Allison M916 + Mk48 Cab = 6x6 "FEMTT"

M920

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Well....since we are blessed with an exceptionally mild winter here in Chama, (No Snow Cat work at all!) I decided to seize the opportunity to do my 6x6 FEMTT (Fast Expanded Mobility Tactical Truck) Project, and do a thead about it on SS! :)


I'm in need of a short wheel base, all wheel drive, on-off road truck, to be used in installing and servicing transmiter buildings and antenaes for Cell Phone Companies and Radio Stations, on mountain tops.

The Idea is to take my M916 with the Allison 7-speed tranny and install one of the brand new Mk48 cabs on it.
This frees up enough room on the chassis to keep the 45,000 pound hydraulic winch and add the Wajax knuckle boom crane of the Mk17 RBU.
A 12 foot lenght of frame remains behind all of this and will have interchangable "Body Modules" :

-Flatbed with fold down sides
-1200 gallon stainless steel tank
-RV module
-Fifth wheel capabillity as a Truck Tractor

Due to the fact that the modules will attach via standard ISO "Container twist locks" there will be the possibillity of hauling short ISO container based loads as well.

The knuckle boom crane, with a maximum capacity of 12,900 pounds, will be able to set the empty modules on and off the truck.

I have all the major components procured except for the Oshkosh 55000 two speed transfer case that I would like to install instead of the single speed Rockwell that is curently part of the M916's drive train. Any leads? :)


So here are a few "before" pics of the M916 and the "tear-down"

Soni
 

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M920

Member
893
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chama/nm
With the "old" M916 cab off the frame and the "new" Mk48 cab mocked up in it's place on the front of the truck, it's time to make the cab mounts.

For the front cab mount and bumper / tow shackle mounts, the frame needed to be extended. Here is where there is a major difference between the HEMTT cab and the Mk48 cab, the later only has one single, large body mount in a lower position, where the HEMTT has two smaller mounts, next to each other, right below the windshield.

Since the front frame extensions on the M916-M920 have the front spring mounts attached to them and are also part of the steering box mount, I opted to make two frame extension brackets from 1/2 inch thick steel, that get welded and through-bolted to the existing heavy duty frame extensions.
A piece of 3" x 3" x 1/4" wall square tubing welded between them and fitted with the appropriate mounting bracket finishes the front mount.
As you can see in the pics, the two rear cab mounts are diffrent left and right because of the close proximity of the steering box on the left side. (To try to keep things as simple as possible I decided to leave the original steering box in place....more about that later)
After fabricating up the two brackets and welding them to each side of the front frame extensions, the cab is now mounted for good on the front of the M916 frame.

Also, I never did like the poor collision / mine protection for the driver and passenger in the original HEMMT / LVS trucks, so I decided to "armor" the bottom and front of the cab for better protection in case of an accident.
The first step is the installation of a "bumper beam" (6" x 6" x 1/4" wall) accross the front of the original M916 bumper mounting plates. The ends had to be modified to accomodate the step brackets below the cab.

Two plates of 1/2" thick steel will be welded to this cross beam and the new front frame extensions to form sort of a tub, better protecting the crews feet and legs.

More later..... :)

Soni
 

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bikeman

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Wow, this is awesome! Looking forward to some of the engineering hurdles and how you over come them.

random question, what about doing a LHS style hook and load vs. doing the crane for the modules? seems like there'd be less work in the swapping and would still enable you to have all those capabilities?
 

Tow4

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This is a cool project! I'm looking forward to seeing the finished product. [thumbzup]
 

NDT

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Whatever you do, the transfer case needs to go back to the original position, so the rear ds can be more than 12" long or whatever it is now.
 

Castle Bravo

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Whatever you do, the transfer case needs to go back to the original position, so the rear ds can be more than 12" long or whatever it is now.
As I've never had a stock 916, I never realized that the driveshafts on the Allison 916s were moved - I guess its because the Allison transmission is so much larger. The transmission to transfer case driveshaft is a few feet long. I went out and looked at mine just now and I'd say 12" is being generous, its more like 8".
 
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