My truck now has over 37,000 miles on it and the tranny seems to be fine except for a harsh shift that has happened twice while pulling a trailer (8,000 lbs.) .I was going about 37 mph under light throttle and let off throttle,when I reapplied light throttle the truck jerked forward violenty making the fifthwheel hitch slap big time.I do not know if tranny was trying to make a shift and momentaraly was in neutral or what.If it did it under heavy throttle I do not think the Allison could survive.At the time this happened the truck had 28,000 miles on it.On the way home Friday running on the I-94 ,traffic got backed up and the tranny did the same thing like above,this time no trailer in tow.Wonder if there is a computer update on this or if its a mechanical problem.

I don't think you have a mechanical problem.....where you in tow/haul? The thing with the Ally is that it tries to learn all the time. If you only tow once in a while it will seem funky as it tries to adjust shift profiles for the added load. I have a power adder in mine and I will notice something similar even changing power levels.


My advice would be to use the tow haul whenever you tow all the time.......the ally will learn to shift smoothly with the load and should calm down. Only use it to tow, it keeps from confusing the computer.

10four on the tow-haul when towing and never use it bobtailing.I once tried kicking the towhaul in and out in changing conditions while towing on a trip and it really gets the allison confused.