What’s the best setup for a modern braking system? I want it to brake like a modern sports car. I’ve got aftermarket 16” wheels so there’s some more room in there? Are there other GM braking parts that fit well and accomplish this? Thanks!
Read the section on brakes in Ogre's Cave on this site. It give you loads of data and allow you to make an informed decision.
FWIW, I believe the best and most cost-effective brake "upgrade" is:
1. Make sure that all the calipers are functioning correctly. (You may want to rebuild or replace them all if they are questionable) 2. Make sure your flexible brake lines from the hard lines to the calipers are fresh. Old lines may swell when you hit the anchors. You could replace them with stainless steel braided lines but I've not been able to tell the difference between new braided lines and new rubber lines. (Yes, i know they aren't really rubber.) 3. Install a new Fiero master cylinder, not one with a larger bore like from a Chevy S-10 Pick-up. Make sure you bench bleed the master cylinder before you install it. 4. Install new, high quality brake pads. I like Wagner Thermoquiets. 5. Flush your brakelines and refill the system with new DOT3 fluid. 6. Bleed the brake system. Lots of discussion on the proper sequence but the the generally accepted sequence is LR, RR, RF, LF. (Although I think that there is likely no appreciable difference between LR, RR, RF, LF and RR, LR, RF, LF. I'm going for cover now because this is likely to cause some controversy.) 7. Install a new Chevy S-10 Pick-up brake booster and check valve. You'll need the extenstion from Rodney Dickman (http://rodneydickman.com/product_info.php?products_id=350).
I know there are other options out there. I've got the Grand Am (Fiero Store) upgrade on one of my GT's and the above upgrade on the other. The one described above out-stops the Grand Am every time. It has better feel and it was a lot easier to do.
Do Not compare Non-ABS Fiero and others to Any ABS AKA "modern braking system" vehicles! Way to many ABS vehicles have Over Boosted PB and more issues then let ABS "Black Box" to stop any problems w/ OE setup. Example: Many ABS cars "trip" the BB and that activates ABS even on Clean Dry Pavement. Many ABS "freak out" when turning and braking even at low speed around a city.
Fix/Restore OE brakes w/ Premium Pads like Wagner Thermo Quiet. But Even many "cheap" pads from big big names are better then OE Fiero and other pads even in the 80's resulting in long stopping distance specs publish by GM and others. See my Cave, Brake Service and rest of section.
SS hoses are a waste and have issues. Use new "rubber" that meets SAE J1401. Many are sold as "Pro grade" hoses. These Hoses have DOT and SAE printed on the hose. See rubber brake lines vs stainless steel //www.fiero.nl/forum/Forum2/HTML/129208.html
Do Not buy "brake upgrades" from TFS. Just ~ maybe ⅔ of the GA crap "upgrade." Most Other Fiero "brake upgrade" have problems too but not covered in cave because so few bought into them. Installing these "upgrades" for street cars can cause big legal problems after a wreck in many places. Even if don't have problems w/ cops etc.
Most claim Big Booster is "great" have problems w/ OE booster. Good OE Fiero Booster Does Not need you to "push hard" or "Stand On Pedal" to stop... When That Happens... Booster could have failed in several ways, 84-86 Booster Filter in the engine bay is full of crap, and more issues making poor brake performance even before 30+ year old brakes can have hydro and other problems. Some claim "better" for "racing" have no clue what is the real problem. AutoX and some other classes can make PB to run out of vacuum during a race. They need to install a vacuum "tank" or even Electric Vac Pump so PB and rest of car have enough vacuum. Big Booster can be dangerous more so when you can easily lock the rear axle. Lock brakes Does Not improve braking to start w/ but Lock rear brakes can easily spin the car or worse.
16" and larger rims w/ bigger tires in Fiero have more issues than just braking issues. Big tires, meaning bigger total diameter/circumference, vs OE size for Any vehicle slows the car "out of the hole" and F'ed w/ Speedo and ECM/PCM. See my Cave, Gear Ratio Some "newer" vehicles can set Tire Size in the PCM to keep Trans Shift Points etc happy but that won't solve total gearing lose for fat rubber.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
What year is your car? '84-'87 have different factory brakes and different mounting than '88's.
