Cooper was approached by an interested customer with a request to build a light weight vehicle powered by the C-Type Jaguar's engine. This was a departure from Cooper's traditional cars; it would be larger and more powerful which lead to Charles Cooper's reluctance to undertake the project. His son, John, was eager and persuaded his father to pursue the idea. Many new designs and mechanical components would be needed; this would be one of the more powerful engines the Company had ever built a car around. For example, the Cooper's traditional transverse-leaf and wishbone suspension setup would not be enough to combat the power produced by the engine.
The chassis of the car was created from large-diameter steel tubes in a similar design to the Mark IX. The drivers seat was positioned just behind the right front wheel; the passenger was seated out to the left. The suspension was comprised of double wishbones with transverse leaf springs and Armstrong telescopic dampers. The chassis rode on sixteen-inch Dunlop perforated disc wheels and Dunlop Racing tires. Dunlop multi-pad disc brakes could be found on all four corners, and helped keep the car in the drivers control. The main fuel tank sat behind the driver and passengers seats. A secondary tank was placed beneath the passenger seat, which aided with weight distribution when the passenger was not in the vehicle. The body was created from lightweight aluminum, and secured in place by Dzus fasteners, which meant it could be quickly removed if needed.
The engine was mounted far back in the frame and produced 225 horsepower. The engine was mated to a Moss gearbox which sent the power to the rear wheels.
The first prototype car was dubbed the Cooper-Jaguar Mark I, also known as the T33. It raced in minor events, where it was a formidable competitor and often beat Jaguar cars powered by similar engines.
In 1955, a second car was ordered, the Mark II also known as the T38. When completed, it was displayed at the Brussels show; its body was set aside to show of the mechanical genius of the car. In comparison to the MKI, the MKII featured only a few changes, but those changes were enough to make a big difference. The engine was now a complete dry-sump XK engine, with a four-gallon dry sump oil tank, with an engine rating of 250 horsepower. The engine and transmission sat farther back in the engine bay. The driver and passenger seating positions were altered slightly.
In total, there were three MKII T-38 cars constructed. The first was the Peter Whitehead prototype car. Whitehead entered his car in the Silverstone event and later brought it to the 24 Hours of LeMans. The car ran for three hours before engine problems side-lined the car prematurely. Its best finish of the season was a fourth place at Oporto.
by Dan Vaughan