Brake system nitemares

[raybies]

I'm not posting this thread because I have a problem, I just figured after all the hair loss I went through I would share. My 1980 Vette had no lasting brake pedal when I got it. You could bleed the system and get brakes for maybe a day if lucky. There was no fluid loss anywhere on the car but the system still kept getting airbound. Well after a ton of investigative work I found out that the cause was multiple caliper failures (Now get this) caused by rotor run out. Since the C3 uses ridgid mounted spring loaded piston calipers all around and the rotor as it's running out causes the pistons and seals in the calipers to oscilate back and forth in such a small area, the seals actually wear a groove in the caliper bore. It allows air in but doesn't allow fluid out due to the fact that when you hit the brake no matter how lame the system is operating it still expands the seal enough to trap the fluid.
Anyway if your experiencing this problem my suggestion is to first check all the rotors for run out using the instructions from GM and if any of the rotors are out of range then the caliper on that wheel is more than likely your culperate. P.S. replace the calipers with ones that have been sleeved with a stainless steel bore sleeve.

 

[petes74ttop]

Hi and welcome to the forum! Now pat yourself on the back for figuring that out on your own. As you found out Vette brakes are easy to fix when you no what to do. PG.

 

[Vettehead Mikey]

The runout issue you found has been around since the first C2 got disk brakes in '65.

The fix is to find out why there is runout, and eliminate it. The stock system can tolerate up to .008", but most owners try to get .003" or less, it's not that hard.

The most common error people make is replacing the rotors, thinking that it's a 'good thing'.