M934a2 bhtrv

Ok, first off I'd like say... I really wish there was a separate category just for our camper builds since there are so many and I really don't know where it is supposed to go!! Ok, rant done lol

Now on to the meat and taters! My end goal for my 934A2 is to hold a 20' ISO shipping container on the back that will be transformed to be my RV/tiny house while I travel the Americas. I can't seem to find many, if any, instances of anyone else doing this kind of build so I thought I would post it up here. I always welcome y'all's opinions so go ahead and chime in any time.

I do have a general idea of where I want certain things to be, but beyond that I'm open to new ideas. I do know for sure that I want the bed to be above the truck cab, with the closets being where the tire davit and muffler normally sits. That is all add-on area to the ISO though, where the cargo bed normally starts is where the ISO will start. Working towards the rear, after the bed and closet area will be the bathroom and as compact as possible. I imagine the bath will be a walkway through the center, with the toilet on one side and shower on the other. After the bathroom will be the kitchen, this is mainly because I want all the plumbing area to be as compact as possible too, to include the gas plumbing as well. Then it will be the dining and living area, possibly followed by a storage area for my Harley. I am torn on where to put the Harley, part of me wants it in "house", but I also like the idea of just putting in a trailer that will also hold my wood shop tools for my business.

I was originally thinking making the sides fold down to create more floor space or a terrace/patio. But the more I think about it the more I'm interested in keeping it totally water tight. I already thought of a few designs for keeping it water tight with the walls folding down, but they will add unnessary complicated work that could fail at the most inoportune times. I might still keep that idea for the wood shop trailer though.

Now as for the truck itself, I've had a few ideas long before I ever bought it and that's where the title of the thread comes from. "BHTRV", Buoyant Half-Track Recreational Vehicle. I wanted it buoyant because of certain roads in the US that require ferry crossings and also because of the Darien Gap in Panama, but it will NOT be a full-time useage. The rear of the truck would be easy to keep buoyant...however the front will be a real engineering challenge. Before I had real weights to work with, yes I already stopped and got on the truck scales before I installed the cargo bed, I used the tare weight of an ISO and what I thought the weight of the truck might be. Of course I was way off for the trucks weights (front/rear), but nothing that would make it impossible. The water line for the ISO alone would be about 7.5in above the floor. I say floor and not the very bottom because I will be welding up and sealing the bottom where the ribs are for water storage, clean grey and black. The front weight of the truck was the only weight that was remotely close. I had figured 11k (true weight being 9840), which would require about 183ft^3 of air to make buoyant. I had thought of 55g drums, but that is impractical as that would require 25 drums. As for the rear I had figured (incorrectly) that the tandem weight would be about 28k (true weight being 9560), this would've put the water line at just under 3'. There are ideas for reducing the water line and increasing stability, but that is for later since the front really needs more work and consideration.

The next part should be self-explanatory, the half track part is for the rear wheels only and only for mud or snow. I think that wheel articulation for rock crawling will be too much for any add-on half-track setup that I come up with. Mind you the half track part (just like the buoyant part) is only as needed and NOT full-time. I have seen several roads in South and Central America (via YouTube) that would make even me nervous. So I figured that I would rather have a standby tire add-on setup to turn it into a half-track rather than be stuck out in the middle of nowhere where no one usually travels, and still not find anyone that would be able to recover this big beast. This will most likely be comprised of heavy chain and angle iron, but that may change. Of course, I missed having my truck during a really soggy winter for our area to test out the rear tire abilities during heavy mud/snow operations. My next chance probably won't be until our monsoon season, or next year at the latest.

Purchasing the truck was the very first part of this goal, now the next part is purchasing a 20' ISO container. I will be buying some heavy steel first to build a frame that will connect the ISO to the truck chassis. If I had a 20' ISO on hand to make measurements and test fit the frame it would be great, but then I would have no of lifting the ISO to put it on the truck. SketchUp has some drawings of them, but I just don't trust someone else's measurements to build for something unseen. I do have someone local that could bring in an ISO for a lot of $$$, and he has some sitting in town so I might try to see if he'll let me mock up a frame using one of his. It would be nice to be able to pick out a one tripper myself at the ports, but I just don't know if that will be cost effective yet considering I'll take the truck to get it and as of right now she only gets 6.5mpg.

