Firstly, some of my general thoughts regarding brake upgrades on Fieros:
Lets not forget the obvious. Get sticky tires.
Leave the factory combination valve unmodified, or gut the factory proportioning valve and install an aftermarket adjustable valve.
A proportioning valve is not a band-aid for poorly sized brake components - it is merely a fine-tuning tool. Brake parts should be sized within the "acceptable range".
Use identical calipers, or calipers with similar piston areas (maybe a touch larger up front) on all four corners.
Use discs of the same diameter all around.
Note that those with Grand AM brakes all around seem very satisfied...
While I'm suggesting that the front and rear brakes should produce roughly equal brake torque per unit line pressure, I also believe that the power dissipation capability should be front-biased, to equally heat up (and thus equally fade) the front and rear brakes on repeated threshold braking. Thicker front discs and thinner rear discs would be a good thing in my book.
Don't go crazy with the rotor diameter. If you have enough mechanical advantage to stop comfortably, then there's no sense in increasing the rotor's moment of inertia. Also, think about the wheels you'll need to clear your choice of brakes.
Proper bias (which depends on the available friction) is key to short stopping distance. Don't confuse gain with stopping distance. If you're capable of locking up the tires, more gain isn't going to shorten stopping distance.
The only way you can hope to improve stopping distance over stock is to optimize the bias better to fully utilize the available friction if it wasn't already optimal. Also, if the "big brakes" are easier to modulate, it will be easier for the driver to make short stops.
A video-game mushy Honda Accord style (over-boosted) pedal makes brake modulation difficult. Lower gain, but firm pedal facilitates modulation and short stops (tires also play a role). Don't over-boost...
Stick with glycol-based, rather than silicone-based brake fluid. I'll leave it at that, as this could be an entire discussion on its own!
For 88 Fiero owners looking for a brake upgrade, I suggest you go with the C4 Corvette 12" rotor upgrade, which retains stock hydraulics, simply moving the factory calipers outwards using brackets. In my opinion, that is hands-down the best overall compromise of cost/weight/performance for a typical Fiero owner.
For us 84-87 Fiero owners, this is a guide on how to install LeBaron brakes (one of the best options for 84-87 Fieros in my opinion) using the 10 degree rotated brackets, with my opinions on the best compromises of cost/weight/performance. Modify the instructions as you see fit. (if you feel comfortable modifying the instructions, you know who you are.)
Possible ways of doing the swap differently:
Use front LeBaron rotors with different thickness caliper bracket spacers and hubcentric rings Different bore master cylinder Different calipers "Hockey stick" parking brake cable brackets Use of different pad compounds front and rear No parking brake Play around with the spacer thicknesses specified by Walt Zettner - consider that you're bolting stuff onto a rough cast surface, so your mileage may vary...
4 x rear caliper bracket spacer, ~0.060" thick 1/2" I.D. washer is fine; I just bought a bunch of washers and picked the four that were closest to 0.060"
4 x 90-94 Chrysler LeBaron GTC 11-1/4" diameter ventilated rear discs
10 x DORMAN 610-323 extra-long lug studs Also listed as the stock wheel stud for a 2006 Hummer H3
[This message has been edited by pmbrunelle (edited 06-19-2010).]
92-94 Chevrolet Blazer MC with 1-1/8" bore (watch out, Blazers were also available with 1-1/4" master cylinders)
The Blazer MC is essentially a large-bore version of the factory Fiero MC. I used this one. The only caveat is that the Blazer MC's brake fluid reservoir is taller than the Fiero's reservoir, which would interfere with the sunroof glass if stowed away in the front trunk. The solution is to swap the Fiero reservoir onto the Blazer MC. The reservoir is simply pressed into the MC - no hidden fasteners. Prying with a screwdriver may be necessary.
67-80 Chevrolet Corvette MC with 1-1/8" bore (watch out, Corvettes also came with 3/4" MCs)
Alternatively, the Corvette MC can also be used. It lacks the quick-take-up feature (large bore during low pressure operation) of the Fiero/Blazer MC, which may lead to a slightly lower pedal. I have no experience with this MC. If you don't have a good Fiero donor reservoir to use on a Blazer MC, this might be a good choice. Some people prefer the styling of this MC.
I happen to like the pedal feel with the factory booster. The pedal is firm, easy to modulate, and not mushy. Maybe if I ever drive an exotic car I'll change my mind about my Fiero's pedal feel...
