My Cummins/Allison 1000 Freightliner MT45 Step Van Build

John906

New member
#1
I have been contemplating an Adventure RV rig for some time now as part of my retirement planning. Wanting worldwide travel capability, I have gone the complete conceptual gambit starting with considering converted military trucks, moving to Fuso based units, and then converting an existing RV to a Cummins 6bt/Allison 1000/Dana 4x4 drivetrain. The drivetrain idea came to me after stumbling onto the “Crawler Hauler” project on the Xtreme Off Road TV show when they converted an Isuzu cab over to haul a rock crawler buggy. is the link to the first show in the series. While there are many different cool RV platforms that would benefit from this swap, they all would require a lot of fitment problem resolution and time consuming work. Also this is my first 4x4 truck project so I'm learning as I go.
:elkgrin:


Then I came across the Freightliner MT45 – Utilimaster Step Van option during my Cummins/Allison research. This is the ubiquitous Fed-Ex delivery van that comes in various lengths, rear door options and load capacities. Besides having the desired 6bt engine, A 1000 transmission, and all the plumbing including the intercooler in place, the beauty of this option is that the box van is the most efficient use of space and has standing headroom throughout. Having the big living room on wheels with everyone in the same space is important to us as I am hoping to have friends and family fly out to travel with me from time to time. Extra sleeping space will be provided with a free standing tent on the upper deck. Separate cab/camper rigs don't have that higher passenger capacity we seek. A disadvantage of this rig is it won't fit into a shipping container.
:elkgrin:

I just started the build process this September by finding a 2004 (pre-low sulfur diesel) Freightliner MT45 with only 50k miles on trucktrader.com. There were a lot out there with high mileage, but with patience I found the ideal unit; low miles, 14'box, and open out (vs. overhead) rear doors. Check the VIN with a Freightliner Dealer to be sure you are getting the A1000 Transmission before you buy if you want to go this route.
:elkgrin:

I also obtained front and rear 4.88 axles from donor leaf spring Ford Super Duty F550's the day after Christmas. Home Run Auto is a recycler specializing in Ford Super Duty Trucks in Tea, SD just outside Sioux Falls. I found Brian very knowledgeable, and a joy to deal with. The front axle is the well-known Dana 60, and the rear is the lesser known Dana Spicer 135. The rear S135 is about as stout as they come for this application, but the parts are expensive; a ring and pinion is over $1,200.00 for this rear end.
:elkgrin:

I just ordered Continental MPT81 335/80R20's on custom conversion single rear wheels from Rickson Wheel Manufacturing. Big wheel wells are another great feature of the Freightliner MT45. Also on the way are 5.38 gears, lockers front & rear, and master rebuild kits from Randy's Ring and Pinion. The transfer case will be a GM NP-261XHD manual shift rebuilt by Midwest Transmissions. They will install an aftermarket slip yoke eliminator by Canada's Northwest Fab along with an oil pump shield to protect the case. Right now I am thinking about keeping the rear springs as is with 13,000 GVW and adding Firestone air bags on all four corners. The total cost of the 4x4 conversion is approaching the cost of the base truck.
:elkgrin:

I am estimating a total project completion time of three years. The 4x4 conversion is planned to be completed by mid-summer this year. By summer 2016 the major body modifications should be complete. They include the upper deck (fiberglass dock planking?), replacing the sliding doors with fabricated automotive style hinged units with roll up windows, and relocating the rear doors w/frame to the right side so they open under the canopy for that “step out to the deck” effect. The rear door opening will be filled so the toilet and shower can be fitted all the way to the rear, and sliding bus windows added to the living area. The aluminum body makes these mods easier than they would be with steel; the panels are thick & flat, easy to cut, they either rivet or are easy to weld with a MIG spool gun with less distortion.
:elkgrin:

Another feature I'm hoping to pull off is a giant bench front seat with a back that will flip over making a sofa that will face the living area when parked. The old railroad coaches had these so passengers could face each other. If I could also make this “sofa” fold down into a bed, that would be slick. I'm hoping to sleep 4 adults in the main cabin. The final summer of 2017 will be installation of all the “Life Support Systems”. I'm going to leave the planning of this phase until later as new product developments are always being released.
:elkgrin:

