M422 Mighty Mite

The AMC M422 'Mighty Mite', or G-843 by its supply catalog designation, is an extra lightweight ¼-ton 4x4 tactical truck, designed for the United States Marine Corps, to be suitable for helicopter airlift and manhandling. It is noted for its exceptionally short length, and resulting very tight turning circle, while still highway approved for a top speed of 55 mph (U.S. military), and capable of 65 mph according to its manufacturer, American Motors Corporation (AMC). From 1959 through 1962, just under 4,000 M422 Mighty Mites were built by American Motors for the U.S. Marines.

History
During World War Two, many prototypes were already developed for a 1⁄4ton jeep, which was still significantly lighter and more compact than the U.S. Army's lightest, all-terrain, all-purpose vehicle at the time, the Willys 1⁄4ton Jeep. They were intended for transport in small (glider) aircraft and such, but none went into production. However, after the war, a self-taught engineer, pilot, and auto racer, Ben F. Gregory, conceived a mini-jeep design and built a successful prototype, later named the "MM-100".

The Mighty Mite was first conceived between 1946 and 1947, by a self-taught engineer, pilot, and auto racer from Missouri, Ben F. Gregory. Gregory designed several front-wheel drive cars after World War I, but was unsuccessful in marketing them. He turned to commercial aviation, but a crash in 1942 ended his flying career. Recovering from serious injuries, he became an aircraft inspector. After the end of World War II, Gregory found new investors. He turned again to front-drive cars, this time culminating in a fully driveable prototype—an innovative 1947 rear-engined, front-drive compact car, the Gregory Sedan. No carmaker was interested in his car, but he was inspired to use some of its design features, such as leading- and trailing-arms suspension, in a more modern four-wheel drive off-road vehicle, or jeep, and he found additional investors willing to fund a prototype.

One investor arranged a 1951 demonstration for the United States Marine Corps (USMC) Equipment Board, which went so well that the investors quickly formed the Mid-America Research Corporation (MARCO) to develop the vehicle for military or commercial markets. That same year, MARCO presented it as the MARCO MM-100, making it the first clean-sheet 1⁄4ton vehicle to be designed for the U.S. military after World War II. The USMC executed a contract for ten test vehicles in August 1951. The vehicles were delivered in December 1952, and the USMC began the test program. For further development, the company decided to hire Harold Crist, American Bantam's original chief engineer on designing the original Bantam BRC, on which Willys MB multi-role vehicle was based. Joining on 1 January 1953 as project manager, Crist brought with him three of the main people who had worked on the original Bantam vehicle: Chet Hempfling, Ralph Turner, and Frank McMillan. From that point, the team included four of the original WW II vehicle engineers. But Gregory, in turn, was eventually forced out of the company.



The MM-100 used a 44 hp, 79 cuin flat-four engine from the "S" version of the Porsche 356, but this choice proved problematic, as using a foreign-built engine would violate regulations requiring U.S.-built equipment in U.S. military vehicles. Attempts were made to substitute the Lycoming O-145, an American aircraft engine, but it was deemed too expensive and difficult to adapt to a ground vehicle. A solution presented itself when MARCO discovered that American Motors Corporation (AMC) was developing a lightweight, air-cooled 50 hp, 95 cuin V4 engine for a proposed economy car to be sold under AMC's Nash Motors brand. AMC quickly became interested in the MM-100 because it needed a new product to keep a former Hudson commercial vehicle plant operating. By 1954, AMC had completely taken over the project.

Problems were encountered with the designers' decision to save weight by not using a conventional exhaust system. The prototype did not have a muffler or pipe – rather the exhaust was routed through some frame tubes. This design was inferior because the condensation and acidic fumes caused premature frame failure. There was a competing prototype built by Willys, the 1953 Bobcat or "Aero Jeep", which was to share as many parts as possible with the M38 and M38A1 to save costs. However, the Willys version was rejected in favor of the more advanced M422. In April 1958, AMC and the USMC executed a contract for delivery of 250 production M422 vehicles contingent upon successful trials of the first seven.