Dual-diaphragm Vacuum booster with more gain than the factory booster. I've already stated my opinion regarding over-sized brake boosters in the "general thoughts" section of this thread. Keep in mind that it won't reduce stopping distance, but if you prefer the reduced pedal effort, or desire a contemporary Honda Accord-esque feel then go for it.
[This message has been edited by pmbrunelle (edited 05-29-2010).]
I don't know if a wheel spacer in conjunction with the factory spare will provide adequate caliper clearance and retain sufficient lug thread engagement.
Originally posted by Fieroseverywhere: I never posted my fix for the spare tire size. I ended up finding a F-body spare in a 16". T135/60-16. It's probably the
max size that can fit under the hood and it still close.
So to summarize...
-96 subaru spare. -Open center bore .1mm. -Mounted F-body tire to suby wheel. (WS6 firebird to be exact) ... -Minor trimming of the lip in the front compartment helped with the increased width of the new tire. It fit before trimming
but fit much easier afterwards.
[This message has been edited by pmbrunelle (edited 05-29-2010).]
The challenge is to find rear calipers of a large enough piston area to complement the front calipers that have a parking brake provision. Some options:
These are heavy cast iron, but at least they're relatively cheap. The bleeders point up-side down, in my installation anyway. The 2-1/4" bore size is "acceptable", but probably a touch on the big side.
2-1/2" bore. Too big if installed on a car with 2-1/8" rears. They are ridiculously cheap though.
Due to the lack of similarly sized rear calipers with parking brakes, I would only consider installing these on all four corners, in an installation that is forgoes parking brake functionality. Their large bore also makes for a higher gain than the others (not necessarily a bad thing).
[This message has been edited by pmbrunelle (edited 05-29-2010).]
This is a typical rear brake installation, with Seville calipers:
Remove rear factory brakes. Drill existing holes and tap M12 x 1.5 mm threads.
Grind off unnecessary "ears" previously used for factory calipers. You will not be able to revert back to stock brakes without another set of knuckles.
Bolt on rear caliper brackets, using a 1/2" washer as a spacer and 25 mm long Class 10.9 bolts. Torque to 83 lb-ft.
Notice that for the "typical" rotated bracket, you'll need to trim a corner of each rear pad to prevent an interference with the knuckle. This will become obvious as you attempt to install the calipers. The trimming isn't critical, personally, I prefer to leave more rather than less clearance.
The rear rotors will need to have their bores opened up slightly or else they will not slip over the hub. I used a dremel...
The rear brakes, complete. Factory Fiero brake cables, hoses, and banjo bolts are used.
[This message has been edited by pmbrunelle (edited 06-19-2010).]
This is a typical front brake installation, with 2-1/4" Blazer-style calipers:
Remove front factory brakes.
Remove the machined braking surface from the Fiero rotor/hub combo. I had a machine shop do this as I didn't have a lathe at the time. I also had the machine shop make me the front spacers.
Replace factory lug studs for extra-long ones.
Clean up the existing caliper bracket mounting holes with an M12 x 1.5 mm tap.
Bolt on front caliper brackets, using spacers and 40 mm long Class 10.9 bolts. Torque to 83 lb-ft.
The front brakes, complete. Factory Fiero brake hoses and banjo bolts are used.
The LeBaron rotor bore is *slightly* larger than the hub, so there is a small amount of play. The anal are encouraged to find a better way. I don't consider the play to be an issue: https://www.fiero.nl/forum/Forum2/HTML/107709.html
[This message has been edited by pmbrunelle (edited 06-19-2010).]
This is more or less complete for now. If there are any innaccuracies, let me know...
The pictures are a bit funky because I took them while putting back my suspension together while reassembling my car after a suspension rebuild. I actually did the brake modification last fall.
[This message has been edited by pmbrunelle (edited 06-19-2010).]
Looks like a great write up for those looking to do this swap. I wish I could remember what front calipers I went with. I'm pretty sure the camaro ones...
If I recall, I *think* some people claim to have had problems with the stock brake lines bolting up the new calipers. Did you have to grind away any materal on the caliper?
Looks like a great write up for those looking to do this swap. I wish I could remember what front calipers I went with. I'm pretty sure the camaro ones...
If I recall, I *think* some people claim to have had problems with the stock brake lines bolting up the new calipers. Did you have to grind away any materal on the caliper?
