The Stovebolt Site Forums The Shop Area The HiPo Shop left front brake locking

hello , I have a 1939 2.5 ton Chevy truck , original Bendix brakes on the front , I installed a check valve in the brake lines 10 lbs one for the right and one for the left . I adjusted the brakes evenly when I step on the brakes with a good solid pedal , the wheels stop equally however the left wheel does not release . I replaced the valve with a new one and the same problem , if I bleed the left wheel cylinder the wheel will turn freely. the system has new end cylinder , brake lines , brake shoes and hoses . any suggestions ? thank you 1pette1

Forgive me, I'm not familiar with '39 brake configurations specifically, but I have built many brake systems and installed many check valves. I'm curious why you're using two check valves in the front - typically there is just one used for both front brakes, installed on the main brake line before it splits to R and L. Could your check valves be doubling up on one another?

If the brake system has two front brake lines exiting the master cylinder then two check valves are needed. I would double check the rubber hose on the locking brake side. Internal swelling of that line is in my experience the most common problem. Bad parts are becoming way to familiar.

I agree with beltfed. I had a '70 Monte Carlo that had that problem sporadically. I was told by an old mechanic to change both front rubber lines as people tend to snap vice grips on them when doing brake jobs to try and save having to bleed the brakes afterwards. This can cause the inner liner to crack and flop down when pressure is applied and then blocks the fluid from releasing when you release the pedal. Once I did that I didn't have any more issues.

Have you made a change of the master cylinder or done some other type of modification to the brake system? It should not be necessary to add check valves to an all stock system since there's already one built into the master cylinder. The only purpose of a check valve is to hold a little pressure in the brake lines to prevent air from being sucked past the wheel cylinder pistons from temperature changes, etc.
Jerry