Weird Brake Issue: Rear Brake Locking on Right Side

zachpeakee

zachpeakee

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Really weird issue popped up today while driving around town.
My passenger REAR brake seems to be locking up while braking.

I noticed it first in a parking lot, while rolling about 4 mph.
Stopped for a crosswalk, soft braking, and the passenger rear tire locked & skidded to stop.
(again, this was under 5mph)
I thought it was weird, and definitely un-normal.

Once I got it on the road (about 45mph) I decided to hit the brakes fairly heavily to see what it was acting like.
There was a very strong pull to the right, and could easily tell that the passenger rear brake was grabbing significantly more aggressively than the driver side.

All brakes, drums, rotors, pads, etc were replaced new less than 4 months ago.
(That's not to say that something didn't fail)

Control arms are 4 months old as well, and show no signs of being loose or failing. (checked torque on them tonight to double check, as well as tightened the lock nuts)

This is my first TJ, and my first rear-drum vehicle.
Would love some guidance on the issue.
 
...instead of asking ppl to guess, maybe you should jack it up and lookie see. Maybe check if the adjustment is equal side to side...maybe rotate each rear wheel to see if one is dragging..you could pull tires off look at brake components, maybe oil or brake fluid on linings, leaky whl cylinder or axle seal. all this will give you experience and confidence.
 
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ger0 said:
...instead of asking ppl to guess, maybe you should jack it up and lookie see. Maybe check if the adjustment is equal side to side...maybe rotate each rear wheel to see if one is dragging..you could pull tires off look at brake components, maybe oil or brake fluid on linings, leaky whl cylinder or axle seal. all this will give you experience and confidence.
Click to expand...

I installed everything brand new 4 months ago.
The issue JUST started happening today.
I also did check everything, and nothing stands out as being broken or 'incorrect'.

I was looking for solutions outside of the generic "check your brakes" comment.
Like a possible proportioning valve I could troubleshoot, or possibly any common parts associated with my issue.

*searching for solutions of 'one rear brake locking' brings up a wormhole*
 
Last edited:
zachpeakee said:
I installed everything brand new 4 months ago.
The issue JUST started happening today.
I also did check everything, and nothing stands out as being broken or 'incorrect'.

I was looking for solutions outside of the generic "check your brakes" comment.
Like a possible proportioning valve I could troubleshoot, or possibly any common parts associated with my issue.

*searching for solutions of 'one rear brake locking' brings up a wormhole*
Click to expand...

He gave you advise you need to follow. It isn't a proportioning valve.
If gear oil is leaking on the shoes it will maķe it lock up,if something else is going on it can brake uneven. Get a jack and tools,then get to it
 
When you changed your brakes did you do a full brake fluid flush? If not - as I learned recently - you can push gunk back into the lines when compressing the pistons to refit the caliper on the new rotor. That gunk can sit there until stirred up and eventually cause the piston to get stuck out and not retract when you let off the pedal.
 
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I have had a leaking axle seal cause that issue, sticky wheel cylinder. Did you do a e-brake adjustment post brake work? Adjustment wheel might just be tighter on that side, I am with the group In that the problem is localized to what you may find behind that rear drum.
 
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zachpeakee said:
I installed everything brand new 4 months ago.
The issue JUST started happening today.
I also did check everything, and nothing stands out as being broken or 'incorrect'.

I was looking for solutions outside of the generic "check your brakes" comment.
Like a possible proportioning valve I could troubleshoot, or possibly any common parts associated with my issue.

*searching for solutions of 'one rear brake locking' brings up a wormhole*
Click to expand...

There is one brake line going to the rear, so it must be something in the wheel
 
Rickyd said:
He gave you advise you need to follow. It isn't a proportioning valve.
If gear oil is leaking on the shoes it will maķe it lock up,if something else is going on it can brake uneven. Get a jack and tools,then get to it
Click to expand...

My first pick. Gear oil on the shoes will do exactly what he is describing.
 
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zachpeakee said:
I installed everything brand new 4 months ago.
The issue JUST started happening today.
I also did check everything, and nothing stands out as being broken or 'incorrect'.

I was looking for solutions outside of the generic "check your brakes" comment.
Like a possible proportioning valve I could troubleshoot, or possibly any common parts associated with my issue.

*searching for solutions of 'one rear brake locking' brings up a wormhole*
Click to expand...

The combination valve under the booster gets blamed for a lot of things it can't cause. This is one of them.
 
Granite said:
When you changed your brakes did you do a full brake fluid flush? If not - as I learned recently - you can push gunk back into the lines when compressing the pistons to refit the caliper on the new rotor. That gunk can sit there until stirred up and eventually cause the piston to get stuck out and not retract when you let off the pedal.
Click to expand...

Not that you wrong, but generally the rear wheel cylinders don't suffer as much as the front piston bores in the calipers do. Gunk settles in the piston bore but the other thing it does is harden on the bore walls so when you push the piston in, that traps it and makes it stick. Flushing won't fix that, it only helps with other crap in there that can be flushed out.

