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February 2013 Backward Glances

1971 FMC XR311, Prototype 004

Jim AllenWriter

In the late ’60s, a new American military vehicle type was born. Initially termed the High Mobility Combat Vehicle, the concept envisioned a fast, multi-purpose light vehicle. A number of companies vied for the contract and a few now-famous vehicles branched out from this developmental tree, including the Lamborghini Cheetah, the military HUMVEE and its civilian counterpart the Hummer H1. Lesser known is the winner of the contract to develop the new vehicle, and the root of the tree, the Ordnance Division of FMC (Food Machinery Corporation), who built a prototype called the XR311.

For generations, American ground forces had relied on vehicles like the legendary jeep for reconnaissance. By the standards of the World War II era, the MB/GPW jeeps were pretty quick. In an era of 400hp muscle cars and “economy” V-8 powered cars that could do 0-60 in 10 seconds, the ’60s-era Army Jeep was a slug on grease.

It’s said XR311 took design cues from the ’60s-era dune buggies. If so, steroids were liberally imbibed. Unlike the VW-based dune buggies, the XR311 had four-wheel drive, with Dana 44 centersections at both ends supplying power through an Olds Toronado-inspired independent suspension. Special 12.4x16 off-road tires, about 34 inches tall, were fitted as well as 11-inch disc brakes at all four corners The backbone was a very heavy-duty tubular chassis that incorporated a full cage for the three occupants. The engine, commonly a 187hp Mopar 318ci, four-barrel, V-8, was rear-mounted and mated to a TorqueFlite automatic. A few were reputedly fitted with 360 four-barrels and the last one had a Deutz air-cooled V-8 diesel.

A variety of weapons systems were mounted, from heavy stuff like TOW missile launchers and 106mm recoilless rifles, down to the basic .50 caliber “Ma Deuce” heavy machine gun, the lighter 7.62mm M60 gun, or even the then-new XM174 40mm automatic grenade launcher. Aluminum retrofit armor kits were designed and the truck’s relatively heavy 1,600-pound payload offered a lot of flexibility in fitting other gear.

The XR311 had a very low silhouette, the bare truck being only a bit over five feet tall. Speed was a strong point. The 318-powered trucks could do 0-60 in 12 seconds empty. The 360 trucks could get there in 10.6 seconds. The rated top speeds empty ranged from 80-90 mph for the 318 trucks with standard 5.89:1 gears. With a max payload, top speed dropped to 67 mph. Nope, the XR311 wasn’t yer grand pappy’s sluggy Jeep!

The XR311 came in three basic evolutions, the first square headlight version of which two were built in 1969 and 1970, the shrouded headlight versions of which a few were made to 1974 and the final sloped nose version that had open headlights protected by guards and built into 1978. The available records are unclear on the exact number built, but it appears there may have been as many as 16, no two exactly alike. Some of each were given a letter suffix in their designation. The XR311T mounted a TOW missile launcher with six reloads. The XR311E was equipped for escort duties and mounted both a XM175 grenade launcher and an M60 machine gun. The XM311R was set up for reconnaissance, with radios and a .50 caliber machine gun on a ring mount. An XR311MRC, for Mobile Radio Communications, mounted a plethora of radio sets.

Testing evolved the concept considerably. By the time FMC built the last XR311, the project had morphed from High Mobility Combat Vehicle to High Mobility Multipurpose Wheeled Vehicle (HUMMWV) and by now you’ve figured out the rest of the story. By the late ’70s, Teledyne and AM General were also competing for contracts. FMC had been paid to develop a vehicle with the government owning the results, so they had no particular “in” for the later contracts. In the end, AM General aced-out Teledyne and FMC and became famous for building the Humvee. FMC went on to other projects but the Teledyne vehicle (originally developed by a company called MTI) became the Lamborghini LM002 and LM004 Cheetah—which is a story in itself.

The truck you see here belonged to Dr. John Bennett at the time it was shot in the ’90s. It’s reputed to be the Fourth unit built by FMC, a second generation shrouded headlight truck, and had been stored for many years at FMC before being sold to a private owner. The current owner could not be found at the time of this writing but when it was seen at a military vehicle show in 1999, it was configured as used in testing. At least a couple of other prototypes have survived, the last one up for sale in 2009. This one is reputedly the most complete, accurate, and original.

The Details
Vehicle: 1971 FMC XR311, Prototype 004
Owner: Currently Unknown
Estimated value: $100,000
Engine: 318ci V-8
Power (hp): 187 @ 4,800 rpm (gross)
Torque (lb-ft): 292 @ 2,200 rpm (gross)
Bore & stroke (in): 3.91 x 3.31
Comp. ratio: 8.6:1
Transmission: 3-spd automatic, Chrysler TF727
Transfer case: full-time, single-spd with lockable center diff
Front axle: Dana 44 IFS (FMC design), w/Trac-Lok
Rear axle: Dana 44 IRS (FMC design), w/Trac-Lok
Axle ratio: 5.89:1
Tires: 12.4-16, 6-ply, Goodyear
L x W x H (in): 170.5x76.5x61
Wheelbase (in): 121
GVW (lbs): 6,000
Curb weight (lbs): 4,400
Fuel capacity (gal): 30
Range (mi): 300
Top speed (mph): 80-90
Cruising speed (mph): 55
Min. grd. clearance (in): 11
Approach angle (deg): 63
Departure angle (deg): 45
Fording depth (in): 30