Clunk when stopping (when cold)

[Offspring22]

So I have a 2017 Sierra 1500 6.2 8spd. 

 

When I start it up in the morning, drive out of my drive way and come to a stop sign, no matter how softly and gently I apply the breaks it feels like someone rear ended me just as I come to a full stop.  A firm clunk from behind.  It only happens for the first 2 or 3 stops (or 2 or 3 minutes if I don't come to any) and only when the truck is cold.  If I park for an hr or so and drive again it doesn't happen but every morning.
 

Any ideas of what it could be?  Been doing it for a while now.  Thank!

Edited July 23, 2020 by Offspring22

[Centex14]

I’ve got the same issue. Feels like either the u-bolts in the axle have loosened up after a 163k miles or the trans mount or something is going out. It’s a very pronounced clunk coming from the drive train and only after sitting for several hours. 

[laughey]

Could be your leaf springs? But then again, mine clunk all the time...mostly first thing in the AM and when driving over pronounced bumps or potholes at a slow pace (i.e., parking lots).

[CAY]

I have the same problem with my 2009 Sierra and if feels like  there is a delay in a solenoid that activates something in the torque converter to causes it so suddenly stop spinning and that jolts the vehicle.

[pokismoki]

try a trans re-learn from the dealer, and have them grease the splines on the output shaft yoke

 

 

these transmissions dont have acuumulators anymore, so if you got harsh shifts it could be due to a seal not holding pressure or the adaptations in the tcu are outta whack..  trans re-learn first

Edited October 1, 2022 by pokismoki