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Clunk in rear end

J

jeepinjim

NAXJA Forum User
Location
Round Lake, Illinois
The rear end in my 94 XJ started making a clanking/clunking sound when taking off from a dead stop. Sounds like something banging off the floor pan til I get going, then it stops. If it is wet out and the tire spins, it won't do it. Any ideas as to what is doing this??? Suspension is currently stock, with 163,000 miles on it. I'm thinking it could be that the rear springs are so saggy that now they are starting to wrap under accel. Sound plausible?? Did a quick visual of the u-joints and they seem to be ok. :worship::helpme:
 
If your jeep is like my 91, it is the catalytic converter brace bouncing on the crossmember. Its a pretty loud thunking that only happens occationally. A worn or failed motor mount can contribute to a noise such as this because the engine will rock over more on acceleration. I'd check for any muffler or pipe hitting the underbody before looking into the rear end.
 
a notorious spot for exaust clunking is on the tranny crossmember the mount gets soaked with oil and grease and decides to come apart when you accelerate the engine rocks forcing the exaust into the crossmember checck there first look for shiny spots on the exaust where its been banging
 
set parking brake, put in neutral. rotate driveline by hand and look for slop in the u joints/pinion.
the tires on the ground will keep the pinion from rotating, so just work it back and forrth looking for slop and listening for clanks and bangs. If that's all tight, then move onto inspecting the diff guts, you could have a spider gear that's trashed or something.
Once you're sure that the drivetrain is good, start inspecting everything else.
pay particular attention to the mounts up by the crossmember as mentioned, and where the pipe exits out back by the shackle.
 
driveshaft u-joints maybe, could also be the slip-yoke banging in the transfer case if the springs are old enough for the rear end to have dropped

the rain effect sounds like brakes maybe, they could be slipping when wet

might also be related to axle wrap so check the u-bolts and spring bushings, also check the swaybar bushings if you still have that

lug nuts will make the tire bonk around too
 
JohnnyTurbo said:
If your jeep is like my 91, it is the catalytic converter brace bouncing on the crossmember. Its a pretty loud thunking that only happens occationally. A worn or failed motor mount can contribute to a noise such as this because the engine will rock over more on acceleration. I'd check for any muffler or pipe hitting the underbody before looking into the rear end.
Click to expand...

I agree i had a broken exhaust bracket on my xj. i thought my diff was the problem also until i broke my tail pipe off backing out of a wash out. but my tail pipe was hitting my hidden hitch. It my also be a motor mount i broke one on my pt cruiser and it made an offal bang when i accelerated and shifted.
 
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