When I was using 2.5" Seville/4WD Blazer calipers, I didn't have to grind away any material, and the banjo fitting was still appropriately clocked.
Issues with the use of stock hoses definitely arise with the use of 2.5" Camaro calipers.
quote
Originally posted by BrewCheese:
Did you just paint your whole rotor? Will the part where the brake pad contacts the rotor just burn/scrap off?
Jason
I spray-painted the rotor hat for cosmetic purposes, but some overspray got on the braking surface. I don't bother to mask rotors when I paint them.
The braking surface was wiped clean by the pad within several kilometers of city driving. Until the paint is wiped off, the brakes will feel weird.
-Patrick
[This message has been edited by pmbrunelle (edited 06-19-2010).]
Very well done post. The lebaron swap is also possible for the 88s as well using different brackets.While I agree the corvette rotors with the stock hydraulics is an excellent upgrade suitable for most 88 Fiero drivers, your pad options are not as varied as they are for the camaro/seville calipers so it depends on your intended useage of the car as to which route is best. You can move bias front to rear or vice versa quite easily with different pad compounds and adjustable prop valve settings to optimize your setup for your intended useage. This may be a band-aid fix in your opinion but it does work and is quite effective.
Most importantly TEST any brake mods you make in a safe controled enviroment, your life and that of others could be dependant upon it
------------------ 88blackchopv8
[This message has been edited by av8fiero (edited 06-21-2010).]
So if you use the Cadillac Rear Calipers on the rear, you can use your OEM E-brake cable / Brake lines without and real modification?
Yes, the Cadillac Seville rear calipers can be used with factory Fiero brake cables and hoses. Note that the Cadillac calipers will be upside-down, so the bleeders will be located on the bottom, so the calipers will have to be unbolted and placed right-side-up for bleeding.
I agree, it's good of you to put this together. I love how 13" rotors look behind 17" wheels, and I love how 13" rotors have the ability to shed more heat, more quickly, than 12". But on a street Fiero, on real-world tires, I must concede that 13s are overkill. In heavy but high-speed traffic, on Dunlop StarSpec tires, then 13s might be a little more appropriate. But the difference in unsprung weight can be felt. Especially carving a rough canyon road, with cracked and patched pavement. And Fieros really aren't very heavy. I love multi-piston calipers, because of the idea of more clamp per psi applied hydraulically. But loving the idea of it doesn't make it right for my commuting, or my canyon-carving. I'm sure I wouldn't want to combine them with huge rotors and the S-10 booster for real-world usage. More, smaller pistons cool back off faster than one huge piston, too.
Linear Motion Shaft Collars Set Screw Shaft Collars
Bore 1/2" OD 1" Width 7/16"
Throw away the set screws before use.
These brakes are enough for my needs, but maybe I just don't drive aggressively enough. The car isn't tracked. That said, in a week or so once I have my Fiero running again, it will be with a set of Bridgestone RE-11s.
where do you find the bolt size you are suggesting i cant find anything other than m12 1.75 threading. in a grade 10.9 ... since i will be having to tap my knuckles cant i just use SAE fine thread grade 8 bolts instead.... Also i installed new rear brake hubs and i found the bolts at home depot and they are grade 8;8 are these gonna be too weak?
A couple small notes on the use of the subaru spare wheel with F-body tire.
First: Credit goes to Fierosound on the subaru wheel. He pointed me in the right direction.
Second: This setup will not work if you plan to stow your sunroof glass under the hood with the larger spare. The spare is the max that will fit and takes up the small amount of room needed for the sunroof glass.
Third: I found out later that the spacer is not needed. There was an issue with my caliper brackets that was corrected. Thats why I only had the issue in the front.
Lastly: If you have a front mount battery the suby spare will not hold it in place. Another solution will need to be found. I just built a simple mounting strap.
Nice write up pmbrunelle. I'm with you on all points!
[This message has been edited by Fieroseverywhere (edited 08-08-2011).]
The front knuckles are already tapped for M12 x 1.5 stock, so you're pretty much stuck with that size unless you want to drill oversize and retap. If you're using oversize fasteners, then get spacers with a hole large enough to accommodate them. If you find a source for M12 x 1.5 bolts, then it's a no-brainer to get matching bolts for the rear. But if you wish, 7/16" bolts, 1" long can be used in the back, preferably fine thread.
As far as the hub-to-knuckle bolts go, you'll probably be okay, but don't shoot me if you end up handicapped. But if you're going to order from Fastenal though, might as well order the correct hub bolts also... It's never really advisable to downgrade a part like that from its original specification.
