Chasing Driveline Clunk

slee22 · Feb 22, 2012

I've got a pretty nasty driveline clunk when going over 40mph and letting off and reapplying the accelerator. The way I'd describe it is: when I let off, it feels like something clunks forward, and when I get back on it, it feels like it clunks backwards.

So far I've had the U-joints replaced, replaced the tranny mount, greased the slip-yolk several times, and just changed the rear diff oil (and found no broken teeth or excessive wear in the gears) and it still does it.

Anyone have any ideas?

JD3020 · Feb 22, 2012

Have you checked the bellhousing bolts? When i bought my truck it had a nasty clunk andthe driveline felt sloppy. Everything looked fine until we went to put the DP in. One bolt had backed all the way out and would've fallen out but the DP held it in. All the others were loose, and maybe only 1 was somewhat tight. Tightened them up and it went away.

slee22 · Feb 22, 2012

Cool I'll check 'em. Thanks.

Charles · Feb 22, 2012

Did you put the truck in neutral and check the ring and pinion backlash? The gears would not "look" worn even if they had tremendous backlash.

Other than that, what about axleshafts? I'm surprised more trucks don't have loose axleshaft bolts.

If you feel it when sitting still with your foot on the brake shifting from R to D, then it's after the trans. If not, it may be something like torque converter bolts or bellhousing bolts, as mentioned.

If you can't locate it, file it under the, "things I don't give a sh*t about" category. Because worst case, you'll know what it was when it FALLS OFF...

Until then, think about something else, lol.

Denver · Feb 22, 2012

Carrier bearing?

JD3020 · Feb 22, 2012

Charles said:
If you can't locate it, file it under the, "things I don't give a sh*t about" category. Because worst case, you'll know what it was when it FALLS OFF...

Until then, think about something else, lol.

I do that with my truck. Had just dropped my injectors off at Unlimited Diesel and was trying to hurry home on the highway. Hit the brakes doing about 75 which unlocked the converter. Got back in the throttle and it took a while to lock again, which it had never done before and i couldn't figure out. A couple weeks later the converter died. LOL

slee22 · Feb 22, 2012

How do you check backlash? With the cover off, I got a pry bar and moved the gears side to side, and they didn't move much. I don't feel it when shifting from R to D, only when over 40mph.
Edit: I have filed it under the I don't care file for a while, but I'm about to put the truck on the market and get everything fixed before I do. I don't want someone else to go through all the sh*t I went through when I bought it

bad12jr · Feb 22, 2012

Drive shaft flange bolts loose. Mine did that once. Locktite on them since.

slee22 · Feb 23, 2012

Driveshaft bolts are tight.

Charles · Feb 24, 2012

slee22 said:
How do you check backlash? With the cover off, I got a pry bar and moved the gears side to side, and they didn't move much. I don't feel it when shifting from R to D, only when over 40mph.
Edit: I have filed it under the I don't care file for a while, but I'm about to put the truck on the market and get everything fixed before I do. I don't want someone else to go through all the sh*t I went through when I bought it

You can check backlash good enough for this situation in a second by leaving the truck in neutral and grabbing the driveshaft and rocking it back and forth.

Secondly..... if you took a prybar and "moved the gears side to side".... did that mean, move the entire carrier side to side???

If so.... holy carrier bearing NON-preload. If so.... you found the problem.

slee22 · Feb 24, 2012

Ok, the driveshaft only moves a tiny bit while rocking back and forth.
I've seen the pry bar thing on a few videos. When I say the "gears didn't move much," I mean they only moved like 1 or 2mm side to side. If that's too much movement, how is that fixed?
I still need to check the bellhousing bolts to make sure they're tight.

bluedevilslax · Feb 24, 2012

I agree with denver check youy r carrier bearing because mine was bad in my truck and it would jump since the bearing was messed up causing a clunk and when I replaced it the clunk went away.

slee22 · Feb 24, 2012

Carrier bearing in the diff? Because Ex's don't have one on the driveshaft.

slee22 · Feb 29, 2012

Update: The bellhousing bolts were pretty loose, but tightening them didn't fix it. The clunk is only present after the TC locks at 37mph. If I tap the brakes to unlock the TC, it won't clunk until it locks again.

suprhlr · Feb 29, 2012

slee22 said:
Ok, the driveshaft only moves a tiny bit while rocking back and forth.
I've seen the pry bar thing on a few videos. When I say the "gears didn't move much," I mean they only moved like 1 or 2mm side to side. If that's too much movement, how is that fixed?
I still need to check the bellhousing bolts to make sure they're tight.

If you can move the carrier side to side 1 to 2mm I think you found your problem. The carrier is supposed to have a press fit in the housing. If it is that loose its going to need new bearings, at least

JLDickmon · Mar 1, 2012

JD3020 said:
I do that with my truck. Had just dropped my injectors off at Unlimited Diesel and was trying to hurry home on the highway. Hit the brakes doing about 75 which unlocked the converter. Got back in the throttle and it took a while to lock again, which it had never done before and i couldn't figure out. A couple weeks later the converter died. LOL

and then you found the issue.

No problem!

JLDickmon · Mar 1, 2012

are we talking a 1 or 2 piece driveline?

I'm confused..

slee22 · Mar 1, 2012

1 piece driveshaft

JLDickmon · Mar 1, 2012

slee22 said:
1 piece driveshaft

drop the driveshaft, clean out the slip yoke and coat with Lubriplate

slee22 · Mar 1, 2012

I've repacked the slip-joint several times since I've owned the truck, without any resolve. Since it clunks when the TC locks, could it be a loose or bad TC?