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Country of origin:United States
Produced in:1967
Numbers built:10 (J-1 - J10)
Predecessor:Ford GT40 Mk II
Author:Wouter Melissen
Last updated:September 26, 2016
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Click here to download printer friendly versionNot convinced that the British built Ford GT (40) with its steel monocoque and small-block V8 was a potential Le Mans winner, Ford USA took a more active role in the project early in 1965. The first step was that Carroll Shelby was put in charge of campaigning and further developing the existing car. He fitted a larger version of the small block engine, new cast alloy wheels and better brakes. There was instant success as the improved GT40 won the Daytona 2000 km and its class at the Sebring 12 Hours. For Le Mans Shelby went a step further and equipped two cars with the Ford Galaxy derived big block V8. These GT40 Mark IIs were quick, but fragile and Le Mans proved to be a disaster once more for Ford.

While Shelby continued to develop the big block engined GT40 Mk II, Ford had even bigger plans. They had realised that Eric Broadley was partly right at the start of the GT40 project when he objected to using steel for the car's monocoque. Being much friendlier to use than lighter materials like aluminium, it allowed for the GT40 to be easily turned into a production car. The additional weight did hamper the cars to the extent that they had to resort to engines almost twice the size of the biggest competitor, Ferrari. Needless to say the additional power and weight also stressed all the running gear further, causing many retirements for the Mk II in its maiden season. The only logical solution was to build a heavily revised version of the chassis.

In the fall of 1965, Ford set out to build that new chassis. The obvious choice would be to replace the steel with aluminium for a considerably lighter monocoque. It was feared, however, that the lightweight metal would not be strong enough to cope with the 500 bhp engine and the strains of racing around Le Mans for 24 Hours. The engineers decided to use a honeycomb structure sandwiched between the sheets of aluminium, resulting in an exceptionally strong material. These honeycombs were already commonly used in aircraft design, but it was a ground-breaking construction method in motor racing. The production of the tubs was out-sourced to Brunswick Aerospace.

By using a similar design for the chassis, many of the Mk II mechanicals could be carried over to the new car. These included the suspension parts, brakes and the big block, seven litre V8 engine. New was the Kar Kraft constructed 2-speed automatic gearbox, replacing the more common four speed manual box. Assembled by Ford in Dearborn, the GT40 evolution was clothed in a tightly wrapped fiberglass body with a high rear deck and an aggressively cut-off 'Kamm' tail. Considered an experimental car, the new racer was simply known as the 'J-car', referring to the Appendix J of the regulations to which the car was constructed. Weighing in at 940 kg, or 200 kg lighter than the Mk II, the first J-car was ready in time for the Le Mans Trials in the spring of 1966.

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  Article Image gallery (81) Chassis (4) Specifications User Comments (3)