M915A1 trans jump?

[AMGeneral]

Folks,I have a question of the 915A1(Allison trans) owners out there,

Seems mine has a odd quirk,hot or cold ,partial or full throttle it will skip from Lockup first gear directly to lockup second gear,skipping converter second all together,I am running the proper weight oil and have changed the filter and oil several times,oil temp stays normal ( 160 to 180 degrees) and does not have any odd smell or color to it,no other odd shifts happen,just that one,and it seems to happen all the time.

Any suggestions?

 

[cornrichard]

All three of mine do the same thing when they are empty. I think it has something to do with the jake brake system. My guess is they need to be locked so the jake will work. It is a lot smoother with a trailer.

 

[stellaruthie]

Mine does the exact same thing,thought I was the one with a problem!thanks