How to Choose a Chassis for your Camper Van: Our LMTV M1078A1

For our adventure vehicle, or MonsterRV, as I also call it, we chose a 15-foot Bliss Mobil expedition camper unit for the living quarters portion. Bliss Mobil is not building a turnkey truck/camper combo, hence, we needed to choose an expedition truck chassis. A surplus U.S. Army LMTV M1078A1 was our final choice. This post focuses on the LMTV and Couch Off-Road Engineering who is making the necessary mods to the stock Army vehicle. Check out previous posts for more on our Bliss Mobil camper.

Our requirements for an expedition-capable truck chassis

• Available in the U.S.
• Good off-pavement capability with more than 2-wheel drive.
• Does not require ultra-low-sulfur diesel (ULSD) – ULSD is not generally available around the world, especially in places like Mexico and most of South America. Non-ULSD trucks are generally pre-2007 models.
• Globally serviceable.
• Adequate payload capacity – The Bliss Mobil 15-foot unit loaded with fluids, all accessories and sub-frame, is roughly 5 U.S. tons.
• Reasonably comfortable cab for driver and passenger.

What did we look at?

Our requirements, especially no-ULSD, limited the number of choices in the U.S. I briefly considered the Freightliner M2 106

and Ford F550

The Mercedes Unimog would be an option if we could find one large enough and older than 25 years old.

But what we settled on is the U.S. Army LMTV M1078A1.

LMTV specs vs our requirements

We purchased a 2006 Stewart & Stevenson M1078A1R through Jay Couch owner of Couch Off-Road Engineering. Here’s some general specs for the M1078:

• Caterpillar C7 engine – late 2006 and onward
• 275 hp / 817 lb-ft torque
• Allison 3000 series transmission
• Automatic/select 7-speed, electronically controlled
• ArvinMeritor axles
• Full-time AWD
• Electronic Central Tire Inflation System (CTIS) – really, really cool!
• ABS brakes
• 22″ ground clearance (loaded)
• Approach / departure angles = 40° / 40°
• 60gal fuel capacity * 7mpg = 400 mile range
• Maximum Grade / Side Slope = 60° / 30°
• Fording = 30″

Added on since acquired from the U.S. Govt:

• 3.07 ring and pinion (6.14 final) in each axle
• 330 hp / 860 lb-ft torque computer reprogram
• Electronic cruise control
• Rear axle locking differential

Available in U.S.

These can be found at a U.S. Gov auction site, like Gov Planet, or the secondary used market. Or like we did, contact Jay as he may be able to help you find one. He can also help you get it ready for expedition and adventure which we get into more below.

Off-road capability

The LMTV is purpose-built for off-road use and abuse. See the previous stats for approach / departure angles, side slope angle, ground clearance, max grade, AWD, CTIS, fording, etc.

ULSD requirement

None.

Globally serviceable

The CAT C7 and Allison transmission are serviceable anywhere in the world.

Payload

The M1078A1 has a listed payload of 2.5 U.S. tons. Our total loaded payload, including sub-frame is 5.2 U.S. tons. This next part is not scientific but the bed and bed sub-frame will be removed to install the Bliss Mobil sub-frame and unit. The M1080 is the 2.5 ton LMTV with no bed and bed sub-frame.

• M1078A1 curb weight = 8.8 (U.S. tons)
• M1080 curb weight = 6.6
• Bed and bed sub-frame weight = 2.2
• Listed payload: 2.5
• Payload without bed and original sub-frame: 4.7 U.S. tons

• Bliss Mobil unit fully loaded with motorcycle: 5.2 U.S. tons

Add on some more for winch, bull-bar, toolboxes, etc. So we’ll be about a 1/2 to 1 U.S. ton short on (listed) payload capacity. The real world capacity of the truck is probably better than 2.5 U.S. Tons. Jay has tested another LMTV with a bed, loaded with 6 tons (water) on the back, and says “she squats and knows it’s there but handling and power are OK.”

We will probably need to do some mods to the suspension (leaf springs, air suspension) to comfortably take on the extra weight. But first of all, we’ll mount the Bliss Mobil unit and observe how it handles.

Comfort

The cab interior is not really designed with comfort in mind, so we’ll need to do some work here to get it to a reasonable, family-friendly state. Some additions we’re considering:

• Air-ride seats for driver and passenger
• Sound-proofing in panels and where else possible
• Air conditioning

Fitting the Bliss Mobil camper onto the LMTV

We want to have the camper unit adjacent to the cab so we can install a pass-through between the two and have a few challenges to overcome. Directly behind the cab is the spare tire, tire crane and engine air manifold assembly (it’s huge). Furthermore, the transmission protrudes above the frame. Consequently, Bliss Mobil engineered the sub-frame to account for this but the box will end up sitting pretty high.

Here’s a couple of photos of our truck stripped down, but before all the assembly has been removed.

Putting it all together

Here’s a PDF of the CAD showing all the parts as they should fit together – truck chassis, sub-frame and Bliss Mobil 15-foot expedition camper.

Conclusion

We’re anxiously awaiting the Bliss Mobil camper unit which is on its way to Denver from The Netherlands. When it arrives (late Oct, early Nov 2016) I will head to Jay’s to create the final punch-list for completing the truck. Return here, or subscribe to my Instagram feed, for updates. If you want to see a more detailed overview of our LMTV chassis, bliss mobil camper, and trailer, see our list of stats.