I am not sure if this is the place to ask this or not. I just picked up my new Duramax 3500 Crew Cab Dulley with the allison trany and I have about 700 miles on it. The truck is shifting hard in the low end gears. It has been doing it the whole time since I got it. At first I thought that the trany was just learning but know I am worried. When the truck is slowing down and is down shifting, it will down shift in the low gears so hard that is slides the rear wheels. Anyone have any ideas? or is this normal?

Mine shifts so smooth you cant feel it.Take to the dealer and ask them to check the trans what you have is not normal

Definitely not normal!!!!!!!!

Thanks guys, I am going to take the truck into the dealer today, see if they can figure it out. I hope that it is nothing serious.

By any chance is it in tow mode? Just asking


Tony

check your fluids as well. try the tranny fluid, and rear diff. there have been instances where the rear diff was low and you might just want to check it all out. if it is low, bring it to the dealer and point it out. then ask them why they didn't do the overall check when prepping for delivery.

good luck and let us know what they find.

The truck has an appointment to go into the shop on 6/7/05. The truck will do the harsh shifts in both reg and tow mode. I did check the fluid levels and everything is right. The dealer said it could be line pressures to high or to low. I will keep you posted.

I just heard from the dealer today and they said that the truck had codes in it about the egr value and the computer was bad, so they are going to put a new computer in it. I am not sure what that has to do with the transmisson but I guess well see.

Which computer: the transmission or the engine?

You might want them to rerun the transmission adaptive process (called fastlearn) again using a Tech2. It's possible the 2-1 shift may have adapted wrong.