I have done a lot of looking and asking and I'm going to swap my 9 speed for a Allison 5 speed auto. I know alot of OTR guys are going to say no. But if I want the Wife to drive it it must be done !
I'm going to use a X-Military Allison MT654cr. This was used in the 5 Ton with the 855 NA Cummins. I will swap out my SAE 1 for the SAE 2 bell housing and build some brackets. Need to add a a trans cooler and think I will go air to oil.My 350 BC IV has a cooling system that was not liked much by the OTR drivers. Something about a slow system ?
The Allison MT654 is not quite as big as I wanted but after talking with people that are using the 400BC in the 5Ton and some Allison guys I should be fine. The MT654cr is made for 300HP and 950 Tq. I'm at 325 and 1150 Tq. Because she comes in at 18,000lbs and the MT654 is able to go 80,000lbs I should be ok. I just can't drive it like I'm 18 ! And its not a sports car.
Only real question is the 3.42 rear end ? Will it fit the trans ratio's ?
Can't seam to get a good answer on this. With a max weight of 35,000 with trailer it looks ok,but don't know for sure.
At governor of 2100 rpm the speed should be 76.75 +- mph. Also with a Jake brake down hill will be easy. Looking for a cruse of 60 mph at 1650 rpm. And a WOT 2300 (Very short time !) of 84.1 mph ? That's like s short down hill ?
So give me any ideas you mite have.
Randy