Hello:
I posted this in allison section but I didn't get any feedback, maybe because it is too simple or stupid but I don't know the answer therefore, help me out here please. When my truck is sitting there for few hours, when I start to drive my trasmission shifts very hard from 2nd to 3rd or 3rd to 4th. It feels like "goop" when it shifts. It disappears when trucks warms up, after 10-15 minutes or so. This happens even if the truch sitting there in 100 F outside temp. No problem with other gears. I have see any codes or light. I was thinking to take it to dealer. One other thing, whithing past month my tranny temp went up over 210-220. I was not towing or anything but outside was warm about 100 F.
you can see in my sig that I have larger wheels and tires. Thanks

Mine does something very similar and I've been able to track it back to the programming associated with my Hypertech...I know that cuz when I put it back to stock it goes away.

The Allison is adaptive learn and will shift differently as the temperature changes. Best advice to give you to try is have all the cells reset and drive it the same power level and style for the best shift characteristics.

Back to the Allison forum we go.