VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 Brakes won't release

Hello everyone,

I am restoring my father's 47 Chevy Convertible. We are 95% complete. The current problem is that all four brakes won't release after we adjust the brakes. The master cylinder has been rebuilt along with all brake cylinders along with new brake lines. We adjust the brakes and they seem fine until we drive it a few blocks and the brake pedal becomes very stiff with no travel and the brakes on all four wheels are very tight. We have gone through adjusting the brakes a couple of times and each time the brakes get tight and the pedal is stiff with no travel.

Any thoughts on what is causing the problem and/or what to do to fix the issues? It is like the hydraulic pressure won't release.

Sounds like the piston in the master cylinder is not coming back far enough to let the fluid return. An easy check is when they get tight crack open a bleeder on a wheel cylinder, if that releases the brakes then check the adjustment on the rod going into the master cylinder.

Dens41 is going good advice. It sounds like the piston is not coming back far enough to uncover the return port to the reservoir.

There should be a small amount of free play before the brake pedal starts to push on the piston in the master cylinder. Look in the shop manual for how to adjust toe board clearance.

instructions are in the shop manual.

I agree with all the advice above. Another consideration to consider is that when adjusting the wheel cylinder it is generally best to lock the wheel from turning using arm pressure on the casing then back off 4 or 5 clicks until the wheel will turn but a little shoe to drum facing is heard. If the suggested help of adjusting the travel of the MC innards doesn't help you may consider your wheel cylinder adjustment.

As Gene pointed out, all this is in the manual which is full of good stuff and well worth the price..

Good luck.

Charlie

As your master cylinder has been rebuilt, was it sleeved? I had a 1939 master cylinder sleeved, but the second hole was not drilled into the sleeve for the compensation port, the compensation port is only a very small hole, and inserting a checking wire is needed to ensure it clears the piston front cup. The other hole is the fill hole which is a lot larger than the compensation port. Both are at the bottom of the master cylinder reservoir.