Trucks, Jeeps

Jeep MA and MB: Military Jeeps — a 49-Day Miracle, Well Worth the Weight

willys MB and jeep Wrangler

Sometime during World War II, a corporal was found sitting in the charred wreckage of a Jeep that had been shelled. He refused to be comforted by assurances that he would get a replacement Jeep,

"But you don't understand," he said, between sobs, "I loved this one."

A few weeks before Pearl Harbor, the highest-ranking officer in the Armed Forces, General George C. Marshall, described the Jeep as "America's greatest contribution to modern warfare." The tough, simple, go anywhere Jeep became the GI's best friend, second only to his rifle. What was it about this drab and boxy little machine that inspired such affection and far into the future, makes it one of the most widely respected and imitated designs in automotive history?

Perhaps part of the answer lies in the Jeep's origins before the war; how it came to be as the embodiment of Yankee ingenuity, tinkering and functional design.

Jeep / GP Genesis

By July of 1940, World War II in Europe had been raging for a year. Great Britain was being threatened and much of Europe was already occupied by the Nazis. During that time, the United States had remained neutral, but as the "Arsenal of Democracy," it supplied the Allies with vital military supplies and equipment. America's peacetime industries were being converted to produce arms for its entry into the war, and the Army was addressing some vital needs of its own.

1943 Jeep MB

Genesis of the Jeep: Curtis Redgap's "The Bantam Jeep"

For much of 1940, the Army had searched for a light, rugged general purpose and scout vehicle. The motorcycle and sidecar vehicle that had previously served were deemed unsatisfactory and the same was true of a small, two-person, four-wheel drive vehicle known as the "Bellyflopper," that required the driver to lie on his stomach. A homemade product, it was a low springless platform on nine-inch airplane wheels built by Colonel Robert G. Howie and Master Sergeant Melvin C. Wiley. "It looked," Delmar Roos said, "like a diving board on wheels." It was too light for rough terrain and had to be transported from point to point by truck. It had virtually no ground clearance. But it was easy to conceal.

It was March 1940 and time was running out to find the perfect vehicle. Germany had evidently found its ideal utility vehicle in the Ferdinand Porsche-designed Volkswagen Type 82 Kübelwage ("Bucket Car") and its amphibious counterpart, the Schwimmwagen. By July of that year, the Army had decided on the specification for what would ultimately become the legendary Jeep MB.

jeep CJ2A

The vehicle was a versatile solution to numerous wartime situations: it had to have four-wheel drive with a front driven axle and a two-speed transfer unit. The engine had to generate 85 foot-pounds of torque and carry a 660-pound payload, including a .30 caliber machine gun on a 75-inch wheelbase. Its rectangular body had to seat three passengers, with a fold-down windshield and blackout lighting; operate from 3-50 mph; and, finally, it could weigh no more than 1,300 pounds.

Jeep MB Specifications

Engine: 60 hp @ 4000 rpm (54 net hp)
Torque 105 lb-ft (95 net) @ 2,000 rpm
3.125 x 4.375 bore x stroke
6.48:1 compression ratio
Champion QM2 or AutoLite AN7 plugs, .030 in
Carter WO-539S downdraft carburetor
Borg & Beck 11123 clutch
Warner Gear T-84-J gearbox, 3 forward speeds
First gear: 2.665, second 1.564, top 1.0
Reverse 3.554, OTGR 4.880 (high) 9.614 (low)
Spicer ovoid axle; 4.88 hypoid-bevel final drive
Ladder type chassis frame
Bendix hydraulic brakes (all four wheels)
Mechanical parking brake on transfer case
30-35 psi in 6.00/16 tires
80 inch wheelbase; 131-132 inch length
62 inch width, 8.25 inch ground clearance
MB curb weight, complete, ~ 2,453 lb
Max trailer load, 1,000 lb; payload, 800 lb

These specifications were sent to 135 automotive manufacturers on July 11, 1940. Bids were to be received just eleven days later on July 22, 1940. The Army bid specification also set a seemingly impossible deadline and task – a working prototype in 49 days.

The initial response was less than overwhelming, with only two companies responding; the Toledo-based Willys Overland Company and American Bantam Company of Butler, Pennsylvania. Willys was denied their request for more time, and the bankrupt American Bantam Car Company had no engineering staff left on the payroll. With some help from the Army, Bantam was able to convince the talented but reluctant Karl Probst – a freelance designer from Detroit – to join them and begin work on July 17, 1940, without salary.

