Do any buses use Allison MT 644 transmissions ?

[3408cat]

Does anyone know if the Allison model Mt 644 was in any buses ? If so, were they any good ? Thanks, Bill.

[robertglines1]

Best I understand that trans was designed for the lighter weight Motor home industry.   Bob: PS  I stand corrected  It appears to be limited only by torque.  I WAS REALLY WRONG ON THAT ONE  Bad Me

[kwidd]

I have a bus in my yard with one in it. It is an mc5c old saudi bus. I run a mt654 in my prevost with a cummins m11. It's been in there for 5 years and about 40k miles. still working good. kent

[belfert]

Isn't the 644 more of a school bus transmission?

[Lin]

The 644 and later the 647 are the heavier duty transmissions in the Allison 600 series.  Aside from whatever small internal differences there may be from the others, they have the same torque converter as a 740.  I have a 647 in my 5a.  I don't remember the exact specs, but I think it is rated for 305 hp and around 900 ft/lbs of torque.  I think it would be questionable to use in a 40 footer, but many have used them without issue in 35's.

[Ed Hackenbruch]

The PO put one in my 5A and it now has 144,928 miles on it. 

[Dave5Cs]

I've got a 5C Saudi with the MT654  in it with the 6V- 71

Dave

[Ed Hackenbruch]

The MT644 is rated for 300 hp max, 780 lb.ft. of net input torque max, and vehicle weight (GVW) of up to 50,000 lbs.  Length is 30.42 in.  width  is 19.25 in. height is 21.60 in. and the dry weight is 565 lbs.  This is info from the sheet i have on my tranny.

[bcaddel]

We have a 1971 MC7, 8V71 with the Allison MT-654. It is the only transmission I have any experience with in the bus, but I think it is great. We have put close to 30,000 miles on it and just today drove it almost 500 miles from Reno to Vegas pulling my wife’s Jeep with a jet ski trailer attached to the jeep. We sailed along at 60 plus mph with no issues.
Living in Nevada, we drive in mountains quite often and always pulling a toad. I do not have a temperature gauge for the transmission but is sounds and feels good to me (for whatever that is worth).
Hope this helps, I know you asked about the MT-644, but I assume they are similar.
Bob Caddel

[bcaddel]

C0zy pulling Triples.MOV

Cat
Here is a link to the video of the MT 654 in action
Bob

[Gary '79 5C]

5c & I have put 30K on my bus since acquisition, never a problem.

I might be incorrect, but I believe this trans is a bit shorter than the 7 series, and was a good fit in the 5 series, sans tag axle.

[Ericbsc]

I just pulled an mt-654 out of my eagle.(P.S. ITS FOR SALE) Bus had an 8-71n, and weighs app. 39k. I put almost 9k miles on it with no problems. It is not as big as the 700 series, but seemed to pul fine. I wouldn't use it behind anything over 300-325 hp if it were me.

[kwidd]

The engine in my bus is set @ 400hp and 1450 tq. The bus weighs just over 30k. I know we gone over 40k miles with this trans. I have been towing the last couple of trips so the gross was about 35k. I do run the same cooler as on a 700 trans. Kent

[3408cat]

Thank you very much for all the information !  Bill.