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Hi I’ve looked around and can’t really find a good place to start tracking down this issue I have a 2000 sport xj 3inch RC lift 2inch tcase drop since I bought the Jeep 6 years ago it has had this clunking/vibration caused by giving it gas when accelerating from a complete stop. I’ve noticed it seems worse when turning left took it to the shop about six years ago and they said it was a bad transmission mount I never fixed it as I had a bad 0331 head to replace, fixed that long story short decided last year to start fixing it up and get it where I wanted it. Lifted,raptor lined it cut and weld, added rubicon wheels and body armorr and finally replaced the transmission mount as well an RC track bar.
it seems to be better as far as the clunking vibration goes but it is still there. Any ideas as to where I should start looking to track down this issue. Sorry for the long winded post thanks for any help.
check the u-joints on your driveshafts - more soo the rear driveshaft. on level ground and potentially with atleast 1 wheel chocked, put the jeep in neutral and crawl underneath the jeep. Grab ahold of that rear driveshaft and try to twist is in either direction (clockwise - counter clockwise) while looking at the 4 points of the ujoint. If there is play between the actual ujoint and the caps then the ujoint is worn out and should be replaced. Seeing brown rusty powder by the cap seals is also another sign of a ujoint on its way out.
A 2" T-case drop seems like way too much with a 3" lift.
Some of the experts on here-help me out, but wouldn't that be putting a huge strain on the motor mounts?
Also, he say he has not yet replaced the trans mount.
I would think that those two things are relatively inexpensive and easy to replace.
Might be a good place to start.
A 2" T-case drop seems like way too much with a 3" lift.
Some of the experts on here-help me out, but wouldn't that be putting a huge strain on the motor mounts?
Also, he say he has not yet replaced the trans mount.
I would think that those two things are relatively inexpensive and easy to replace.
Might be a good place to start.
Agreed. Check and replace mounts if needed, but inspect the driveline as well. U joints are often overlooked...
A 2" T-case drop seems like way too much with a 3" lift.
Some of the experts on here-help me out, but wouldn't that be putting a huge strain on the motor mounts?
Also, he say he has not yet replaced the trans mount.
I would think that those two things are relatively inexpensive and easy to replace.
Might be a good place to start.
Sorry for the error it indeed is a 4 inch lift. I did replace the transmission mount as stated in op, sorry it was very long winded. It seemed to do the clunking beforehand but now it’s a little more constant before the replacement it was just when taking off or turning hard while taking off. I’m definitely going to go out and check motor mounts tomorrow and u joints any other suggestions are welcome thanks again.
Is the clunking coming from the driver front? Kinda feel it at your feet? If so then im have the same issue. Changed my driverside ujoint thinking it was that. But im still hearing the clunking.
There a lots of things that can cause Vibrations. Bad motor mounts, trans mounts, exhaust, driveline angles, slip yoke needing grease. Also just because you have a t case drop, which is really a temporary bandaid, doesn't mean the rear drives haft and yoke angles are correct.
Your slip yoke is on the transfer case side of the rear drive shaft. Pull the whole drive shaft off, undo bolts, and pull the slip joint from the tcase and inspect the condition of unjoint caps by carefully pulling them off one at a time and putting them back. Your looking for rust and worn parts. Check the amount of grease on the slip yoke and add some for good measure.
Inspect motor mounts all over for missing rubber, trans mount for collapse, exhaust and exhaust hangers.
consider getting an sye kit or hack n tap sye.
That's all I can think of for now. You could pull the front drive shaft and drive around just to make sure it's not involved. Remember when you drop the TC the rear output goes down, but the front output is now angled higher up.
There a lots of things that can cause Vibrations. Bad motor mounts, trans mounts, exhaust, driveline angles, slip yoke needing grease. Also just because you have a t case drop, which is really a temporary bandaid, doesn't mean the rear drives haft and yoke angles are correct.
Your slip yoke is on the transfer case side of the rear drive shaft. Pull the whole drive shaft off, undo bolts, and pull the slip joint from the tcase and inspect the condition of unjoint caps by carefully pulling them off one at a time and putting them back. Your looking for rust and worn parts. Check the amount of grease on the slip yoke and add some for good measure.
Inspect motor mounts all over for missing rubber, trans mount for collapse, exhaust and exhaust hangers.
consider getting an sye kit or hack n tap sye.
That's all I can think of for now. You could pull the front drive shaft and drive around just to make sure it's not involved. Remember when you drop the TC the rear output goes down, but the front output is now angled higher up.
Thank u I’ll definitely get under it when it warms up and c if any of that helps. I’m definitely new to lifts and suspension tech. I appreciate all the solid advice!
Ok wanted to come back and follow up with the results…after a long while it’s fixed! It’s a long read but I hope it helps someone dealing with a similar issue.
After the lift and new front bushings tie rod ends lower controls arms extended sway links ball joints track bar ect. I installed a cheap auto zone trans mount which did not fix the clunking at takeoff.
I then replaced motor mounts with Rusty’s clevite rubber..
I hated those, vibes at idle and sounded like a jet at high rpm’s from all the vibes. Not for me!
took those off and replaced em with rubber oem better on vibes still clunking…. After installing a Polyurethane trans mount I borrowed from my buddy’s jeep it fixed the clunking!!! But it vibrated a bit to much it felt good but to much driveline vibration, much more torque though! I would absolutely use one for a non DD.
So finally I replaced the trans mount with an oem rubber one, but first I compared it to the auto zone mount and discovered the az mount to be one inch shorter than the new oem mount. After installing it I’m happy to say it worked perfectly!
Thanks for all the help and suggestions. I hope someone can use my many mistakes to help em make the choices of different available types of mounts and to always compare new parts to old ones.
Last edited by Swampanther; Sep 27, 2024 at 09:57 PM.
Reason: Missing word
Glad you got it figured out and fixed... Those aftermarket trans mounts just don't get it done... I put OEM in mine as well after buying what I thought was a good replacement...The difference and quality is easy to see...OEM on the right, look at the mount's rubber thickness..The trans weight alone drops the aftermarket piece's install height...
Clunking/vibration when giving it gas from stop