Probst completed the plans for the Bantam prototype in two days, and on the third day estimated the total vehicle cost. Bantam's completed bid was submitted on July 22, 1940. The hand built prototype was completed in Butler, Pennsylvania, and driven to Camp Holabird, MD for testing by the Army on 21 September 1940.

Much of the vehicle had to be assembled from existing off-the-shelf automotive parts, and the custom four-wheel drive train components were supplied by Spicer, originally of Plainfield, New Jersey, relocated to Toledo, Ohio. The vehicle met the Army's criteria, except for the engine's torque. The Army, however, felt that Bantam was too small to supply the number of vehicles it needed, so it supplied the Bantam design to the rival Willys and the Ford Motor Company – a late bidder – who were both encouraged to make their own changes and modifications.

The resulting Ford 'Pygmy' and Willys 'Quad' prototypes looked very similar to the Bantam BRC (Bantam Reconnaissance Car) prototype, and Spicer supplied similar 4-wheel drive train components to all three manufacturers. The Probst/Bantam entry, known as "The Blitz Buggy," was first tested by then Colonel (later General) Dwight D. Eisenhower, and was accepted after twenty days with a contract ordering 70 more units.

bantam jeepEncouraged by Bantam's success, Willys-Overland's chief engineer, Delmar "Barney" Roos, continued to develop its Quad prototype, delivering it on Armistice Day, November 11, 1940, ten days ahead of Ford's prototype.

When Roos had arrived at Willys-Overland in 1938, after solving engineering problems for Pierce Arrow, Locomobile, and Studebaker, Willys' basic "Go Devil" 4-cylinder L-engine head was already in production. It had the same bore and stroke as the improved version that would later power the Jeep MB, but it only produced 45 horsepower at 3,400 rpm. When operated at full throttle for 22 minutes, the cylinders began to score and the bearing burned out.

Roos pulled the engine out of production, redesigned the cooling system, replaced the cast-iron pistons with tin-plated aluminum ones, and ran the engine for 50 hours at 3,600 rpm. While these modifications were helpful, now the valves burned out. After more modifications, Roos was able to produce an engine that would run at 4,000 rpm for 100 hours without engine failure –a capacity that would prove significant for the Willy-Overland entry.

The Willys' test at Camp Holabird set higher standards of performance. There was only one flaw: the Willys jeep weighed 2,423 pounds, well over the target of 1,600. "The problem that confronted me," said Ross, "was whether or not we should redesign our pilot model to meet this weight specification and stick to the Willys engine, or simply go out and buy a Continental engine as Bantam was doing." Fortunately, the engine stayed.

go-devil engineRoos' experience, tenacity, and resourcefulness were put to the test as the engine was disassembled piece by piece in an effort to reduce weight. The body and chassis were stripped and every part studied. Unnecessarily long bolts were shortened; the thickness of the steel was reduced on body and fenders. Tough alloys were substituted in the frame for heavier carbon steel (aluminum and magnesium were unavailable). Reinforcing plates were reduced. New paints were tested and spray methods analyzed; only one coat of paint was applied, eliminating nearly ten pounds of paint. The redesigned vehicle made the weight restriction by a mere seven ounces. Barney Roos' faith in the "Go Devil" engine and its future performance would prove that it was indeed "well worth the weight."

The Army recognized the unrealistic nature of their original weight requirement and raised it to 2,160 pounds, contracting for 1,500 of each of the three prototype models with delivery to begin in June 1941 built; the Army then extensively field-tested each vehicle.

Looking back, the vehicle that became the respected, multi-purpose Jeep MB has roots that go deeper than the three prototype entries. The driveline layout was used by Spyker, Dutch car manufacturer, in 1902; the driven front axle was pioneered by Otto Zachow, a Wisconsin blacksmith and four-wheel drive designer in 1907; and, mechanically, the Willys Quad was a scaled-down Marmon-Herrington half-ton 4x4 originally designed in 1936.

