Thread: Brake problems

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Another thought, is the brake pedal returning completely to a relaxed position or is it possible it's leaving pressure on the master? On my truck I needed to install a return spring. I do have a booster but the weight of the pedal assembly kept just enough pressure on the master cylinder to cause the brakes to drag....Just a thought

Hi guys thanks for the replys. At first I thought my problem was the rod going into the cylinder but I don't think that's the problem now. I did some playing around today, and I think that the problem is the residual valve. Perhaps my master cylinder already has one built in. today i got the brakes to the point were they were locking up, I then opened the brake line up after the residual valve going back to the master, the pressure never released at the calipers. I then reconnected blead the lines got them brakes locked up again and opened up the line just before the residual valve, and long behold the wheels spun freely again. I'm convinced that it's the residual valve holding to much pressure in the line. tomorrow I will rerun a temp line eliminating the residual valve and see what happens. I like the idea of just drilling out the internals of the residual valve rather than rebending/crimping new lines. thanks for the advice I'll let you know how it goes.

Yep, your problem sounded exactly like what we had going on. After gutting the residual valve the problem went away. We did the same test you did, and found there was still pressure at the wheel when the brake was not being applied. To be honest, I'm not sure most applications even need one. I know they are supposed to be used where the master cylinder is lower than the wheel cylinders to keep the fluid from draining back, but ours are working fine now without one.

Don