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Loud Clunk When Putting Into Drive

J33PsRock

NAXJA Forum User
When I go from Reverse to Drive, there is a pretty loud clunk coming from the tranny area under my 90 Cherokee 4.0, 225k miles. I also notice this when I accelerate up to about 30 or 40 and then let off the gas and then accelerate again.

I have searched and don't think it is engine or tranny mounts, but I guess I am not sure. It just sounds like some grinding POP. Things are smooth as far as shifting up and down the gears while I am driving...no other drive line problems. This noise is just so loud I am afraid I am about to break something.

Checked the tranny fluid, it was a little low, topped it off.

I have never had the transmission serviced. I got this jeep at about 175k miles and a friend said (before finding NAXJA:) ) changing the fluid and doing the flush can break up so much that you may have problems...so I never changed the tranny fluid.

I put a Jasper engine in this about 4 years ago, love that decision, but I am hoping I am not about to lose my transmission. Talking about transmissions is scarier to me than f'in around with electricity...help me out brothers.
 
with 225k if you havent changed your motor or tranny mounts id do those first along with your control arm bushings. is it lifted? are you running a tcase drop if it is lifted? t case drop can cause the tranny and motor mounts to prematurely wear out. i just replaced my tranny and motor mounts twice each this year. first with some used ones that were better than my crappy worn out mounts, that i still had issues with and then finally with some new stock mounts. i plan on swapping in the brown dog motor mounts soon though, the stock mounts dont look like they are made to take lockers, gears and 33's too well.....are you running stock or aftermarket control arms? how are your rear driveshaft u joints? just a few things to check. id bet on tranny and motor mounts. id say if youre gonna wheel it do the more bombproof or the browndog mounts, or the summit mounts, something that is better than stock, its worth the extra cash for peice of mind along with a better product.
 
i forgot to second the rear end play. i pulled a 35 outta guys jeep for him and he was complaining about some terrible noises and clunking. i could slide his chunk back and forth in the diff after i pulled the cover! and it was very low on fluid. overall it was a scary thing, i gave him my old 35 that was in decent shape.
 
check your rear diff, mounts and lca and uca bushings
 
I'll check on those things. I also just thought of another couple of things that could be related.

1) My rear leaf springs are so flat they are almost inverted the other way. I know this is pretty easy to replace, I just haven't had the days off to tackle that yet, but quite a bit of sag. When I a hot a bump one of the rear wheels scrapes the upper wheel well.

2) I began to notice this (clunking) after pulling a light trailer camping. The trailer and all of the gear and everything was probably no more than 1500 lbs. max. (Fold-up trailer and just tent, sleeping bags, kids bikes, and coolers.) IT has gotten progressively worse since then.
 
your springs are a very good place to start as well if they are that flat and sagging. might as well lift it while youre at it....
 
No play whatsoever in the U-Joints. Definitely coming from the rear end, where the drive shaft goes into the diff. Other than the oil, what else can I check without taking stuff apart? I am thinking I will have to take it to a driveline shop.

Any ideers?
 
So...turns out it was the rear U-joint. I am such an idiot. I was thinking big $ for a transmission or a differential rebuild or something...and it was a $16 u-joint.

I couldn't tell that there was any play in it before, then I just changed it...fixed the problem. Thanks NAXJA fellas.
 
Glad to hear you found the problem and it didn't cost ya alot..

Nick
 
I am having the same problem but my cherokee is a 2000 with only 34K on it I guess I will replace the u joints and hope for the best.
 
Ok I have been reading everythibng I can about this issue. I am starting to think I may need to do the STY since I have a 4" lift. Man I am ready to drive this thing in to a wall and buy a toyota...

Please help...

Things I will check tomarrow morning.

U-Joints
Tranny mount.
Pinion angle
???(Anything else)

I need to get rid of this clunk....
 
So...turns out it was the rear U-joint. I am such an idiot. I was thinking big $ for a transmission or a differential rebuild or something...and it was a $16 u-joint.

I couldn't tell that there was any play in it before, then I just changed it...fixed the problem. Thanks NAXJA fellas.

I just bought a stock 1999 XJ, never been off road or abused, 97K mileage...all u-joints, engine/transmission mounts seem good, and yet it clunks and lurches when put into any forward gear, but not at all when put into reverse. Did yours clunk when put into reverse, or only when put into a forward gear?
 
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