Assuming your car is an '84-'87, it has tiny solid rotors and aluminum calipers. In good working condition, they are fine for driving around town or for one panic stop from highway speeds. They are not sporting brakes. The fact that they are so small means all possible brake upgrades are heavier. As brakes are unsprung weight, this will impact ride quality. I'm guessing that doesn't matter much to you, as you've already done a wheel upsize.
The best combo in terms of keeping weight low while significantly improving capabilities, I've come across is the 11.25" "LeBaron" upgrade. There's been a LOT written about it over the years, so searching this forum and Google should get you info and parts suppliers. This setup uses 11.25" Chrysler LeBaron brake rotors, which have the Fiero 5x100 hub bolt pattern along with GM Metric calipers. GM Metric chassis refers to '80's G-bodies and similar cars and actually has quite a bit of racing hardware built to fit those parts.
Beware, most kit suppliers try to sell you third gen Camaro/Firebird front calipers. You're better off with 4WD S10 front calipers, as they will hook up to the STOCK Fiero hoses. These calipers are iron. If you want to spend more money, Wilwood and other companies make aluminum versions of the GM Metric calipers.
I also installed a larger diameter master cylinder with mine. The pedal is high, firm and easy to modulate. Also as noted, new DOT rubber brakes lines are just as good as braided stainless brake lines, but are more reliable and less subject to damage and wear during normal use.
[This message has been edited by Will (edited 10-16-2020).]
Sorry to nitpick, but any modern braking system will have ABS and maybe traction control. Retrofitting that stuff from another vehicle will be problematic, to say the least.
That said, the pre-88 brakes are pretty terrible. There are several upgrades that use vented rotors. And of course, they have different calipers, so the hydraulic system needs to be altered. If you're not familiar with how hydraulic systems operate, you could cause more problems than you solve.
That said, I have personal experience with the Grand Am upgrade (the Fiero Store upgrade uses the Grand Am parts) and the LeBaron upgrade. I personally prefer the LeBaron upgrade. Not only are the rotors larger, but IMO the hydraulics work better. With the Grand Am upgrade, the stock Fiero master cylinder gives you a mushy brake pedal. And after you take up the slack, the brakes can be grabby. With a larger master cylinder, the brake pedal is pretty stiff. You really have to stand on the brakes to make things happen. The hydraulics used with the LeBaron upgrade give a brake pedal feel closer to stock.
For the '88 Fiero brakes, I think all that's needed is larger rotors, and some good pads. People used to make kits that allow the use of 12" rotors with the '88 calipers. I'm not sure if anyone still makes that. But IMO, that would be the ticket for an '88 Fiero.
Do Not compare Non-ABS Fiero and others to Any ABS AKA "modern braking system" vehicles! Way to many ABS vehicles have Over Boosted PB and more issues then let ABS "Black Box" to stop any problems w/ OE setup. Example: Many ABS cars "trip" the BB and that activates ABS even on Clean Dry Pavement. Many ABS "freak out" when turning and braking even at low speed around a city.
Fix/Restore OE brakes w/ Premium Pads like Wagner Thermo Quiet. But Even many "cheap" pads from big big names are better then OE Fiero and other pads even in the 80's resulting in long stopping distance specs publish by GM and others. See my Cave, Brake Service and rest of section.
SS hoses are a waste and have issues. Use new "rubber" that meets SAE J1401. Many are sold as "Pro grade" hoses. These Hoses have DOT and SAE printed on the hose. See rubber brake lines vs stainless steel //www.fiero.nl/forum/Forum2/HTML/129208.html
Do Not buy "brake upgrades" from TFS. Just ~ maybe ⅔ of the GA crap "upgrade." Most Other Fiero "brake upgrade" have problems too but not covered in cave because so few bought into them. Installing these "upgrades" for street cars can cause big legal problems after a wreck in many places. Even if don't have problems w/ cops etc.
