The hub is somewhat standard milled off rotor of of the stock hub. Corners had to be taken down a bit to clear the rotors. I should mention the rotors are Subaru and not ATS that are 5x100. Rotors are 13" ish
The bracket can be seen below is around 5/8" mild steel with M14 10.4 bolts.
The rear brakes will be upgraded after the booster/master cylinder. The plan is to disable the stock proportioning valve and replace it with an adjustable one that can be dialed in.
This goes on next
[This message has been edited by Dan W (edited 10-18-2022).]
What a great thread. Brakes are ALWAYS an interesting topic on the Forum. Please share with us the details on your Fiero along with the details on your swap. Drawings of the brackets and other details will be appreciated by almost everyone.
Bracket to convert ATS booster to Fiero is complete, its a little bigger than the stock but whos complaining. For anyone wondering, the stock fiero master cylinder does not have the volume for decent brakes, plus its nice being able to buy replacement parts off the shelf.
Also for anyone wondering, below is the dimensions of the adapter bracket for the front calipers.
Next step, adapter to connect the new booster rod to the Fiero brake pedal.
[This message has been edited by Dan W (edited 10-18-2022).]
That's a good looking brake swap! Has got me interested as Subaru discs are easier to get in France. However, the ATS calipers cost an arm and a leg (and are not available from parts suppliers in France): Rockauto is as least 220€ + shipping + import taxes !!
By the way, those are the 4-piston and not the 6-piston calipers?
For those that asked the question, his 1st photo shows clearly that it's an '84 to '87. (Canted backwards shock.)
Nice next job on the brake swap. Looks a bit complex for the average Fiero owner but something to consider. For the time being S-10 booster new pads and rebuilt calipers will have to do on my Fiero. I can lock them so I don't consider them all that bad.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Nice next job on the brake swap. Looks a bit complex for the average Fiero owner but something to consider. For the time being S-10 booster new pads and rebuilt calipers will have to do on my Fiero. I can lock them so I don't consider them all that bad.
Yes, you can lock them but for how long. For daily driving to the grocery store the S10 booster on stock new pads is great. Once you drive it in a spirited way you'll get the point. This would be a great upgrade because the calipers are light and the clamping force would increase. The ATS is a very heavy car (3800lbs) compared to our Fieros (2800lbs) so the pads are more than adequate to use as an upgrade. I don't know how many track pad choices there are for the ATS. But since I use the D154 Metric GM calipers made by Wilwood, they are much lighter than the stock Camaro Metric calipers. Also there is a plethora of racing compound pads for these calipers. And, I can find the calipers and pads in my local parts store if I run into a problem.
By the way, those are the 4-piston and not the 6-piston calipers?
These are 4-piston, cheapness was the main driver for that. But also 4-pot are a major upgrade over stock especially considering we are comparing late 80s tech to 2019 tech.
quote
Originally posted by Dennis LaGrua:
Nice next job on the brake swap. Looks a bit complex for the average Fiero owner but something to consider.
Im gonna go on record and say this isnt a how-to thread, its more of a how i dun-it thread.
quote
Originally posted by Frenchrafe:
Has got me interested as Subaru discs are easier to get in France. However, the ATS calipers cost an arm and a leg (and are not available from parts suppliers in France):
If you can get suabru rotors easier, you can get the equivelet subaru 2004-2012 Brembo. Lots of cars used this particular one such as infiniti/nissan. I went with ATS because where im from they are cheaper. Also the fiero has its legacy of being pieced together from random GM cars and i wanted to keep that style.
quote
Originally posted by La fiera:
I don't know how many track pad choices there are for the ATS.
One reason I went with these is that they have been an entry-level performance part since the 2000's. There is a good amount of aftermarket support for them since they come factory on the corvette, camero, and other off-the-lot sports cars.
Here is the adjustable break rod adapter, made to be accurate within 3/4" and dialed in on the car.
I just about have the new master/booster in there, then its time for a few trial runs. On paper the master cylinder volume should be adequate for two front calipers, lets hope reality thinks so too...
Got the booster/MC assembly together. Decided to ditch the distribution block (brass block w/ built in prop valve) as its only function now would have been to illuminate a warning light on the dash that no longer exists.
Adjustable prop value is attached, line lock is bottom left.
I have also found the two sets of wheels I have available wont fit, go figure. 18x8 47mm (rear wheel clearance issues, needed 1" spacer) 17x7 38mm (great fit with stock brakes, wheel taper makes it hit everything)
So im on the market for some new ones that will fit. Ill keep you posted on the specs and clearances of the ones that do fit... I made a measurement dongle to check the clearance, I got a few below I need to go out and check.
