Legend “according to Jim Hall” has the idea for the Chaparral 2J came to him through a child’s drawing that was sent to him as part of the fan mail that made its way to Midland. Whether true or not it must be remembered that Hall, always self effacing may have just come up with the story to deflect the constant questions on how the Chaparral 2J came to be. Tall wings and other moving aero devices were being banned and Hall was looking for some other means for producing aerodynamic downforce. The disappointment of his last project, the Chaparral 2H was still fresh in his mind but that did not stop Hall in reaching for his next major innovation, for genius is not so easily thwarted.
“A kid sent me a drawing of a car that looked like a beanie cap, those little caps kids used to wear with a propeller on top,” Hall recounts. “It had four wheels, with the driver peering out through a window of the beanie and the propeller on top. We looked at it and thought, ‘Wouldn’t this be a good way to do it?’ It wasn’t my original idea; somebody did send that to me.”
Originally conceived along the lines of a hovercraft but with negative pressure, Hall realizing the complexity involved partners, General Motors and GE in his project. Initial testing of the vacuum concept took place at a GM test facility in Michigan. Chevy R&D made available their Suspension Test vehicle (STV), which was more of a test rig than an actual vehicle that allowed the testing of roll-center heights, roll stiffness, pitch axis, anti-squat and anti-dive configurations. The STV became the test mule for the 2J. Skirts were required to maintain the vacuum and these were sourced from GE, using their Lexan material, originally invented by Dr. Daniel W. Fox while conducting a series of experiments while on a project to develop new wire insulation material, and famously used by NASA for it’s astronaut helmets. The skirts rather than simply dragging on the ground were controlled by a Rube Goldberg series of push/pull cables so that when the suspension moved and the chassis went up and down, the skirts went up and down as well maintaining a constant gap with the road service.
Held on the same weekend as the 1970 World Championship for Sports Cars race the Can-Am race at Watkins Glen was bolstered by a number of sports cars. While Denny Hulme won the race the next six places were captured by the European sports cars, one, a Porsche 917K was driven by Vic Elford. Back at the hotel, after the race Elford was asked by Jim Hall if he would like to drive his Chaparral 2J for the rest of the year. An incredulous Elford remarked that Hall had Jackie Stewart to which Hall replied:
“Yes but that was just a one-off deal,” he explained, “and we think you would be the ideal guy to drive it for the rest of the year.” I was over the moon at the opportunity to drive such a radical car and that someone like Jim Hall should have such confidence in me. Vic Elford – Reflections on Golden Era in Motorsports
When Elford arrived in Midland, Texas from his home in France to test the 2J he was met by Jim Hall who told the Englishman that “If you go off the road don’t even think about getting out; just sit and wait, and we’ll come and find you. If not, the rattlesnakes may get there first.”
The starting sequence was quite different for this car: First the driver need to press down the brake peddle while the JLO motor that powered the fans were started. This would immediately cause the car to squat as the suction under the car took hold. Then the ignition was switched on and the main engine was came on at which point the driver would release pressure from the brake and the car was off. Elford like Stewart before him quickly realized that driving the Chaparral 2J would be like no other car that they had ever driven.
“With my former car, the 2G, we could get wheel spin and make it violently oversteer by over controlling the throttle at almost any speed and at almost any place on the race course. But not the 2J,” stated Chaparral co-founder Jim Hall. “We can go full throttle without wheel spin or uncontrollable oversteer, at a much lower speed and accelerate out of the corners at a much higher speed than ever before.” Jim Hall
The suction effect was created by the use of dual fans powered by a Rockwell JLO engine which when turned on automatically caused the car to squat another 2 inches. Theoretically, the 2J could generate up to 2200 pounds of downforce which unlike normal vehicle downforce, was independent of the speed of the car.
One of the side effects was that the car would do a wonderful job of hoovering dust, debris, oil sprays, and the occasional grass clippings—to the back, into the faces of other drivers behind it.
During practice of what was to be it’s final race at Riverside, Elford put on a remarkable demonstration of the car’s potential. “Coming in to the long, fast, 180-degree Turn 9,” he says, “I was behind Denny, close to flat, and I just drove around the outside of him. He was so pissed off, he pulled into the pits and sulked. A wonderful car!” Vic Elford
Unfortunately the car was beset by various issues with the skirts and the suction sub-system. At Road Atlanta in September. Elford put the car on the pole by 1.26sec over Denny Hulme’s McLaren, then finished sixth after ignition issues with the snowmobile engine. At Laguna Seca, Elford was on pole again by 1.8sec, but didn’t start after his engine blew in the warm-up (see page 34). The 2J’s final race was Riverside, with another pole, by 2.2 sec, and another DNF. If fact Hall remarked that one of the cars complexities was that it was actually two cars in one. Hall had wanted to debut the car in ’71, after the kinks had been ironed out but were pushed to race it earlier by General Motors who thought they’d have a hard time keeping the technology under wraps fearing someone else might jump in and race the concept before Chaparral. In the end the car and technology was banned after one season. Even Hall would later admit that perhaps the car was too far ahead of its time.
“The potential of that kind of car was so great that it could have put a strain on the whole infrastructure,” he says. “And we understood that. If you’re going to corner 50 percent faster than last year, boy, that’s going to make for a hell of an accident. So maybe the tracks and safety equipment weren’t ready to handle such a thing.” Jim Hall