Clunk when slowing or accelerating
 

I have an 08 H2 that has some play somewhere in the drivetrain that I am trying to locate. It is noticeable when I slow to take a turn or stop and then give it gas to accelerate. Almost seems like a u joint or something but they seem fine. My mechanic said it may be the transfer case but he hasn't looked into it further. Is slop in the transfer case common or are there other places I should look? Known issues with the 6 speed transmissions? It only has 86K miles on it.

Noise coming from front? Left or Right?


https://cimg0.ibsrv.net/gimg/www.hum...8f5d550717.jpg

did he at least check the normal issues like suspension, ball joints, wheel hubs, drive shafts, body mounts and bushes for play or slop? on my 2003 H2 i had a similar issue when i went from like 15 to 25 miles an hour. updating the powertrain software with a tech 2 gm scanner with the latest tis 2000 update it had made it go away. it felt like slop in the transfer case in stop and go city driving.

I can't tell exactly where it is coming from and I do think he checked ball joints and such but I will check with him. I will look into the software update, I was unaware of that. And it does feel like slop in stop and go driving.

There is an update for the Trans Control Module to address this issue during throttle tip in/out in first gear. I can't find the timeline on the update to see when GM published it, this would kinda let us know if it was an issue from the beginning or if it is an issue due to ware over time.

I'll be doing a gear swap in the future so was planning on setting the backlash on the tight side to see if this makes a difference. I've not tried the software update due to having a custom tune in the TCM and not wanting to change to many things all at once.

Neal

Common for the 4l60e to have a clunk from 1 to 2(15mph-25mph) depending on throttle percentage, only when accelerating. 08 has the 6l80e, not related. Open windows and drive with a passenger, or take it to a shop, and they can drive it on a rack, get under it, and easily find the noise.

The A6 trans has a good bit of adaptive learning built into the programming which is supposed to compensate for wear over time, this may lead to the clunk after a few miles.

Neal

08 has the A6 (6L80)

Could also be the driveshaft slip yoke sticking.... Older GM's has that problem and GM even made an updated nickel plated slip yoke that addressed it but even that did not always stop it.

What is the slip yoke? The front part of the driveshaft that goes into the transfer case?