allison 5 to 6 speed transmisson change out
I currently have an 06 newmar mountain aire with the 8.1 engine and Allison 5 speed. We love our MH but would like to have the 6 speed tranny. Would I see many benifits and is this feasible and cost e...
Forum Discussion
The gear ratios for the first five gears is the same for the 5 speed and the 6 speed Allison transmissions. Adding the 6th gear added an additional overdrive that went from 1:1 ratio in 4th to a .71:1 ratio in 5th and a .61 ratio in 6th.
For that reason Monaco/Workhorse changed the rear axle ratio to allow the engine to be able to pull the second overdrive. I'm not sure what the other manufacturers did but it seems to me that the ONLY place that you may be able to use the 6 speed conversion would be on flat and level roads, with a lightly loaded coach, unless you change the rear axle ratio as well. Naturally you will need to reprogram the TCM and the ECM so that all of the electronics recognize the change in the transmission.
I think the gain is going to be very slight and only useful in a minimum of conditions.
For that reason Monaco/Workhorse changed the rear axle ratio to allow the engine to be able to pull the second overdrive. I'm not sure what the other manufacturers did but it seems to me that the ONLY place that you may be able to use the 6 speed conversion would be on flat and level roads, with a lightly loaded coach, unless you change the rear axle ratio as well. Naturally you will need to reprogram the TCM and the ECM so that all of the electronics recognize the change in the transmission.
I think the gain is going to be very slight and only useful in a minimum of conditions.
