1. Caliper upgrade for the 88 Fieros - mainly looking for a caliper with the same or slightly larger piston bore, that has the same bolt pattern for mounting. 2. Brake upgrade for the 88s that will fit under the stock 88 15" wheels.
I think what I have figured out so far is really cool and wanting some feedback as to the potential market.
First up is a new caliper option that I will call Caliper X. A stock 88 front caliper is on the right, Caliper X is on the left in both pictures.
Caliper X is very similar to the 88 Fiero caliper and has some cool key features. 1. Looks very similar to the stock 88 caliper - for a stealthy upgrade. 2. Same mounting pattern, so it will bolt directly to the stock 88 knuckle. 3. Same caliper bridge bolt pattern, so Fiero bridge will bolt to Caliper X and Caliper X's bridge will bolt to the stock 88 caliper. 4. Caliper bridge is about 1/8" wider, so this caliper with accept rotors thicker than 20mm. 5. Available with caliper piston diameters of 48mm (stock 88 Fiero) or 52mm (17% increase in clamp pressure and should be a small enough change to keep the stock brake master). 6. Caliper piston and bridge placement are shifted away from the rotor, which gives them 9% more braking leverage, and allows an 11 1/8" larger rotor to fit under it (stock 88 is 10.4") 7. Caliper body for the piston is cast iron.
So caliper X has the potential to improve braking 9% through increased leverage as well as 17% (with 52mm piston) with increased clamp pressure by 17%, allow for a larger than stock rotor to improve heat dissipation and fade resistance, and can be installed under the stock 88 15" front wheel.
88 Fiero caliper mounted on an 88 Fiero rotor:
Caliper X mounted on an 88 Fiero rotor:
I am still sorting out the rotor options that will fit under Caliper X w/o a caliper bracket. I am trying to find the best compromise between, largest OD, lightest weight, and availability/cost. The 11 1/8" rotor shown below is a strong contender. It fits perfectly, is readily available and weights 12 lbs (stock 88 rotor is about 11 lbs). I have 4 more rotors to check fitment on before narrowing down the selection, but this one certainly works!
Caliper X mounted on an 11 1/8" rotor and inside an 88 Fiero front wheel:
I still need to develop the concentric rings and find the proper brake hoses as the hose connections are slightly different, but most of the hard work is done.
Unfortunately, this is front only option at the moment, as this caliper doesn't have a parking brake setup. We could think of it as the grand am style upgrade for the 88s, where it is plug & play using stock parts w/o needing any caliper brackets.
I might be able to pair the Caliper X front kit with an other 88 stock wheel kit I was working on, but stopped because it wouldn't fit under the stock 88 front wheel (but did fit the 15" rear). I have found a rotor slightly smaller than 11 3/4" that can be made to work with the 88 Fiero 15". It will need a caliper bracket, concentric ring, and either a small wheel spacer (1/16" would be plenty), or clearance the head of the brake line bolt. This kit would provide about 19% increase in braking leverage and allow reusing the stock 88 rear caliper for parking brake function. This would end up being a slightly less overall improvement vs. the front using 52mm Caliper X , but it could be an option for a more closely balanced approach.
Thoughts and feedback?
[This message has been edited by fieroguru (edited 11-22-2018).]
I like it! I have your 13" brakes on my 3800sc GT and will be reusing the old 12" set-up it replaced on another Fiero and like them with the bigger aftermarket wheels. I also have a bone stock '88 GT and Formula that I plan on keeping stock. I would be very interested in improved braking on these cars while keeping the stock wheels.
Hi Paul, this would be a great addition to the Targa car as I need to keep the 15" wheels now due to needing the taller sidewall tires for the brutal road conditions. Even just a larger front kit would be advantageous for heat dissipation for the tight in-town sections. Please soldier on with this development!
Interesting, but a brake kit is uninteresting if one of its components is referred to only as "Caliper X".
Vendors go out of business, so I would never buy a brake kit having a caliper that can only be purchased from the kit vendor. Ditto for the rotors.
A known second source (hence divulging the identity of the caliper) is a requirement for any wise consumer.
As far as the parking brake, what about a drum-in-hat setup? After my present engine project, I'll be trying to make the drum parking brake work on my LeBaron discs, in order to get a good parking brake and 2.5" bore calipers all around.
Other than the LeBaron disc commonly used on Fieros, there are other Chryslers having the same drum-in-hat, but having different outer disc portions. Maybe one of those would fit within the diameter requirement of Caliper X.
