2500HD with Allison Clunk noise when going back and forth(Slipjoint?)

Mortgage Paul · February 17, 2016

Hey All, I have a pretty good clunk when shifting from forward and stopping to reverse and vice versa.

While it was on the rack for the stuff in the other thread, I had them poke around.

That thread is here.

http://www.gm-trucks.com/forums/topic/183410-2500-hd-need-serious-mechanical-help-fellas/'>http://www.gm-trucks.com/forums/topic/183410-2500-hd-need-serious-mechanical-help-fellas/'>http://www.gm-trucks.com/forums/topic/183410-2500-hd-need-serious-mechanical-help-fellas/'>http://www.gm-trucks.com/forums/topic/183410-2500-hd-need-serious-mechanical-help-fellas/

http://www.gm-trucks.com/forums/topic/183410-2500-hd-need-serious-mechanical-help-fellas/

I had climbed underneath and couldnt find a loose U joint or Center bearing or anything obvious, but sometimes it sounds like its coming from the front end and the noise is traveling.

Dealer originally said its the slip joint and no worries, nothing you can really do.

Then I asked them to take another look and check the ball joints and stuff like that. They said all was good (Only 70,000 Miles) and that the most it could be is the idler arm/pitman arm or whatever GM calls it.

It needs replacing, but it sounds more under the seats/floorboard.

Trans shifts etc as normal. Any other ideas?

Mortgage Paul · February 28, 2016

UPDATE- Took service manager for a ride and he said it sounds like a Trans Mount or something. You can really hear/Feel it when pulling away from a light(Like something is moving around and loose)

Also said there was a TSB or a notice that Mounts were breaking etc. Anyone heard of this? I have been out of town and havent had a chance to climb underneath it yet, but with the LYING I have gotten from them so far, it's hard to belive anything at this point.

At 70K on this truck, this just seems like BS to me. This things been babied both use and maintainance wise.