Light clunk, when letting go of the clutch

Tigerman

Tigerman

TJ Enthusiast
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North Hills, CA
Hello All,

Couple of days ago, a friend of mine borrowed my jeep for a joy ride. When he brought it back, he said everything was pretty good but there was a slight clunk, after every gear shift. I started paying attention to this and indeed, there was a slight clunk right when you let go of the clutch.

Background Info
  • The rear drive shaft u-joints are new (the front drive shaft u-joints are not, but in good condition).
  • All the suspension components, including the control arms are also new and everything is tight.
  • The rear differential doesn't have much backlash play, the front, however has too much? you be the judge (take a look at the pic below). Maybe it is normal.
20180917_144551.jpg


I also noticed that the rear differential has a small, new leak (it wasn't there a few days ago). Here is the picture of that. How bad is it? Can this be fixed easily or the diff has to be taken apart completely?
20180917_144613.jpg


My next idea was the transmission mount, so I attached a GoPro to the bottom of the jeep and drove around. It is three separate videos stitched together (looking at the transfer case, looking at the mount and looking at the rear diff). You can here the clunk sometimes in the video, it is not very loud in the video, but inside the jeep you can hear and feel it better.


I am not sure what it is. Can you help me figure this out? Is that mount still good? could it be the front diff? Should I take the front driveshaft off and test without it?

P.S. The rear diff is Dana 44 and the front is Dana 30. Both diff are LSD.
 
Im not an expert on clunks pops or clicks.

My first thought might have some slop in you transfer case chain.

But when you release your clutch you also flex the suspension. It could be anything. You also twist the drive train. It could be any number of bushing links attachment points.
 
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Thanks Boinked,

The bushings (except the rear sway bar ones) are all new and rubber. You think the rear sway bar links or bushings could be the cause? I am not so convinced it could be the chain either. It just doesn't sound like a chain and I didn't even think steel chains stretched enough to cause a slop, maybe wear out, but that much? Considering the millage of 140K, I am doubtful it is the chain, forgive me.

What do you think of the backlash play on the front diff? Too much or normal?

Tiger
 
There is no way to check backlash by looking at the driveshaft rotation. You would have to open the dif cover and set up a dial indicator on the ring gear to be sure.

You can rock your tj side to side and see if you hear any noise. That would be my first step.

That is a quick easy test. I know I have more pops and clunking than I can find in a week. Im slowly finding them.
 
Boinked said:
There is no way to check backlash by looking at the driveshaft rotation. You would have to open the dif cover and set up a dial indicator on the ring gear to be sure.

You can rock your tj side to side and see if you hear any noise. That would be my first step.

That is a quick easy test. I know I have more pops and clunking than I can find in a week. Im slowly finding them.
Click to expand...

Did it. Nothing, just a very faint sound of the control arm bushings. :)

Anyway, it is not the transmission mount. I replaced it and the sound is there. I will be returning the new one back to the store. It sucks anyway. Too stiff, the idle vibration transfers to the frame.

I will experiment by removing the drive shafts one out of time.
 
Mine was clunking on shift, turns out my LCA bushings were shot. I replaced the bushings and the clunk has since gone away. I still have a little clunk on a hard shift, i believe it to be the UCA bushings. Those I have not touched.

Edit: Looks like you have new bushings anyways.
 
BillNyeIsHigh said:
Mine was clunking on shift, turns out my LCA bushings were shot. I replaced the bushings and the clunk has since gone away. I still have a little clunk on a hard shift, i believe it to be the UCA bushings. Those I have not touched.
Click to expand...



I just watched you video. @42 seconds, seems like it clunks as you go over that speed bump just as it does when you are shifting.
 
Tigerman said:
Thanks Boinked,

The bushings (except the rear sway bar ones) are all new and rubber. You think the rear sway bar links or bushings could be the cause? I am not so convinced it could be the chain either. It just doesn't sound like a chain and I didn't even think steel chains stretched enough to cause a slop, maybe wear out, but that much? Considering the millage of 140K, I am doubtful it is the chain, forgive me.

What do you think of the backlash play on the front diff? Too much or normal?

Tiger
Click to expand...
I have a 2005 Wrangler X six speed I bought new. I have behind the wheel long enought to cobclude
 
Tigerman said:
I am not sure I understand Ron :)
Click to expand...
Sorry about that. As I was saying, I bought my TJ new in 2005. I have always felt a clunk when shifting. A clunk letting up on the clutch and one when letting off the gas. Thats backkash in the differential. I recently discovered how easy it would be to fix but, I've lived with it this long why bother.
 
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