Anyways, that's enough rambling on for me, if y'all have any ideas or suggestions I'm all ears. This project will be a long going one since I live on my meager military/VA pension.

No suggestions here, sir - other than to please post lots of pics so that those of us who dream such dreams can learn from your build!! (Grabbing popcorn and ready to watch this build!)

Lol better share that popcorn! This whole project will go at a snails pace to what I'd like, but oh well. I will most like focus on the living area first, then the half track add-on. I know the B part will be an engineering challenge, so it's a good thing that is what I'm going to school for! Once I have a shipping container in hand I'll start working in SketchUp and post pics of the intended outcome. I will probably do the same with the ISO frame for the chassis, in case any one wants to do something similar. What I'd really like to be able to do is make the ISO frame pivot left or right with air bags so that the angle to make the truck overturn is greater. Normally we would be far more uncomfortable than the truck would be, but that will be a lot of weight up high so I know that will negatively impact the rollover angle. The airbags would be controlled by an arduino microprocessor, and I may even piggyback an arduino into the CTIS so that I can get exactly what tire pressures I want in each tire individually instead of as a batch like it runs in stock form.

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Large expedition camper build, plenty of room with the 20ft shipping container.

The military did have a 'slip on' half track setup for these trucks with the smaller 11x20"s. Not many were made, think they were rubber tracks. Why not just install lockers into each axle instead?

red said:

Large expedition camper build, plenty of room with the 20ft shipping container.

The military did have a 'slip on' half track setup for these trucks with the smaller 11x20"s. Not many were made, think they were rubber tracks. Why not just install lockers into each axle instead?

Click to expand...

Are there any places to find a pic of those?

Another Ahab said:

Are there any places to find a pic of those?

Click to expand...

Only seen 1 picture of the original military setup (was here on steel soldiers) that goes over both rear tandems. Heres a pic of tracks for each individual wheel that apparently came on the older trucks.





A set made using the tracks from a APC (gotta be heavy and difficult to setup)





And some commercial made tracks that are a 'slip on'

if the tandems stay at a pretty regular distance apart during articulation building grouser tracks like a skid steer uses would be fairly easy, if they travel apart more then a acceptable amount of slack can absorb the binding may damage the rear suspension, weak point would likely be kicking a rod end off the joint. i have completely rebuilt my bobcats logering tracks using the existing pads but if scratch building a easier/cheaper design uses 2 loops of grade 80 chain with [ shaped pieces welded to the chains every half foot or so

red said:

Large expedition camper build, plenty of room with the 20ft shipping container.

The military did have a 'slip on' half track setup for these trucks with the smaller 11x20"s. Not many were made, think they were rubber tracks. Why not just install lockers into each axle instead?

Click to expand...

Yup, I'm aiming to be comfortable it in for a few years while I travel. I most likely won't take it off until I find my new home. Not sure where it will be or when, when I decide I'm done traveling I think back to where I loved it the most, people and geography considered, and go back there most likely. I would love to go to Colombia but it is already out of the question since I would be able to import the truck.


Red, your 3rd and 4th pics is kinda what I'm after.

winfred said:

if the tandems stay at a pretty regular distance apart during articulation building grouser tracks like a skid steer uses would be fairly easy, if they travel apart more then a acceptable amount of slack can absorb the binding may damage the rear suspension, weak point would likely be kicking a rod end off the joint. i have completely rebuilt my bobcats logering tracks using the existing pads but if scratch building a easier/cheaper design uses 2 loops of grade 80 chain with [ shaped pieces welded to the chains every half foot or so

Click to expand...

I've already thought about the articulation and while I think that it will be highly unlikely that I would employ them for any kind of rock crawling I also won't rule it out either.

