Oh snap!

 

It isn't necessarily the R&P. I had a bad R&P in the Dana 35 in mine, and I also had the clunk. We have replaced the entire rear axle with a C8.25 out of a 2001 that is in excellent shape (checked the play in it before we installed it), along with a driveshaft with new U joints, and I still get the same clunk I had before. I think he may be on to something with the T-case idea.

 

I've got a similar clunk developing. 1987 XJ, Automatic Transmission. When cruising at 55 - 60 mph (with cruise control it occurs more often) the transmission feels like it is trying to shift but it is very rough. Loud clunk sound and you feel it clunk. Doesn't seem to shift. No increase or decrease in RPMs. Not accelerating or decelerating when the clunk occurs. Tried running in 4-hi to see if it changed anything, but still go the clunk. Went back down to 2-hi about 3 miles from home and it didn't clunk the rest of the way. Seems to clunk at random times but generally once every 2-4 miles. Changed the AT fluid yesterday afternoon and put in a new filter. No change. Also checked the U joints and they are solid. Still get the "clunk". A buddy of mine said it could be the torque converter, but I am really not sure. After changing the trans fluid and letting the Jeep sit overnight, I go out to start it up and shift into reverse to back out the driveway and it a pretty harsh shift into reverse. Same harshness between drive to reverse and back. Sometimes it sounds like a clunk and other times there is no clunk but rather just a large lurch of the vehicle forward or back. Any advice is appreciated.

 

As I said earlier, try changing the transfer case fluid. Can't hurt. It did help me. I don't exactly know why.

 

i have the same thing happening to me and this guy i had talked to said the same thing about the t case fluid and i decided to wait till i got my sye it kit well i installed the sye kit and a brand new drive shaft and u joints. Mine still does it and like kansas jeeping said the jeep doesn't always make the clunk but does lurk forward.

 

Change. The. Fluid.

 

t-case or at fluid?

 

Changing the fluid in a TC will not eliminate a clunk coming from the TC. It might only hide/mask it because of the higher density/viscosity of a new fluid respect to an old one.
It is not a fix.

 

Transfer case.

 

It worked for me both times on my 2 Jeeps. Clunk is gone. Seems fixed to me. Whatever. It doesn't clunk.

As I said earler, I'm not exactly sure why. Also as I said earler, can't hurt, might help. Part of maintenance anyway.

 

I'll still change it, as it does likely need to be done. Any recommendations as to what I might look for when changing it that could be causing the "clunk"? Thanks in advance!