[This message has been edited by Dan W (edited 10-18-2022).]
If you look closely at the pads on that picture you will see they are being held in with drill bits as at the time I did not have the correct hardware. Now that I have the real set of pins its about flush. Ill take a closeup picture or two with it on the car.
Edit: I snuck in there to get a picture of the pad position on the car.
[This message has been edited by Dan W (edited 10-20-2022).]
After dealing with a LOT of guys with corollas and subarus, i found the following:
17" wheels will be tight, they will have maybe 2-3mm around the barrel clearance if your lucky and it does not taper. There were a set of 17" wheels that fit very tight I found but most hit. Pictured below - 17x8 40mm offset
I found that the following specs will get 90% of the way there, the rest is up to fate and I would 100% not recommend buying wheels on the internet without measuring it using the dongle.
18 x 7.5 with 30-40mm offset <----
This cleared the suspension, had a good amount of room around the calipers, and did not rub lock to lock.
PS: 18 or 17 x 8" 45+mm offset will hit the stock coil overs in the back and rub in the front lock to lock.
The ones that made it on the car: 18 x 7.5 45mm offset with a 5mm spacer. The spacer was not required to fit, but it had maybe 1mm clearance so for practical purposes its required due to the 45mm offset.
The brake pedal adjustment worked great, and honestly without it would have been a disaster. The booster on the car with the best measured guess of pedal rod length was just slightly off the mark, and the pedal no longer depressed the button (pic below):
Three full turns on the adjustable rod and it aligned perfect.
The booster from the ATS fit with only needing to clearance the frame slightly. The new bracket bolted right to the Fiero without issue
The vacuum line fit without modification
Finally the install looks nice, of course new brake lines needed to be bent and flanged. I did not have all the hardware required to finish it but its very close to trial runs. You can also see the adjustable prop valve and line lock in the video. As mentioned above the brass cube was removed to allow for bigger lines and remove a point of failure (the old prop valve).
Out of curiosity, are you using the stock rear calipers at present? What are you doing for an e-brake? You mentioned a line-lock. Are you using it on the front brake circuitry as a parking brake?
Out of curiosity, are you using the stock rear calipers at present? What are you doing for an e-brake? You mentioned a line-lock. Are you using it on the front brake circuitry as a parking brake?
Right now it has the stock rear calipers, I adjusted the prop value to full-brake and the rear calipers don’t bite as hard as I want. So I’m going to replace them with the rear brakes from an Infinity. The Infinity has an electric e-brake so I can throw the stock fiero cable system far away in a burning dumpster where it belongs.
The line lock is for burnout purposes. I’ll post the test videos tomorrow when I get a chance.
[This message has been edited by Dan W (edited 10-24-2022).]
Right now it has the stock rear calipers, I adjusted the prop value to full-brake and the rear calipers don’t bite as hard as I want. So I’m going to replace them with the rear brakes from an Infinity. The Infinity has an electric e-brake so I can throw the stock fiero cable system far away in a burning dumpster where it belongs.
The line lock is for burnout purposes. I’ll post the test videos tomorrow when I get a chance.
The Good It feels like a Cadillac, the pedal needs a light touch. It could be depressed with two fingers and stop shorter than it did. The wheels can be locked up on demand without much effort. Driving around feels great, but I will need to tighten up the front shocks as a fast stop makes it nose dive. That was never an issue before. We ran some tests on a private stretch of road, winter conditions, 32 deg. The goal was to verify the rear brakes would not lock up in an emergency stop. Then I did one pass to show off and put a flat spot on the tires for you guys... im sure it will round back out...
The Bad The rear calipers do work but dont bite hard enough. The prop value adjusted to full-brake still feels a little light in the back. The plan is to replace them with some rear calipers from a 2021 Nissan 370Z with rear rotors from the STI. This will have the electric parking brake motor on it as well.
The Ugly The front rotors had a slight gap, this was the difference between the STI rotor and the stock hub circumference. I could have just centered it best I could and it would have been fine but instead I found that 26 gauge sheet metal was the exact difference. So i got some and cut strips. The install was a nice tight almost press fit that perfectly centered the rotor.
Yes, you can lock them but for how long. For daily driving to the grocery store the S10 booster on stock new pads is great. Once you drive it in a spirited way you'll get the point. This would be a great upgrade because the calipers are light and the clamping force would increase. The ATS is a very heavy car (3800lbs) compared to our Fieros (2800lbs) so the pads are more than adequate to use as an upgrade. I don't know how many track pad choices there are for the ATS. But since I use the D154 Metric GM calipers made by Wilwood, they are much lighter than the stock Camaro Metric calipers. Also there is a plethora of racing compound pads for these calipers. And, I can find the calipers and pads in my local parts store if I run into a problem.
