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wierd THUNK tranny mount?searched

A

aduke

NAXJA Forum User
Location
monson mass
90' xj 242 slec-trac auto rusty's 3in lift

for about two months i have been able to feel a clunk, thunk. on the floor under my feet when i go over a small bump. it almost feel like the tcase gets bumped up a little towards the floor.

after wheeling saterday its gotten much worse. it can be felt/heard when going straight or turning. i diconnected the front drive shaft. but it still makes the same noise. my friend says it might be an axel u joint. i think it may be something with the tranny mount. our t case bolted to the tranny. tomarrow i will put it up on jack stands and see if i can get any wierd noise from the front axel.

the tcase/tranny and diff are full of proper fluid

what are the sympotms of a bad tranny mount? my search didnt help much.

thanks a lot
 
Well, the thunk that you describe is a good indication. Try getting under your XJ with a jack, and gently try to raise the t-case/tranny. You are go to look at the tranny mounts' rubber biscuit. If it looks like it is moving easily or you can see rips/or tears, then it is bad. Also, if it looks "gooey" then I would look at changing it. HTH
Ren.
 
I've got the same thing going on, I looked at my tranny mounts today, didn't see anything out of the ordinary. Was thinking it may be the UCA bushing, but it looks fine. Possible the left front ball joint, is transmitting a thump to the floor area, through the UCA. Know I have one bad ball joint, but it seems kind of a stretch, that it would be causing a thump, felt under my left foot.
I did notice a scratch on my down pipe, I don´t remember being there before. Looks like the pinion yoke has made contact, the front driveshaft is in the garage.
Hope somebody comes up with an answer also.
 
when im in 4lo and on the gas pretty good such as climbing a steep hill, i get a series of firm thumping coming through the floor. It doesnt happen on flat ground or under normal circumstances....only when im really gettin on it. Ive crawled all under the xj checking stuff for looseness and im starting to think it may be the exhaust banging up against something. you might check that.
 
Yeah I've got the same thing going on... First it was the exhaust pipe bouncing off the x-member, then the tranny mount went. After fixing all that it went away for awhile and now it's back. Checked all the usual suspects. I read somewhere about when the rear shock(s)/mounts go bad they make a good racket and bang around. I have to replace mine anyway, so that will be the next thing.

With the exhaust, whoever fixed it before I bought messed it up... it was a crappy weld job.

My '91 is starting to show all the abuse and poor care that it went thru before I got it :explosion !!!

Marty

'91 2 door 4x4, 4.0 HO... Stock w/ 264,000 KMs (and counting).
 
putting the entire vehicle on jackstands will remove all the load from the wheels and i bet you wont find it that way.

go out to the driveway and GET UNDER YOUR RIG!

use a jack, prybar or even a long screwdriver and try to lift the tranny. look at the mount with a flashlight to look for any separation.

i'd troubleshoot in this order:
t/case mount
engine motor mounts
exhaust mounting/hangers

a bad ball joint will transmit thru your steeringwheel and probably give some "death wobble" if its not in the steering wheel i doudt this is a ball joint problem. UCA bushings is a possibility but you would likely be feeling a "clunk" when braking.
 
8Mud said:
I did notice a scratch on my down pipe, I don´t remember being there before. Looks like the pinion yoke has made contact, the front driveshaft is in the garage.
check your trackbar/front axle alignment, but both my lifted XJs have "self-clearanced" themselves after a few runs thru the rocks. if not careful it can rip a hole in the pipe so make sure you 2X check it.
Click to expand...
Click to expand...
 
im pretty sure its my tranny mount. i stuck a jack under the t-case and gap between the tcase and crossmember increased by at least 1.5-2 inches. i saw a rip. i think its definatly it. has anybody done these. it seems really easy.
 
Yes, on the XJ, you need to support the tranny just in front of the X-member, after you take the nuts off of the mount inside the x-member, then jack-up the tranny just a little to remove weight from the x-member. Then unbolt the x-member, place it to the side out of the way and unbolt the tranny mount from the tranny. reverse to install.
 
When I was running my T-case drop @ 3" I would get the same thing. basically it was my Jeep saying it wasn't happy with the line vibes.
 
I've got a similar clunk too. Pretty sure my Trans mount is shot. How much do they run at a parts store? Can you even get them there or is it a stealership thing?
 
Re: weird THUNK tranny mount?searched

I had about a quarter of an inch clearance between the exhaust pipe and the cross member, near the rear of the cross member. My tranny mount is probably a little soft, but I recently replace the down/cross over pipe and I'm thinking it was a poor fit. My solution was to take a BFH and dimple the pipe near where it was hitting, seems to be doing OK. I´m probably gonna get a new tranny mount, next paycheck.
 
Hello Fellow menbers, If any one are in need of tranny mounts or any other hard to find jeep parts, Like the tranny mount for a peugot transmission or your just look for repair parts for your jeep i can help. I can be reached @607-239-4379 EST after 6pm or email [email protected]
 
the tranny mount solved the problem. but i broke off both bolts on the cross member( i even used heat and pb!!!) so the cross member is temperaroly welded to the uni body until i have time to drill and tap them. an i will probably be making a t case drop at that time too.
 
Hey just a thought,
When I did my TC drop I broke a bolt also. What I did was drill a hole right next to the broken one (for bolt) then drilled a hole about a 1 1/4", (I think), big enough to get wrench in then put a nut on. Problem solved, took about 10 min.
 
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