87 GT Brake Woes (Page 2/2)
fierofool AUG 28, 08:34 PM
Autozone lists the piston boot and o-ring kit but all stores say it's not available, even at the Lilburn distribution center. You probably can polish up the piston and the piston bore. It might be that NAPA in Norcross or one of the other chain store might carry it. This is the Autozone listing:

https://www.autozone.com/br...sIgnoreVehicle=false

Brakeware Brake Caliper Kit 66596
Part #
66596
SKU #
189829
Fits your 1987 Pontiac Fiero
Notes: 1.9375" dia. bore.

You don't need to drive your Fiero to attend. One month we had a Bring Your Truck meeting when no one drove their Fiero. Wasn't planned. That's just the way it happened.

Edited: Found it at The Fiero Store. https://www.fierostore.com/...0%208487FT&d=376&p=1

[This message has been edited by fierofool (edited 08-28-2022).]

AndrewTHG SEP 06, 03:55 PM
Well, I found a new piston as well as seal, so I am going to rebuild the fronts with new parts. As to the rears, I think they are toast. Was going to replace the seals but it does not seem worth it. One of them has already had a bleeder repaired on it, and was full of dust when I popped the piston out. Does not seem worth the time.

That being said, I have read a lot about the function of the rear brakes and have a question about them just for my sanity. The two that I have, the parking brake lever and piston are operating differently on each caliper.

On the one, I pull the lever and the piston pushes out to apply pad pressure like it should. When I bring it back to the stop, the piston comes the whole way back to where it was before. (i.e. if the piston was bottomed out, I rotate the parking brake lever max travel, the piston moves, and then when I bring the lever back, the piston is bottomed out again).

On the other rear caliper, I pull the lever and the piston pushes out to apply pad pressure (again like it should). However, when I rotate the lever back to the stop, the piston pretty much stays out where it was.


I have read a lot about the "slip clutch" design etc, and assume the second caliper (the one where the piston does not move much after returning the lever) is actually the correct one, as this one is accounting for pad wear? If each time the piston always went back to being bottomed out in the caliper, when you apply the pedal, as your pads wear it would keep having to travel further and further. But I'll let the experts tell me! Again, just gonna buy some remanufactured ones at this point because I think mine are too far gone, but still want to know the correct operation.

Thanks! Fierofool - hopefully post wedding I'll have some more free time for meetups, and fingers crossed this thing will be road worthy before the end of the year. Although as I dig deeper I find more problems
fierofool SEP 06, 05:03 PM
Without hands-on, I'm going to guess that the caliper that retracts was not adjusted properly when it was installed. It's a process that needs a lot of caution because you can lose the screw post into the caliper. I carefully remove the nut and lever and even more carefully replace the lever onto the hex of the screw post, install the nut and then hand activate the lever to apply the brake. I repeat this process until the pads are sitting against the rotor. I then reposition the lever so that it's about 1/8 to 3/16 inch off it's forward position rest stop, install the nut and then the cable. You must be careful to not lose the washer or damage the screw post seal or to let the screw post retract into the caliper.
theogre SEP 06, 09:26 PM
See my Cave, Rear Piston notes

Anyone turning P-brake "Screw" to "adjust the rears" should have their car impounded and tools taken.

But easy to very easy to "loose" the screw for several reasons. When that happens you best hope the bleeder works on top of whatever cause this issue.

If you have "to adjust" the rear piston(s)... Including the cave method as said on that and other pages. The Piston Is Bad.
If the rear brakes are all in their place to drive the car...
P-brake levers will move the pads out but not return to the starting point if the pistons are good.

If P-brake levers does return to the starting point, Very Likely the piston is have problems now and will have Low Pedal and other problems in the near future.

Rear pistons Should Not be Force by using the clamp method in the cave. if the clamp needs more "finger tight" effort,,, Something Is Wrong.
Example: Many use more effort to retract because can't get < 5mm easy... Real Reason is already blown the piston's back and your force is Pressing In the parts again. Results: This Piston Is F'ed.

Good pistons will self adjust when you Slowly push the pedal after brake work. That "Screw" does not prevent the inner piston to rotate to self adjust.
If you push the pedal Fast or pistons are iffy/bad, the hydro Force can "blow out" the piston's back and cause way bigger problems that in turn can warp the rotors to cause a Fire and Brake Failure.
fierofool SEP 07, 08:33 AM
It's always worked for me and nobody is getting my cars or my tools.