The vehicle was intended to be liftable, underslung the strongest helicopters of the era, the Sikorski H-19 being the benchmark. Although the vehicle was to be used only by the U.S. Marine Corps, it was evident from the beginning that production numbers would remain limited, the vehicle was extensively engineered and incorporated many innovations.

Engineering


To keep the weight low, the M422 became the first U.S. jeep fitted with an aluminum body. At 1700 lb, it is the lightest conventional U.S. military truck to date. Also, this was the first U.S. small military vehicle designed with independent suspension all around (front: leading arms/trailing arms rear), sprung by ¼-elliptical leaf springs. Among the M422's many unique features were front and rear limited-slip differentials, inboard differential mounted drum brakes, center-point steering, and the aluminum "AMC AV-108-4" V4 engine developed by American Motors. The air-cooled 107.8 cuin developed 52 bhp and 90 lbft of torque, which propelled the vehicle to a top speed of 65 mph, with a 55 mph military rating. As with the M151, the single-speed transfer case only engages/disengages the front wheel drive and is part of the transmission. The full-synchronization meant it could be shifted from two-wheel drive to four-wheel drive on the fly.

Although a two-seater, the little vehicle could theoretically move six people. There were no conventional rear seats. Instead, the two additional seats are integrated into the functional tailgate, and two small folding backrests are placed on the top of the rear fenders. Additionally, the M422 was rated to carry 850 lb off-road, while all other standard military 1⁄4ton vehicles (even the M151) were rated at 800 lb.

There was a version of the M416 trailer specially adapted for towing by an M422: the M416B1. Early production M416B1 came with magnesium M151 wheels, that later switched to steel wheels as on the M422. Other features included USMC lifting rings and holders in front of the fenders to store aluminum water cans.

Like other Marine Corps contract vehicles, the M422s came from the factory with all deep-water fording equipment installed, except for the pipes. In its early development stage the Marines developed a lightweight flotation kit that could easily be stored on the M422 when not in need, in which four large tubes inflated by exhaust encompassed the bottom part of the frame that allowed the vehicle to swim deeper waters. The vehicle's spinning wheels provided propulsion and steering in the water.

In 1958, seven prototypes passed grueling tests, and the first 250 vehicles were built by American Motors. These units went into mass production in 1960, and AMC built 3,922 Mighty Mites through 1962 for the U.S. Marine Corps. Over the years, the vehicle was produced in two model versions: the M422 and M422A1. The M422 had a short 65 in wheelbase. After production of 1,045 units, the Mighty Mite evolved into the M422A1, 6 in longer in both wheelbase and overall length, as well as 80 lb heavier. The first Mighty Mites with the 71-inch wheelbase were experimental models built from production M422s. They had an extended frame and aluminum bracing added behind the seat as well as crudely fashioned tool storage boxes. This model was the M422E1, of which only a few were made. Once put into production, the longer wheelbase model was designated the M422A1 and featured a reinforcing rib on the rear fender forward of the wheel opening.

The M422 came with 6.00-16 NDT tires on steel wheels. The vehicles did not come from the factory with spare tires, but kits were later produced that could be added. However, the rear-mounted spare tires rendered the tailgate unusable. There is no provision for a gas can carrier. Either model could be fitted with a sturdier windshield similar to the Willys M38A1 that, along with top bows, would facilitate using a canvas winter top.

At over US$5,000 per unit, it was relatively expensive,. Development and certification of the M422 took through 1959. When the M422 debuted, it coincided with the adoption of helicopters like the Bell UH-1 “Huey” with much more carrying capacity than The Marine Corps' Sikorsky H-19 with its 2650 lb cargo limit (including crew and fuel), for which the M422 had been developed. Except for parachute airdrops, the vehicle became obsolete. These factors quickly rendered the Mite an outmoded, redundant supply chain complication, more expensive and largely less capable than a regular 1⁄4ton Jeep, which accounts for the short production period, as well as the small production total.