Most claim Big Booster is "great" have problems w/ OE booster. Good OE Fiero Booster Does Not need you to "push hard" or "Stand On Pedal" to stop... When That Happens... Booster could have failed in several ways, 84-86 Booster Filter in the engine bay is full of crap, and more issues making poor brake performance even before 30+ year old brakes can have hydro and other problems. Some claim "better" for "racing" have no clue what is the real problem. AutoX and some other classes can make PB to run out of vacuum during a race. They need to install a vacuum "tank" or even Electric Vac Pump so PB and rest of car have enough vacuum. Big Booster can be dangerous more so when you can easily lock the rear axle. Lock brakes Does Not improve braking to start w/ but Lock rear brakes can easily spin the car or worse.
16" and larger rims w/ bigger tires in Fiero have more issues than just braking issues. Big tires, meaning bigger total diameter/circumference, vs OE size for Any vehicle slows the car "out of the hole" and F'ed w/ Speedo and ECM/PCM. See my Cave, Gear Ratio Some "newer" vehicles can set Tire Size in the PCM to keep Trans Shift Points etc happy but that won't solve total gearing lose for fat rubber.
Ogre, I have re-read your comment about the TFS brake upgrade and didn't really understand it.
I am thinking about the GA front brakes for my application which is very specific. Stopping from 114 in the 1/4 is getting a little sketchy with the non-vented front rotor getting pretty hot. I am thinking the GA front rotor might make a decent difference for this purpose as it is vented and has more mass. I understand your concerns about liability and rear lockup issues etc on the street (which can be warm, cold, hot, icy, snowy etc) and lawyers look for any angle they can take in an injury lawsuit.
That having been said, I am interested in your opinion as to what you would do to make your Fiero stop better and safer at the RACETRACK from 114 (and hopefully closer to 120) soon.
Thanks in advance,
Dime
------------------ 84/87 NB, 3800SC, E-85, VS Cam, 2.8 Pulley, 4T65E-HD, HP Tuners, AEM Wideband, Regal GS Gauges, S-10 Brake Booster. 1/4 mile -11.85 at 114mph
[This message has been edited by DimeMachine (edited 10-20-2020).]
Originally posted by DimeMachine: rear lockup issues etc on the street (which can be warm, cold, hot, icy, snowy etc)
The problem with oversized front brakes (without similar matching rear brakes) is premature FRONT lockup.
With an unbalanced setup like this, when you are modulating the brake pedal so the front tires are just on the verge of lockup (the threshold), the rear calipers aren't squeezing very hard. Therefore, you're not getting much rear braking force, despite being at the front tire lockup limit.
The result is that you increase your stopping distance.
I ignored common sense, and I tried the LeBaron with the very different calipers that are typically suggested: Front: 2.5" bore Rear: 2.125" bore
It was awful, and not only in rain, but it was terrible in the dry as well (in terms of stopping distance).
I found 2.25" bore front calipers, and braking performance was much better. For short stopping distance, you want all four tires to be at the verge of lockup, with the rears slightly underbraked, so they keep rolling, maintaining stability under braking.
The easy solution to balance the system is to install the GA setup on the rear as well.
If you want a nice balanced setup with a working parking brake, you'll have some head scratching to do. I have no off-hand solution for that, but the big-brake mod I hope do on my Fiero will be balanced and include a parking brake. Some study will be required.
[This message has been edited by pmbrunelle (edited 10-20-2020).]
If you are determined to do the brake "upgrade" and want to keep it balanced, you can try the Grand Am Rotor / Seville caliper upgrade for the rear. See //www.fiero.nl/forum/A...130314-2-083566.html for information. This is supposed to allow you to keep a working parking brake.
I can't comment on the efficacy of this system as while I have the parts, I don't have it on either of my GT's yet and in all likelihood won't install them.
Originally posted by Mike in Sydney: If you are determined to do the brake "upgrade" and want to keep it balanced, you can try the Grand Am Rotor / Seville caliper upgrade for the rear. See //www.fiero.nl/forum/A...130314-2-083566.html for information. This is supposed to allow you to keep a working parking brake.
