Different Kinda Clunk From The Rear??

[commercialcobb]

I have read all the posts about clunking in the rear-end but mine are not the same. No clunk as I come to a stop, but as I accelerate right off the line I get a thumb in the back and as I pass through 4-5mph I get the second. This is not a gear change, and if I get on it the two bumps become one and if I accelerate really slowly no bumps at all. I don't hear a clunk, it's like a kid is kicking the back of my seat.

Sorry for second post so quickly but at 200k on a 1999 Yukon, these are my only 2 issues.

Thanks again in advance for help on either issue..

I look forward to helping you all in the future if I can offer options and advice as well.

Thank you

 

[bwright81]

i am having the same problem on my 99 tahoe, it is the only problem i have yet to solve and i am dying to know what the hell it is any help would be awesome, u-joints are good so... rear diff maybe?

 

[commercialcobb]

I thought rear diff too but it should clunk when we come to the stop, not just upon acceleration. I have two wild anomalies with my truck that I have not encountered before in any vehicle. Actually my Jaguar used to kick me too and they said it needed grease in the drive-shaft splines. Haven't tried this on the Yukon but it didn't work on the Jag. Maybe I'll give it a shot if nobody has any ideas.

 

[TigerEyz3]

Greasing the splines is a known "issue resolution." I've got 270k+ on my Tahoe and I was having the same thud/kick on acceleration (still do actually). Greasing the drive shaft splines helps, but didn't eliminate the kick on mine - thinking some of it is trans/wheel-hop.

Since I've practically got a new rearend, I can eliminate the following in my case, but your kick could also be the rear diff/gears needing attention.

 

[commercialcobb]

:Caution- Girlfriend insists on smiley's:

Needing attention as in replacing the gears.. Just did that on my 1966 Shelby Cobra 429 (replica) because some SH$*HEAD mechanic (please don't take offense anyone, read further) drained the rear-end a few years back and replaced the drain plug without telling anyone. I came to a screeching halt in a fit-of-rage from 70mph in traffic. The mechanic barred me from his shop and threatened to call the cops when I got done with him.

On a side note, here in Charlotte NCwe have lots of race shops in the area that sell rear-end gears that are slightly worn from a race or two that I could get. Put those in the Cobra's Ford 9in and love it.. Light weight race gears shaved 4lbs off the rear-end.

That being said;

1. Grease splines (If it works problem solved, if not see #2)
2. U-joints (Might as well anyways, they are old)
3. Pull the Diff cover and have a look-see
4. Sell truck as a boat anchor on Ebay

P.S. Sorry, girlfriend likes the smiley's, what can you say?

 

[TigerEyz3]

Sounds like a plan of action. :handshake:
No hate from me on the smilies... Been married for 13yrs this July - small things to keep the peace are worth the extra step or two. ;-)

 

[raptorforme93]

Hahahahahaha. Gotta love option #4

 

[the 18th letter]

Could the rear drums have anything to do with it? I have a clunk at take off that sounds like the brakes are releasing late or something. I don't feel a hesitation or drag but the sound reminds me of the sound the drum makes when removing. I'm gonna check the things mentioned and see what happens.

 

[commercialcobb]

I doubt drums, it literally feels like some kid behind has kicked my seat..

 

[Devious_Tahoe96]

I have the same issue....but on my rear driver drums, they are covered in grease....now i know thats not normal, but i think the bearing is cracked or the seal gave out and its leaking axle grease into my drum. Thats what i thought was the problem. Still haven't serviced it cuz i have no time to get something like that done. So...for now i'll just have to bare the "clunk" at every stop sign/red light i encounter.