The M38A1 was the replacement for the M38. Unlike other military vehicles where the A1 suffix would denote a minor revision (e.g. M151, M151A1, M151A2), the M38A1 is a very different vehicle from the M38. It has a different frame, body, engine, and axles.
This utility truck is a four-wheel vehicle with both a front and rear driving axle. Designed for use as a general purpose personnel or cargo carrier, the vehicle is readily adaptable for reconnaissance, communications or other special duties. It is capable of operating with the engine completely submerged in water.
Department of National Defense Repair Manual 7610-21-848-1570
The M38A1 was the first jeep to drop the flat fenders for a more rounded, aerodynamic look. Because of this, it is easily distinguishable from the earlier jeep models.
The m38a1 used the F-head "Hurricane" engine rather than the earlier L-head "Go Devil". Check out the F-Head page for much more information.
The front axle is a Spicer (now Dana) 25 full-floating axle while the back is a Spicer 44 semi-floating axle. The 4x series axle is much stronger than the 2x series.
In high range, high gear, both the transfer case and the transmission are direct (1.0:1). With a rear ratio of 5.38:1, this gives a top speed of 60 MPH.
Emergency
Where difficulty is experienced with front axle differential making the vehicle inoperative, remove axle driving flanges. This will allow bringing vehicle in under its own power. Be sure front wheel drive shift lever is in the forward (disengaged) position.Department of National Defense Repair Manual 7610-21-848-1570
The m38a1 has a Warner T90 transmission. It is a three speed manual transmission with "synchronous mesh in 2nd and 3rd". Hmmm, they seem to have left out 1st! Synchronous mesh (or synchromesh) makes it easier to shift gears without grinding. It can be hard to shift into first when at a complete stop or moving faster than a crawl.
A great description about how manual transmissions work with a description of syncronizers (synchromesh).
The m38a1 uses a Spicer Model 18 transfer case. This transfer case is basically a two-speed transmission which is located after the standard transmission. It provides a means of transferring the power to the front axle. It can also provide a PTO for a variety of uses, commonly for a Ramsey winch.
The most asked question while stopped at a street light: "What are all the gear shifts for?" There are a total of three "gear shifts", one for the transmission and two for the transfer case. Going from left to right, the first is the gear shift proper (i.e. reverse-1-2-3). The next engages or disengages the front wheel drive. The last selects low, neutral or high. You can only select the low range in 4WD. And yes, it has shift on the fly.
If equipped with the PTO winch, there would be a fourth lever to engage and disengage the winch.
I have more drive train specifications and comparisons on this page.
The M38A1 is also available as the Truck, Ambulance: 1/4 ton, 4x4, M170, Front Line. The M170 is basically a long wheelbase (101" vs 81") version of the M38A1. Its civilian version is the CJ6. It can carry a driver and three stretchers or 6 people sitting. It was produced from 1954 to 1962.
Jim Allen has found some information on a prototype of the M38A1 called the M38E1. Check it out on Derek Redmond's CJ3B site. It looks very much like an M38A1 but the fenders are slightly different. The M38E1 picture also shows the complete snorkel kit. Note that the tailpipe goes straight up the back to keep it out of the water.
Below is a timeline for the three main producers of the M38A1:
Canada, the U.S., and the Netherlands. Green marks the years of
production and yellow marks the military lifespan.
A more subjective view of military trucks.
M38A1 CDN M38A1 CDN2 M38A1 CDN3
1952-1953 1953-1969 1970-1971
------------------------ ---------------------- ----------------------
* front grill hinged * front grill bolted * windshield washer
* generator * alternator * solid state flashers
* battery cover bolted * battery cover clamps * self-adjusting brakes
with 8 thumb screws down * front wheel bearings
* wire headlight * no wire headlight and hubs changed
protector protector * M151 air filter
* embossed brass data * painted data plates
plates * dash changed
* convoy light * blackout brake light
* right rear light
cluster sticks out
* heater
Thanks to Clive Reddin for information used in this page.
Dedicated to the memory of Tony Lapinskie.