Caliper Locking UP.....

[LouisianaZJ]

Over the past 4 yrs at least 4 times I have a had a problem with a caliper locking up on me. I always fixed by replacing with a set of 2 new calipers and new pads if necessary. Why do I keep having this problem?

Autozone rotors
bendix calipers (about $20 ea, cheap)
Stainless lines (problem has happened with OEM rubber lines and new stainless)
OEM brake booster/clyinder 140k on it
Brake fluid has been flushed 90% once a few yrs ago, and flush about 1/8 quart when putting on new calipers...
caliper slide pins greased with hi temp caliper grease

"Fixed" on saturday:
Replaced caliper Sat. Noticed there were grooves worn into the knuckles. What I ended up doing is filing down the sharp edges of the grooves, so the pad was free to shift across the groove smoothly. Bled the system and all seemed well. The hub and rotor appeared to be in good shape.

Drove sat/sunday with no signs of problems. Today it started locking up again....same caliper, all the rest were ok

where do I go from here?

[ATL ZJ]

If you have replaced everything BUT the master and booster, I would look at those rather than the items that you replaced that didn't solve the problem.

Does your XJ have ABS? I know many didn't come with it.

[LouisianaZJ]

no abs

I believe both fronts are off the same line of the master? maybe not

[piku303]

Over the past 4 yrs at least 4 times I have a had a problem with a caliper locking up on me. I always fixed by replacing with a set of 2 new calipers and new pads if necessary. Why do I keep having this problem?

Autozone rotors
bendix calipers (about $20 ea, cheap)
Stainless lines (problem has happened with OEM rubber lines and new stainless)
OEM brake booster/clyinder 140k on it
Brake fluid has been flushed 90% once a few yrs ago, and flush about 1/8 quart when putting on new calipers...
caliper slide pins greased with hi temp caliper grease

"Fixed" on saturday:
Replaced caliper Sat. Noticed there were grooves worn into the knuckles. What I ended up doing is filing down the sharp edges of the grooves, so the pad was free to shift across the groove smoothly. Bled the system and all seemed well. The hub and rotor appeared to be in good shape.

Drove sat/sunday with no signs of problems. Today it started locking up again....same caliper, all the rest were ok

where do I go from here?

sorry if this sounds obvious but do you wheel in a lot of mud/water? i make it a point to remove the front wheels and wash all around the brakes after wheeling through a lot of mud. its kept my brakes great considering the shit ive driven through. i have had my front passenger caliper lock up at freeway speeds in rush hour traffic in atlanta and it was scary as hell. i asked my girlfriend riding shotgun to look out the window to see what was happening and she was meet with a plume of smoke in the face. and this was while my car was loaded down with everything i was bringing to college for the first time.

[CurtP]

I had a similar problem on my 5.9 - it was the knuckles. More specifically, it was the grooves on the abutments that were catching the pads and making them stay against the rotor. After the pad would start wearing, the pad would bow and crack, then start flaking apart. After the third set of pads (thank you VatoZone for the free replacements!), I was sick of it. New knuckles were stupid expensive and I didn't trust trying to fill in the grooves with weld.

The ZJ has such shitty front brakes anyway, and it seems like a waste of time trying to fix all that is wrong with them. The only solution, IMO, is to get rid of them. Good time to upgrade the front axle, do a WJ brake swap or go aftermarket. I went with Vanco.

[Sudz]

to add to CurtP's post

in the photo below look at the area where the pads rest (mount) on the outer knuckle – over time the brake pads mounting feet wear grooves in the knuckle surface which prevents them from sliding freely – this is a common problem with the dana 30 – ford axles have a small stainless clip on the their knuckles to prevent this wear condition.

as regular maintenance, i use synthetic brake caliper grease on these contact areas to prevent lockup – as an additional step, i have also filed these spots as flat and smooth as i could without rendering the knuckles useless (you’ll need to replace the knuckles eventually) – this should be a recall item – hopefully before somebody gets killed – there are millions of these axles on the road and it’s just a matter of time







btw, i use this stuff – a good marine grease works too - just be careful not to get any on your rotor or brake pad surfaces



hth

-Sudz

[nate]

If there is a groove you can weld it up and grind it smooth. I have fixed a few like that.

[CurtP]

If there is a groove you can weld it up and grind it smooth. I have fixed a few like that.

I just didn't trust my welding skills, plus I think that if you run over a 30" tire, you should upgrade the brakes anyway. I think the brakes on a ZJ are horribly undersized.

The grooves in mine were worse than what was in Sudz's pictures.