hey. having some issues. i tried to search but didn't come up with much. I recently got my A back on the road after doing some work. I'm using 42-48 ford brakes all around. a 70s ford truck M/C with a 1 1/8 bore size. (i think). the front driver brake keeps locking up on me. the cylinder was replaced... still did it. the hose was replaced.. and again still does it. Could the return spring on the shoes be too weak? im not sure what else to check. when the drum is off and i push the brake pedal the drums move out and stay out unless i give it a sturdy whack with a hammer. im just sort of rambling haha but please throw some ideas my way.
It's probably not the driver side at all. Check the pass side wheel cyl. and see if the pistons are frozen up. If the right side don't work at all the it makes sense the driver side when it makes contact it would grab and turn you left.
How are the lower pivot points? Grease on the double D inserts? Or are the bronze inserts thin and the shoes binding on the retainer plate, retainer plate too tight ? Also older brake hoses can come apart inside, and act as a check valve, not letting fluid pressure back out.
Both of the above posts are great. In internally collapsed brake hose will make you crazy. Get a helper, jack it up, apply the brakes while the helper spins the wheels. Start with a light then a medium pedal. But when in doubt, replace hoses in pairs. Also get new spring kits just to rule them out. If the wheel cylinders are of unknown age, replace them too. Of course, you've ruled out grease or brake fluid on the shoes. Bob
thanks for the ideas guys. like i said i have replaced the driver side wheel cylinder and hose. i will re-grease everything too so i can make sure nothing is binding. now is it possible that the passenger side could effect the drivers? since i didnt replace that side with new parts also?
yeah it sure can just like Pist n broke said. id replace the other side hose and cylinder , do the springs kits and lube all the correct parts up hopefully that il do it.
When you installed the 70's master cylinder did you also add some inline residual check valves? Were I you I'd first just lift the front wheels off the ground, spin the right side wheel and push the pedal. Does that tire stop spinning? The Wizzard
im pretty sure i don't need the valves. this is a new problem. it worked fine before. i think what i will do either tonite or tomorrow is check for binding at the bottom pins. im thinking maybe the shoes are rubbing the backing plate to much? maybe space them out abit more with thin washers? grease it up. the only difference between how the car was and how it is now is that im now using the same ford brakes in the rear. before i had lincolns but i put a A rear in and now have to use ford brakes. the back seems to be working fine. basically what seems to happen up front is that the shoes go out and just dont wanna come back in. if that makes sense? thanks alot for the help guys. i appreciate it.
Some times a small amount or grease on the lining will make a self-energizing brake very grabby. I once had a 57 Chrysler that would lock up a rear wheel at the slightest touch. It turned out that a rear seal had just started leaking and contaminated the brakes in that one corner. A new seal and fresh shoes cleared it up. I had some brakes that acted exactly opposite of that when contaminated- they would slip more and require much higher pedal pressure for the same stop. How likely your brakes are to get grabby due to contamination depends a lot on the degree of "self-energizing" that is built into the brake shoes and their mounting points or pivot points. The more self-energizing they are, the more sensitive they are to anything that changes the coeficient of friction even slightly. Decades ago a friend had a stock 52 Chevy that on damp foggy days would be extremely sensitive to a very light touch on the pedal and become very sensitive and "grabby", but would act normal on dry days. You might want to check the shoes for greasy fingerprints or the inside of the drum for oil or gunk. ?
Yes oily shoes will grab. Did you have a grease or brake fluid on the DS shoes? If so you will most likley need to replace. DO NOT shim the shoes away from the backing plate but make sure the pads on the BP where the shoes contact are smooth with no ridges. If you replace shoes on one side do both same for the springs.
I agree with the greasy fingerprints causing issues. I used to see a lot of that with brakes that guys did themselves and then brought to me when they didn't work right. Also are the primary and secondary shoes installed correctly on both sides of the car? Primary to front side secondary to the rear. Primary being the shoe with shorter lining or sometimes a different lining composition and marked on the side of the lining. Check the backing plate (s) for wear ridges where the shoes ride against them. Quite often they get worn there and that area needs to be dressed up and smoothed off so the shoes will slide freely. That can be done with a gentle touch with a flapwheel usually. Then just a thin smear of grease on it. One more thing, the working on brakes rule of thumb is to never push the brake pedal with the drum (s) off as it will let the pistons move out of the cylinders too far and leak or stick.
Mr48Chevy : Read the original post ,he is running pre 48 ford brakes . Those are NOT self energising so LONG shoe goes to the front. Rear shoe originally had the shorter lining but a lot of relined shoes nowadays have long lining on all shoes.
I've also seen shoes mixed up in any combination possible, 2 shorts on one side, 2 longs on the other side, etc..could it be that simple? Bob
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