I have a 92 Cherokee, 4.0, 4x4, AW-4, NP-231. When I am slowing down everything is normal until i get to about 5 mph and 600 rpm. Then the brake pedal shakes/pulsates slightly. It feels like something is slapping it. It also feels like this when I put the car in reverse. The best way to describe the feeling is as if someone is slapping the pedal with a belt or something. I have no clue what it is.

I'm pretty sure I need new brakes anyway, could this be the problem?

 

Pads and possibly rotors. Your XJ got the ABS system?

 

You might also check the U-joints.

 

I'm not sure, how do I check?

 

Update: It's also doing it when in not moving. Sitting in reverse with foot on brake and sometimes when in park and drive it does it, but not when in neutral.

 

An easy way to tell if you have ABS is to turn the key to the run position and see if the ABS light comes on for the two second bulb check. We really need to know if you have ABS.

 

Will the light be to the left of the dash? Where the check engine light is?

 

Yep. Bottom right hand corner in that panel I believe.

 

I turned the car on and the light didn't popup. I then shined a flashlight on the panel and there is an abs light but it never became lit when i turned the car on, is it supposed to light up?

 

Yes it should light up..

Look under your rear seat and you should see the rear abs lines on the driver side, they come into a power box there. You can also just glance at your front brakes and see if you have them. If you have them you will have a brake line and an abs line coming down your inner fender from the engine compartment.

 

I looked under the front fender and there is one line coming from the engine compartment. I also looked under the back left wheel and there is two lines going to the brake area, ones a little thicker than the other.

Front:


Rear:

 

I'm not expert, but it looks like you do not have abs. One brake line in the front, and two in the rear, one for brakes and the other for hand brake. I also was going to say warped rotors but if it does it while not moving than I'm stumped.

 

Update: The thudding was the aftermarket intake slightly tapping the master cylinder reservoir. Thanks for the help anyways.