I apologize in advance for adding yet another braking question, but my problem seems a tad different.

Front right was locking up under medium to firm application of the brakes, so much so that it would lock up and it felt like the only wheel getting ANY braking power. This happened shortly after (~300 miles) I changed the calipers (rebuilds), rotors, pads and fluid. I bled the system again and all seemed good, really good actually for about 3 weeks, or about 500 miles.

Now today, again, the right front is locking up. Strange in that after bleeding it works great then has a problem. Any thoughts?

The patient:
2000 Jeep Cherokee Classic
85k miles
non-ABS

 

change brake hoses

 

I'm willing to try. Easy enough and cheap enough. Pressure seemed fine on both sides when I was bleeding but you never know I guess.

Some additional info:
The thing that prompted the brake change was badly warped rotors. Then I noticed that the front right inside pad was extremely worn compared to the outside. So I decided on new calipers, maybe I should have troubleshot a bit better.

 

brake hoses can collapse internally letting pressure into the caliper and not out... I never change calipers without hoses, I will refuse the job from a customer before ill do that..

 

Okay, time to revisit.

Been trying to solve this issue for some time, with little success.

I changed both front brake hoses, new banjo bolts with new crush washers, fresh brake fluid. Right front still locking and skidding way before any other wheel with moderately hard pressure on the brake pedal. Releases just fine, just seems to be getting more pressure at that corner under braking. I'm at a loss. Brakes are well bled, pedal feel is good.

So... new (rebuilt) calipers, pads, rotors, banjo bolts, crush washers, fluid, hoses. Same problem. <Sigh>

 

Have you checked knuckle for grooves that can cause pads to get slightly crosswise and lock up?


Your post is like deja vu, as my right front locked up yesterday for the second time in several months but I have new hoses and knuckles with everything else?????

 

At the master cylinder is a proportioning valve to distribute pressure appropriate to R and L front and then the rear. Maybe the R front line is clogged?

Just throwing this out there as you have already checked everything else at the wheels... It may also be an issue with the ABS system.

If the issue still eludes your troubleshooting efforts, you probably should take it to a good shop. Brake problems can be dangerous.

 

My XJ brakes lock up all the time with any moderate braking.
I thought this was just normal XJ bonus feature.

 

X2 on this.

 

That should not be happening, even on a non-abs model. You should have to "stand" on the brakes to make that happen.

 

X3. I had this same problem.

 

Has anyone checked for oil/grease/brake fluid contamination on the pads? It does not take much, a drop or two will cause early brake lockup.

Disassemble and spray liberally with brake parts cleaner to be sure this is not the problem. Inspect for leaks and insure that the surrounding areas are free of grease and oils/fluids as well.

 

I'll check for contamination, quite possible. Also saw in previous threads that a few had a power steering line leaking into the brakes on the driver's side? Can't see a PS line that would be close enough to do that, can someone shed some light? Also will check those knuckles thanks

Also, new thing I noticed is that the "speed" at which I press the brake pedal triggers the skidding at well even at medium pressure. If I hit the brake pedal down fast, even if it's just medium pressure the right front locks up. Does this shed any light?

 

I think I misread your original post. You seem to be saying that the right front locks up on application but always releases normally when you get off the pedal.


I don't know if this makes sense, but I wonder if this might be more of a case of the left front not applying properly as opposed to right front locking? I will have to think about that for a bit.