Tranny slippage
 

Hey guys. Just traded my junk ford 6.0 in for an 08 cummins 6.7 auto. However my tranny is slipping when downshifting and accelerating on hills. How can i fix it. Please help!

Does it shift in-between gears then catch? If so, time for some clutch packs!

revs about 500rpms too high then slowly Drops down and hooks up. None of the tranny shops around me have worked on any of these yet. I hate to b the test dummy but gotta get it fixed. I have always worked on my own vehicles but have never been into an auto tranny before
:argh:

truck still under warranty?

sounds like its time for a rebuild.

I have a 2010 with an auto.Since new, it has down shifted from 6 t0 5 while hauling 10,000 lbs exactly as you described. I was told it is normal. You are going from 6th with the torque converter locked up down to 6th unlocked to 5th with torque converter locked to 5th unlocked. If you are hauling on cruise control this shift happens under full throttle. To save the tranny touch it down into 5th manually before the hill. Why won't they put an Allison in this truck?