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Backward Glances: 1960 AMC M-422 Mighty Mite

Posted in Features on April 16, 2018
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Special thanks to Tom Price and Jim Gilmore

Look at the history of American tactical military vehicle procurement and you’ll see what some have called an obsession with lightweight 4x4 vehicles. Since before World War II, there has been a procession of lightweight prototypes, but almost none of them resulted in a production model. One of the few to make the jump from prototype to production was the American Motors M-422 Mighty Mite.

The idea behind the lightweights was portability with rapid-deployment forces. In World War II, it was something that could be landed in a glider or carried in transport aircraft. In the ’50s and early ’60s, it was about parachute drops. As helicopters grew in size and power in the 1960s, they were able to transport light vehicles carrying them underslung by cable. This is the era into which the Mighty Mite was conceived.

The Mighty Mite started in the mind of a colorful self-taught engineer, pilot, and race car driver from Missouri named Ben F. Gregory (1889-1974). Ben was a gearhead and a go-getter whose quest became front-wheel-drive cars. After World War I, he designed and unsuccessfully tried to market several designs. By the early ’20s, nearly broke and in need of a new career, he turned to commercial aviation, and that lasted into World War II. A crash in 1942 ended his commercial flying days, so he spend the rest of World War II recovering from serious injuries and working as an aircraft inspector. After the war, he found a few investors in Kansas City and turned again to designing front-drive automobiles. This culminated in an innovative rear-engined, front-drive compact car in 1947. One prototype car was built, but Gregory didn’t find any auto manufacturers willing to take it on. The inspiration and exact timing are unclear, but along the way he translated some of the car ideas into a 4x4 platform.

Tom Price’s ’60 M-422 is the 373rd Mighty Mite built and was delivered on December 21, 1960. It’s set up with a fording kit, which enabled it to ford water as deep as 5 feet. It’s also got the winterization kit, which included the top and a gasoline heater between the seats. Tom is a Marine from the Vietnam era and has a collection of Mighty Mites that includes one of the ten experimental M-422E1s.

Seeing a strong concept taking shape, Gregory gathered up a few more investors. One of them, an advertising professional named Clarence Summers, talked the Marine Corps Equipment Board into an April 1951 demonstration that went very well. In order to capitalize on that, the investors quickly formed the Mid-America Research Corporation (MARCO) to fully develop and market the vehicle for military or commercial markets. That same year, MARCO presented the new rig as the MARCO MM-100.

The MM-100 was only 96 inches long and weighed a mere 1,500 pounds with its aluminum body. It was much smaller than the production jeep, but still rated to carry a 1/4-ton cross-country. Power came from a front-mounted, air-cooled flat-four from Porsche. Yeah, Porsche! It was a 1,300cc dual-carb engine that made 44 horsepower at 4,200 rpm. In Porsches, this was the “S” engine, which was an upgrade over the standard 1,100cc 40hp unit that powered the 356 Sport Coupes.

Behind the Porsche ’plant was a three-speed transmission with a married two-speed full-time transfer case, both built by the Transmission & Gear Company of Detroit. It featured a No-Spin (aka Detroit Locker) as a center differential. The MM-100 had a tubular chassis and the exhaust was fed through the main tubes. The Gregory-designed axles were independent with 5.38:1 ratios, No-Spin diffs and inboard drum brakes. The suspension consisted of longitudinal quarter-elliptic leaf springs acting on leading/training arms, very much like the ’47 Gregory car.

The USMC’s interest proved strong enough to generate a contract for 10 test vehicles in August of ’51. These were done by December of 1952 and the Marines began testing them extensively. These tests culminated with a big demonstration in March of 1953 at Quantico, Virginia, in front Department of Defense representatives, contractors, and military personnel. A separate event was held a few days later for the press. It was at this time the MM-100 acquired the name, “Mighty Mite.” According to a 1958 Kansas City Times newspaper article, the wife of investor and MARCO executive Arthur Guettel exclaimed, “It looks like a mite, but a mighty mite!”

Tom’s Mighty Mite is set up as a radio vehicle, and you can see the lower part of the antenna to the left of the spare tire. The silver thing forward of the rear tire is the exhaust pipe shield for the gasoline heater. The M-422 was rated to tow 1,000 pounds cross-country and 1,500 pounds on the highway. That was enough grunt to tow the USMC M-98 howtar, which was a 4.2-inch (107 mm) mortar on an M2 pack howitzer carriage. The howtar was a common sight in Vietnam.

The Marine Corps Equipment Board was all for going ahead with the procurement, but because it was tested outside normal Defense Department guidelines some turf battles with the Army occurred. With rules about foreign content in American military vehicles, the biggest hitch was the German engine. A 65hp Lycoming 0-145 flat-four aircraft engine was in the mix as a possible alternate, but it was expensive and required a fair bit of adaptation.

MARCO got word that the newly formed American Motors had an aluminum air-cooled V-4 in development and contacted them about it. Reportedly, this engine was instigated by Nash as an economy car engine. By the time Nash and Hudson were merged to form American Motors in 1954, development was well advanced. At the time, it displaced 95 cubic inches and made about 50 horsepower. According to the few remaining sources of information, the engine project was in limbo as being too small for the existing AMC car platforms. It seemed a perfect option for the 1,500-pound Mighty Mite.

In the course of the engine discussion, AMC developed a strong interest in the project. MARCO was about out of money at this point and facing big roadblocks getting the Mighty Mite into production. AMC was looking for commercial projects to keep the former Hudson factory going as their commercial products division, so they made an offer, and by the end of 1954 AMC owned the project. The Mighty Mite went on the fast track and in April of 1958, a contract was signed for a run of 250 production vehicles contingent upon the successful tests of the first seven. Serial numbers started at 101.

