OK. I bought an 87 es a while back.(back story of previous owners skill and logic)The kid blew the motor by not adding oil after an oil change,so dad had a tech4 rebuilt and installed.Then the kid did some brake work,place a 12 inch hula dancer on the dash (yes it blocked out the view) then went for a drive.This ended abruptly in the back end of a BMW.Dad was a little upset with kid and sold me the car cheap. A gallon of fiberglass,some paint,tube stock,and a welder fixed the front end.found a leak in the master cylinder brake line fitting.bled the brakes checked the rotors and pads look new.Front looks stock but the back has no ebrake linkage.The rears do apply when tested on jack stands but if i drop it into reverse on a rock hill it will drag the locked up front tires down the hill. FINALLY MY QUESTION... Was this a GP upgrade attempt or maybe some other mod.How to tell if the master was swapped.Any suggestions getting the balance correct. I have only played with fieros for a few years but i built a 10sec street class chevy before this car rolled off the assembly line.looking for fiero mod details to figure out what they were trying to do so I can finish.Half done is not working well. Thanks for reading my rambling and any info is appreciated
The '87 Fiero comes stock with solid rotors on all 4 corners. If any of the rotors on your car are vented, then the brakes have been upgraded. You can usually tell the type of upgrade by the rotor diameter. Some examples:
The Grand Am / Beretta brake upgrade uses 9.75" rotors. The LeBaron brake upgrade uses 11.25" rotors. The Corvette brake upgrade uses 12" or 13" rotors.
If all the rotors are solid, then the car most likely has stock brakes, and they just need some repair.
Thanks for the response.I have seen both of the links in the past. The front has the bearing race in the disk so it is stock or the fiero stores over sized disk with the built in race. No milled hub under the disk.I don't know the specs for the fiero stores disk. I just bought 86gt so I need to measure and compare to be sure the 87 fronts are stock.( assuming the gt is stock)From what I have seen oversize front caliper will starve the front so you get rear bias.The mystery is the back has no ebrake setup on the caliper and I forgot to mention the disk is not vented,single disk plate.maybe he added the gp calipers but kept the stock disk? I read one place you need to raise the rear end when you bleed the rears.They made it sound like more than just enough to pull the tires.Never seen that before but worth asking if it is a fiero thing.
The rear brakes could just be Fiero front calipers, used to avoid the expense of replacing with rear calipers. 88's use the same piston diameter front and rear. Pre-88 have different piston diameters front and rear, which could explain your bias problem. If, indeed, all of the calipers on the car are front calipers, your bias problem could be solved by using an 88 bias valve.
[This message has been edited by olejoedad (edited 07-04-2015).]
Originally posted by Blacktree: I'm guessing one of two things happened: 1) The car still has the stock rear calipers. But since the parking brake hardware is gone, the rear calipers are out of adjustment. 2) The rear calipers were replaced with front calipers, which threw off the brake balance.
1 is very possible. BUT Good rear pistons will self-adjust without parking cables. So when true then need rear calipers and e-park parts and cables for everything to work. 2 if used Fiero front calipers is a minor issue. if used GA front is a very big problem.
I pulled apart the drivers front and rear,took pictures as I went with a measuring tape to show scale.The front look smaller but it was the different paint colors he used on the front and rear.So the calipers on the rear are definitely front calipers.Switching to an 88 bias valve or an adjustable valve sounds like my next direction.Do I need to upgrade the master or booster?
Drive it for a while, the bias may be just fine. The 88 bias valve is set up for matching diameter pistons all around. If your existing master and booster work OK, there is no need to change them due to the calipers.
Thanks to everyone for the help.I have 10,000 miles over the last 17 months so i don't think it will blow out anymore cobwebs.The brakes work and normally stop good but it is that rare occasion on rock,hard rain,or fade from overheating that stop your heart for a second.Sometime you need that extra 20% braking from the rear.
SOOOO... replacing the portioning valve isn't as simple as I thought. Nobody has one.Unless there is another model that is a direct replacement part.Nothing is listed in my parts interchange book. A few people were building them years ago for around $150. The Universal valves I found are simply a variable flow reducer. The opposite of what I need. So plan B. Upgrade the front brakes to GP. The larger caliper should help the bias balance.? Parts are under $150. I can machine the old disks myself to keep the hub. Should reduce brake fade. No two people seem to agree on the right combination to do the brake upgrade or the effects.Since this is all fiero specific I am in uncharted waters. I don't want to waste time and money making it worse so I appreciate any input.
Just saw I typed GP (grand prix) was trying to type GA (grand am). I may start with the front swap and go from there. I can't tell you how many times I have tore the brakes apart,scuffed,cleaned,reassembled and bled. Always thinking I will find the problem.Never do.