TRUCK, UTILITY, 1/4 TON, 4X4, M151

The M151 Mutt (Military Unit Tactical Truck) replaced the M38A1. It was designed by Ford and later built by Kaiser, AM General Corporation, and GM.

The M151 is a large departure from previous jeeps, both in looks and design. The M151 has a unitized body with a box frame. It is the same weight as an MB/GPW even though it is a larger vehicle. It has a longer wheelbase, is wider and is lower than an M38A1. It *looks* very stable. But in practice, due mainly to its primitive four wheel independent coil suspension , it tended to roll.

An 'A' arm with a coil spring is used on each wheel. The M151 and the M151A1 have the pivots on the inside of the wheel. The M151A2 changed the rear A arms to pivot front to back. This greatly reduced the tendency to roll over during a high speed turn.

Because of the tendency to roll, the US Army cut the M151s up before disposing of them.

The Canadian Military only used the M151A2 by AM General Corp. and always installed the roll bar kit (ROPS).

The M151 had many kits including:

M107/M108 - Communications
M718/M718A1 - Ambulance
The M151 was replaced by the Iltis in Canada and the M998 in the U.S.

History
1950 Continental Army Command places requirement for a new 1/4 ton 4x4 with the Ordnance Corps.
1951 Ford awarded development contract.
1952 Ford produces first prototype.
1954 XM151: second prototype.
1956 XM151E1 steel.
XM151E2 aluminum.
1959 XM151E2 chosen for production.
1960 M151 starts production.
1964 M151A1 starts production.
1970 M151A2 starts production.
1978 Production stops.

Engine
It looks like the M151 used at least two engines.

Model .............. Ordnance/Continental
Block .............. Cast iron 4
Displacement ....... 141.5 cu. in. (2.3L)
Horsepower ......... 71 bhp @ 4,000 rpm
Bore ............... 3 7/8 inch
Stroke ............. 3 inch
Compression ........ 7.5:1
Values ............. Overhead / mechanical lifters
Carburetor ......... Down draft

Model .............. Hercules industrial (military version)
Block .............. Cast iron 4
Displacement ....... 151.5 cu. in. (2.5L)
Horse Power ........ 55 bhp
Carburetor ......... Side draft

Drivetrain
The M151 has a four speed synchromesh manual tranmission. The transfer case is used to engage/disengage the front axle only. It does not have a low/high range. Because of this, the M151 has two gearshifts instead of the normal three. From left to right, the first smaller gearshift engages/disengages the front axle, and the second larger gearshift is the gear shift proper (i.e. 1-2-3-4-reverse).

Gearing
While jeeps like the M38 and M38A1 went for lower gearing, the M151 seems to keep the higher gearing of the MB. It is interesting to compare the "Maximum Permissible Road Speeds" for the MB and the M151.

MAXIMUM PERMISSIBLE ROAD SPEEDS
(MPH)
M151 MB
GEAR SPEED GEAR SPEED

1ST 11 1ST LOW 12
2ND 21 1ST HIGH 24
3RD 40 2ND HIGH 41
4TH 65 3RD HIGH 65

As can be seen from the table, the M151 basically uses the four speed transmission to give the entire high range of the MB, with first being a very close match for the MB's low range first. This gives the basic range of the MB without requiring a two-speed transfer case.

One of the goals of the M151 was to simplify driving it. You can drive it as a three speed with first as a low "off-road" gear

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