6T9VETT

After having the brakes drag for a while now I finally got around to working on it with a good buddy of mine who is great with cars and vettes.

Initially was told on the forum that it might be a brake line problem or calipers sticking. After removing the wheels, the rotors would not budge an inch. We cracked open the brake line and as soon as the pressure was released the rear calipers released and the rotors turned. We bled the rear brakes and took it for a test drive. Same problem occurred again.

Did the same thing to the front and as soon as we cracked the break line the pressure was relieved and the front brakes released as well. We bled the front lines and again took it for a test drive. Same problem but not as bad.

So this is what we know so far. The brake lines all bled ok and the calipers seem to be in good shape. After driving a very short distance pressure is building up in the brake system and not being relieved, causing the calipers to grab on all four wheels. For the 69 the valves are not proportioning valves so it makes sence that all four wheels are grabbing with the same pressure.

Anyone experienced this problem before? Does it sound like a bad master cylinder?
:banghead: :chevy

vettemack

You say you cracked open the brake line. Did you open it at the caliper or the master cylinder. The rubber flexible brake line are notorious for not releasing pressure, but four of them going bad at all the same time does not sound reasonable.

6T9VETT

For the rear brakes we opened the line where the rubber hose joins the metal line attached to the caliper. For the front, we opened the line at the bleed valve. We got the exact same release of pressure either way. When we bled either front or rear, the brake fluid seemed to flow normal so I am thinking that it is not a brake line problem.


[Modified by 6T9VETT, 4:47 PM 9/1/2003]

bloodvette80

here's an easy test to find out if your master is bad (in your case). when the brakes are locked up, as you described, crack the line at the master. If it doesn't relieve, well then something else is blocking it. because when you release your foot off the brake pedal, the master cylinder reservoir is opened to the lines (to put it blatantly) and there should be no pressure at all.

Scott A

I have had the exact same problem - it's the master cylinder. It was brand new. Swapped it out and the problem went away.

6T9VETT

Thanks for all the help. Will get a new master in this weekend. I'll post the results when I get it fixed. Thanks again. :chevy