traction control setup came in awhile back. It is a race based traction control with a knob adjustable rate of slip from 0 to 100% slip to help dial it how intrusive I want it to be. It works by intercepting and blocking the injector signals to individual cylinders to cut power to maintain traction. It is built for race cars, so I might need to add some stickers to the Fiero to make it work.



A while back I posted the new head unit that will mount where the Aux gauges go. I also want to build a new sub box to mount an 8 to 10" sub up under the dash. Knowing this, I spent a lot of time looking at amp options. I am not an audiophile... but wanted a 5 channel amp to boost the sound. This one was compact, relatively light weight, and the right dimensions to mount in the dash pocket area.



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Report this Post06-27-2021 08:21 PM Click Here to See the Profile for Rickady88GTClick Here to Email Rickady88GTSend a Private Message to Rickady88GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
This is very cool, thanks
Some day I will start on my project again. I need Brembo brakes for a Solsice suspension with larger disks.

[This message has been edited by Rickady88GT (edited 06-27-2021).]

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Report this Post06-30-2021 06:59 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:

I would like the new rotor to have an OEM drum brake parking brake setup so I can use the same caliper front/rear.



The issue that becomes quickly apparent is the very same that you noted above... the drum-in-hat rotors are designed to be rear rotors in front engine vehicles. This means they're designed for relatively small calipers and thus do not have a large enough annulus to work with large & high performance front calipers.

The Mitsubishi Evo VII parking brake (In the US a Diamante uses the same parts) has a drum ID of 6.614 which is small enough to fit inside a 8x7.62" rotor bolt circle. The Mitsu P-Brake uses a monolithic shoe like the C5 & C6 Corvettes, and the Corvette expander even operates the Mitsubishi shoe correctly. The Corvette and Diamante even use the same P-Brake hardware parts kit, per RockAuto.

I designed a backing plate and expander block to use the Corvette/Diamante expander parts with the Diamante shoe, although the shoe has to be bored a smidge to fit around the mounting flange of a Corvette wheel bearing. I'm using C7 Corvette bearings which accept 33 spline outers, just like the ones from '90's & '00's FWD GM large cars, like the Pontiac TranSport & U-body minivans.

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Report this Post07-02-2021 02:32 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:

Since I am going down the route of building new uprights, based on C5 wheel bearings for strength/obsolescence issues,


Dude, it's almost like you don't keep up with my build thread

33 spline C7 wheel bearings + U-body minivan axles: https://www.fiero.nl/forum/.../000121-22.html#p879
C5 & non-ZO6 C6 bearings are 30 spline, so this trick for cheap CVs doesn't work on those. These or similar 33 spline CV's were also used on basically all of GM's large FWD cars (Like the W-bodies with L67's) and the front ends of 4WD pickups until 2010.

Mitsubishi parking brake shoe & C6 Corvette expander: https://www.fiero.nl/forum/.../000121-23.html#p888

Boring the shoe: https://www.fiero.nl/forum/.../000121-23.html#p891

More P-Brake prototyping: https://www.fiero.nl/forum/.../000121-23.html#p899 + https://www.fiero.nl/forum/.../000121-23.html#p900

Custom hats for 2 piece rotors: https://www.fiero.nl/forum/.../000121-23.html#p902
This had duplicates the rotor offset of the hat Wilwood uses in their 140-8032-DR C6 Z51 rear kit.

Test fitting with a rotor: https://www.fiero.nl/forum/.../000121-23.html#p912

Using the small diameter Mitsu brake shoe lets me use rotors with a 7.62" bolt circle. Wilwood's 160-2900/1 pair and 160-5844. Prices have come up (Thanks, Biden ) but both of these options are still under $100/corner. I like cheap consumables on a car that sees track time.


And here's my take on fabbed hub carriers: https://www.fiero.nl/forum/.../000121-24.html#p951
The 5/16" thick P-Brake backing plate shown in posts linked above would sandwich under the C7 wheel bearing when bolted to this knuckle. That provides the right spacing to use rotors up to 1.25" thick. Also, the entire C5/6 parking brake assembly will bolt directly to this fabbed knuckle and a C6 Z51 rear brake kit will then bolt on... although to use the 1" thick rotor with the kit linked above would probably still require a 1/16"-1/8" thick spacer between the knuckle and the bearing.

