Clunk From Rear End

[profdlp]

{Insert thread title joke here}

I have noticed that upon initial acceleration I sometimes get a mild clunk from somewhere in the rear of the Jeep. It's most obvious when accelerating very slowly, such as in stop-and-go traffic. It almost sounds like something has to "catch up" with the rest of the Jeep, then bangs into something once it gets there. (Kind of like a fat kid running for the school bus who flattens the guy in front of him once he finally gets there.)

What do I look for and how do I check it?

 

[twowings]

You've run over your mother-in-law, man!

 

[profdlp]

You've run over your mother-in-law, man!

A) I do not have a Mother-In-Law. (And it's not because I just ran over her.)

B) If I did just run over my Mother-In-Law (assuming I had one), I would not be coming here to complain about it. I would probably be out celebrating. :icon_lol:

 

[CzarKJ]

Either rear tri-link or lower control arm bushings. So the tri-link has two bushings and a ball joint.

good vs bad

 

[tommudd]

Yes first place is the tri-link
does it do alright on the highway? Any dancing around or just the clunk?

 

[profdlp]

Stable and quiet as can be after I get rolling. It's always the initial takeoff when I get it. No problem when accelerating at any speed once I'm even barely rolling, say over 2-3 mph.

It will be dark here soon. I'll crawl under there tomorrow and have a look around. Better hose what's left of my Mother-In-Law off the undercarriage first, though.

 

[twowings]

Initial startup=driveline check driveshafts

 

[John3seventeen]

Initial startup=driveline check driveshafts

Or Bowling ball in the cargo area

 

[CzarKJ]

Or Bowling ball in the cargo area

mother-in-law's head....

 

[profdlp]

Or Bowling ball in the cargo area

If it's any help with the diagnosis, that's pretty much what it sounds like. :shrug:

 

[tommudd]

If it's any help with the diagnosis, that's pretty much what it sounds like. :shrug:

Easy way to check if you have some help is to put a 4 way or socket with breaker bar on a lug nut sitting on level ground. Have one person just rock it back and forth lightly while you look under it to see whats moving

 

[HoosierJeeper]

If it's just when starting out it might be more of a ****** thing. Mine does it, always has. My 99 WJ did it too and I took it to the dealer for it, and they said it's a jeep thing.

 

[ftaa]

If it's just when starting out it might be more of a ****** thing. Mine does it, always has. My 99 WJ did it too and I took it to the dealer for it, and they said it's a jeep thing.

aggreed ... could be a sticky solenoid.

 

[dude1116]

OK. Might just be me thinking this but it sounds normal. Mine has always done it and I've always taken it as slack in the rear driveline. For instance...if you crawl under and twist the shaft, it should move maybe an eight or a sixteenth of an inch back and forth. Makes a little clunking noise too. I just figured that's what happens when the t-case puts torque on the shaft while slowly rolling.

 

[RenKJ]

Yes first place is the tri-link
does it do alright on the highway? Any dancing around or just the clunk?

If you get a slight dancing around of the rear end on bumps would that indicate a worn trilink? I have a slight clunk sound from the driver rear on light bumps ajd a slight side to side on big bumps

 

[profdlp]

Never anything side-to-side under any conditions. I got busy the last two days and haven't looked at it yet and it is supposed to rain heavily tomorrow. I will have a look-see soon, though.

The "slack in the driveline" theory sounds quite plausible. It's like when all the stuff starts moving there is something with just a tiny bit of play which gets a tiny extra push to get started.

EDIT: Meant to add, if it's a transmission thing would it make the clunking noise in the rear? :shrug:

 

[tommudd]

If you get a slight dancing around of the rear end on bumps would that indicate a worn trilink? I have a slight clunk sound from the driver rear on light bumps ajd a slight side to side on big bumps

When the Kj starts feeling like she wanting to do the hula , most all times its the lower control arms
Or when you get on the Interstates and hit the grooves from big trucks and the rear dances / feels like you are on ice almost then its the LCAs

 

[ftaa]

Never anything side-to-side under any conditions. I got busy the last two days and haven't looked at it yet and it is supposed to rain heavily tomorrow. I will have a look-see soon, though.

The "slack in the driveline" theory sounds quite plausible. It's like when all the stuff starts moving there is something with just a tiny bit of play which gets a tiny extra push to get started.

EDIT: Meant to add, if it's a transmission thing would it make the clunking noise in the rear? :shrug:

yup it sure does. i have a sticky solenoid .. when i leave it in od i get a clunk in the rear end ...no od no clunk ... so 199% it can do it.

 

[tommudd]

Never anything side-to-side under any conditions. I got busy the last two days and haven't looked at it yet and it is supposed to rain heavily tomorrow. I will have a look-see soon, though.

The "slack in the driveline" theory sounds quite plausible. It's like when all the stuff starts moving there is something with just a tiny bit of play which gets a tiny extra push to get started.

EDIT: Meant to add, if it's a transmission thing would it make the clunking noise in the rear? :shrug:

Yes it could transmit through the driveline
Mines never done it but have rode in a couple that did

 

[CactusJacked]

Mine started making a clunk in the rear. It did it hard last week in the rain when the slipping tires finally grabbed, I got a good (bad) "wham". Whilst changing the oil yesterday, I gave my rearend a once-over. With it in gear and the parking brake off, I rocked the Jeep fore and aft while looking at the boomerang. The center portion is going up and down separate from the link on the rear housing. Yep, mine is a goner, and that certainly would be the source of the clunk.