I have put a new master, traded out Abs units, new lines and blead the living crap out of them.

The car is an auto with a basicly stock converter and a raised idle (because of cam) and will not stop the rear tires on the emissions dyno. So because of this i cant test, let alone see if it passes

I just ordered caliper rebuild kits for the back, the pads are new, but the roters arnt. The emergency brake will stop them ( up on jack stands) and hold. But the pedel only slows, and barely stops them for a sec and then they take off spinning.

I posted this a while ago in the brakes section, but got ( bleed the brakes) so i will try it here.

This is driving me nuts and puting a hold on all other plans.
Any Help would be awsome
Thanks Faded

 

I had the same exact problem with my 89 IROC, also discovered at inspection time, turned out to be the proportioning valve.

 

Yeah, thats what i thought too. But ours on a 4th gen is one with the abs unit and I put another one on. so unless they were both bad. I am gonna replace the line and T at the back too.

 

Here's another thought -- could one or both rear calipers be siezed up? I had a Toyota front caliper do this but with ~70% of the braking done by the front wheels, it warped the rotor real bad. With the proportioner reducing the pressure to the rears, it might have too much drag on the caliper piston to clamp the rotor tight enough.

The rears on the Toyota had hardly any wear on the shoes after 4 yrs because the adjusters had siezed up, too. But those were drum brakes so I don't think the adjusters apply to rear calipers.

 

Yeah, my next plan of attack was to rebuild both calipers. I think I may have compressed them too much when I did the brakes last march.

If it helps, when bleeding the rears there is a quick spurt followed by not too much else ( not nice steady stream ).But there is no air, I confirmed this with a vaccume pump and clear hose.

 

I'm sorry I have to say it. You have rear brake problems so you work on everything except the rear brakes! Sorry again.
To the problem, I hope you don't mean you accually compressed them? The rear brake pucks are threaded back into the calipers, clockwise I believe not pushed. So you may have broken the ratcheting mech. that keeps them against the rotors. You'll find out when you rebuild them.

 

Screw style, hummm dont think the were. But hey could be wrong. As far as not working on the rears when your not getting good fluid pressure to the back, one would usuly look at the Hydraulics .

 

My 89 Iroc with rear disc, the piston is screwed back into the caliper, but my 1994 TA they are pushed back in with a "c" clamp.

 

It's all a blur. I've done so many different years and models I sometimes get them confused. So, how does your emergency brake work? Do you have the baby drum inside of the rotor like the old Vettes?

 

As Frank pointed out, I'm probably wrong on this any way. So what do I know. Good luck on getting them fixed. Doesn't seem like there's much left to change.

 

I know it gonna be the freaking last thing I do.

I got the only rear hose I didn't replace on the way, some caliper rebuild kits and maybe new roters. hopefully that takes care of it.