sticking wheel cylinders?

I have just completed an overhaul on my brake system on a 1959 CJ5 with 9" drum brakes. The only things not replaced were the drums, three of the four wheel cylinders (more on this later), and the shoes, which were not excessively worn.

After bleeding the brakes and doing a quick functions check on each wheel, I test drove it. Upon return, I noticed each drum was somewhere between warm and hot, and discovered the shoes on each wheel were lightly dragging (they hadn't been before). Each cam adjuster is turned to the furthest inner setting so the shoes have as much clearance as possible. Then I took the drums off and had the wife pump the brakes a couple times, and noticed that only one shoe is extending at a time, and alternating between the front and back every few pumps.

At this point, I'm guessing a wheel cylinder issue. As mentioned, 3 of the four wheel cylinders are original, although I did install rebuild kits in those 3 (new cups, springs, and dust boots). The fourth cylinder is a new one which came assembled. It sticks exactly like the other 3. Has anybody had a similar problem to this? I did lubricate each of the rebuilt cylinders lightly with brake fluid, but did not take the new cylinder apart. If it was just the old cylinders sticking, I would have figured my carelessness allowed dirt or something to cause the sticking, but since the new one sticks too, I'm wondering if I just missed something along the way.

Thanks for the help.

 

with drums off . it's quite possible for one piston in a wheel cylinder to move before the other . but I also had some new cylinders sitting on shelf for some time and they were stuck . took them apart and ran a hone through them

 

I had heard that shoes could over-extend with the drums off, but would it also cause one shoe not to move at all?

 

I should add that the movement of each brake shoe was erratic at best...I would adjust all four wheels so they all seemed to be spinning freely, then pump the brakes a few times and re-check the wheels. The shoes would then be dragging. I figured the only way to confirm that the shoes were actually retracting fully was to take the drum off and watch their movement. Seems like they just weren't retracting fully.

 

Definitely possible, even likely.

I would try driving around the block, stomping the brakes hard a few times, both forward and backward.

Then see how they adjust, and how they function.

 

Usually if I want to check function like this with the drums off, I've used either those big rubber bands like moving companies use to hold moving blankets on, or a chunk of surgical tubing, to just tie around the shoes, and it 1) keeps them from over extending and 2) provides a little more to push against, and usually verifies that both sides of the wheel cylinder piston is moving. Assuming you're not just stomping on the pedal that is, I'm sure theres enough hydraulic force there to break the rubber stuff if you bang on it too hard.

 

Return springs are all new, as is the master cylinder (a couple months old...been doing this job in phases.) All the lines are new as well, both steel and rubber.

 

So in normal operation, does one shoe extend, contact the drum, and then continued hydraulic force extends the other shoe out? I had always pictured them extending together but one at a time actually makes sense.

 

I was going to mention the flex lines but you covered that. Whichever shoe with the least resistance will move first. About the only thing left to my mind is the MC. Make sure the actuator rod can return properly and good luck.

 

Try adjusting the shoes properly then Drive it. Wear on the shoes and in the drums plus having the shoes adjusted all the way in could be overextending the wheel cylinders causing the pistons to not return properly (stick).
And yes, with the drum off the wheel cylinders can overextend and blow the pistons out, so be very careful about stepping on the brake with a drum or caliper not installed.

 

Another thing to check is the brake shoes themselves. In some applications, linings are all the same length on all the shoes, while others are longer and shorter- leading and trailing shoe.
If your shoes have different length linings, make sure there is one of each at each drum, and they are in their appropriate locations.
This could be a case of erratic braking if they are not properly installed. I have seen this occur more than once.
-Donny

 

The shoes on the front wheels seemed not to retract as far as they should, so I released some pressure from the bleeder valve while squeezing in on both shoes simultaneously. Then I re-adjusted all the shoes again, bled the entire system again, re-checked the master cylinder pushrod adjustment (it seemed ok) and everything now it all seems to be working fine. Not sure exactly what changed, but sometimes it just helps to take a day off and come back to the problem fresh. Appreciate the help everyone!