Interesting, but a brake kit is uninteresting if one of its components is referred to only as "Caliper X".
Vendors go out of business, so I would never buy a brake kit having a caliper that can only be purchased from the kit vendor. Ditto for the rotors.
A known second source (hence divulging the identity of the caliper) is a requirement for any wise consumer.
In the event I bring this kit to the market, anyone who purchases the kit, will get the application information for all parts, so they will be able to source replacement parts from where ever they wish, when ever they need to.
[This message has been edited by fieroguru (edited 11-23-2018).]
In the event I bring this kit to the market, anyone who purchases the kit, will get the application information for all parts, so they will be able to source replacement parts from where ever they wish, when ever they need to.
So long as it's a caliper that isn't an odd duck (obscure unit) that will go into discontinued status in short order, it sounds like a good option if you want to retain stock wheels. QUESTION: has anyone considered machining the stock caliper for a larger piston? It doesn't allow for a larger rotor, I know.
Interesting, especially since 'X' is made in France, a bit closer to me than the States! I suspect the cost will probably be cheaper from you than our froggy neighbours though. I have been looking into different calipers as I'm not terribly impressed with the various Wildwood calipers I've been trying to fit up. Will uou be selling just the calipers on their own? I have Ali hats with a variety of rotors, the wider bridge would give me better options.
Originally posted by sourmash: So long as it's a caliper that isn't an odd duck (obscure unit) that will go into discontinued status in short order, it sounds like a good option if you want to retain stock wheels. QUESTION: has anyone considered machining the stock caliper for a larger piston? It doesn't allow for a larger rotor, I know.
The production numbers for this application far exceed those of the 88 Fiero. Additionally, there is a newer version from a later model application that uses the pad abutment brackets like everyone is switching to, so that will further expand the caliper availability.
The OD of the piston bore housing for the 88 Fiero caliper is about 64mm. So with a 48mm bore, the wall thickness is 8mm. Going up to the 52 mm bore would reduce it to 6mm. With 100 lbs force on the brake pedal, the line pressure will be about 1500 psi. Add the S10 booster and will be nearly 1700 psi. For reference, the bore housing on Caliper X is 68mm, so it has the same 8mm wall thickness, but is cast iron.
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Originally posted by Iain: Will you be selling just the calipers on their own? I have Ali hats with a variety of rotors, the wider bridge would give me better options.
I will likely have various levels of kits with one of them being just the calipers.
My 2nd car has the C4 rotors, using the 88 calipers, and a knockoff of Jon Lagler's (dogbone shaped) brackets. That was the kit that I was going to install on my gray car, before I got your 13" kit. If I didn't already have what I do, this new kit would be a definite consideration. (FWIW, I particularly don't like the 88 brackets that are currently available elsewhere, due to the way that the calipers are offset, upward - for several reasons. But that's just one man's opinion.)
[This message has been edited by Raydar (edited 11-24-2018).]
On the front of my car I use a Lebarron front rotor instead of the commonly used rear rotor. This rotor is slightly lighter, still about 11" in diameter but of course it is 5X100 bolt pattern like a Fiero. It does not have a parking brake hat like the rear rotor does. There are 2 minor drawbacks that are easy to deal with: You have to shim your mounting bracket to get the rotor centred in the caliper and the centre hole is slightly smaller than the fiero hub. This is easily fixed with a cylinder hone fitted with some rough sandpaper resulting in a perfect fit.
When I ordered this rotor it took a couple of tries to get the right one. There are 4 different rotors used on Lebarron's because some models had 14" wheels and were equipped with smaller rotors.
[This message has been edited by wftb (edited 11-23-2018).]
On the front of my car I use a Lebarron front rotor instead of the commonly used rear rotor. This rotor is slightly lighter, still about 11" in diameter but of course it is 5X100 bolt pattern like a Fiero. It does not have a parking brake hat like the rear rotor does. There are 2 minor drawbacks that are easy to deal with: You have to shim your mounting bracket to get the rotor centred in the caliper and the centre hole is slightly smaller than the fiero hub. This is easily fixed with a cylinder hone fitted with some rough sandpaper resulting in a perfect fit.
When I ordered this rotor it took a couple of tries to get the right one. There are 4 different rotors used on Lebarron's because some models had 14" wheels and were equipped with smaller rotors.
The LeBaron front rotors won't fit over the 88 Front wheel flange. If you use the rear rotors, you have to machine the backside of the rotor, and machine the face of the caliper bridge... so no Lebaron rotors are in the mix.
Only modifications I want for the rotors is drilling the 5x100 pattern.
