Hi all.
I have been having some issues getting my brakes working properly on my '76 L48. After reading most of the other posts on this fourm, it seems that I have all the symtoms of rotor "run out" I have replaced all the calipers, hoses, and master cylinder. Oddly enough, I can only get good pedal during brake bleeding after bleeding the back brakes. After I bleed the front, the pedal goes away. The back have new pads, but the front doesn't. Would that indicate the "run out" condition that many people are talking about? If so, is there some place that sells just the replacement pistons and O-rings? I really don't want to buy another 4 calipers after replacing them all last year.

Any input would be a great help.

Thanks.

Have had simular problems. Found that any rotor runout over 4 thousands will create air in the system. I installed new rotors and replaced the pistons in the calipers with stainless that uses an actual O-ring seal.
The new pistons do not use the spring behing the piston, therefore eliminating the pumping action that causes the air. However, you must use a caliper that does not have any runout

John73

Hi

Yes, sounds like air sucking due to runout problem.
Yes, you should get the VBP O-ring conversion kit.
It's 125 $ and includes all new pistons with O-rings, dustseals , caliper bolts , pad pins, bleeders etc.
It even contains new piston springs, wich I suggest not to install.
Installing the O-ring conversion kit solved the problem on my car. Run out was measured to be still within limits, but the old lipseals still didn't like it.
The lip seals should be forbidden for this non floating calipers.

Good luck. Gunther

Thanks guys.
I've replaced a lot of brakes on different cars, but I had never heard of the "run out" and/or "air pumping" issues before. I will definetly be consulting these Forums before I try fixing other problems.
Vettes just seem to have very specific issues, even when compared to their GM counterparts.

Thanks again for the advice.

Dave K