Need help with the evolution of 5 ton trucks.

[Kellico]

Hi Everyone, I'm a newbie to steel soldiers.

Can some of you knowledgeable gents on here please help me understanding the evolution of 5 ton trucks?

I have recently become an army vet (18B), and don't have much knowledge of these rigs other than seeing them around in motorpools ectr. I am looking to turn a 5 ton into an expedition vehicle/ tiny home and go live the vegabond life for a bit, clear my head, travel be a nobody and disconnect to reconnect if that makes sense.

I have an understanding that the M939 series is the replacement to the M809 series? I like the looks of the M809, but what are the differences vs manual and auto trans.
Can someone please guide me to understanding some of these questions. I'm sorry in advance if I pester or agitate anyone on here, I just have no clue to understanding these machines.

M39 vs M54
M809 vs M814/813 vs M939

I like the front end of the M809 it looks more ventage (Powerwagon)
I am comfortable with a standard trans.
I would like super singles
a winch
preferable a short cargo version to build living quarters on
I'm going to travel distance coast to coast, exploring and living in the rig, so I'm looking for reliability and hopefully a model that allows access to available parts.

I really appreciate the guidance any of you awesome gents can provide at helping me narrow down a suitable base model.

With much respect,

Kellico (Kelly White)

 

[M813rc]

Partial answer -
M809 is the series of trucks of which M813/M814/etc. are members. All have manual transmissions. All had dual rear wheels, 11.00x20 tires, at first, late service Marine Corps trucks had 14.00s.

M939 is the series that M925/M931/etc. belong to. All have automatic transmissions. First type (nicknamed on here A0 for clarity, that is not an official designation) had the same NHC250 engine and 11.00s as the M809s; A1s had NHC250 and 14.00s; A2 had 6CTA engine, air brakes, 14.00s and CTIS.

M939 started out as a PIP (Product Improvement Program) of the M809s, which in turn had started out as a PIP of the earlier trucks. Some later trucks are actually rebuilt earlier trucks, for example my M813 started life as an M54.

There's a place to start, go forth and continue your research. A good place to go next is the Technical Manuals forum on here and take a look at the -10s (operators manuals) which explain a lot of the differences between trucks.

Cheers

 

[NDT]

My 10 cents: skip the ancient 5 tons for cross-United States adventures. Get a MTVR from California.

 

[fasttruck]

M809s have 5 speed manual transmissions and air over hydraulic brakes. Can you shift gears ? I understand 80% of the current US population can not do this. 900s have straight airbrakes and automatic transmissions. All of these trucks max out at 50mph (on stock tires) and do not get attractive fuel mileage numbers. Parts are available, but for the most part not at Auto Zone. If you want to live the free lifestyle and tour the country think about a Volkswagen bus.

 

[Ajax MD]

@fasttruck oh, it's not as bad as 80%. I'd say 80% don't want to shift.

 

[98G]

18B, VERY impressive.

I like the 939series trucks. Full airbrakes are to be preferred over the air over hydraulic brakes on the 809series. Even if the transmission and transfer case in the 939's aren't as robust as the 809series.

Cruising speed in a 939 with 11.00R20 tires is 57ish. Super singles take this to 60+.

Cruising speed in an 809series is 53mph on 11.00s. Singles will take this to 60+.

Mileage is 5-6mpg in a 5ton equipped with an NH250. 9ish in the 939A2 variant with the 8.3 liter Cummins.


NDT may very well be right in his assertion that the MTVR would be the choice. Having no seat time in them, I have no opinion.

 

[Ajax MD]

18B, VERY impressive.

I like the 939series trucks. Full airbrakes are to be preferred over the air over hydraulic brakes on the 809series. Even if the transmission and transfer case in the 939's aren't as robust as the 809series.

Cruising speed in a 939 with 11.00R20 tires is 57ish. Super singles take this to 60+.

Cruising speed in an 809series is 53mph on 11.00s. Singles will take this to 60+.

Mileage is 5-6mpg in a 5ton equipped with an NH250. 9ish in the 939A2 variant with the 8.3 liter Cummins.


NDT may very well be right in his assertion that the MTVR would be the choice. Having no seat time in them, I have no opinion.

Since you're pointing out fuel economy numbers, I wonder what the fuel consumption is in an MTVR? It's a 7 ton truck. Saying that the OP should get an MTVR because they have better fuel economy (for their size) while still getting 6 mpg seems circular.

- The 809's are plenty reliable if you just go through the truck and correct any maintenance issues before starting off. Their advantage is that they are dead simple, easy to troubleshoot and in some cases easier to repair.

- Is a manual transmission really a hinderence when you ride 5th gear on the highway for hours on end?
- All of these trucks are slow. The OP states that he is looking to do the "van life" and disconnect for a period of time. I doubt that 55 or 65 mph matters much if you're not on any kind of a schedule.

- The one area that I concede is that full air brakes on the 939's are safer. No arguement there.

Another option would be to locate a HMMWV with a 4L80e in 2-man configuration. Cruise at 65mph, put the soft cargo cover over the back (or even the helmet top) and camp out in the back. Smaller, more manuverable, fuel economy of about 11mpg.

 

[USAFSS-ColdWarrior]

Olivedrab.com is a good source for some historical information. AND, overall a good place to spend some quality time reading abou all things military.

