M817 Spicer to Allison

[tobyS]

Hi guys...just won an M817 on GL and have a question. Has anyone changed to an Alison auto? I really don't like shifting.

 

[Sephirothq]

You would be better off buying the m929

 

[tobyS]

I thought so too, but kind of like the body style of the M817 and it has only 17k miles (very straight bed, not abused). Price was within budget and I can sell after doing my job if I don't like it.

 

[tobyS]

Bump. Has anyone changed an 809 series to an Alison?

 

[wheelspinner]

I've also wondered about changing a 939 truck to the stick, hmmmmmmm

 

[tobyS]

They are both Cummins 250 wheelspinner. And my truck has under 17K, so not worn out. Yours?

Edit; They are 250 if yours is the older 939 as apposed to a BMY.

Edit again; Is the tranny from an AM General 939 series also the same mount to the later 8.3T Cummins in the BMY? In other words, will trannys swap years? That would imply the Spicer manual would also mount up if they match between years with the Allison. Is it possible they are that consistent in this size truck?

 

[wheelspinner]

One of mine was a long term storage with 402 miles when I got it, one has 12K. Both are with 8.3T. I have wondered how that truck would be with the OD transfer case and a 5 speed stick. I have an extra Allison here (its listed in the classifieds for sale).

 

[BrushMaster Builder]

We've done it on a couple of our brush truck conversions awhile back. I'd have to dig up my notes but I know we robbed a trans, trans cooler, shift tower and shifter, from a basket case M939 and did the conversion in about a week. You'll need a good driveline shop who is a Dana/Spicer driveline builder to build you the output driveshaft to the correct length. The current drive shaft in the M800 or M939 series will not just "bolt up".

 

[BrushMaster Builder]

Oh, scratch that on the trans cooler from the M939.....we utilized a Thermal Dynamics aftermarket cooler.

 

[patracy]

I know it's not much, but if anyone is going down this path, I've got a shifter tower and cable they can have.

 

[tobyS]

Thanks BrushMasterBuilder and patracy. Do either of you know if the engine to transmission connections are the same in the M809 series (70's) with 250, through the 80's model 923's with 250, clear to the BMY 923 with the 8.3T? That is, aside from drive shaft modifications. Or asked another way...do the engines and transmissions mate through all the years?

 

[cumminsbandit]

I also was thinking of this. Soon I am hoping to get a 923 with the 8.3 and i would love to put a 5 speed out of an older 5 ton in it. Is this possible with the current bellhousing or is there something else needed for this? I cant stand automatics and stay away from then whenever possible!

 

[tobyS]

Hi cumminsbandit, I can't tell if Brushmaster Builder has went to the 8.3 or 250 (putting auto into an 809 series). Maybe he will say. When I have a bit more time I will follow up. My 817 would be a good candidate for a swap with less than 17k and 1983. Also, does the transfer case have to be changed or just drive-shaft build?

Without seeing the shift pattern difference of a normal five speed, in my rush to see how my 817 drives out, I noticed there was a huge ratio gap between third and fourth gears....then I read the instructions and realized that four and five are switched from a normal H pattern. I was going from third to fifth. DUH !

Surprisingly, I kinda like the manual...but I'll see if my left knee does. I have about 40 loads to haul a few miles.

 

[dikwks]

Do you guys know if the transmission from an A2 5 ton will change up with the transmission in an A/A1? What are the Allison model numbers in the two trucks? I've only found a P/N or NSN in the TMs. I would like to put an A2 engine in an A model 925, but I can't tell if the bolt patterns, etc. are compatible.

 

[tobyS]

I would like to know that too dikwks. Are the engine crank connection and bell housing the same from early 250 through the later 8.3 turbo? One would think it is possible that all 250's and 8.3's have a consistent pattern over a lot of years. If they are the same between Spicer and Alison on the 250 and 8.3, they would also be for your engine swap, 250 to 8.3. Hope someone knows and will answer.

 

[cumminsbandit]

I would have to believe someone on here would know this or know what is needed...? Would be interesting project! Someone spill it! Haha