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Report this Post07-02-2021 08:06 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Will:
Dude, it's almost like you don't keep up with my build thread


I am very familiar with everything in your build thread... we are both very capable/creative, and working toward similar goals, but we approach things from different perspectives and will have different solutions.

C5 wheel bearings are 30 spline, same as the G6 axles used for the F40 and when I looked into it they come with the ABS sensor being easier to tie into my traction control. The difference between C5 or C7 is really a matter of preferences, both will be significant strength upgrades vs. stock 88 Fiero front/rear wheel bearings. The G6 interchange and ABS connectivity definitely biased me towards the C5.

At this point I am not looking to run 2 piece rotors (I like cheap OEM replacement rotors) , which means I don't have to find a drum based parking brake small enough to fit inside the 2 piece rotor hat diameter. I don't even have to find a rotor with the right OD, thickness, mounting depth, and parking brake drum... I just need to find a relatively compact parking brake drum setup, cut the rotor surface away and use it as an insert to whatever rotor best fits the Brembos.

Your fabricated knuckle design is for the 84-87, mine is focused on the 88s and while both will accomplish the same end result, the path, # of parts, fabrication process to make them, and the overall finished look will likely be very different between the two.

Differences keep things interesting and enjoyable.

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Report this Post07-03-2021 09:42 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Started detailing out the calipers:
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Report this Post07-04-2021 09:01 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
More playing around detailing out the caliper, wheel bearings and the Kappa platform rotors that won't work (I have had these detailed for a long time). But based on this layout and some measurements, I sorted the rotor list and picked out the first 3 rotors to buy and try.



Taking a closer look at the specs of 375 rotors in my list, I found something really interesting... an OEM 13+" rotor that only weights 14.5 lbs. They cost about $250 per rotor (vs. the $15 - $60 of the 3 purchased today), but I don't think the ID of the hat will clear the 5.73" oversized flange on the C5 wheel bearing (same OD as 88 Fiero front wheel flange).
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Report this Post07-04-2021 09:51 PM Click Here to See the Profile for TrintenSend a Private Message to TrintenEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm sorry if I missed this somewhere in your thread already -- where did you find a resource spreadsheet/database with all of the rotor dimensions and specs? That's kind of a cool thing. I'd love to get a copy of it!

There are a lot of things that Mike and I have tried where I couldn't find exact dimensions, so I would just be like "well... it doesn't cost too much. I'll buy one so we can check it out."
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Report this Post07-04-2021 11:44 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Trinten:

I'm sorry if I missed this somewhere in your thread already -- where did you find a resource spreadsheet/database with all of the rotor dimensions and specs? That's kind of a cool thing. I'd love to get a copy of it!

There are a lot of things that Mike and I have tried where I couldn't find exact dimensions, so I would just be like "well... it doesn't cost too much. I'll buy one so we can check it out."


The short answer is I took the time to build it.

The list with dimensions doesn't exist, or at least I haven't found it. What is available from one supplier are these spec sheets (pic below - stock 88 rotor FWIW). I took the time to find and record these numbers 375 times and counting. Even with those numbers, there is still some variation in fitment, so the only way to know for sure is to buy samples and test, which is why there are about 30 different rotors (and about 10 calipers) collecting dust around the shop. I started doing this back in 2010 and have continued to add to it as I make the time to find more rotors. Every year, new rotors become available, which might work where other rotors have not... yet.



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Report this Post07-05-2021 09:26 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:

I am very familiar with everything in your build thread... we are both very capable/creative, and working toward similar goals, but we approach things from different perspectives and will have different solutions.

C5 wheel bearings are 30 spline, same as the G6 axles used for the F40 and when I looked into it they come with the ABS sensor being easier to tie into my traction control. The difference between C5 or C7 is really a matter of preferences, both will be significant strength upgrades vs. stock 88 Fiero front/rear wheel bearings. The G6 interchange and ABS connectivity definitely biased me towards the C5.

At this point I am not looking to run 2 piece rotors (I like cheap OEM replacement rotors) , which means I don't have to find a drum based parking brake small enough to fit inside the 2 piece rotor hat diameter. I don't even have to find a rotor with the right OD, thickness, mounting depth, and parking brake drum... I just need to find a relatively compact parking brake drum setup, cut the rotor surface away and use it as an insert to whatever rotor best fits the Brembos.

