Can’t figure out rear drum brake issue

Lowcountryearl

Lowcountryearl

TJ Enthusiast
Joined
Jul 20, 2020
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129
Location
Charleston SC
Been chasing a rear drum brake issue for months. Every once in a while my rear drum brakes sticks, causing excessive heat and vibrations. Both sides stick equally measuring with a infrared thermometer. I can go hundreds of miles, no issues and then it happens again. I have replaced all components of both brakes. Bled the system multiple times, I have to be missing somethingjust don't have the knowledge to figure it out. Master cylinder, brake lines, IDK, any help would be appreciated
 
It was just a thought even though not so helpful :)

What do you use parking on a hill a brick on a bit of rope lol
 
Can you remove the drums and post pictures of both sides?
 
I did on a previous thread, let's assume for the sake of troubleshooting the brakes are properly assembled verified by a local brake shop. I assume the springs are not the only thing that allows the brakes go back to the rest position, is there something else in the hydraulic system that would not let the brakes go back to the rest position?
 
Lowcountryearl said:
I did on a previous thread, let's assume for the sake of troubleshooting the brakes are properly assembled verified by a local brake shop. I assume the springs are not the only thing that allows the brakes go back to the rest position, is there something else in the hydraulic system that would not let the brakes go back to the rest position?
Click to expand...
Does the red brake light on the dash work when you engage the parking brake?
 
Lowcountryearl said:
I did on a previous thread, let's assume for the sake of troubleshooting the brakes are properly assembled verified by a local brake shop. I assume the springs are not the only thing that allows the brakes go back to the rest position, is there something else in the hydraulic system that would not let the brakes go back to the rest position?
Click to expand...
The return springs are the only thing that pulls the shoes back to the anchor pin. Have we verified that the primary and secondary shoes are on correctly?
 
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Lowcountryearl said:
Yes
Click to expand...
The only ways they can self apply other than the return springs being deficient is if the master cylinder push rod is maladjusted too close and the booster has a defective vacuum valve. If the booster moves the diaphragm slightly and causes the pistons to cover the replenishment ports, as the fluid heats up from dragging shoes/pads, it will expand and self apply the brakes because the fluid can't be pushed back into the reservoir like it should be. That will generally not be intermittent and will generally happen faster with the front calipers.

The other thing that may be going on is rust inside the clamp on the rear brake line is expanding and closing off the line making it act like a check valve.
 
~So what would you do next, change the rear brake lines

20201004_123426.jpg


20201004_123416.jpg
 
Lowcountryearl said:
~So what would you do next, change the rear brake lines

View attachment 211846

View attachment 211847
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In your first pic the adjuster cable is not installed correctly, See how the green spring is on the outside of the adjuster lever? That can cause your symptoms.

In the second pic it's installed correctly, with the silver spring holder/bracket/whatever on the outside of the adjuster lever, and the spring running behind it.
 
There's two ways you could slip the spring over the adjuster lever. The first pic is wrong, the second pic is right. It should look exactly like this.

IMG_20200331_152844665.jpg
 
Actually, could be the angle. Just can't see the end of the spring.

After this happened and you pulled the drums, were they really hard to remove? Like the shoes were adjusted out too far even then?
 
Lowcountryearl said:
No, actually maybe a little loose. Seems to be more of an issue in heavier traffic.
Click to expand...

Ok, I'd say that rules out a problem with the adjuster.

The pics appear to be new wheel cylinders.

Would think that a master cylinder issue would affect the front as well. But that's not always true.

Intermittent stuff like this is annoying. I'd probably replace the axle hard lines, see if that does anything, and keep moving up the line replacing things. Just on the general principle that it's old and might as well do it before they rust anyway. I've bought stainless steel line kits from Inline Tube on Amazon before, good stuff.
 
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