Help With A Brake Problem

I'm working on my '73 with, as far as I know, factory drum brakes.
I'm having a problem with the right front brake.

I had the body off the frame and had completely removed the master cylinder. Now, the body is back on the frame, the master cylinder is installed and the brakes have been bled.

Before I got the jeep the drums were turned and new shoes installed. I did a visual inspection, everything looks serviceable. When I pump the brakes the right front acts as if it is not releasing. Or, the self adjuster is actuating and over-adjusting that brake assembly.

I had my wife pump the brakes while I held a screw driver on the adjuster wheel, it did not move.
Thinking it still had pressure on it I opened the bleeder but it did not free up the brake, i.e. it did not release the pressure.

There was some muck in the master cylinder that I cleaned out the best I could before installing and bleeding it, however some was in the cylinder inlet port. Is there anything in there that could be hung up with muck and causing this problem?

The left front is not seizing like this so I don't think it's a problem in the entire circuit.

I'm trying to not buy more parts or do more work than I need. If it's just a bad brake hose I'll gladly replace it, however I'd like to confirm the problem first if possible.

 

"Muck" is not a word you ever want to use about a hydraulic brake system. It should be surgically clean.

Muck in the wheel cylinder? Rust can easily form in them, since the fluid is hygroscopic. How much more "muck" might be inside the cylinder bore, jamming the piston(s)? Or about to ruin a seal and cause a failure?

Wheel cylinders are very little money, if that is indeed the source of the trouble.

 

I agree check wheel cylinder to see if in fact . both pistons move
also over time brake line hoses then to swell inside . not releasing pressure

 

I hadn't considered a jammed piston, thanks.
When I bled the brakes I flushed them until the fluid was clean but there may be residual muck in there causing something to stick.

 

I had hoped to prove the swollen brake line theory when I cracked the bleeder screw, trying to release the pressure.
When I got no spurt of fluid, and the brake didn't release, I figured there is something else going on.

A stuck piston due to muck could be it.

 

If you are getting fluid through the brake line then i would move to the wheel cylinder. They are pretty cheep i think i got mine for my rear for under $10 a piece.

 

JMO - I would replace everything that is available - cylinders, hardware, self-adjusters, cables, pawls, hoses. Parts for these brakes are not expensive. Pull the cylinders and throw them in the trash. Replace everything that is available. Cheap insurance.

Strip them to the backing plates and put back everything new that you can, and paint the rest. Inspect the backing plates for grooves. A little grease on the "plateaus" will help prevent the shoes from grooving the backing plates.

Put everything back in the right orientation. Left is the mirror image of the right, and the self-adjusters are handed too, left and right. When you pull the self-adjuster cable, the pawl should climb the toothed wheel and tighten the self-adjuster when released.

 

Thanks, it was a stuck wheel cylinder. I had to use a C-clamp to get it to move.
I'd never encountered that before. I did a lot of brakes when I was working on cars for a living but they were all running when they came to the shop.

This jeep had been abandoned, I bought it from the property owner who knew nothing of it's history.

When I saw the turned drums, new shoes and decent looking hardware I assumed the wheel cylinders were good. This one was dry and rusty inside.
I did everything new on the rear, because it was missing everything on one side when I got it home. Now the front will be getting all the new bits that Tim mentioned.

I'll disassemble the master cylinder and see how it looks, if it's bad I'll replace it too.

 

I opened up the master cylinder off the '74 (I thought it was the better of the two), thinking I'd clean it up and replace the one on the '73.
It's filthy and will need a rebuild kit. I figure the one I installed in the '73 is probably just as bad, I'll pick up a rebuilt unit.

 

My experience with rebuilding cylinders has been maybe 50%? Probably a bit better than that, since I remember the ones that fail more. Looking on the RockAuto site, both Raybestos and Centric master cylinder are less than $40 new, and no more expensive than the reman they show. Raybestos is a good brand, and the Centric brake parts I've bought have been good. The repair kit is more than 50% of the complete new cylinder. I'd spend the extra $20 for a new name-brand master cylinder. Brakes are the wrong place to go cheap.

 

Yeah. I used to rebuild my cylinders, honing them and all. But back then a rebuild kit was way cheaper than new parts, and you could buy lunch for a dollar.

Especially with a Master, I'd buy one complete. Are rebuild kits even available anymore?

 

Thanks again Tim. I keep forgetting about Rockauto, I have a credit there I need to use.

I have a reman on order through O'Reilly's, it should be in today. I should get one ordered through Rockauto for the other jeep, then it will be on the shelf if I have a problem with this reman.

Pete, Napa lists a rebuild kit for the master cylinder. I tried to rebuild one once years ago when I was poor and in the service. The next payday I ended up buying a new one anyway.

Years ago I bought a new one through 4WD Hardware for my first CJ7, it only lasted a few years and failed on me while I was away from home on a trip. I ended up with a Napa reman at that time.