Front right brake locks up

[wmctbrown]

New member here. 2000 TJ auto 4.0L. Original problem was right front brake grabbing when light brake pressure applied. Replaced calipers, pads and bled system. Same issue. Replaced front hoses, bled system, same issue. The front right caliper is releasing. Only brake affected is front right. Any help will be greatly appreciated. I don’t have much hair left to pull out.

 

[Chris]

New member here. 2000 TJ auto 4.0L. Original problem was right front brake grabbing when light brake pressure applied. Replaced calipers, pads and bled system. Same issue. Replaced front hoses, bled system, same issue. The front right caliper is releasing. Only brake affected is front right. Any help will be greatly appreciated. I don’t have much hair left to pull out.

Sometimes, issues with the master cylinder can lead to uneven brake pressure. It might be worth checking if the master cylinder is functioning properly.

Double check that the brake pads and calipers are installed correctly.

A stuck piston in the caliper can cause this. You say the calipers are new, but that doesn't matter. If you bought them from a local auto part store then there's a good chance you got a bad caliper. It's happened to me before with cheap, Chinese parts.

 

[MBDIAGMAN]

Over the years I’ve seen a few rubber brake hoses flake off on the inside and a piece of rubber becomes a one way valve, trapping pressure against the caliper or wheel cylinder. The car is over 20 years old and rubber brake lines are cheap. Replace them, bleed the system, and you may very well solve the problem.

 

[KennethS]

Replaced calipers, pads and bled system. Same issue. Replaced front hoses, bled system, same issue.

So the issue persists with new pads, calipers, and hoses. There's not many parts left in the braking system.

 

[dbbd1]

Just to confirm- you did both fronts with all of the replacement parts?

 

[hear]

It wouldn't be the first time that a new part was bad. IJS.

 

[wmctbrown]

Just to confirm- you did both fronts with all of the replacement parts?

Yes, both fronts.

 

[WestCoastDan]

Have you looked at the condition of the hard lines to confirm that the right one isn't crushed?
If it were crushed, then the release of pressure on the right side would likely be slower than the left side, resulting in drag.

 

[wmctbrown]

Sometimes, issues with the master cylinder can lead to uneven brake pressure. It might be worth checking if the master cylinder is functioning properly.

Double check that the brake pads and calipers are installed correctly.

A stuck piston in the caliper can cause this. You say the calipers are new, but that doesn't matter. If you bought them from a local auto part store then there's a good chance you got a bad caliper. It's happened to me before with cheap, Chinese parts.

I questioned the new caliper also, but the issue is the same as before it was changed.

 

[macleanflood]

Bleeder screws are up, right? Let's cover the basics.

I had intermittent front caliper locking issues for years. Every time I thought I had it sorted it would come back. Got to the point where if just hit the calipers a few times with a dead blow a few times a week to free them up.

I finally put a Black Magic Brakes big brake kit on my front and it's amazing how quality parts just work as expected.

I'd suggest junkyard parts too. I went through several rear O2 sensors...Mopar, NGK...used NGK from a 2k finally solved my issues.

-Mac

 

[any4xx]

It’s already been mentioned and I second the suggestion to replace your rubber brake lines. Very easy job and worthwhile even if your old lines look good. I’ve had a few vehicles over the years that benefited from this replacement. In fact, I just replaced all three on my new-to-me ‘99 a couple of days ago as a matter of prevention. And it turned out that I did have a bad one. My Jeep stopped straight but it felt like one corner was sticking slightly when I’d take my foot off the brake to start out from a stop. Not bad, but just a very slight chassis “jiggle” when taking my foot off the brake. That effect went away with the line replacement. One had obviously been internally obstructed and was holding pressure on for just a moment with every application.

 

[dbbd1]

Bleeder screws are up, right? Let's cover the basics.


-Mac

That was my next question too. But, I would have thought they would NOT lock up. Yes, back to basics though.

 

[mrblaine]

Sometimes, issues with the master cylinder can lead to uneven brake pressure. It might be worth checking if the master cylinder is functioning properly.

The front brakes are common to each other via the combo valve. There is no way to create differential pressure side to side from the master all the way to each caliper. The rear circuit is also common side to side and all the way to the master and there is no way to create differential fluid pressure side to side for it either. The only differential pressure in the system happens via the proportioning section of the combo valve.

Double check that the brake pads and calipers are installed correctly.

A stuck piston in the caliper can cause this. You say the calipers are new, but that doesn't matter. If you bought them from a local auto part store then there's a good chance you got a bad caliper. It's happened to me before with cheap, Chinese parts.

Yep, check the guide sleeves, divots in the reaction bars, pads are correctly installed, etc.

 

[wmctbrown]

Just to confirm- you did both fronts with all of the replacement parts?

The front brakes are common to each other via the combo valve. There is no way to create differential pressure side to side from the master all the way to each caliper. The rear circuit is also common side to side and all the way to the master and there is no way to create differential fluid pressure side to side for it either. The only differential pressure in the system happens via the proportioning section of the combo valve.

Yep, check the guide sleeves, divots in the reaction bars, pads are correctly installed, etc.

Is there a chance that the proportioning valve could be the issue??

 

[mrblaine]

Is there a chance that the proportioning valve could be the issue??

No, read the explanation.