Production and deployment of the Jeep (GP Vehicle)

In the end, the Jeep MB was an amalgam of the prototype designs. The bodywork and general design owes much to the Bantam Company; the shift lever, hand brake arrangement and familiar pressed metal Jeep grille were from Ford, to lower manufacturing cost. The dominant design element proved to be the Willys powerplant; its 60 horsepower and 105 foot-pounds of torque exceeded the requirements, and dwarfed Bantam's 83 and Ford's 85 foot-pounds of torque. Moreover, the Willys "Go Devil" engine had come from their well-built compact passenger vehicle, the Americar, and had proven to be rugged, reliable and strong.

ford jeepThe Willy Quad was tested by a number of parties, but the report of the Army's Infantry Board is representative of them all:

"Willys performance was superior to that of Bantam and Ford in acceleration, maximum speed, grade climbing and cross country."

The War Department required a large number of vehicles to be manufactured in a short time, so Willys-Overland granted the United States Government a non-exclusive license to allow other companies to make them. Ford was the second supplier to build Jeeps to the Willys' specification, while American Bantam, the creators of the first Jeep, spent the rest of the war building heavy-duty trailers for the army.

Willys-Overland and Ford turned out 651,068 Jeeps, at a rate of one every two minutes, at a cost of $749 per unit, the price escalating as the war continued from the original contract price of $648.74. With the 2,500 produced by Bantam, the total of manufactured military jeeps came to 653,568. Nearly 30% of all Jeep production was supplied to allies, Great Britain and the Soviet Union.

The origin of the name "Jeep" remains a topic of debate (see our history of the name along with contemporary sketches of Jeeps at work). Regardless of names, the Jeep MB's record of performance is unquestioned. The Jeep's versatility seemed endless and the truck was virtually indestructible, serving in every theater of WWII.

When General George Patton's armored divisions raced across France the lead vehicle, out in front of the foremost tanks, was often as not a Jeep. The Jeep was in the Ardennes during the Battle of the Bulge, in New Guinea, the sands of the Sahara, and the snow of Iceland.

It was a reconnaissance vehicle, with a machine gun mount. Fitted with stretchers, it became a frontline ambulance. A Jeep with a radio became a mobile command post. Jeeps hauled planes to dispersal bunkers. Soldiers raced them uphill and climbed forty per cent grades. As illustrated in a famous cartoon by Bill Mauldin, the Jeep even provided hot radiator water for shaving.

In the Philippines, a Jeep equipped with flanged wheels pulled a fifty-two-ton railroad supply train for nineteen miles at twenty miles an hour. It was widely modified for long-range desert patrol, snow ploughing, telephone cable laying, saw milling, and fire fighting (with pumps); stateside farmers would use it as a tractor. Jeeps could be loaded into transport aircraft for rapid deployment and were small enough to fit into the large gliders used in the D-day invasion of Europe.

Jeep CJs

In perhaps one of the most dramatic Jeep offensives of the war, an attack on enemy aircraft was led by David Stirling, the "Phantom Major." The target was Landing Ground 12 at Sidi Haneish, seventy miles west of El Alamein, Egypt. Each jeep was armed with four Vickers "K" machine guns capable of firing one thousand rounds a minute. Formed in a flying wedge, the Jeeps charged out of the desert onto the airfield between the rows of parked planes, all guns blazing. After one complete circle of the airfield, they attacked planes parked on the perimeter; then they roared away into the safety of the desert. The final score: twenty-five planes destroyed, and a dozen damaged. The attacking force: seventy-five men and eighteen jeeps.

The Jeep was also present in the Pacific theater, at places like Guadalcanal, with the U.S. Marines. Jeeps MBs were used by every division of the U.S. military and an average of 145 were supplied to every infantry regiment.

1941 Willys MA

Willys MA and MB: the original Willys Jeeps

The initial Willys Jeep production model, the Jeep MA, was produced from 1940 to 1941. The second and final wartime production version, Jeep MB, was built by Willys-Overland in Toledo from 1941 to 1945. The "MB" model designation denoted the design modifications from the original "MA" (Military model "A") design (of which just 1,500 were made). The Ford built models were designated "Model GPW" (G = government vehicle, P designated the 80" wheelbase, and W = the Willys engine design).

willys maThere were subtle differences between the MA and GWP. The Fords had every component (including bolt heads) marked with an "F." Willys followed this by stamping its name into some body parts until 1942.

The two had slightly different frames, and Ford used a torque reaction stabilizer spring under the left spring (as did some Willys units); Ford-built engines used studs instead of bolts for connecting rod bearing caps (the rods themselves were the same).