Would the calipers work on your 13" kit without additional modification to utilize the bigger pistons and better leverage of caliper X?
The short answer is no. The body of Caliper X is taller than the stock 88 caliper, so when you install Caliper X, you also need to install a larger rotor to keep the brake pad on the rotor surface. The larger rotor may or may not use the same concentric rings, but that is a relatively minor issue to resolve.
In theory, you could install Caliper X on the existing 13" brackets and run a 13.8" rotor. The issue is that 13" is the maximum diameter rotor that will fit under the caliper, clear the edges of the caliper bridge, and keep the pad on the rotor. Go larger and the edge of the brake pad will hang off the end of the rotor due to the shallower curvature of the larger rotor. I have identified a 13.8 rotor application that would likely fit the 88 Fiero suspension, but I am almost certain the brake pad will be off the edge when used with the stock 88 caliper.
People with 12" brake kits using the 88 Fiero caliper (84-87 Fieros & 88 Fiero) could use Caliper X to install a roughly 12.8" rotor while using the same brackets. There are 2 rotors I have identified as potentials for this application. The challenge here is the various designs of the 12" brackets. There is roughly 1/8" freedom of caliper placement between the rotor clearing the caliper bridges, and keeping the brake pad on the rotor. So some might work and some might not, it all depends on who designed the bracket and how they determined optimal placement.
There are also 14", 14.4" and 15.5" rotors I have identified that would likely clear the 88 suspension components and are thin enough for Caliper X to clamp, but are too large to keep the pad on the rotor surface.
It is a 1999+ caliper from the same OEM as Caliper X and bolts directly to the 88 FIero knuckle. It is 52mm (17% increase in clamp pressure and will allow a slightly larger rotor.
I've kept an eye on brakes of some cars for possible conversions, havent physically tried putting parts together but
Ford Transit 250 (2017ish) rear calipers have integrated parking brake, a 54mm piston, and are cheap. They sit on a 12.1" solid rotor -that being not compatible in any way. The Caliper bracket width for the rotor is 18mm, so a somewhat thin rotor would have to be utilized.
A 2010 WRX STI rear rotor is 12.4" at 20mm thick. Could be turned down to 18 (its minimum thickness), or maybe transit caliper bracket opened up slightly.
2007 GTI rear rotor is 11.26" at 12mm wide. Unsure if the Transit caliper piston can make up that 6mm distance, and if the caliper would sit ok on a rotor 3/4" smaller diameter.
Just out loud thinking and this could all be useless information
Definitely keeping an eye on this one. The brakes on my stock Formula won't lock up no matter how hard I put my foot in it... I've replaced both master and slave cylinders, brake hoses, lines, and bled and bled.
Originally posted by blackrams: I applaud and appreciate your efforts to continue to improve these fun little rides. What you do, you do so well. Keep it up.
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Originally posted by qwikgta: Like, Like, Like. Thanks from all of us "88" folks out here.
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Originally posted by Notorio: What Rob said. Great little research project you have going there for the benefit of the Community.
Thanks guys!
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Originally posted by anaverin: does this mean your close to a new kit?
I wouldn't say I am close, just still looking for possibilities as I R&D for my personal car finds new options for consideration. I would love to find a simple bolt on upgrade that didn't require any brackets or other custom parts... which is really stupid from a business perspective...
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Originally posted by GTFiero1: I've kept an eye on brakes of some cars for possible conversions, havent physically tried putting parts together but
Ford Transit 250 (2017ish) rear calipers have integrated parking brake, a 54mm piston, and are cheap. They sit on a 12.1" solid rotor -that being not compatible in any way. The Caliper bracket width for the rotor is 18mm, so a somewhat thin rotor would have to be utilized.
A 2010 WRX STI rear rotor is 12.4" at 20mm thick. Could be turned down to 18 (its minimum thickness), or maybe transit caliper bracket opened up slightly.
2007 GTI rear rotor is 11.26" at 12mm wide. Unsure if the Transit caliper piston can make up that 6mm distance, and if the caliper would sit ok on a rotor 3/4" smaller diameter.
Just out loud thinking and this could all be useless information
54mm is a 27% increase in piston area, which is large enough to require changing the master cylinder. There are a lot of calipers in the 48, 51 and 52mm range that would be a better starting point.
The WRX STI rear rotor is 10mm too deep to clear the nose of the lower a-arm on the 88s in the front. Might work OK in the rear.
GTI rotor almost certainly will not fit over the 88 front wheel flange and also not a fan of going from vented to solid.