I can't comment on the efficacy of this system as while I have the parts, I don't have it on either of my GT's yet and in all likelihood won't install them.
I installed Seville calipers on my LeBaron setup. It was a downgrade in terms of serviceability, because I mounted the calipers with the bleeders upside-down.
I wouldn't do another brake "upgrade" that downgrades serviceability... the next big brake mod must maintain serviceability.
What might work is to add a bleeder at the high point. You can buy bleeder repair kits; normally you drill + tap 1/8 NPT, then you thread in the repair insert. Not sure what keeps the insert from unscrewing when you go to crack open the bleeder some time later.
Another alternative is to use a banjo bolt with integrated bleeder. This might work if the banjo bolt is at the high point of the caliper.
What might work is to add a bleeder at the high point. You can buy bleeder repair kits; normally you drill + tap 1/8 NPT, then you thread in the repair insert. Not sure what keeps the insert from unscrewing when you go to crack open the bleeder some time later.
r.
Wonder if you could machine a flat place on the caliper and then drill it for the bleeder without the insert? I'm guessing that would prevent the insert from unscrewing when you go to crack open the bleeder.
Originally posted by Mike in Sydney: Wonder if you could machine a flat place on the caliper and then drill it for the bleeder without the insert? I'm guessing that would prevent the insert from unscrewing when you go to crack open the bleeder.
If you can find a spot on the caliper with enough meat to cut the bleeder hole directly, that would be nice.
However, the bleeder hole looks tricky to cut (well, to me). I looked for tools to cut a brake bleeder hole, but I didn't find anything. I may have been looking in the wrong places.
It could be possible to drill a hole at the edge between the insert and the caliper, then press in a pin to prevent rotation.
I did something similar to that for the V6 throttle body.
At the air outlet to the IAC pipe, there's a pressed-in aluminium ring.
Since I wanted to cut threads in that ring (to screw a pipe plug into the hole), I needed to stop the ring from turning. I did just that technique, with three holes and pins around the ring.
[This message has been edited by pmbrunelle (edited 10-20-2020).]
A really well done test and video of a big brake booster mod.This has been posted here before but I doubt that a lot of people have seen it.
I own a G Tech performance meter and until today I did not realize I could measure stopping distances with it. It involves doing a timed run up to the 60 mph red light comes on and then hitting the brakes till the car is completely stopped. I tried it twice, the first time I was doing 70 before I got on the brakes, the second run I got on the brakes too soon and did not get a distance.
So my distance stopping from 70 was 166 feet. And no lockup on the fronts until the car was completely stopped and that was just a small squawk from both fronts. Stops were dead straight and smooth. I know I can do better, but I doubt if I can get a really accurate distance with the Gtech. At least not my old one.
But 166' from 70mph is a huge improvement over the 200 foot distance that my 86 GT was tested at when it was new. And no premature lock up.
Willwood 2 piston GM metric style AL calipers with Lebaron front 11" discs, stock rear brakes with working parking brakes. Stock MC and brake booster. Willwood brake balance valve. Stock prop valve disabled.
I do not recommend that anyone copy what I have done. Because you really have to know what you are doing to get this right. I have experimented with 5 different calipers to get to this point. But I am happy now and it is going to stay as is.
------------------ 86 GT built 2.2 ecotec turbo rear SLA suspension QA1 coilovers on tube arms
Originally posted by DimeMachine: Ogre, I have re-read your comment about the TFS brake upgrade and didn't really understand it.
I am thinking about the GA front brakes for my application which is very specific. Stopping from 114 in the 1/4 is getting a little sketchy with the non-vented front rotor getting pretty hot. I am thinking the GA front rotor might make a decent difference for this purpose as it is vented and has more mass. I understand your concerns about liability and rear lockup issues etc on the street (which can be warm, cold, hot, icy, snowy etc) and lawyers look for any angle they can take in an injury lawsuit.
That having been said, I am interested in your opinion as to what you would do to make your Fiero stop better and safer at the RACETRACK from 114 (and hopefully closer to 120) soon.
