Bad Brakes

Recently the brakes on my '92 XJ 4.0 have been acting strangely. When I start driving the car around, particularly after it's been raining, for the first minute or so the brakes grab way too hard when I hardly press the brake pedal down. Today they made an awful thunking sound when I pressed them. Any help is much appreciated!

possibly sticky calipers and pads need replacing?

Heinz said:

possibly sticky calipers and pads need replacing?

Click to expand...

Whenever my brake pads got worn down, my MJ would break the pad...the pad would crack/crumble. I noticed atleast 2 broken pads whenever I change them, either side, doesn't matter.

I just got finished fixing that exact problem. it is definately the rear wheel cyclinders. one side of them is seized, replace them and u will have great brakes again

The problem of the rear brakes grabbing when cold and/or damp is fairly common. I don't think anyone has definitively identified the cause. It isn't just a sticking wheel cylinder, because I've had it happen with new cylinders. I think (unconfirmed by testing) that some brake lining materials are more susceptible to absorbing moisture out of the air than others, and when the lining material gets damp it swells. After a few miles of driving and a few applications of the brakes generate some heat, the moisture is driven off, the linings revert to their normal dimension, and the brakes don't grab.

Try changing the shoes to a carbon fiber or semi-metallic type and see if that eliminates the problem.

I've had this problem with my 94. I assumed it was the surface rust that forms on the rotors, especially in really wet or damp air. I usually experience it after parking the Jeep for the night after it's been raining or really humid. Next day when leave my apts it's only like 40 or 50 ft to the street, I don't go above 10 or 15 mph and I've had my front wheels lock up at the slightest tap of the brake pedal. It usually goes away with one good stop from 40 mph or so, I figured it was enough to wear off that coat of rust and get things back to normal. Either way, I agree with Eagle, it's not a new or serious problem, just really annoying sometimes, especially if you're not expecting that unearthly groaning noise from your Jeep at the first stop you make. If you want to be sure though, go somewhere that gives free estimates on brakes and have them take a look, won't cost you anything and then you'll know if there is a undiagnosed problem.