Yep, I can't stow away the sunroof when I carry the Subaru spare (mine has a Jeep tire on it I think, I don't remember the size). I don't know if the stock Fiero spare would fit over these brakes with the help of a ~5 mm spacer. That would solve the sunroof storage issue.
If someone wants to argue with me about the safety of a spare tire installed with a spacer such that the centerbore is no longer touching the shoulder on the hub, please keep this brake modification thread clean. Concerns about thread engagement with a spacer are legitimate and to be verified before use.
[This message has been edited by pmbrunelle (edited 08-08-2011).]
So I just picked up a set of silver ASA AR1 wheels and Bridgestone Potenza RE-11 tires from tirerack. The quality of these wheels leaves something to be desired, but they look good when you're not looking too carefully.
17x8 rear, 35 mm offset. Good size for 245/40R17
17x7 front, 48 mm offset - to compensate for the spacer effect of the LeBaron rotor hats. Reduce scrub radius and thus kickback over bumps, steering effort.. Good size for 205/45R17
The rear lug nuts go on fine.
It appears that the position of the "virtual cone vertex" of the lug nut seat is further inboard than with my old MSR Style 113 wheels. Result - the closed-end lug nuts bottom out on the DORMAN 610-323 lug studs I suggested.
You may want to evaluate your situation before jumping straight to the extra-long studs I mentioned.
Tomorrow when it's bright, I'll see if I revert to the stock DORMAN 610-254, or maybe I'll need to trim the 610-323s.
I'm trimming down the 610-323s to an under head length of 44 mm.
This will give the same stud protrusion as in the rear. (which doesn't have issues with closed-end lugs bottoming)
In my case, I'm getting ~9 turns before the lug nuts are touching the wheel. At 1.5 mm pitch, that's ~13.5 mm of thread engagement. It's above the classic recommendation of having thread engagement length equal to the diameter of the fastener.
Anyway, so a mechanical engineer I trust tells me, often 2-3 threads is all that is needed to develop the full tensile strength of a fastener.
[This message has been edited by pmbrunelle (edited 08-13-2011).]
Thanks for putting the work into making this thread. I know it's going to come in handy!
Also, as another Caliper option, it appears Wilwood does have some calipers that work when using the 10 degree brackets - still waiting to hear if they'll clear the GT wheels. Here's a link to the thread of the guy using them.
A request - would it be too much to ask if you could post pics of your car with your wheels on?
I ask because I *thought* I knew what offset I was going to need, then I saw your post with the ones you used, which were fairly different from mine, so I'd like to see how yours sit. I'd hate to get new wheels and find out that things aren't going to fit/clear because I messed up with how the swap changed things!
[This message has been edited by Trinten (edited 05-17-2012).]
I've been doing modified Fieros for a lot of years and I've had the Lebaron brakes for a few years on my 87 GT. I've run them hard and a lot. In my opinion, they are little improvement over the stock brakes althought mine are cross drilled, the calipers are powdercoated, and the rotors are vented so they look great - great for show but not for go. In addition, the Lebaron ebrake setup sucks. I've never been able to adjust the ebrake to where it would hold the car on the slightest incline. That is my opinion and my experience with the lebaron swap. I'm currently switching to the C4 12" brake swap. Hopefully they will fill the bill. If not, they'll look even better anyway.
I've been seriously considering using these rotors:
as opposed to the lebaron rotors:
The size difference isn't much, The lebaron rotors are 11.27" and the Subaru Forester rotors are 11.56" The offset on the rotor is a bit deeper, don't know if thats ok till it's tried. They weigh the same, but the Forester rotors are thicker. I found that the Cadillac calipers, with the pistons completely retracted, and with new pads measure 1.2" between the friction surfaces, but they can only be used practically to about 1" thick. The Lebaron rotors are only .870 thick, and the Forester rotors are .945" thick, so there is a slight advantage there. The snout on the Fiero's bearing is the same size as the both of the rotors too. They look like a perfect fit. They vent from the inside, as opposed to the lebaron rotors venting from the outside. If these rotors work, it's a nice alternative, but it might rule out factory 15" wheels, as it would push the calipers out .129" and that might be the point of scraping the wheel... or maybe not?
They are more money but they are somewhat a better rotor. I just wonder if they would fit over the hub's hat OD. These look a bit small in that dimension.