Unless you're going to surrender the car's tag and trailer it to a track, any brake "upgrade" can have any problems in cave page and more.
TFS/GA "upgrade" will have same problems on a track. Plus Depending on Race Org Safety Rules may not pass track inspection w/ hack job to fit GA and other calipers and pads. Plus GA calipers and rotors weigh more then OE mean more unsprung weight that suspension must deal w/.
Fiero will take a lot more heat then most think but need premium pads to work better then OE w/o brake fade. "Race Pads" may help or not depend on race type and pad formula. Oval/"road" racing is different heat load vs drag race. Some "race pads" won't work until heated and stay hot and drag or street use can see way more stopping distance, often worse w/ OE spec in the owners book, because they won't heat and stay hot. Some brake "upgrade" may handle more heat but whether or not helps depend on race type too.
More complicated... You have bigger engine w/ auto trans and likely lower gearing... Meaning rear brakes do less then normal even when everything is 100% good. Even at idle engine and auto trans setup has more power to the rear brakes to stop. Likely have to check wiring and programming for the trans in PCM to making sure the trans will down shift and disable TCC locking properly when stopping the 4T__E trans.
[QUOTE]Originally posted by DimeMachine: Ogre, I have re-read your comment about the TFS brake upgrade and didn't really understand it.
I am thinking about the GA front brakes for my application which is very specific. Stopping from 114 in the 1/4 is getting a little sketchy with the non-vented front rotor getting pretty hot. I am thinking the GA front rotor might make a decent difference for this purpose as it is vented and has more mass. I understand your concerns about liability and rear lockup issues etc on the street (which can be warm, cold, hot, icy, snowy etc) and lawyers look for any angle they can take in an injury lawsuit.
That having been said, I am interested in your opinion as to what you would do to make your Fiero stop better and safer at the RACETRACK from 114 (and hopefully closer to 120) soon.
Unless you're going to surrender the car's tag and trailer it to a track, any brake "upgrade" can have any problems in cave page and more.
TFS/GA "upgrade" will have same problems on a track. Plus Depending on Race Org Safety Rules may not pass track inspection w/ hack job to fit GA and other calipers and pads. Plus GA calipers and rotors weigh more then OE mean more unsprung weight that suspension must deal w/.
Fiero will take a lot more heat then most think but need premium pads to work better then OE w/o brake fade. "Race Pads" may help or not depend on race type and pad formula. Oval/"road" racing is different heat load vs drag race. Some "race pads" won't work until heated and stay hot and drag or street use can see way more stopping distance, often worse w/ OE spec in the owners book, because they won't heat and stay hot. Some brake "upgrade" may handle more heat but whether or not helps depend on race type too.
More complicated... You have bigger engine w/ auto trans and likely lower gearing... Meaning rear brakes do less then normal even when everything is 100% good. Even at idle engine and auto trans setup has more power to the rear brakes to stop. Likely have to check wiring and programming for the trans in PCM to making sure the trans will down shift and disable TCC locking properly when stopping the 4T__E trans.[/QUOTE]
Ogre, to further clarify, this Fiero would be trailered to the track and we are only talking about the 1/4 mile drag race. Assume starting the 1/4 mile with cold brakes and stopping from 120mph with the 3800 4t65e HD powertrain combo.
What mods if any would you do to the brakes and this was your Fiero and you were forced to take her up to 120mph in the 1/4 mile. Assume in this situation if you were not able to stop you stand a high probability of going into the sand and trees at the end of the track and facing serious injury.
Thanks in advance!
Dime
------------------ 84/87 NB, 3800SC, E-85, VS Cam, 2.8 Pulley, 4T65E-HD, HP Tuners, AEM Wideband, Regal GS Gauges, S-10 Brake Booster. 1/4 mile -11.85 at 114mph
[This message has been edited by DimeMachine (edited 10-22-2020).]
For a car that is not driven on the street and is only track driven you do not need a parking brake. So you can put either Grand Am parts front and rear or a Lebarron setup front and rear. Or just about any big brake kit you can fit inside your wheels.