My retirement vision includes initially living without real estate, and having a 30' trawler cruiser to add variety to the Overlander adventures. Having the extra Cummins power will be helpful in moving the boat from venue to venue. My first destination will be the Baja with discovering the world's most beautiful and remote beaches a retirement objective.
:elkgrin:

The common thread of all the build threads here is patience in getting updates and answers to questions, and I am no exception. We have quite a bit going on getting ready for retirement, and the build is only a small part of what needs to be accomplished, but I'll try my best to be timely to questions and comments. Thank you for your interest in this build
:elkgrin:

Concept Rendering.jpg


2004 MT 45.jpg


Rear Axle.jpg


Front Axle.jpg
 

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brian94ht

Chateau spotter
#3
Watching with interest.
I think this is a recipe for my future "RV"

I have seen single rear wheel models, and the hinged front doors you mentioned, I like the sliding doors for airflow but the loss of window/wall space for the door cavity is a bummer.

Also, what is the total height of this currently, and what do you expect to gain from the 4x4 swap?

If you go anywhere off the road I think you are going to have to highly modify the rear departure angle....
 
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John906

New member
#4
Gaining wall space was the deciding factor in wanting hinged doors; suicide or regular opening is the current question. These vans have the old school cowl vents on the side and can possibly be enlarged for more flow. Adding a cabin filter element to these would also keep down the dust. Also the current step up wells would be better used with potable water tanks under a raised floorboard.
:elkgrin:
Right now the overall height is about 10'-2" unloaded. The larger dia. tires should raise the truck 5" on their own. I'm hoping to avoid a lift kit as the front wheel wells are huge, and the rear wheel boxes can be easily raised. Your absolutely right about the departure angle; a rear bob job with an extending telescopic receiver tow hitch to reduce rear clutter is part of my current thinking.
 

ExpoMike

American Adventurist
#5
Cool build idea. Looks like it could end up being a really nice build.

I hope you have better luck than some of the forum members have had with Rickson wheels. IIRC, long delays and wheel failures have occured.
 

John906

New member
#6
I have done the weight thing, basically I have a 13,000 GVW rear axle, with an empty rear weight of 5,000 lbs. The rest is math and as a geeked out mechanical engineer that is something I do better than most. Good point about simplicity; withstanding shake and bake will be in my thought process throughout the build.
 

Ozrockrat

Expedition Leader
#8
I'll do more research on Rickson. I did not see any other options out there for high capacity SRW conversions
Try John at Stazworks. Also if you are getting wheels made you might want to consider running 22.5 super singles. Easier to get replacements on the road and will never wear out in your application. The ones they run on logging trucks should be suitable. If you go with a set of adapters and 10 lug hub pilot rims you could even consider just getting surplus 20" alloy rims.
 

mhiscox

Expedition Leader
#10
Many good ideas here. Having built out living quarters in a number of different vehicles, I guarantee that the advantages of your truck's long, straight, vertical walls will pay off for you in easier construction. And you'll also appreciate the increased volume you get over something like a Sprinter van with the same length load floor.

Best of luck with this outstanding project, and thanks for sharing the details.
 
#12
I checked into the super singles and the diameter is significantly larger. 5.38 is the lowest ratio I can use in my S135 without replacing the carrier and the ratio already 10% taller than ideal with the Conti MPT's. Also I think the super singles can't be aired down much for beach travel. Most of the Rickson complaints are about delivery and the Heather the sales manager mentioned she's keeping Dan the owner from over committing. They also now manufacture everything in a new facility because of supplier QC issues. Thanks for the tip; everything is worth checking out before you buy and you alway learn something in the process.
 
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java

Expedition Leader
#14
Thanks Java, I checked out your Winne 4x4; that looks like a great way to go with much less work than my project.
Definitely quicker and for me more cost effective. I will rebuild the box at some point and go through the whole building process....

Excited to see how it comes together.
 
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