i replaced a master cylinder on an 89 iroc w/ the pbr setup because the rear brakes weren't working at all. can't exactly get an emissions test this way. anyways, before i replaced it, the rear brakes weren't working at all, just the emergency brake did. now with the new master cylinder and the car in drive and the rear jacked up, the rear tires are slowed down significantly when the brake is applied, but won't lock up completely without the help of the emergency brake. First question, is this normal? the brake system is fully bled, and there are no leaks. could there be a problem with the proportioning valve?

 

Are you still running the '85 prop valve? I'd change it out too just to be sure. I'm sure someone in here will say that you need to install an adjustable prop valve to help.

Ed

 

no, this is a seperate car from my 85. its an 89 iroc that came with the pbr setup, but the rear was swapped by the previous owner from i think a 2.77 to a 3.70 9 bolt rear. everything else should be the same besides the rearend/gears. i do have another proportioning valve in my garage that came w/ a 3.27 rearend from an 89 TA, should i just try that one? are any of the stock prop. valves adjustable, or just aftermarket ones?

 

I'm having the same problem on my 89 GTA. Master cylinder was just changed, and the prop. valve as well, flushed, etc.
Rears still aren't working. Any ideas anyone?