Your fabricated knuckle design is for the 84-87, mine is focused on the 88s and while both will accomplish the same end result, the path, # of parts, fabrication process to make them, and the overall finished look will likely be very different between the two.

Differences keep things interesting and enjoyable.


Just trying to be collaborative, man

You've seen DSS's Corvette output flanges, right? https://driveshaftshop.com/...s/corvette-cv-axles/

I went to the small diamter P-brake drum because the particular rotors I picked--that is, the cheap ones!--use the 8x7.62 bolt circle. It might make sense for your goals just to stick with Corvette-based brakes. if you're not constrained like I was, then the P-Brake that makes the most sense is the unit that was used with the C5/C6 hubs. C5 fronts and C6 Z51 rear brakes put together make a relatively square brake setup.
I can tell you that the BMW E30 & Chrysler PT Cruiser P-Brake hardware does not fit around the Corvette hub and the small Subaru P-Brake shoes are too wide for the Corvette flange offset.

I'll have a version of my knuckles for '88's as well. I've done 90% of the modeling that will make the common structure work with both.

 
quote
Originally posted by fieroguru:

Taking a closer look at the specs of 375 rotors in my list, I found something really interesting... an OEM 13+" rotor that only weights 14.5 lbs. They cost about $250 per rotor (vs. the $15 - $60 of the 3 purchased today), but I don't think the ID of the hat will clear the 5.73" oversized flange on the C5 wheel bearing (same OD as 88 Fiero front wheel flange).


*THAT* is why I went with the 2 piece rotors... Sure there might be something OEM out there that fits well enough, but it's from a weird application, is expensive to replace and the supply chain is thin. OEM drum-in-hat rear rotors are designed for front engine cars. Yadda yadda.
Hats are a one-time expense, recurring costs can be kept in check with the right rotor selection, and I end up with exactly what I want.

I know you like the quest for that one perfect part, though.
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Report this Post07-05-2021 04:16 PM Click Here to See the Profile for TrintenSend a Private Message to TrintenEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:


The short answer is I took the time to build it.




Holy... my hats off to your dedication, man. I would not be able to stay focused enough to do that.
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Report this Post07-11-2021 06:32 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
So far I have one front rotor that will work with the front and custom upright.

The largest limit of clearance is the nose of the lower a-arm. This mimics the front suspension bottomed out, which is where the chance for interference is the greatest and we have adequate clearance w/o any work to the A-arm.


Then it was a matter of checking fitment of the caliper. You can see here that the calipers needs to go closer to the rotor, but there is interference to the stock 88 caliper mounting ears on the stock upright. Not an issue since I will not be using the stock upright, I can simply design the new caliper ears into the new uprights.




The other two rotors were a bust.
One the brake hat was too large and interfered with the caliper body about 1/8" - close, but won't work.
One didn't even get that far as the rotor pilot ID was too small for the C5 wheel bearing...

Time to do a little more scrubbing of the rotor list...

[This message has been edited by fieroguru (edited 07-11-2021).]

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Report this Post07-11-2021 08:58 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
Snazzy... directional vanes too. Originally a drum-in-hat rear?
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Report this Post08-01-2021 07:59 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
In mid-September my LS4/F40 Fiero will have been off the road for 2 years... My day job continues to keep me busy 60-70 hrs a week and 2021 has been the best year for Fieroguru Performance LLC so far, so the time demands for filling customer orders has increased significantly as well. The downside of both is my personal car isn't going to be back on the road anytime soon unless I make some hard decisions...

Fieroguru Performance LLC will effectively be closed for the months of August and September so I can focus what limited free time I have to getting my car much closer to running. It wasn't an easy decision to make, but is the right thing so I can stay focused on what I love doing with Fieros and get my car back on the road sooner.

This weekend was one of those 2 steps forward, 1 step back kind of weekend. The ideal brembo calipers were supposed to have 42mm & 28mm pistons based on some documentation online. I noticed a while back that they didn't "look" right and the exposed lip isn't the actual piston OD, so I pulled 2 pistons from all the brembo calipers just to check them all. The pistons in the ideal brembo I was planning to use are 32mm & 28mm... which would result in a 75% reduction in clamp force and an absolute no-go.


