Strange Clunking Noise

[benny3577]

Ever since I bought my Jeep a few years ago it has had a clunking noise that seems to come from the back end, particularly the back passenger side. I have laid underneath and yanked on various suspension components (shocks, control arms, track bar, etc.), but nothing is obviously loose. I was hoping someone has experienced the noise (played in the video below) before and could give me any ideas as to what it could be. I will likely replace the control arms soon as they are original. I’ve attached a few video. I’m talking about a sort of clunking noise that occurs when I go over uneven terrain.

The video is here.

The noise is at 0:09, 0:20, and 0:26.


Thanks for the help.

 

[bedhed]

Really hard to pinpoint without being there in the Jeep. I'm really not sure, but your description of the sound is pretty much spot-on with my recent description of a problem. My issue turned out to be the front driveshaft. The splines (for whatever reason) gradually worn down, making them tapered on the ends and the shaft's rotation to be more of an oval motion than a circular one. I never heard the clunking sound from mine until I slowly crossed uneven terrain.

https://www.dropbox.com/s/82out6sxk0baco0/VID_20190719_210324428.mp4?dl=0

 

[LieutenantJohnson]

This could be a bunch of things.

Control arm bushings - can you duplicate the sound on load? Meaning, can you let the clutch out in first fast and hear /feel the clunk? I was able to "lerch" forward with my manual to duplicate a rear upper CA bolt not torqued, causing a clunk

Swar Bar links - should be able to tell if they are worn visibly. They will have to be pretty worn to clunk like that

I had a buddy sit under my jeep while I lurched forward a bunch of times over and over to nail down the sound/clunk. Be careful doing it though

 

[bedhed]

I had buddy sit under my jeep while I lurched forward a bunch of times over and over to nail down the sound/clunk. Be careful doing it though

Lay on the ground AND let you have it in gear. Only the true friends go that distance.

 

[LieutenantJohnson]

Lay on the ground AND let you have it in gear. Only the true friends go that distance.

Yes only JEEP friends will do this for you haha.

OR have someone do the clutching in your jeep AND you go under

 

[Dilly Dilly]

Lay on the ground AND let you have it in gear. Only the true friends go that distance.

Ok I'll go there or ask your ex wife to do it. All in jest.

 

[afitzray97]

Just a guess, but I’ve had similar clunks on my Tj and xj. The Tj had worn rear sway bar bushings on the axle which are cheap and easy to replace. The xj just had one loose rear top shock mount that needed tightening but didn’t appear loose. When trying to find the sounds, neither would budge from me pushing or pulling on parts while underneath, but having a buddy stand on the bumper and jump up and down cycled the suspension just enough to make a guess. I also uselessly took apart, drove around the block, and put back a lot of stuff trying to find the source so it can definitely be frustrating. Good luck

 

[bedhed]

Good call! I'd slide my ass under there in a heartbeat for a buddy. But! I can think of a couple ex's that I would offer the job to first.

 

[Jim Byrne]

Inspect everything up front too. I found that sometimes the noise sounds like it comes from one area but is the other end of the car (or inside).

 

[Mike Patterson]

One of my rear control arm mounts cracked and then broke which caused a similar noise. Also check your transmission mount. Similar noise. I would check that first.

 

[benny3577]

Thanks, everybody. I've replaced the transmission mount and the rear sway bar bushings on the axle over the last few days. I think I'll have somebody bounce on the front bumper and see what is going on when I get a chance. I was stopped on a smooth and paved uphill incline the other day and let off the clutch rather quickly in first gear and the clunk presented itself there too. Does that give any more hints?

 

[bedhed]

Thanks, everybody. I've replaced the transmission mount and the rear sway bar bushings on the axle over the last few days. I think I'll have somebody bounce on the front bumper and see what is going on when I get a chance. I was stopped on a smooth and paved uphill incline the other day and let off the clutch rather quickly in first gear and the clunk presented itself there too. Does that give any more hints?

I'm still thinking either the shaft. Maybe the control arms like the other guys mentioned. I guess that would depend on how hard it lunged forward, yeah?
Did you get a chance to check for play in either one of the prop shafts?

 

[benny3577]

I'm still thinking either the shaft. Maybe the control arms like the other guys mentioned. I guess that would depend on how hard it lunged forward, yeah?
Did you get a chance to check for play in either one of the prop shafts?

I didn't lurch too hard, that's for sure. Unfortunately, I'm over 250 miles from the Jeep right now because I'm at school. I'm going to have my brother take a look and I'll report what I find out.

 

[LieutenantJohnson]

I didn't lurch too hard, that's for sure. Unfortunately, I'm over 250 miles from the Jeep right now because I'm at school. I'm going to have my brother take a look and I'll report what I find out.

Control arm bushings and/or bolts not torqued properly. Have you replaced any CAs lately ? Were they torqued properly with tires on the ground ?

 

[benny3577]

Control arm bushings and/or bolts not torqued properly. Have you replaced any CAs lately ? Were they torqued properly with tires on the ground ?

I have not replaced any lately. I think they are original, and the bushings don't look too good. I hope to replace them soon though.

 

[LieutenantJohnson]

I have not replaced any lately. I think they are original, and the bushings don't look too good. I hope to replace them soon though.

I suspect the CA bushings are the culprit..

 

[benny3577]

I suspect the CA bushings are the culprit..

You were indeed correct about the control arm bushings. I changed them this weekend. The passenger-side rear control arm had a bushing that wasn't even pressed into the arm anymore. The clunking noise has now seemingly disappeared.

 

[LieutenantJohnson]

You were indeed correct about the control arm bushings. I changed them this weekend. The passenger-side rear control arm had a bushing that wasn't even pressed into the arm anymore. The clunking noise has now seemingly disappeared.

Awesome glad it was an easy fix. Re check the torque after a couple hundred miles just to make sure they are still tight.

 

[Tycarver]

Really hard to pinpoint without being there in the Jeep. I'm really not sure, but your description of the sound is pretty much spot-on with my recent description of a problem. My issue turned out to be the front driveshaft. The splines (for whatever reason) gradually worn down, making them tapered on the ends and the shaft's rotation to be more of an oval motion than a circular one. I never heard the clunking sound from mine until I slowly crossed uneven terrain.

https://www.dropbox.com/s/82out6sxk0baco0/VID_20190719_210324428.mp4?dl=0

did this only happen when in 4wd?

 

[bedhed]

did this only happen when in 4wd?

It was just the opposite. I assumed that it's disappearance while it was in 4wd was due to the shaft having torque applied to it.