Clunking when in reverse

[MattA]

Any one have any ideas? When I put the Jeep in reverse, push in the clutch, and press on the brake, there is a clunk from underneath as I let off the brake. It will keep on doing it evey time a I push and release the brake, as long as I am rolling backwards. I have checked the motor mounts, tranny mounts, and all of the suspension components. Could it be driveshaft related? Possibly a ujoint? How do I check the ujoints? If it's a ujoint, where's the best place to buy an upgraded ujoint? Thanks for the help.
Matt

[RokNRich]

Hey Matt,

Not sure what lift you are running and which suspension components you checked over, but I was having a similiar clunking going on until I replaced the control arm bushings in my lift.

Not sure what type of Jeep you have or what you've done to it, but I think it's pretty common for those of us with Tera lifts.

Good Luck

[Sedona Jeep School]

Could be a U-joint. My pre-flight routine starts with rocking the Jeep without the motor running. If the noise is suspension related, you would be able hear it by rocking the Jeep. A U-joint commonly has other symptoms: clunking in reverse or starting off the line, a vibration in the driveline, or even a sloppy tranny response.

If you have a lift on your Jeep, this puts more strain on your U-joint, from not only the driveline angle, but the additional mobility of the rear end.

U-joints are cheap and easy to replace. There are lots of different theories on this, but mine is to keep the cheaper U-joints as your "weak link", so it will blow out, but not your drive shaft, pinion yoke, transfer case, etc. On tour Jeeps, we replace the U-joints every 12,000 miles.

Let us know what you find.

[OlneyJeeps]

What kind of Jeep/milage (is it a 2005 Rubicon Unlimited or a 64 M715?)
Any Idea where clunk is coming from (tranny,front end ,rear end, CB antenna)?
Have you tried (on loose dirt) 4wd to check for difference in tone/loudness?
lifted rear on jack and attempted?
can you hold the microphone up to it and get a sound sample so we can all listen to it? :D
just some thoughts :eek:

[MattA]

It's a 98 with a 4.5" RE lift. It sounds like it is coming from the front end and I can feel it through the brake pedal. I haven't tried putting it in 4wd yet. There are no sounds from the Jeep if I just rock it back and forth. It has to be rolling backwards and then have the brake on. It doesn't matter if the engine is on or off. As soon as I release the brake, I get the clunk.