Flushing is always recommended, it will not always prevent the issues. For some reason that I don't understand, if you don't flush first, that almost guarantees an issue and if you do, generally they are good and that shouldn't be true as often as it is given how poorly maintained most Jeep hydraulic systems are.
 
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Granite said:
When you changed your brakes did you do a full brake fluid flush? If not - as I learned recently - you can push gunk back into the lines when compressing the pistons to refit the caliper on the new rotor. That gunk can sit there until stirred up and eventually cause the piston to get stuck out and not retract when you let off the pedal.
Click to expand...

Yep. Full flush when everything was installed.

JustDandee said:
I have had a leaking axle seal cause that issue, sticky wheel cylinder. Did you do a e-brake adjustment post brake work? Adjustment wheel might just be tighter on that side, I am with the group In that the problem is localized to what you may find behind that rear drum.
Click to expand...

Axle seal was my first idea.
After looking it all over, it doesn't seem to be the issue, but maybe i'm overlooking something?
I'm wondering if it's leaking slowly while parked, making the issue more prevalent on the first few brake taps.
After it locks up a few times, it eases off, and drives as normal until it's parked for 30+ minutes again.
Which is what is throwing my head for a loop.

Is there a specific way to 'equalize' the adjustment wheel between sides?
Last night I adjusted it per side, and they feel similar when rotating by hand, but the issue is still there.
wanting to double check that there's not some special "step" i'm not seeing.


mrblaine said:
The combination valve under the booster gets blamed for a lot of things it can't cause. This is one of them.
Click to expand...

My thoughts exactly. I initially thought of the valve, but it doesn't make sense for that valve to go and cause issues ONLY on one side.

I'm currently just confused as to what is causing the issues.
Everything checks out in the drum, and nothing seems out of place. No obvious leaks, etc.

-
-

I'm almost considering that the E-brake cable might be binding up somewhere along the way, hence why the issue is most common after parking for awhile. E-brake not letting itself loose, or binding on one side, etc.

I need to do some control arm adjusting today, so I'll get some photos posted for you guys to dissect.
 
Rickyd said:
He gave you advise you need to follow. It isn't a proportioning valve.
If gear oil is leaking on the shoes it will maķe it lock up,if something else is going on it can brake uneven. Get a jack and tools,then get to it
Click to expand...

I'm not disregarding any advice, and I appreciate all the advice.
Just looking for something a bit more in depth than "look and see".

Possibly something that someone has encountered a similar issue with in the past, because everything i'm looking at and seeing is checking out to be okay.

It felt like an improperly functioning proportioning valve to me, but from what i'm seeing (and what @mrblaine confirmed) it's just not reasonable for the valve on the TJ system to cause this issue, now that I see/understand how it's set up.

Going to run to Oreilly's today, and pick up a new drum cylinder.
I'm wondering if mine isn't gunked up and seizing, allthough it seems to operate as it should on jack stands.
Not sure if on-road load would affect that at all, but it's the only thing I can somewhat point my finger to at the moment.
 
zachpeakee said:
I'm not disregarding any advice, and I appreciate all the advice.
Just looking for something a bit more in depth than "look and see".

Possibly something that someone has encountered a similar issue with in the past, because everything i'm looking at and seeing is checking out to be okay.

It felt like an improperly functioning proportioning valve to me, but from what i'm seeing (and what @mrblaine confirmed) it's just not reasonable for the valve on the TJ system to cause this issue, now that I see/understand how it's set up.

Going to run to Oreilly's today, and pick up a new drum cylinder.
I'm wondering if mine isn't gunked up and seizing, allthough it seems to operate as it should on jack stands.
Not sure if on-road load would affect that at all, but it's the only thing I can somewhat point my finger to at the moment.
Click to expand...

Did you replace the wheel cylinders when you did the brakes? Make sure they are the same bore diameter
 
NskLJ said:
Did you replace the wheel cylinders when you did the brakes? Make sure they are the same bore diameter
Click to expand...

I did not.
From what I could understand they were in good working order.

Although, this is my first dive into drum brakes, so the only "knowledge" I have of the cylinders is from guides/youtube videos.
I assumed they checked out fine, just based on what I had read/watched.
 
zachpeakee said:
I did not.
From what I could understand they were in good working order.

Although, this is my first dive into drum brakes, so the only "knowledge" I have of the cylinders is from guides/youtube videos.
I assumed they checked out fine, just based on what I had read/watched.
Click to expand...

Then should be an issue I have seen 2 different diameter cause one brake to apply more than the other. I would pull the wheel and drum to inspect
 
mrblaine said:
back to normal after it burns off the gear oil
Click to expand...

This makes the most sense to me as being the issue.
However, nothing looks to have gear oil on it.
For the most part, it's fairly clean in there.

Do you think it's possible it could be so minimal of a leak that i'm burning it off, it's dripping a bit, and burning off again?

I could leave the jeep in the garage for the day without driving and see if I can catch any drips/leaks...

(as I said, it ONLY seems to be happening after the jeep sits for 30+ minutes or so. Which is the odd part)
 
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