But the real problem is that stock Fiero's have a combination proportioning valve that puts way too much bias to the front brakes. The rear brakes are doing almost nothing in the stock configuration. A car that is heavier in the back like a Fiero needs a lot more braking force in the rear than a normal front wheel drive sedan that is a lot heavier in the front. The stock prop valve does not allow the kind of adjustment you need to get the front to rear balance right. And adding an aftermarket valve to the rear circuit does not work because they are designed for vehicles that have too much rear bias, ie almost every car built in the 60's and 70's. So those valves reduce braking to the rear to avoid rear wheel lockup. Exactly what the stock Fiero prop valve already does, and the opposite of what a Fiero needs.
If this is a track-only car, I'd delete (or disable) the stock proportioning valve. Then I'd install an aftermarket prop valve, and adjust it until the brake bias is where you want it.
[This message has been edited by Blacktree (edited 10-22-2020).]
If this is a track-only car, I'd delete (or disable) the stock proportioning valve. Then I'd install an aftermarket prop valve, and adjust it until the brake bias is where you want it.
Something to think about 4 sure!
Would take low speed controlled road testing to make sure I get the bias right for warm road/tire conditions but not too close to the edge of rear wheel lockup that a guy gets into trouble.
Does your track not have a long exit for the 1/4? I've not had issues slowing down from those speeds in a straight line unless the headlights popped up and dropped unevenly.
Where did op go? Started a best oil debate and ran
[This message has been edited by skywurz (edited 10-31-2020).]
84-87 Fiero Brake Bias has Little to Nothing to do w/ the Prop-valve unless you're Panic Stopping or close to it all the time. Most Bias for daily driving is "Hard Bias" built into the system's hydro for Fiero w/ different piston diameter. Unlike most others even today have "Hard Bias" w/ different hydro and mechanics w/ smaller "weaker" pads etc on rear as said in the cave "upgrade" page.
If you run out of shut off space at Drag track very likely something is wrong w/ the car, the track, or maybe both. Examples:
Pads could drag for several reasons and heat up cause "Fade" problems. Doesn't help for low time for a run either. Big engine and low gearing can hind brake problems more easily.
"Cheap" pads may out gas stopping at high speeds and cause true Fade problems even when not overheated. This is partly why Drilled/Slotted rotors were made but that has large problems and not needed by most pads even in the 80's and not recommended by Wilwood and other real Engineers.
If Fiero rear brake have piston problems or you're dumb enough to "Power Brake" to spin the rear wheels then often the Rear brakes get hot or overheat and worse often Glaze the pads and do very little or nothing after. Glazing problem is close to Fade problem but Doesn't go away when brakes are cool/cold. Front brakes dragging pads can have same Glaze problems. You might be able to sand/grind the pads to remove Glazing but not a good idea for many reasons. (Brake Dust doesn't have Asbestos now but still can hurt you and more. Is Why some states and others restrict Copper etc in pads/shoes. see https://www.counterman.com/...ppearing-brake-pads/ )
Some Tracks have problems but not getting into that. 1 Quick Example: Driving over X speeds and/or < Y seconds put many "Street cars" in another Class w/ more rules how the car is built, safety equipment required, etc. but some tracks ignore that w/o NHRA etc in town. Or NHRA etc won't use a track at all like F1 etc left Watkins Glen many years ago then went bankrupt because of many big problems there. (Not only the track was in very poor shape at that time.)
Does your track not have a long exit for the 1/4? I've not had issues slowing down from those speeds in a straight line unless the headlights popped up and dropped unevenly.
Where did op go? Started a best oil debate and ran
Yes, there is a short and a long one. It shuts down fine using the longer exit - but clearly could be better. Might be in my head, I also take my C5 there and perhaps I am contrasting the how much more confident the C5 stops from 130 than the Fiero does from 115. It also sticks in my mind that you don't see too many cars with solid rotors at the track (or on the street even).
