Ok so ive got a '29 A ive got an under the floor master, wilwood prop valve and 10 lbs residual valves early 39 drums up front and later bendix style in the rear and it stops good enough. After i drive a bit itll feel like im draggin a boat and the pedal will get really hard. Sometimes itll let go sometimes not and when its taken on this behavior itll leave the brake lites lit l. the brakelite switch is on the prop valve just off the master. If it sits the condition will subside. Hard to tell if its draggin all 4 when its doing it. Im so irritated when i get home i havent jacked it up and spun em. I suspect a bad rubber line swelling but everything is new.. Any suggestions before i just tear it apart. Thanks P.S. i dont have a return spring on the pedal but when it builds this pressure the pedals all the way out. It seems somethings swelling or ???
usually this s caused by no free play in brake pedal. shorten rod that goes into m/c what happens is brakes are staying partially engaged ,hence the brake lite staying on. May have to install return spring tom
Crack a bleeder to see which end the problem lies. Which end is the brake switch assuming it's hydraulic?
You always NEED a pedal return spring, and about 1/16" free play in the input rod to the master cylinder.
A friend os mine suggested cracking the bleeder my brake lite switch is up front on the prop valve i tgink my problem lies in the front.. Im gonna look into the free play first its strange it creeps on after ive been driving a bit..thanks
A little explanation on what the guys are saying. With no return spring the weight of the pedal assembly puts a bit of pressure on the brakes. The spring pulls it back so there will be just a little freeplay between the push rod and the piston. The adjusting the push rod, same thing, you have to have that bit of free play or it can push the piston just enough to cover the return port between the cylinder and the reservoir not letting the fluid go back in.
Ok so last nite i adjusted the rod back until ive got the slightlest play but it was late ive gotta take the car around town as the problem comes on after driving a bit i can see that theres some movement in the pedal before the lites lite up so its not holding pressure the way it was but as i said after a quick run lets see. As for the return im goin to install/make one but im running a later style master and i mention that because on later cars ive never seen a return spring i can see where it cant hurt but i guess i assumed they were build in the later style mast cyls.. Thanks for the help ill let u know in a day if ive made any progress in regard to the free play i can tell u i was snug on the master i dont remember setting it up that way when i did the brake system. Thanks again
I encountered the same situation and found after an extensive search that the push rod was nor exactly 90 degrees to the piston and would drag slightly on the rim of the M/C and after a short while keep the brakes applied. I would open a bleeder and it went but always returned until the M/C was squared. Warren
Another thing to consider.... Is your exhaust close to your master cylinder? I’ve had to wrap one with heat tape to prevent the MC from getting hot and expanding the fluid.
The reason I asked what MC you’re running is there are a few with built in residual valves... if you’re running one with an additional residual valve inline that could be your issue Sent from my iPhone using The H.A.M.B. mobile app
It also can be a brake hose failing. If it's only one front or both rear wheels, check the rubber brake hose going to that wheel. When they fail the inside comes apart and acts as a one way valve. It lets the fluid under pressure go to the brake, but not back to the master cylinder.
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