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Hard Clunk-Jolt When Throttle Released

TheAce

NAXJA Forum User
Location
Idaho
Recently acquired this Cherokee and working thru a few issues , this is the latest:

'95, 4.0, AW4, np242, 35 rear, 173K miles. Rear diff rebuilt 40K ago, all u-joints checked good, all mounts good no vibrations.

* Has 180 degree stat installed scheduled to be replaced with 195 degree*

THE PROBLEM: Hot or cold in any gear (I think) if I take my foot completely off the gas pedal the drivetrain clunks real hard. It's not audible but is very abrupt feeling. If I ease my foot off the gas it won't do it.

What am I up against guru's ?
 
Suspect drive shaft u-joints first, then the rear diff. Inspect transmission and motor mounts also. While under there make sure the exhaust in not excessively loose and able to clunk on the frame or suspension.
 
Thanks Tim I'll crawl under it myself and see. Had a respected garage check it a couple weeks ago because I assumed it was u-joints.... except there's virtually no 'noise' associated with it - but it's a hell of a jolt.

Thanks again....
 
Usually when you a clunk like that, the joints not loose it's dry/frozen.
 
How has the trans mount been checked?

I ask because I thought mine looked fine. Looking at it from underneath there was nothing that I thought indicated any problem. But, since I was doing motor mounts I decided to go ahead and replace the trans mount anyway. Turned out it was shot. But I couldn't tell until I dropped the crossmember.
 
Usually when you a clunk like that, the joints not loose it's dry/frozen.

Interesting....

This would explain the lack of a clunking sound leaving just the sensation.

As for bad mounts , especially trans, it usually comes with a 'shimmy' under hard accel . Got none of that. It was suggested to me that the stat not letting things come up to normal operating temps could be messing with electronics - but I can't picture how it could cause this particular position issue.
 
It was also suggested that it could be a failing converter since it's ONLY on sharp deceleration . Trans feels perfect otherwise.
 
It could be lots of other things, or none of them. Start with the mechanical basics and the usual suspects, inspect fully the simple things ( push/poke/twist ).
 
Mine had it and i simply greased the driveshaft splines. Went away for. While and then came back but not as bad, regreased. The driveshaft was driven dry for a while so im guessing theres so damage to the metal splines and needs to be greased real well now, planning on jut throwing a new one in when i do the sye.
 
Thanks Mickey!

I'll give that a try - I know the splines haven't been touched and got to be dry.

That would be nice if it works!
 
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