P.S. 1. At the starting line I do a very short screech in the Fiero to clean of the rear tires (not heat them up) so the rotors are leaving the starting line at room temp. P.S. 2. I am seriously considering the 4 wheel GA setup with larger master to make up for the larger volume of fluid to move the larger caliper pistons and keep my larger S10 booster. If anyone could tell me specifically what they find hackish about it I would appreciate it. The rear seems solid - direct bolt on. I do have some concerns about having the front rotor perfectly centered on the Fiero hub as that part does seem like it could be an issue to me. From those that have the front GA set up - have you had any issues with the GA roter being perfectly centered on the fiero brake "modified hub"?
Thanks Guys!!
------------------ 84/87 NB, 3800SC, E-85, VS Cam, 2.8 Pulley, 4T65E-HD, HP Tuners, AEM Wideband, Regal GS Gauges, S-10 Brake Booster. 1/4 mile -11.85 at 114mph
[This message has been edited by DimeMachine (edited 11-01-2020).]
Originally posted by DimeMachine: If anyone could tell me specifically what they find hackish about it I would appreciate it.
No parking brake is pretty hackish. That's about it in my book.
quote
Originally posted by DimeMachine: I do have some concerns about having the front rotor perfectly centered on the Fiero hub as that part does seem like it could be an issue to me.
On most cars, the hub has a small-diameter (57.1 mm in the case of Fiero) stub protruding outwards. This is used to pre-center the wheels before the lug nuts are tightened.
In cars with divorced discs (or drums), the disc or drum is also centered on the stub before it is sandwiched in place by the wheel.
The modification done to the Fiero rotor is to part off the braking surface on the periphery. The centering stub remains factory, and therefore, centering of the GA rotor remains as per a factory install.
I don't remember if the Fiero stub is long enough to pre-center the wheel once the thickness of an additional rotor hat has been added. Personally, I don't find the pre-centering of the wheel to be a strict requirement, since you can center via the tapered-seat lug nuts, but the most detail-oriented car modders will consider the loss of wheel pre-centering to be hackish. This obviously will depend on the wheel you choose; some have bigger chamfers than others.
On most cars, the hub has a small-diameter (57.1 mm in the case of Fiero) stub protruding outwards. This is used to pre-center the wheels before the lug nuts are tightened.
In cars with divorced discs (or drums), the disc or drum is also centered on the stub before it is sandwiched in place by the wheel.
The modification done to the Fiero rotor is to part off the braking surface on the periphery. The centering stub remains factory, and therefore, centering of the GA rotor remains as per a factory install.
I don't remember if the Fiero stub is long enough to pre-center the wheel once the thickness of an additional rotor hat has been added. Personally, I don't find the pre-centering of the wheel to be a strict requirement, since you can center via the tapered-seat lug nuts, but the most detail-oriented car modders will consider the loss of wheel pre-centering to be hackish. This obviously will depend on the wheel you choose; some have bigger chamfers than others.
Thanks for your response!
In MN, due to rust, most of the fiero's brake cables corroded stuck years ago and almost nobody has a working parking brake. Plus I live in a flat area, the car is an auto and this is a toy for me so I don't care about the PB. If I lived in a state that deemed my car not roadworthy due to a bad parking brake, that would be a deal breaker for sure.
Not talking about the wheel centering - I totally get what you are saying about the tapered lug nuts doing that. Seems like it might be possible for the GA rotor to not be perfectly centered as the holes on the studs allow it to move around a touch prior to tightening the wheel. This is the area of concen in my mind that I want worked out prior to pulling the trigger $$$
Yes, there is a short and a long one. It shuts down fine using the longer exit - but clearly could be better. Might be in my head, I also take my C5 there and perhaps I am contrasting the how much more confident the C5 stops from 130 than the Fiero does from 115. It also sticks in my mind that you don't see too many cars with solid rotors at the track (or on the street even).
P.S. 1. At the starting line I do a very short screech in the Fiero to clean of the rear tires (not heat them up) so the rotors are leaving the starting line at room temp. P.S. 2. I am seriously considering the 4 wheel GA setup with larger master to make up for the larger volume of fluid to move the larger caliper pistons and keep my larger S10 booster. If anyone could tell me specifically what they find hackish about it I would appreciate it. The rear seems solid - direct bolt on. I do have some concerns about having the front rotor perfectly centered on the Fiero hub as that part does seem like it could be an issue to me. From those that have the front GA set up - have you had any issues with the GA roter being perfectly centered on the fiero brake "modified hub"?
