Ford GT40 J-car

The first J-car was completed in March 1966 and set the fastest time at the Le Mans trials that year. The tub weighed only 86 lb (39 kg), and the entire car weighed only 2,660 lb (1,207 kg), 300 lb (136 kg) less than the Mk II. It was decided to run the Mk IIs due to their proven reliability, however, and little or no development was done on the J-car for the rest of the season. Following Le Mans, the development program for the J-car was resumed, and a second car was built. During a test session at Riverside International Raceway in August 1966 with Ken Miles driving, the car suddenly went out of control at the end of Riverside's high-speed, 1-mile-long back straight. The aluminum honeycomb chassis did not live up to its design goal, shattering upon impact. The car burst into flames, killing Miles. It was determined that the unique, flat-topped "bread van" aerodynamics of the car, lacking any sort of spoiler, were implicated in generating excess lift. Therefore, a conventional but significantly more aerodynamic body was designed for the subsequent development of the J-car which was officially known as the Mk IV. A total of nine cars were constructed with J-car chassis numbers although six were designated as Mk IVs and one as the G7A.

This page lists statistics about the Ford GT40 J-car.