That's what I'm planning on doing, either using C channel or double up angle iron. The other biggest factor is that I want to keep as much mud out from between the tires. I won't be using it on pavement at all, unless roads are icy and I absolutely HAVE to move the truck for some reason. Like I said before, I doubt that I would ever use it much, but I would rather have a half-track setup for it than to want it and not have it. I also envision something similar to tire chains since they wrap around the side of the tire to hold them in place. I just don't want to make it too tight for the reasons already mentioned about popping the dogbones off, possible heavy spring tensioner?

A single tensioner wheel centered between the tandems would work for that.

Familiar with the expedition rig, eventually want to make one as well.

Forgot to mention that lockers are on my list, but these will most likely be cheaper and I feel as though these would have a better chance of getting through the worst of possible places vs just having lockers alone. As long as wheel location stays the same relative to each other during articulation and single tensioner is what I'll make, but it'll be on the bottom between the two tires for a little more solid traction, although if the tracks do well without it I may not bother.

Edit; Still need to put some sort of traction material between the tire and tracks so that the tires don't spin in the tracks, I'm thinking of maybe old used tires, but if y'all have any better ideas I'm open.

Wouldn't count on tracks being cheaper than lockers. Lockers are about 550 to 800 each, those tracks in the last 2 pics are 15,000. Might be able to build a set for around 2000 that would work properly but would be heavy. Not concerned with rolling resistance, the weight to install and pack them up. Even rubber sets are a few hundred pounds for this size.

Tracks have their place, just for more of a dedicated vehicle for that location in my opinion.

Don't know how well tracks and lockers interact, they might fight each other.

Personally I'd go with lockers and a good set of snow/mud chains. With true 6x6 and chains, not many snow or mud areas you can't reach.

There is no way I would purchase tracks, if I have any for the truck I'll make them myself. They may be super heavy but that's why I bought a 5t instead of something smaller. As far as the interaction between the tracks and lockers...in theory there shouldn't be any problems since they essentially both create the same effect of not letting the wheels slip, but that is in theory, we shall see how they react in real life...assuming I get that far.

couple pic links to chain tracks http://www.goldenbellinc.com/track29.jpg http://www.eelriversteel.com/images/eel-trax.jpg

my own grouser tracks
the chain style would be easier and weigh less, these are a royal pain to reinstall even with the screw track jack i built due to the weight and these are probably 1/3 1/4 the size of truck sized units, would need a autocrane and various binders and other tackle to handle something big enough to ride on 46"s or bigger, the chain style is simple enough could probably make the bars with a hydraulic press and a vee block.
they do slip on the tires when wet some but it doesn't take much to grip and take off, i think the bar/chain style might be less prone to slip

www.unusuallocomotion.com/pages/mor...i-tracked-wheel-cum-track-vehicles.html#page2

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That website has some cool history!

Right now I'm trying to figure out the math to decide on the tubing sizes I want to use for the ISO mounting frame. Once I figure that out I may start drawing up the frame and half-track setup at the same time in SketchUp.

Did they change the axles between the M51 and the M939 series trucks? I have a line on an older truck chassis and want to be sure that I can swap tires and wheels between all the axles. This chassis would be the trailer frame for my woodworking workshop ISO container. Of course because of our lovely federal laws this will force me into the class A CDL because of the trailer weight, otherwise without the trailer weight I could get away with a class B CDL. B is for trailer weights UP TO 10k# and A is for 10k# and up. The tare weight for the ISO container is about 5k# and if my M934 is any sort of example I'll be looking at close to 10k# for the trailer chassis and ISO frame. That'll put the trailer at 15k# before I start putting any of my tools, wood, or products inside it.

The axles are the same but the brakes are different. The older m51 uses single circuit hydraulic brakes, m939 series has air brakes.

If the stock hydraulic brake components are on the 'trailer' your m939 series will activate them using the standard glad hands, just won't have a parking brake on the trailer. The hydraulic brakes are strong enough to lock up the wheels.