Need help with the evolution of 5 ton trucks.

[US6x4]

Hi Guys,
I am deep in the midst of finishing up my Studebaker US6 book,

This sounds exciting - my brother and I will definitely be looking forward to the release of this book!

 

[steelcaptain]

Can I chime in to ask confirmation regarding early M939 trucks where rebuilds of M809 trucks? If true was this rebuild done to trucks already in inventory or to trucks built by AM General but not yet delivered to the DoD (or both)?

 

[fasttruck]

I seriously doubt any significant rebuilding of M 809 series trucks into M 939s occurred. Maybe one someplace to test the concept. Too many parts are different between the two to make it economic or easy to convert trucks already in the field from 809s tom 939s. I saw M809 trucks converted to straight air brakes using the same components later fielded in the 939 series. But the newer cabs are wider, the frame is different, engine is different, transmission and transfer case are different, wheels and tires may be different, in the case of cargo trucks, the body is different and so on. David Doyle is supposed to have some info on this but I am skeptical of people who "know" this happened but have no info on place and time.

 

[fasttruck]

Also if any of this type work ever went on it would have been a long time ago, like early 1980s and any DOD civilian or military personnel involved have been retired for a very long time.

 

[steelcaptain]

this is according to Wikipedia:

"Early M939s were rebuilds of M809 vehicle chassis with a new automatic transmission, transfer cases, cab, and hood"

 

[98G]

this is according to Wikipedia:

"Early M939s were rebuilds of M809 vehicle chassis with a new automatic transmission, transfer cases, cab, and hood"

I've seen that also. I just can't bring myself to believe it. Too many differences in the frames and hole locations in the frame. It would be far more work/expense to turn an 809 into a 939 than it would be to make a 939 from scratch.

That isn't the first bit of misinformation to be found in Wikipedia.

 

[jasonjc]

It has not escaped notice that a lot of "fuzzy" information gets out on this site based on what someone thinks someone else thought about the subject at hand.@ Doyle's comment in post 18 is plausible: a "one off" unit could be built to test something, but there is no hard info on this as to when and how many. I saw a small number (less than 6) 809 series trucks that were decked out with straight air brakes same as a 939 series would have. Maybe a kit was being introduced to do conversions. But as production of the 939s commenced the idea was shelved. As to the M54-813 conversion, could @813rc could post some pics of his truck, especially the area ahead of the firewall and under the front fenders ?

Doyle said they used new frame and sheet metal. Its like the M915's , they upgraded a bunch of them by getting new cab and chassis and drive train , but kept the rear axles off the older trucks. Then sold off the old trucks with no rear axles. I can see the money thing you have money in the repair part of the budget but not new , plus it would save on some of the bidding requirements.

 

[MyothersanM1]

I converted an M809-series truck to straight air brakes ridding myself of the questionable air-hydraulic brakes.

M809-series (M81 Air Brake Retrofit

 

[Guyfang]

I do remember seeing and driving series 809 trucks here in Germany, that had been converted to straight air brakes. This was sometimes after 1985, when I went from the Hawk missile system, to the Patriot missile system. The Hydro Vac component of the Air over Hyd system being probably the most hated component in the Army, that ever was. I lit a candle in church, when I drove an updated truck.

 

[Guyfang]

I just sent a whatsapp off to a guy I still know in TACOM, (Tank and Automotive Command) who might be able to shed some light here.

 

[Guyfang]

This is the reply I got back from the Senior TACOM guy in the Truck arena.

NO!! Never happened.


I suppose some body with time and free parts could take the 809 apart and re power it with everything out of the 939 basic and there are enough people with nothing but the need to tinker that had or have access to the parts and tooling to do this but that's not an official action.


I would take the power train from a 809 and put the whole thing in a 939 but that's just because I started live with the old m52 gassed dump truck and tractors which were really strong pulling.
Then the 809 came with the 855 cubic inch diesel and there was a lack of pulling power compared to the gas powered ones but when the cummins 250 came, that was about a slow but more parts supportable at the time truck.


So take it for what its worth.

 

[fasttruck]

Even the Army is not stupid enough to rebuilt 808s into 939s. What they did was order enough 939s for the high priority deployable units. Then push their 809s and any not issued from depot down on lower priority and reserve components which would then allow them to surplus off their M54A1 and 2s and any gas jobs still on hand. No point in playing around with remodeling M809s to keep M 54s in the system.