 

[98G]

Since you're pointing out fuel economy numbers, I wonder what the fuel consumption is in an MTVR? It's a 7 ton truck. Saying that the OP should get an MTVR because they have better fuel economy (for their size) while still getting 6 mpg seems circular.

- The 809's are plenty reliable if you just go through the truck and correct any maintenance issues before starting off. Their advantage is that they are dead simple, easy to troubleshoot and in some cases easier to repair.

- Is a manual transmission really a hinderence when you ride 5th gear on the highway for hours on end?
- All of these trucks are slow. The OP states that he is looking to do the "van life" and disconnect for a period of time. I doubt that 55 or 65 mph matters much if you're not on any kind of a schedule.

- The one area that I concede is that full air brakes on the 939's are safer. No arguement there.

Another option would be to locate a HMMWV with a 4L80e in 2-man configuration. Cruise at 65mph, put the soft cargo cover over the back (or even the helmet top) and camp out in the back. Smaller, more manuverable, fuel economy of about 11mpg.

MTVR specific questions should probably be directed towards elijah95 as he recently drove one from California to Georgia.

MTVR RECOVERY from Yermo cali to Georgia

being? Egay

www.steelsoldiers.com

As to transmission differences between the 5speed manual in the 809 series and the Allison in the 939's , I prefer the 809's manual. For me, it's a close choice between 809s and 939s but the brakes are what tips the balance. ( I have tens of thousands of miles on both platforms)

 

[msgjd]

Some later trucks are actually rebuilt earlier trucks, for example my M813 started life as an M54.

Can you please explain how this came about? The cargo bed, cab, tranny, xfer, & axles are the same, yes. But the frame ahead of the firewall is much longer on the M809-series. Does yours have gusseted frame extensions for the M809-series cummins 250? thanks

 

[fasttruck]

I have seen M 54s and M35s upgraded to A1 and A 2 status. I have seen M35A2s made into A 3s. I have seen the steering gear from wrecked 809 series trucks transplanted to M62s. But I have never seen a M39 series truck like an M 54 turned into an 809 because as mentioned in post 10, the frame and the front end sheet metal is longer. All the wiring and such in front of the dashboard is different. It would make economic sense, even for the military, to start with new components as all that is reusable is the cab tub, cargo body and axles. All of which would have to rebuilt in a depot level overhaul. It is like making an apple pie with oranges.

 

[Elijah95]

I can say being both an m35a2 owner that transitioned into a m923a2 then into an MTVR, the simplest, cheapest, and best performing truck overall with best cost-to-maintain ratio would be a m939a2 series. Having an mtvr any proprietary component could fail and ruin your day

 

[Robo McDuff]

M39 is the official series name for the 5-tons which started in the 1950s as replacement for the WWII heavy trucks. The most common of these are the M51 (Dump) , M52 (tractor) and the M54 cargo bed. A lot of people talk about the M54 series, because that was the most common version, but an M54 is an M39 series truck.

M39 and M809 series: biggest hidden problem: SINGLE BRAKE CIRCUIT, hydraulic. ONE leaking seal, burst flex or fixed line, bad master cylinder or airpack hydraulic leak and you are virtually without brakes with 10 tons of metal on the road. IF the air part of the brakes goes south, you have unsupported hydraulic brakes, meaning literally standing on the brakes to get it to stop sometime. Emergency brake is good for nothing.

 

[M813rc]

Msgjd and Fasttruck, since you seem to have a problem with that conversion from M54 to M813, ask David Doyle about it, since he is who I got my information from.
I don't think you will find many people who will dispute that he is an authority on military vehicles, and he has done the research to back up his claim, therefore I will put a lot more stock in what he says than in the opinion of someone who thinks it can't be true because the trucks look different.

 

[fasttruck]

Hope we can hear from Doyle on what he has on rebuilding M39s into 809 series. Pictures, Production numbers ? I imagine production would be limited. On the face of it it appears to be an inefficient way to do business but that wouldn't bother the Army . A prototype to test the concept ? The M35A3 program did not last too long and the Army switched to FMTVs.

 

[USAFSS-ColdWarrior]

Hope we can hear from Doyle

With the new website platform you no longer have to "hope" someone sees a thread. You can TAG any member by simply putting a "@" in front of their username.

Like this if I was the Member you wanted to tag: @USAFSS-ColdWarrior


(I'm unsure of who "Doyle" is that you wish to see this thread, so just follow my lead with the @ thingie and he'll get an email flagging him of the tagging.)

 

[simp5782]

@DDoyle

 

[DDoyle]

Hi Guys,
I am deep in the midst of finishing up my Studebaker US6 book, and the need to pay bills won't really allow me to stop and go wading through a mountain of 5-ton data - but in short, as incredible as it may seem, some M39 trucks were rebuilt into M809-series trucks. As I recall, this was USMC. My personal opinion, and I have yet to find the "smoking gun" on this, is that this was an effort, for budget reasons, to spend maintenance dollars rather than get funding for new vehicles. The rebuild, as i recall, involved a new frame, power plant and sheet metal, and if you think about it, would not have been THAT far removed from a normal depot-level rebuild.
Hope this helps,
David

 

[eaw46]

Expedition Portal

The global resource for overland and adventure travel.

expeditionportal.com

This is a very good site to get some info on. Although not specific to the 5 ton it has a ton of info on off road camping and equipment for it.

 

[fasttruck]

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 ?