Clunk that slightly moves truck after first start up each day

[Tomato]

2022 Sierra 3500 Duramax. I am getting a clunk that I can feel in my seat and slightly moves the truck after what seems to be initial start each day. Feels like the Allison or maybe transfer case engaging? My 2020 Sierra 3500 DRW Duramax did not do this...

 

Anyone else experience this?

[gemarsh]

Yes, but on a drw. First 2000 miles or so. Now with over 4700 miles, it's not doing it, or I have become used to it. I will pay attention tomorrow morning and report back if it's still doing it.

[gemarsh]

Hasn't done it all week.

 

I did have the TCM update done to it right around 2000 miles also. I can't remember if that is when the movement stopped. Kinda forgot about it, cause it quit doing it, till I read this topic.

 

I know it was scary every time I would start it in the morning and having it lurch/rock forward a .50". 'Cause I reach in and push the brake pedal down with my left hand and hit the start button with my right to let it warm up.

 

First time it did it, I about had a heart attack, thinking the damn thing is going to run me over and drive through the shop wall.