Begun as a project at Chevrolet and inherited by Jim Hall, a sports-racing car with phenomenal potential became the Chaparral 2J. Although framed and intended to encourage innovation, the Can-Am series had seen nothing like it.
At Watkins Glen they said, “It looks like the box it came in.” Even that harsh judgement of the appearance of the new Chaparral 2J may have been too generous. However, handsome is as handsome does and in its astonishing way the 2J did handsomely.
A World Champion was sufficiently impressed with its concept to drive the Chaparral 2J at Watkins Glen in 1970 and set a fastest lap while running in very fast company. Although the 2J did not last long enough to get close to winning, it showed great potential and restored its developer, Jim Hall, to his well-won status of the Wizard Technician of Group 7 racing. In the rest of the 1970 Can-Am season it revealed phenomenal pace.
But was it the Chaparral Show...or was it really the Chevy Show with Jim Hall as master of ceremonies? In fact the new 2J Chaparral was conceived and constructed, in its major essentials, at the Chevrolet Engineering Center in Warren, Michigan. This was not a new relationship. Since 1964 Chaparral and Chevrolet’s secretive R&D Department had been closely cooperating on the building, testing and even racing of advanced sports-racing cars.
The 2J’s basic concept was simple enough. If a vacuum could be maintained underneath a moving automobile, it would hold the car down with greater force. With the latest racing tires, more force would mean more grip, translating into vastly increased cornering power. The idea was not new. Dresden, Germany’s Vasa Nićin applied for a patent on it on December 29, 1925.
The wider and larger the tires, the bigger the contact patch on the pavement and the more work they will do before sliding as the downforce is increased. Faster cornering is the key to success on road-racing tracks. This would later be exploited in so-called “ground effect” racing cars but these were a decade in the future when the basis of the 2J was created in the winter of 1968.
This concept was available long before the FIA implemented a height reduction on aerodynamic wings that sent all Can-Am and other competitors scrambling for some new “unfair advantage.” During 1968 engineers in Chevrolet’s Research and Development Department seized on suction downforce as a radical breakthrough that could revitalize their activities under new chief Charlie Simmons.
With Jim Hall building his Chaparral 2H on his own for the 1969 season, they needed something new that might help the Texan in the future. After tests with mockups and mule vehicles showed promise, said R&D engineer Paul Van Valkenburgh, “Simmons gave Don Gates all the draftsmen, technicians and budget he needed to have it ready for the next racing season.”
Gates, the brainy engineer who had won Simmons’ approval, concentrated on the suction system of Chevy’s “Suspension Test Vehicle” or STV. Don Cox, Joe Marasco and Ernie DeFusco designed the car that would carry it. The challenge they faced in creating a suitable body forced them to ignore conventional aerodynamic ideas. Their dominant need was for a robust box that would not collapse under the vacuum generated inside it…
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by Karl Ludvigsen
Photographs: Ludvigsen Library