Thanks for the input. I guess I should have mentioned that I was getting air into the system, on jacks and the car not moving. After I installed the new master cylinder, and still was not able to get all the air out of the system and not being able to find any visible brake fluid leakage, I started from the master cylinder and determined that the problem I had, seemed to affect the whole brake system, not just the front or just the rear brakes. The only other common component besides the master cylinder is the portioning valve, which in my case was the problem. For those that do not know what the valve does or is located, it is located directly beneath the master cylinder. There are two lines going in, one from the front of the cylinder and one from the back. From the valve there are three lines, two going out to the front brakes and one to the rear brakes. On the line going to the rear brakes there is a fitting, that looks like it has a one way safety valve. This fitting was actual loose, allowing air to come into the system. I now know EVERY component, line, fitting, and valve on a 1975 corvette. So I guess that's the positive note. TWO NOTES, 1) If you don't have a set of line wrenches, purchase a set. They are about 24 bucks at Sears. These fittings are easily rounded off and it will cost you a lot more then 24 dollars when you have to replace brake lines and/or have fittings. 2) Soak the fittings with some penetrating oil, before starting, as they will probally be rusted in place. HAPPY Vetting...........





|UPDATED|12/16/2002 2:23:55 PM|/UPDATED|

Congrats on finding the problem Bill...!!!

I've had my share of problems with the brakes on "The Toy", but you're several levels above me in the knowledge department now. Good tool tip also!

it is called rotor run out. your rotors are pushing air back into the lines with each turn. check for run out with a dial indicator. no more than a few thou, will pump air. i know this first hand.