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Originally posted by Sundowner:
Definitely keeping an eye on this one. The brakes on my stock Formula won't lock up no matter how hard I put my foot in it... I've replaced both master and slave cylinders, brake hoses, lines, and bled and bled.
That isn't normal. You should focus on fixing this issue before making any major changes to components Have you measured the vacuum assist at the booster - a vacuum leak would make for a harder pedal and greatly reduced braking. Also, if the pad gap in the rear isn't properly adjusted, you will have a soft pedal and poor braking.
While I was doing some research on quad piston calipers for my car, I came across this one.
The mounting bolt pattern is very close to the stock 88 caliper bolt spacing, so it should bolt directly to the 88 knuckle. Not sure if there is an acceptable rotor to work with it yet, or if that rotor would have to be larger or smaller than stock 88 size. It has quad 38mm pistons, so it would result in 25.3% increase in clamp force, but might require a master cylinder change. I ordered one just to check it out further...
Originally posted by fieroguru: I still need to develop the concentric rings and find the proper brake hoses as the hose connections are slightly different, but most of the hard work is done.
Unfortunately, this is front only option at the moment, as this caliper doesn't have a parking brake setup. We could think of it as the grand am style upgrade for the 88s, where it is plug & play using stock parts w/o needing any caliper brackets.
I might be able to pair the Caliper X front kit with an other 88 stock wheel kit I was working on, but stopped because it wouldn't fit under the stock 88 front wheel (but did fit the 15" rear). I have found a rotor slightly smaller than 11 3/4" that can be made to work with the 88 Fiero 15". It will need a caliper bracket, concentric ring, and either a small wheel spacer (1/16" would be plenty), or clearance the head of the brake line bolt. This kit would provide about 19% increase in braking leverage and allow reusing the stock 88 rear caliper for parking brake function. This would end up being a slightly less overall improvement vs. the front using 52mm Caliper X , but it could be an option for a more closely balanced approach.
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Originally posted by fieroguru:
In the event I bring this kit to the market, anyone who purchases the kit, will get the application information for all parts, so they will be able to source replacement parts from where ever they wish, when ever they need to.
Any update to this product Mr. Guru? I'm interested in a front only kit but prefer a front and rear kit. I like the idea of using 88 rear calipers to keep the e-brake functionality. I like your 13" kit but want the option of being able to put the stock wheels back on for winter, storage, paint, construction time. Would this kit be possible with fancy slotted and zinc rotors?
Originally posted by 87_special: Any update to this product Mr. Guru? I'm interested in a front only kit but prefer a front and rear kit. I like the idea of using 88 rear calipers to keep the e-brake functionality. I like your 13" kit but want the option of being able to put the stock wheels back on for winter, storage, paint, construction time. Would this kit be possible with fancy slotted and zinc rotors?
I haven't played around with Caliper X in a while.
This thread is 3 years old with only 24 posts and 8 of them are mine. That is the community speaking very loudly that there isn't much interest in an brake upgrade that fits under stock 15" wheels. I am OK with this reality, as I have plenty of other fun things to focus on. I have continued to find what I think are cool caliper options that might work for brake kit that fits under the 15" wheels, but most of these discoveries are byproducts of research for other goals.
I haven't given up on it, just way back on the back burner until something about it motivates me to bring it closer to the forefront.
I haven't played around with Caliper X in a while.
This thread is 3 years old with only 24 posts and 8 of them are mine. That is the community speaking very loudly that there isn't much interest in an brake upgrade that fits under stock 15" wheels. I am OK with this reality, as I have plenty of other fun things to focus on. I have continued to find what I think are cool caliper options that might work for brake kit that fits under the 15" wheels, but most of these discoveries are byproducts of research for other goals.
I haven't given up on it, just way back on the back burner until something about it motivates me to bring it closer to the forefront.
Thank you for the reply. I just got back into Fieros after a 10 year hiatus so I've been out of the loop. I'd be interested in a set of hub centering rings and rotors with info on "caliper X" so I can source them. Have you thought of doing a small job like that? I understand not wanting to give the info online for IP purposes. Maybe we should move this to email for confidentiality.
Would caliper X be a good replacement for stock calipers since they are becoming hard to find? And is there a rear caliper with parking brake functionality for 88 that is still being made that would be a good replacement?
Those are the 2 things I think we need to find. Because that is the biggest complaint of 88 owners is findings brake caliper, because they were a one off year. Even if they fit the stock size rotor and 15 inch wheel I think there would be a market.