By this time, AMC had improved upon the original MARCO design, starting with the engine swap. The AMC V-4 engine was upgraded to 108 cubic inches and 54 horsepower to meet the Marine Corps Equipment Board’s power requirements. Other changes came later and included a less costly open-channel ladder-style chassis and an integrated four-speed transmission and transfer case, the NP-4300, designed and built by New Process. It featured a single-speed, part-time transfer case. Instead of a low-range, the trans had an extra-low first gear (5.22:1). The axlehousings were revised and built by Spicer. Instead of No-Spin lockers, they used Powr-Lok limited slips but still have mounted inboard drum brakes. The suspension remained largely the same as the original MARCO design, though small details changed. The body was very much revised and made a little more roomy, yet with a lower profile. The AMC Mighty Mite gained 200 pounds over the MARCO and tipped the scales right at 1,700 pounds.

The registration numbers on the hood are the originals, but Tom has painted unit markings (see red shield) to represent a vehicle in F Company, 2nd Battalion, 9th Marine Division, “Hell in a Helmet.” In Vietnam, this unit distinguished itself in the defense of Khe Sanh in 1968.

The seven test rigs passed muster in December of 1959. After the usual rounds of deficiency corrections, production of the remaining 243 began. That number was quickly updated to 1,000 units. Once in the hands of Marines, more inadequacies came to light. To save weight they didn’t have a spare tire at first, but a retrofit campaign soon remedied that oversight. The windshield proved fragile, so it was updated in production and a retrofit was developed for the earlier rigs. Cargo space became a serious issue, so with further contracts coming, AMC worked to make a running upgrade to address it.

As an experiment, AMC stretched the M-422 6 inches to a 71-inch wheelbase. Ten prototypes, called the M-422E1, were built for tests. The extra room allowed for radios and a set of inward-facing troop seats in back, replacing the evil tailgate-mounted seats. Best of all, the stretch only added 80 pounds to the curb weight. A change order was made and AMC updated production to the longer M-422A1 after only 1,250 M-422s were built. They would build another 2,672 M-422A1s, and production ended in December of 1962 with a total of 3,922 units built.

Operationally, the Marines had few complaints about the Mighty Mite. It was agile, capable, and reliable, and very soon battle-tested in Vietnam. The few issues it had out in the bush related to its bantam weight. Vietnam is a wet country, and during water crossings in current it was easily swept away. The bigger problem was redundancy. The M-422 existed to meet helicopter lift requirements at the time it was contracted. Helicopter capability had advanced a couple of generations by the time the Mighty Mite was in production. The legendary Bell UH-1 “Huey” debuted at the same time as the M-422, with three times the lift capacity of the old H-19 Sikorsky that had been the benchmark chopper when the M-422 was conceived. The Mighty Mite quickly became a supply complication and was rendered obsolete. AMC briefly considered civilian Mighty Mite applications, but quickly came to the conclusion it was simpler to design a new product if needed than to adapt the M-422.

By the end of the ’60s, M-422s began showing up on the surplus market, and by the mid-’70s, they were largely out of USMC inventory. What remained of a “lifetime” supply of parts was liquidated and, for a while, Mighty Mites were cheap and plentiful surplus fodder with lots of N.O.S. parts available. Today, they enjoy collector status in the historical military vehicle community, and though they are technically not a “Jeep” they are accepted in the Jeep enthusiast community. Parts availability has tightened a lot but seems adequate for the surviving population.

As military vehicles go, the Mighty Mite was comfortable. It rode nicely and had more than the average military ration of padding on the seats. The gasoline heater (the cover is off here) can turn the interior toasty in no time.
We don’t know one military radio from another, so we won’t try to explain them. Above the set, note the sorry excuse for seats¬¬. These were the field updates for the tailgate-mounted seats of the early M-422s, which were an even greater form of torture.
The air-cooled AMC AV-108-4 engine was all aluminum and weighed 296 pounds ready to run. It used finned aluminum cylinder assemblies with chrome-plated bores. Those can be a problem many decades down the road but they can be replated with Nickasil. A shutter system on the cooling air inlet made sure the engine was efficiently warm in all climates. It was fed by a Holley 1904F one-barrel carburetor and fired by an Autolite waterproof distributor.
The suspension was pretty whizbang—leading arms up front and trailing arms in back, with quarter-elliptic springs on each. The lowest point is the bottom of the transfer case, about 8.5 inches above the ground. The diffs have about an inch more clearance than that.
The big end of the spring is clamped to the arm and the eye is attached to the chassis via a shackle. The control arms pivot directly perpendicular to the springs. Note the overload springs on the rear.

The Details

Vehicle: ’60 M-422 Mighty Mite
Owner: Tom Price
Estimated value: $12-15,000
Engine: AMC AV-108-4 V-4
Power (hp @ rpm): 54 @ 3,600
Torque (lb-ft @ rpm): 90 @ 2,500
Bore & stroke (in): 3.25 x 3.25
Comp. ratio: 7.5:1
Transmission: NP-4300 four-speed
Transfer case: Single-speed, integral with transmission
Front axle: Independent, Dana 27 hybrid w/Powr-Lok
Rear axle: Independent, Dana 27 hybrid w/Powr-Lok
Axle ratio: 5.38:1
Tires: 6.00-16
Wheelbase (in): 65
GVW (lb): 2,700 (highway, 2,550 cross-country)
Curb weight (lb): 1,700
Fuel capacity (gal): 13
Min. grd. clearance (in): 8.5
Approach angle (deg): 55
Departure angle (deg): 47

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