huge "clunk" during braking...help!

Ok, this *just* started today. I have no idea why. As I press the brake pedal slightly, it slows down fine. If i press it down kinda hard, it clunks like crazy up front and underneath me it seems, and the right rear wheel locks up. It also stops really quickly...it feels like as I press the brake pedal, it does nothing, then all of a sudden the brakes grab really hard and fast. There arent any leaks, there dont seem to be any problems underneath, but WTF? The only thing different is that I dont have my front bumper on...I see no correlation between that and the brakes, but it started the day after I took it off. HELP.:wierd:

oh, and it doesnt happen in reverse...it works perfectly in reverse, but not forward.

ok, so Ive isolated the sound...its def. the right rear drum...I took the rear wheels off, turned on the jeep, put it in drive and hit the brakes and it sounds like its gonna friggin snap something....it sounds like its loading up, then all of a sudden snapping the shoes out into the drum...ANYBODY?

Don't forget to note your Cherokeee model year, axle, engine, transmission or Tcase as needed. The correct answers may be different for different options or model years.

Possible cause below. It seems that a good used axle shaft will fix the problem.

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http://autorepair.about.com/library/faqs/bl485f.htm

Number: 05-05-00
Group: Brakes
Date: May 26, 2000

Subject:
Rear Brake Clunk Or Thump When Brakes Are Applied

Models:
1997 - 1999 Cherokee

Overview: This bulletin involves installing a rear axle shaft(s).

NOTE: this bulletin applies to vehicles equipped with an 8¼" rear axle.
Symptom/Condition:
A clunk or thump may be heard coming from the rear of the vehicle when the brakes are applied on some vehicles equipped with an 8¼" rear axle. This may be caused by an axle shaft, which does not have a correct size brake drum pilot flange.

Diagnosis:
If the vehicle exhibits the condition, remove the rear wheels and brake drums and inspect the rear axle shafts at the center pilot for the wheel and brake drum. There must be two separate pilot diameters on this area (See Figure 1). The outboard diameter for the wheel (2.812-2.808 inches) and the slightly larger inner diameter to support the brake drum (2.832-2.826 inches). The brake drum pilot may be missing or may not be deep enough to support the drum. If the drum pilot does not adequately support the drum, some movement of the drum may occur when the brakes are applied causing this noise. If this condition is present, install a new axle shaft or shafts, P/N 05018393AA, as necessary.

and this could happen all of a sudden?

its a strange strange world. So after fooling around with it a bit, I adjusted the shoes out until the barely touched the inside of the drums...they were way in previously. I dont know if that did it or what, I put it all back together to head to autozone for a new wheel cylinder and it clunked much quieter a couple of times and then....nothing. Like it never even happened in the first place. Stopping hard, stopping slowly, reverse, forward...works fine. No leaks...WTF? Whatever...I guess I have a spare pass. side wheel cylinder...

check the cables for the auto adjusters. Mine did the same thing.

it must have been the adjusters...