Quick mounting bolt question... I see people recommend drilling + tapping the rear knuckles to M12x1.5. Is this purely because the M11x1.5 thread bolts are hard to find? Anyone think using M11x1.5 bolts would be a problem? GM LS flywheel / flexplate bolts are M11x1.5, and come in 1" (25mm) and .880" (22.3mm) lengths, which should fit the rear perfectly. Summit (and I'm sure others) carry a few brands of these bolts (ex: http://www.summitracing.com...1mm%20x%201.5&dds=1) I can't find a grade on the GM ones but shouldn't they be at least 10.9 rated being flywheel bolts? Sure, they're $6 a piece if you get them full-price, but at least you don't have to worry about messing up the knuckle threads... And it seems an M12x1.5 tap from McMaster runs almost $40 anyway..
------------------ Bob Williams (still) working on the 3800 swap... It'll drive some day!
[This message has been edited by Riceburner98 (edited 07-09-2012).]
Did some digging, 10.9 bolts are rated @ 130,000 psi yield strength. Looks like the ARP Pro-Series flexplate (244-2901) bolts are rated @ 200,000 psi yield strength.. 12-point heads, should look good even though nobody will see them. Guess I'll give them a try for the rears anyway.
I figured out my "stupid-me" error in why I thought the fronts were M11x1.5 - you have to remove the factory caliper bracket! LOL The front bracket holes are M11x1.5, but are bolted on to the front spindles with M12x1.5 bolts... Mine were so rusted I thought they were one piece and didn't separate them! Whoops. That said, the factory M12x1.5 bolts that held the factory brackets to the knuckles seem just about right for the job, so I'm either going to re-use them or get Fastenal P/N 11114837 if they're in stock when I stop in on the way down to work on the car.. --> Haha! Ordered the bolts from Fastenal, picked them up and went to use them a couple days later - they put the wrong P/N bolts (M12x1.75x40) in the bag, with the right P/N! Awesome.. I re-used the factory bolts, and they seem fine..
[This message has been edited by Riceburner98 (edited 07-13-2012).]
Question for you brake gurus. I have an '87 GT which is shortly getting an '88 cradle rear swap. I have a complete 11-1/4" LeBaron upgrade kit but am wondering if anyone has done this swap on '88's as everything I am seeing is for '87 and earlier. Does the same rear bracket work?
Edit: I just answered my own question. Let me ask the question in a different way. What is the difference in the rear brackets between the '87 and '88's?
Dr. W.
------------------ Is your Fastback GT's trunk seal shot? My Gen III replacement GT trunk seals with solid molded corners are now in production. $95 + $15 flat rate shipping to the US (contact me for international shipping rates) or buy two and pay only a single shipping rate! More info can be found here GT Trunk Seal Project
[This message has been edited by infinitewill (edited 08-10-2012).]
I know this is an old post but since it`s relevant here`s my question. To those who are running the LeBaron upgrade with aftermarket wheels since the shoulder on the front is so small are you using hub centric rings. If so, do you know what mm they happen to be. I think the wheels I have are 74.1 bore but I don`t know the LeBaron hub size.
A couple small notes on the use of the subaru spare wheel with F-body tire. First: Credit goes to Fierosound on the subaru wheel. He pointed me in the right direction.
Second: This setup will not work if you plan to stow your sunroof glass under the hood with the larger spare. The spare is the max that will fit and takes up the small amount of room needed for the sunroof glass.
The smallest 16" spare TIRE you can find is a T115/70D16. This fits exactly the same as stock. I needed this for my GT because of that huge Mcintosh 6-channel amp I have up front.
I know this thread is a decade old, but THANK YOU. I'm in the middle of a Lebaron / Cadillac brake swap to the rear of my 87GT that has the Held Motorsports tubular A-Arms on it, your post with the awesome pics, helped me make sense of why my install was different than the other peoples swaps.
I used similar rear calipers to you, but I believe they came from a 79 Olds. I had no interference between the pad and knuckle which I assume is due to the held kit changing things around.
David aka Capt Fiero.
------------------ 857GT Part 85GT Part 87GT , 5spd Custom Exhaust. MS3 Gold Box 6.0 LS Turbo.
Price Drop!!! Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front. For Sale $3750 USD SOLD.
[This message has been edited by Capt Fiero (edited 05-08-2021).]
And it seems an M12x1.5 tap from McMaster runs almost $40 anyway..