An amphibious jeep, the model GPA, or "Seep" (Sea Jeep), was built by Ford in modest numbers but could not be considered successful - it was neither a good off road vehicle nor a good amphibious vehicle, and the government relied on GM's amphibious design instead.

Throughout the war, the Jeep continued to be improved, with the MB using a standard government 2-H 6-volt battery, changing the position of the hand brake, driving lights, tie rods and spring shackles, and adding more seals to retain lubricant and keep water out. The rigors of war also required a number of field improvements for winter and desert conditions, including over-sized tires, surge tanks, and other changes that enhanced the heating, cold starting, and cooling of the engine, and better accommodated 12-volt radio equipment.

The accolades for the Jeep continued to pour in during and after the war; according to General (soon to be President) Dwight D. Eisenhower, "America could not have won World War II without it."

The wartime performance of the Jeep had stimulated interest in its potential postwar uses. Before the fighting was over, the Department of Agriculture had already begun publicizing potential Jeep solutions to farm labor problems. The Agriculture people had concluded that the Jeep could plow, harrow, or disc; plant corn or cotton, all on one gallon of gas to the acre—claims that were later far exceeded in practice. As a result, civilian desire to own a Jeep was widespread by the time the first combat vehicles were put on the market in November 1943.

At the end of the war, 647,343 Jeeps had been made: 2,642 by Bantam, around 350,000 by Willys, and around 290,000 by Ford. Despite prewar concerns about Willys' production ability, which nearly landed Ford an exclusive contract, the company had done quite well — albeit with Ford making some difficult parts, and fewer other demands on its plants. Ford used no less than six plants across the country, from New Jersey to California, for production. The high production led to much greater use of the Jeep in combat that original plans called for.

Jeep MB on display

In 1947, Bantam sued Willys to stop using the term, since Bantam had created the concept; Willys won and registered the trademark in the US. They would soon take advantage of their newfound gain... at least, in the United States.

The first post-war Jeep was the prototype Jeep CJ-1A (CJ stands for Civilian Jeep); the production model, Jeep CJ-2A, was unveiled in August 1945, at $1,090. Closely based on the Jeep MB military design, it was manufactured under the "CJ" designation until 1986. At that point, the suspension was bound up to prevent flipping by untrained or unwary drivers, and the Jeep was renamed Wrangler. It had gained a considerable amount of size and weight over the years, but had a similar look and was designed with similar versatility in mind — and always had the removable doors and fold-down windshield.

Willys Jeep CJ-2A

Matthew Parij wrote,

Mitsubishi acquired the rights to locally produce the Jeep CJ-3 in Japan around 1948, and did so for fifty years, finally ceasing production in 1998. They adapted the Willys Go-Devil and Hurricane engines into diesel engines (KE31 and KE36, respectively) for their Fuso medium-duty truck and bus line, and kept those versions going until at least 1965.

1946 Cj2A

The basic Jeep was modified, upgraded, and enlarged for later military use, resulting in, among others, the Jeep M38 (1950-52) and M38A1 (1955-1963).

The utilitarian good looks of the original Jeep have been hailed by industrial designers and museum curators alike. Willys copyrighted the "Jeep" name in 1946 and it has been owned as a trademark of Willys-Overland, Kaiser, American Motors, and Chrysler Corporation. The Museum of Modern Art described the Jeep as a masterpiece of functionalist design, and has periodically exhibited the Jeep as part of its collection. The famous WWII news correspondent Ernie Pyle called the Jeep, along with the Coleman G.I. Pocket Stove, "the two most important pieces of noncombat equipment ever developed."



The influence and presence of the Jeep, its earlier models and the more recent high-powered, "luxury SUV" incarnations, is nothing short of ubiquitous, simply put – they are everywhere. There is no mistaking it as the inspiration for the sport utility vehicles of Land Rover, Toyota, Nissan, Mitsubishi, Suzuki, Mahindra, or AM General (which was split off from AMC, when that company owned Jeep). The mystique and unique place of the Jeep as a rugged, versatile, and nearly indestructible World War II's legends remains… the love affair with the brand continues.


The original Jeep MB can be seen on display at the Smithsonian Institution in Washington D.C., the Gen. MacArthur Memorial and Historical Center in Norfolk, Virginia, the Chrysler Museum in Auburn Hills, and the Jeep House in Toledo, Ohio, the original site of the Willys-Overland factory where it was designed and built.

Willys-Overland Jeep CJ-2A

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