I am not here to convince anyone that the stock Fiero brakes are great but with all new parts, bled correctly and the S-10 booster added they seem to work fine. Perhaps not for road racing but we have seen Fiero run in the 11's with stock brakes. There certainly must be better alternatives than stock Fiero brakes such as the one by the OP and the one mentioned above. They take fabrication work that most of us are unwilling to do it but some believe that the reward is worth the fuss. As time progresses it is logical that most Fiero owners will need to consider a brake swap. Fiero calipers are getting difficult to find and when you do find them they are expensive and rebuilds don't always work correctly.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
I have heavy duty sway bars front and back, koni adjustable shocks, stiff lowering springs, heavy duty bearings, polyurethane bushings, new hardware, 3800 supercharger swap, cams, valves, tuned ECU, custom exhaust, digital dashboard, non-leaky sunroof… and also brembo brakes and a tank full of super premium gas. Not that I need all that to drive to work, but once you get locked into a serious collection of mods, the tendency is to push it as far as you can.
The Good It feels like a Cadillac, the pedal needs a light touch. It could be depressed with two fingers and stop shorter than it did. The wheels can be locked up on demand without much effort. Driving around feels great, but I will need to tighten up the front shocks as a fast stop makes it nose dive. That was never an issue before. We ran some tests on a private stretch of road, winter conditions, 32 deg. The goal was to verify the rear brakes would not lock up in an emergency stop. Then I did one pass to show off and put a flat spot on the tires for you guys... im sure it will round back out...
The Bad The rear calipers do work but dont bite hard enough. The prop value adjusted to full-brake still feels a little light in the back. The plan is to replace them with some rear calipers from a 2021 Nissan 370Z with rear rotors from the STI. This will have the electric parking brake motor on it as well.
The Ugly The front rotors had a slight gap, this was the difference between the STI rotor and the stock hub circumference. I could have just centered it best I could and it would have been fine but instead I found that 26 gauge sheet metal was the exact difference. So i got some and cut strips. The install was a nice tight almost press fit that perfectly centered the rotor.
That's the last thing I want to do, lock the fronts like in your video!! Specially in a Fiero. I would soften the shocks even more to transfer more weight to the nose or give it more rear bias. (I know you are working on that). With the LeBaron kit at the front with Hawk DTC 30 race pads and stock rears I can lock up all fours. Actually, the rears bite harder first than the fronts giving the Fiero a "whiplash" effect during hard braking, the back end squats then the front end squats. Just like a Toyota Prius. And It stops in a dime. The other reason I have it set up like that is because I do a lot of left foot braking to point the car where I want to go while flat foot on the gas pedal. It works for me. I don't have a 3800 SC like yours but with 324whp and 360 wtq NA at 2400lbs I don't need bigger rotors unless I'm doing endurance racing.
That's the last thing I want to do, lock the fronts like in your video!! Specially in a Fiero. I would soften the shocks even more to transfer more weight to the nose or give it more rear bias. (I know you are working on that). With the LeBaron kit at the front with Hawk DTC 30 race pads and stock rears I can lock up all fours. Actually, the rears bite harder first than the fronts giving the Fiero a "whiplash" effect during hard braking, the back end squats then the front end squats. Just like a Toyota Prius. And It stops in a dime. The other reason I have it set up like that is because I do a lot of left foot braking to point the car where I want to go while flat foot on the gas pedal. It works for me. I don't have a 3800 SC like yours but with 324whp and 360 wtq NA at 2400lbs I don't need bigger rotors unless I'm doing endurance racing.
It sounds like you found a nice setup for yourself. Although for most people the very last thing you want is for the rear tires to lock up. Gonna send the average person ass backwards into a wall.. or traffic. That’s what that test was all about, the reason I locked up the fronts was because I stomped on the pedal as hard as I could to ensure that in a full emergency stop the rears would not lock up. Also I don’t want my car nose diving for what I use it for, I need to keep the balance even for the next corner.
As for the blazer booster boys, the Lebanon kits, the 90s corvette kit, or the out of production willwoods. Those are all good options.
But mine has a 2022 set of brembos on it with 13” callipers. The rears are on their way. Now people know there is yet another option when choosing a brake upgrade and can see what it’s gonna take to do it, and also know it will work when it’s done.
Originally posted by Dan W: It sounds like you found a nice setup for yourself. Although for most people the very last thing you want is for the rear tires to lock up. Gonna send the average person ass backwards into a wall.. or traffic. That’s what that test was all about, the reason I locked up the fronts was because I stomped on the pedal as hard as I could to ensure that in a full emergency stop the rears would not lock up. Also I don’t want my car nose diving for what I use it for, I need to keep the balance even for the next corner.
