After getting my 68 cat back from the shop; engine rebuild, radiator and transmission serviced, and the brake booster was cleaned and painted, I began experiencing an issue with the front disc brakes. They continue to lock up requiring me to release the pressure on the front brakes by bleeding either of the front brakes. This is only a temporary fix as after applying pressure to the brake pedal 15-20 times, the front brakes remain engaged. The brakes appear to begin remaining engaged with each stopping motion as the tires will rotate less freely after each stopping action. Since it is an older vehicle I began with replacement the master cylinder, brake distribution block, all the rubber brake lines, and brake fluid. The problem persists. Before suggesting I return to the shop, 1) I had to relocate across country and my 68 was shipped to me once it was running and 2) the shop owner retired and closed business. Some of my research has also pointed towards the brake booster as being an issue. I don’t understand why fluid pressure to the front brakes is not released once the pedal is disengaged. As assistance would be greatly appreciated.
This happened to me on my '70 a dozen or so years ago. Replacing the front calipers solved the issue. Since you are throwing parts at it…
The rod between the master cylinder and the booster is adjusted too long. It needs to be just under 1"
What Bill says is the likely cause. Simply remove the master cylinder and adjust the rod length.
Also the 1" dimension is the amount the rod protrudes beyond the booster and the spacer. The entire rod length is much longer.
Thank you for your input, I’ll check those. Your assumption about throwing parts at it is incorrect: the hoses were breaking down, both master cylinder and distribution block were inoperative . Personally, I find it appalling when shops want to just throw parts at a problem. Thanks again.
The push rod was indeed too long. It was shortened, re-inserted and after almost 100 stops, the front tires continue to operate normally. Thank you gentlemen for your assistance.