So I get a pretty noticeable clunk 8/10 times when letting off the gas pedal, its not horrific when I slowly let off but it's noticeably worse when I let off abruptly. I've only started to have the issue as of the last few months and still haven't been able to track it down. It's especially noticeable when driving around town at low speeds.

From what I've been able to gather off the forums, people usually blame a cracked flywheel, faulty transfer case chain, faulty torque converter. bad driveshaft u-joints. Basically too many different options for me to keep trying out spare parts.

I'm also chasing down some front and rear diff/pinion gremlins at the moment, could this knock be caused by a bad pinion bearing or a dying diff?

If anyone has experienced anything similar please shoot with any experience/fixes you've done/witnessed!

 

I had that same clunking. I just went to a new rear driveshaft (went with a slip yoke eliminator) with my lift and the clunk has disappeared.

the u-joints in the stock rear driveshaft seemed fine-ish. The slip yoke at the transfer case is what I'm guessing was worn.

Not saying this is your issue...but there is a high change it's a worn rear driveshaft. I would not bank on it being the front.

 

get under there and start wiggling stuff.
And, look at engine and trans mounts.

 

When was the last time you greased your slip yoke?

 

Or inspected the u joints? Or checked the trans, transfer case and diff levels?
Inspected the engine and trans mounts?

 

Shock mounts and rubber ok? Control arm bushings worn?

Sounds like...


NOGGIN' POKIN' TIME

 

SURE DOES!!!!!!

 

Just thought I'd grab your attention, haha

 

NOGGIN POKIN' will do that!!!

The only way you're gonna find what you're looking for is to GO LOOK!

Around the Jeep that is. In these parts, we call it "noggin pokin".

That's where you use your God given senses to inspect YOUR Jeep for problems. We can only provide you with guidance as to where to poke your noggin.

There's no Silver Bullet cure you're gonna find from a keyboard, mouse and monitor.

 

"Go look"
best advice ever

 

I've just changed all oils and checked them a few days later and all seem to look healthy, I've just swapped out a front driveshaft + u-joint. My rear driveshaft seems to be in good enough condition, though there's like a quarter turn worth of slop in the driveline? Also just greased anything greaseable on the car including the slip yoke. I guess I'll have to drop my t-case next and inspect that.

 

Also just for reference, the noggin pokin, IT IS ALL I DO, DAY IN, DAY OUT. Guess it's just a matter of my eye not being trained enough to spot exactly what is causing the problem. Also the clunk all xj's have when shifting form P to R to D etc. (AW4) is getting worse and worse, is my trans possibly on it's way out. My salary barely covers my *** and here in Egypt almost all parts are junkyard spec with close to zero aftermarket so I'm hella limited with regards to decent parts unless I wanna import **** from the us and that is mucho $$$$$$.

 

I wouldn't drop the transfer case. Post a pic of your engine and trans mounts.
I have seen where the bracket that bolts to the bottom of the transfer case adapter, the one holding the mount, have backed out or are gone.

 

I second that.

Look at motor and transmission mounts. Youl likely not find anything dropping the tcase

 

I had the same problem with my 2002 Jeep grand Cherokee Laredo 4.0L. When letting my foot off the gas I would get a clunk in the rear. Possible causes listed were U joints/drive shaft/rear differential etc. I had already replaced the u joints and had all new suspension including rear upper/lower control arms. After months of trying to figure out what the problem was and (2) different mechanics telling me it was the rear differential it was discovered that I actually had a broken rear ball joint. I replaced it and the clunk was gone. It can still be any of the above mentioned causes but I would most definitely be sure to check the ball joint.