I had planned to cut some parts for the knuckles and brake brackets, but that is delayed until I find another caliper.

I think it took about 8 hrs of research and documenting a bunch of other quad piston brembo calipers before I found (and verified via OEM specifications documentation) an OEM quad piston brembo caliper with 34mm pistons. 2x34mm will have the exact same clamp force as the stock 88 caliper, which makes it a perfect replacement. They are more expensive, but will be more common than the black one. I purchased a brand new one for 275 shipped and it should be here this coming week for review.

I did get to play around with some 1/8" steel and the front knuckle design (notice the caliper bracket is missing for now). For the ball joint studs to clear the CV, I did need to spread the top/bottom ball joint locations by 1/2", specifically I lowered the bottom on which effectively makes it a 1/2" dropped knuckle. This knuckle design is an experiment to see if I can make the wheel bearing attachment not rely on the flange being welded to the rest of the knuckle support structure. It also makes the lower ball joint flange wider to help spread any loads, and the sides will be all boxed in. I made it with 1/8" to start so t would be stiff enough I could make the ball joint locations and start playing around with the placement of the tie rod. The current tie rod arms are about 1/4" lower than stock as I plan to run more than the 6 degrees caster. As more caster is dialed in, it raises the tie rod attachment point relative to the upper/lower ball joints and messes with the bump steer. By lowering them, I can dial in more caster, and keep them closer to the stock height (which still might not be right give the additional 1/2" in overall knuckle height.

The intention is for all the gaps between the inboard and outboard pieces to be the same gap all around, so I need to tweak a few of the bends to get the gaps and final ball joint boss placements dialed in.









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Report this Post08-07-2021 05:06 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Somedays are better than others and today was a pretty good day.

Caliper Q (direct bolt on quad piston caliper for 88 knuckle) came in and one of my failure rotors (11 1/4") was a very, very close fit to it. Based on the mockup with it, I found another rotor to try and have it on order.








Then I shifted my focus to the work on the front upright. Bending the 1/8" in specific radius a precise manner wasn't working great and after I had looked over the design some, I wanted to alter the design some as well. So I reworked the design to widen the material between the bearing and ball joints, changed the larger radius bents to sharper bends, added in relief slots to help with the bending (and bend alignment) and even added the top and lower ball joint locations. Overall I am really pleased with the new outboard piece that was made out of 3/16".

I have had this press brake for a few years, but this was the first time I have put it to actual use. Made easy work on most of the bends.


This is my other one that also comes in handy from time to time:


Here are several comparisons to the stock 88 front:




Different bearing offset accounted for, so the wheel flange to the lower ball joint remains the same:


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Report this Post08-09-2021 07:43 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
I guess we could call this take 3... getting closer, but still some details to work out.




To give a better visual of what the end knuckle will look like, I wrapped it in painters tape. The lower ball joint ear will carry the majority of the load on the front end, so there will be some triangulation flanges on the sides (also shown poorly with the the tape).





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Report this Post08-10-2021 07:36 PM Click Here to See the Profile for qwikgtaClick Here to Email qwikgtaSend a Private Message to qwikgtaEdit/Delete MessageReply w/QuoteDirect Link to This Post
i'll take two sets, please take my money.

Rob

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Report this Post08-12-2021 07:32 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
It is hard to believe it took almost 8 months to go from this:
 
quote
Originally posted by fieroguru:
Over the last couple of months, I have been working with a local CNC shop to start making several of my parts...and we have finished the redesign of the LS water manifold.


To this...

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Report this Post08-12-2021 08:08 PM Click Here to See the Profile for TrintenSend a Private Message to TrintenEdit/Delete MessageReply w/QuoteDirect Link to This Post
It looks good man... I really hope you aren't about to say they'll be ready for sale in a week or two... I took one of your recommendations from a few months ago and got one of those alternatives!
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Report this Post08-13-2021 12:37 AM Click Here to See the Profile for Bob2112Send a Private Message to Bob2112Edit/Delete MessageReply w/QuoteDirect Link to This Post
Oh man oh man oh man. I can't wait until these are ready to buy.
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