The Stovebolt Site Forums The Shop Area Engine Shop one wheel cylinder locks up

Hey all-
I have a 49 1/2 ton. stock everything. I have tried about everything and so far nothing works.
On the right rear wheel the when I apply the brake pedal the wheel locks up.

I have tried-
Adjusting shoes first- slight drag, then backed off 4 clicks, the brake stuck again, so 5 clicks, again so 6 clicks.

I have tried bleeding fluid until it ran nice and clean from the wheel cylinder.

I replaced the brake shoe return springs

I have tried adjust the shoes even further out and it still eventually locks up-

the only thing I have not done is to replace the wheel cylinder.

Any ideas?

Thanks

did you replace the rubber line to the axle?

Bill

one of the few things I have not-
Other than waiting on the responses here I plan on a new hose- and cleaning out that cylinder and using a rebuild kit on it.

Yup, replace that PESKY rubber line to the axle, mine cost me a full day of frustration and curse words a sailor wouldnt want to hear when I was trying to get the new sytem (less that line) bled and adjusted....NEW LINE an WHALLA all was good.
Tim

Why would a rear brake hose lock up one rear wheel specifically? I would suspect contaminated shoes. There is or has been gear lube or brake fluid on the shoes at one time. Cleaning and sanding won't fix them, just replacement,
Scott

I think Scott is right. Check to see if the other side is soaked.

Same problem with my 49 half ton last year. Wheel cylinder? Piston not returning? Contaminated drum or shoes. Try sanding them. Rubber line feeds both sides. On the front I could see that as a potential problem.

When I re-did my brakes on my '47 1/2 ton, one of the wheel cylinders was almost seized. Turns out that someone had put in cups that were too large for the cylinder(1 and 1/4 inch instead of 1 and 3/16 inch)Maybe something to check.

The reason you could get one side bleeding off and the other side not is resistance from wheel cylinder it will prevent flow. Anything in the cylinder not moving at the same rate as the other side, oversized cup, dirty cylinder will cause this.

I had a similar problem with the right rear brake on my '49.
I had rebuilt all the wheel cylinders and they seemed to be working fine.
I inspected my work several times and then one day it locked up worse than usual.
I took it apart and the drum was cracked.
The earlier problem must have been from when the crack was not yet visible when at rest but would expand under braking pressure.

Ray

thanks all- looks like a good saturday project

I had a Honda 750 with a new replacement cup that was too long (as darylbb63 mentions). When the piston retracted, the cup did not pass the relief port. Each squeeze of the brake handle caused the calipers to tighten. By the 3d squeeze the front wheel locked up. Not what you want on a motorcycle! I shaved the cup with a razor blade (I was too poor to buy another) and she worked fine another 60k.

This truck has all the original brake components- it has just had fluid flushes over the years-
I am planning to rebuild/replace the four cylinders- along with inspecting the pads-
yes the back right shoes had brake fluid on them from a leaky wheel cylinder-

So it is a definate candidate for service

I would say you are on the right track Yelostn78.

Even if the pads look good but have been oil soaked, cleaning them may still result in sticky brakes. Might want to consider replacing them.