BruceB

I started to notice a thumping noise from the rear of the Jeep as I applied my brakes.
I didn't feel any driveabilty or stopping issues or symptoms.
Obvious places to check was the rear brakes, which I had replaced including new drums about 12 months ago. Everything looked fine.
Checked the parking brake for correct adjustment.
Checked both U joints and greased them. (both new less than 2 years)
Removed yoke and lubricated it.
Test drove, still there.
Jacked up rear end and hand turned the wheels, no noise.
I had put a Powertrax No-slip locker in a few years ago so I removed the differential cover and inspected as much as I could....replaced cover and added new lubrication.
Started Jeep with rear wheels off the ground, put it in Drive and applied brakes. Very light thumping noise coming from left side behind the wheel and tire.

Removed tire and removed drum. After disassembling the entire brake system I found the problem. The spring on the spreader bar that holds the shoes apart had rusted away some and lost its ability to hold the shoes apart tightly and the top of the spreader bar was hitting the bottom of the wheel cylinder when braking. The shop that did the brakes did not replace any of the springs, just the shoes and drum. So I went to O'Reilly's and and purchased a spring kits for both sides, installed them and there is no more thumping when braking.

Hopefully this will help some one who is experiencing the same symptoms.

Have a good day!

Idunno

Thanks for volunteering this problem and fix. Noted.

trublue

I wish I had seen your post earlier. I had my 96 XJ looked at by a local shop for the exact same symptoms. I test drove it with them so they could hear the thumping noise. They confidently said it was brakes. I left it with them and came back about 2 hours later. They had inspected and cleaned the brakes, and found nothing wrong. They then checked the differential and transfer case and suspension, but were completely mystified as the noise suddenly went away without replacing anything. I was betting it was an out of round drum, but they said they checked the drum dimensions. That little green spring is hard to see with the axles in place. The spring kits are cheap, so if it comes back again, I will replace all the springs.

Silver01Bullet

Over many years of changing out drum brakes, by the way, about my least favorite job, I have come to the conclusion that by the time the brakes need replaced, so does the hardware. I just spend the $10 and get new hardware kits as well.

Newtothis

I have the same noise but it only started happening after I changed all 4 shocks. Those upper rear mounts are a beast. I had to drill out all 4 nuts since I could not bang them out with a BFH.
I am hoping it is not anything to do with the shocks but the thumping sound goes away after a few times breaking.
did your thumping go away after you broke a few times or was it consistent?

RocketMouse

Check the posting dates... this is a couple year old thread.

BruceB

Once I replaced the springs, the thumping stopped immediately.

Sounds like your shocks may not be secured and move during acceleration and braking and that is possibly what is making your thumping sounds.