Thanks Guys!!
I had a z06 C5... The Fiero will never be a Corvette. You could swap the brakes engine trans body it will still be a Fiero.
Honestly the stability control in the C5 saved me a couple times but really didn't make me a better driver. It made me a lazy less respectful (of the machine) driver.
Learn the car you are driving and make sure the equipment you have currently is functioning. Thats my advice.
Originally posted by DimeMachine: Not talking about the wheel centering - I totally get what you are saying about the tapered lug nuts doing that. Seems like it might be possible for the GA rotor to not be perfectly centered as the holes on the studs allow it to move around a touch prior to tightening the wheel.
Slip-on brake rotors are centered by the stub on the hub; the same stub that centers the wheels. Sometimes the stub is stepped with two different diameters.
Rotors are NOT centered by the lug studs. The holes need to be big enough to let the studs pass through, but that's about it. The brake rotor holes can be drilled in an imprecise manner, and that's fine.
I was assuming that the GA rotor has a precise slide-fit on the Fiero rotor stub. If that's not the case, I'd be shocked that people do this... that would be really hackish.
Slip-on brake rotors are centered by the stub on the hub; the same stub that centers the wheels. Sometimes the stub is stepped with two different diameters.
Rotors are NOT centered by the lug studs. The holes need to be big enough to let the studs pass through, but that's about it. The brake rotor holes can be drilled in an imprecise manner, and that's fine.
I was assuming that the GA rotor has a precise slide-fit on the Fiero rotor stub. If that's not the case, I'd be shocked that people do this... that would be really hackish.
A good machinist could be handed Fiero rotors, GA rotors, and told to make the two fit each other, with machining for a Speedi-Sleeve if necessary.
The issue is most hubs (including the 84-87 rear and 88 front hubs) have 2 pilots, a slightly larger one for the rotor and a slightly smaller one for the wheel. For FIeros and Grand Ams the rotor pilot is 0.71mm or 0.20" larger than the wheel pilot.
Since the 84-87 front hubs never had slip on rotors, they do not have the slightly larger rotor pilot, just the smaller wheel pilot. This means that all brake kits designed for the 84-87s should have different concentric rings for the front vs. the rear. In regards to the grand am, there isn't room for concentric rings so when you install the rotor there ends up being 0.020" more sloppiness than the rear.
One method to reduce the sloppiness is to get some 0.010" shim stock and cut it in a 1/4" strip and insert it between the rotor and the wheel pilot area.
[This message has been edited by fieroguru (edited 11-01-2020).]
The issue is most hubs (including the 84-87 rear and 88 front hubs) have 2 pilots, a slightly larger one for the rotor and a slightly smaller one for the wheel. For FIeros and Grand Ams the rotor pilot is 0.71mm or 0.20" larger than the wheel pilot.
Since the 84-87 front hubs never had slip on rotors, they do not have the slightly larger rotor pilot, just the smaller wheel pilot. This means that all brake kits designed for the 84-87s should have different concentric rings for the front vs. the rear. In regards to the grand am, there isn't room for concentric rings so when you install the rotor there ends up being 0.020" more sloppiness than the rear.
One method to reduce the sloppiness is to get some 0.010" shim stock and cut it in a 1/4" strip and insert it between the rotor and the wheel pilot area.
And the wheel pilot bores typically have a lead-in chamfer that results in little to no contact between the wheel pilot journal and the wheel pilot bore when the journal is shorter due to adding the brake rotor.
What’s the best setup for a modern braking system? I want it to brake like a modern sports car. I’ve got aftermarket 16” wheels so there’s some more room in there? Are there other GM braking parts that fit well and accomplish this? Thanks!
If you want modern day sports car braking, buy a modern day sports car. Your comparing a 35 YO economy car with a new sports car. They are not the same class. It would be better to compare your fiero to U-Haul or UPS truck.