As for the blazer booster boys, the Lebanon kits, the 90s corvette kit, or the out of production willwoods. Those are all good options.
But mine has a 2022 set of brembos on it with 13” callipers. The rears are on their way. Now people know there is yet another option when choosing a brake upgrade and can see what it’s gonna take to do it, and also know it will work when it’s done.
And trying to stop suddenly locking the fronts like that will make you overshoot an intersection and getting hammered sideways by the traffic that got the green light after you couldn't stop on the red light you blew. What I'm saying is exceeding the limits of a braking threshold is dangerous specially in a car that most drivers can't understand its behavior. From a driver's perspective I use the extra rear bias to help the car rotate easier while trail braking. The 2019 ATS Caddy has double the weight of the Fiero even with the SC L67 so it needs those big calipers and bigger rotors, its basically a pig. But for the Fiero that is too much brake power for such little weight. Now, if bling is what you want, the Brembo is the way to impress at the Cars & Coffee. But you are right about the average Fiero driver, It'll get them in trouble if too much rear bias is used. The Fiero has to be driven like the "Widow Maker" 1980's Porsche 911, do all your braking before turning and apply power smoothly while turning to shift the weight to the rear and keep the ass end planted just like a GoKart. That is counter intuitive for must Fiero drivers because in panic mode the first thing they do is slam on the brakes! But let me say your Brembo option looks pretty rad and makes look the Fiero very racy!
Looks like 2001-2005 Sti fronts. Later subaru's changed to 5x114 PCD, 5x100 PCD rotors like the Fiero are rarely used nowadays. Problem with 4pot calipers is that you need more space between the rotor and the wheel so "deeper" discs are better. I plan to use the Sti rears which are 316mm and 68mm deep and do not need a spacer. Out of all other rotors I researched like Audi TT/VW etc. Subaru comes most close for wanted size and fitment.
Subaru centerhole is 58mm so slightly bigger than the Fiero (I measured 56mm)
Looks like 2001-2005 Sti fronts. Later subaru's changed to 5x114 PCD, 5x100 PCD rotors like the Fiero are rarely used nowadays. Problem with 4pot calipers is that you need more space between the rotor and the wheel so "deeper" discs are better. I plan to use the Sti rears which are 316mm and 68mm deep and do not need a spacer. Out of all other rotors I researched like Audi TT/VW etc. Subaru comes most close for wanted size and fitment.
Subaru centerhole is 58mm so slightly bigger than the Fiero (I measured 56mm)
Thanks! I didn't know when Subaru made the 5x100 to 5x4.5 bolt circle switch.
Big Rear Update Over the last few of weeks we have been able to put together a possible working rear brake system. It took a lot of trail and error, reading spec sheets to find a reasonable rear rotor that will not interfere with the hub or caliper bracket.
Rotor Specs The main issue was finding a rotor that clears. It has to be 5x100 or drillable, it has to have a 47mm offset or less (pictured below), and it has to be 13" diameter range. The Doge Viper rotors of course will fit but I was looking for something more accessible. After going through spec sheets and trying / returning a few sets we got one that works.
It fits without interference, cheap, easy to get. 13.5" diameter. (12 jurors, 1 judge, 1/2 a chance). They have high carbon, cross drilled variants of it if your after that look.
Bracket The bracket is made out of 1/2" mild steel, someone asked why mild. You generally want your brake to fail in a way its still attached to your car and not snap off. I will post a spec diagram later.
Rotor Fit The rear rotor fits well, the caliper may need a shim to perfectly center. Another snag with rotors was also finding one with a smaller center bore size, too many of them were 5x114.3 and had a big bore making it un-advisable to drill it to 5x100. These have a smaller bore and have a lot of meat on them. Check out the nice hole spacing on these versus the 6 bolt viper rotors.
If people think this is safe, mine are bullet proof...
Wheel Fit The wheels that cleared the large front calipers also cleared the backs, but as you can see just barely. I will also put on a 3-5mm spacer on the wheels to give it a little extra. (same as fronts)
It doesn't matter what calipers I put on the back, the 87 and earlier Fiero just wasn't made with modern caliper spacing in mind. If your buying wheels make sure they will clear. Ill post the dimensions of my fitment dong(le) if anyone wants it.
Center Ring I had to make a custom center ring, the fronts just needed a shim but the backs have enough to warrant a ring. This was made on a mini-lathe It will both center the hub-centric wheels and rotor.
I will keep you posted on how well it goes back on the car. Edit: added more rotor details
[This message has been edited by Dan W (edited 12-29-2022).]
, turns lock to lock with customized hub and bracket.
