Harley WAC Peep Jeep: The Willys Air Cooled WWII Prototype
During WWII, the US Army was faced with getting vehicles to ground troops which were sometimes located deep inside enemy lines. As a possible solution to this problem, the Army came up with the idea of a lightweight four-wheel vehicle which could be dropped from a plane.
They solicited prototypes from a variety of companies including Ford, Chevrolet, Crosley, Kaiser, Nuffield, and Willys. The Willys prototype was called the WAC, or Peep, and it used a Harley-Davidson two-cylinder engine. That alone makes it one of the stranger side roads in both Jeep history and Harley-Davidson military history.
The Willys WAC, or Peep
The WAC name is usually expanded as Willys Air Cooled, while Peep was the nickname commonly attached to the little prototype. It was not a production Jeep, and it was not a motorcycle. It was a small four-wheel military vehicle built around an unusual Harley-Davidson powerplant.
The idea was simple enough: give forward troops a smaller, lighter vehicle that could move men, supplies, or equipment in places where a full-size truck or standard Jeep might be too large or too difficult to deliver. In that sense, the WAC belongs to the same wartime world as the standard Jeep, the Harley WLA, and the other odd experimental machines that manufacturers tried while the Army was looking for better ways to move troops and equipment.
A Harley Engine Instead of the Standard V-Twin
The engine is what makes the WAC especially interesting on Riding Vintage. This was not the standard V-twin motor that Harley-Davidson was known for, and it was not the same engine used in the familiar Harley-Davidson WLA military motorcycle.
Instead, the WAC used a 750cc opposed-cylinder engine based on a BMW R75. Harley had previously experimented with a side-valve opposed-cylinder engine for its Harley-Davidson XA and the two-wheel-drive Harley-Davidson XS prototype, but the WAC used an updated version of the XOD engine with overhead valves.
That puts the WAC in a very small branch of Harley history. Most people think of wartime Harley-Davidsons as WLAs, side-valve V-twins, and dispatch motorcycles. The WAC points in a different direction: Harley’s wartime flat-twin experiments, where the company was trying ideas well outside its normal production pattern.
How the WAC Fits with the XA and XS
The WAC makes the most sense when it is viewed next to Harley-Davidson’s other WWII prototype work. The XA was Harley’s best-known opposed-cylinder military motorcycle, and the XS pushed that idea toward a two-wheel-drive military motorcycle concept. The WAC took the same basic flat-twin branch and placed it in a small Willys four-wheel vehicle.
There was also the prototype Harley-Davidson Servi-Car with an XA powerplant, another example of Harley trying the opposed-twin engine outside the normal solo-motorcycle package. None of these projects replaced the standard Harley military V-twin, but together they show how much wartime experimenting was happening around the edges.
That is what makes the WAC such a good historical oddity. It was not just a Willys experiment, and it was not just a Harley engine sitting in a random chassis. It was part of a larger wartime attempt to see how Harley-Davidson’s opposed-cylinder engine work could be used in machines very different from the motorcycles the company was actually producing in volume.
Four WAC Prototypes Were Built
Four WAC were built, with two going to the Army and two remaining with Harley-Davidson. That keeps the WAC firmly in prototype territory, but it also makes it more than a sketch-board idea. These were real machines, built and divided between Army testing and Harley-Davidson retention.
The WAC never turned into a production military vehicle, and it never became a regular Harley-Davidson model. It stayed one of those wartime experiments that shows what companies were willing to try when the Army needed answers quickly and conventional machines were not always the right answer.
At Least One Must Still Be Around
At least one WAC must still be around, as indicated by the recent color photo at the end of the article. That photo is one of the reasons this story is so interesting. The WAC was a tiny prototype program, but the color image suggests that at least one example survived long enough to be photographed outside the original wartime test period.
