Rear breaks stick

Good morning all.

92 Sport
4.0 HO
AW4
NP231
ABS - Pump relay is removed

I have had nagging issue with my rear breaks. I have solid breaks for a while after I start up my XJ. After a bit, like 20 min or so, the breaks begin to feel softer and the pedal does not return to its full unpressed position. The rear breaks will also start to stick. To release them I have to put my foot under the break pedal and pull up on it.

An annoying side effect is the dang break lights will stay on if the pedal is not in the fully unpressed position.

I am just looking for a starting place to look at. I am thinking it may have something to do with vacuum since the breaks start off just fine.

Thanks in advance for your input!

It sounds like there is something wrong with your brake booster assembly. I believe there is a spring in there that returns the master cylinder and brake pedal to the "non braking" position when you let your foot off the brake. Springs can wear out or bind up and I think your brakes would have different issues due to loss of vacuum than what you have described. Thats a theory as I've only looked inside a brake booster and not actually taken one completely apart. That is where I would recommend to start looking for issues. You could consider upgrading to a WJ brake booster or 96+ with the dual diaphragm if you're going to replace it.

OkieXJ said:

It sounds like there is something wrong with your brake booster assembly. I believe there is a spring in there that returns the master cylinder and brake pedal to the "non braking" position when you let your foot off the brake. Springs can wear out or bind up and I think your brakes would have different issues due to loss of vacuum than what you have described. Thats a theory as I've only looked inside a brake booster and not actually taken one completely apart. That is where I would recommend to start looking for issues. You could consider upgrading to a WJ brake booster or 96+ with the dual diaphragm if you're going to replace it.

Click to expand...

Thank you very much for your insight. I will search the WJ brake booster threads.

http://www.naxja.org/forum/showthread.php?t=983426

This can be found in the FAQ and writeups forum here at . There are a lot of other great articles in there also.

check your rear spring hardware carefully as well. As I understand, the springs should be responsible for retracting the shoes and forcing the fluid back toward the master cylinder. If the springs are weak or there is a restriction in the hydraulic lines (pinched line, deteriorated hose, plugged proportioning valve) you can get the symptoms described.

OkieXJ said:

http://www.naxja.org/forum/showthread.php?t=983426

This can be found in the FAQ and writeups forum here at . There are a lot of other great articles in there also.

Click to expand...

Thank you for the link!

Shorty said:

check your rear spring hardware carefully as well. As I understand, the springs should be responsible for retracting the shoes and forcing the fluid back toward the master cylinder. If the springs are weak or there is a restriction in the hydraulic lines (pinched line, deteriorated hose, plugged proportioning valve) you can get the symptoms described.

Click to expand...

I will check the springs tonight after work.