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  Chaparral 2J Chevrolet
 

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Country of origin:United States
Produced in:1970
Numbers built:one-off
Designed by:Jim Hall
Author:Wouter Melissen
Last updated:June 30, 2011
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Click here to download printer friendly versionFor many years aerodynamic tweaks were predominantly used in sportscar racing to find a balance between low drag and high speed stability. Especially at tracks like Le Mans, a high top speed was vital and to achieve that most of the 1950s and 1960s racers actually produced lift, making them lethally unstable. The designers were well aware that aerodynamics could also be used to generate downforce, but this was usually discarded as the common belief was that cornering forces could never exceed 1g. This misconception was caused by the limitation of the tires and with the move to fatter tires in the 1960s it became obvious that there really was no limit.

One of the first to successfully use aerodynamics to generate downforce was American Jim Hall. The Texan oil man was a successful racing car driver with an interest in engineering and started developing and producing his own 'Chaparral' cars in 1961. The first Chaparral was a relatively conventional front engined sports racer. Shortly into its career, Hall fitted it with a small metal strip on the nose, under the air-intake. This was most likely the first 'spoiler', designed specifically to produce downforce. It is no coincidence that this type of device was developed in the United States as the tracks there were much shorter and twistier than in Europe, making high top speeds less relevant.

In the next few years, the mid-engined Chaparrals grew all sorts of lips and wings and they no doubt greatly contributed to successes of the white racers in the SCCA and later Can-Am championships. The most influential of these was probably the Chaparral 2E, which used a high-mounted aerofoil. On the straights it was set as horizontal as possible to lower drag and during braking and in corners it was angled upwards to generate downforce. This was possible by the use of a semi-automatic gearbox, which enabled the driver to push a pedal on straights. Similar systems were quickly adopted in Formula with the wings usually installed on the suspension to maximize the effect. This led to excessive stress on the system and not much later suspension mounted wings and movable aerodynamic devices were banned.

By the end of the decade, the other teams had caught on and one or sometimes two-car Chaparral team struggled against the hordes of Lolas and McLarens. To once more get an edge over his competitors, Hall designed his most extreme machine yet for the 1969 season; the 2H. The car's body was shaped like a wing with only a very small opening for the driver. The fiberglass shell also served as the car's monocoque chassis. The designated driver, 1966 Can-Am champ John Surtees, greatly disliked the machine due to poor visibility. There were also some teething technical problems and for the first time in many seasons, Hall had to fall back to a customer chassis for his campaign. The innovative design produced so much downforce that the cornering forces got the car on two wheels; Hall had clearly reached the edge of tire and suspension technology.

Bitterly disappointed in the failure of the 2H, Hall went back to the drawing boards and came up with something even more extreme. Officially known as the 2J, the 1970 Chaparral has gone into history as the 'sucker car'. Setting aside his long experience with wings and aerofoil, Hall found a completely new way of generating downforce and without the penalty of additional drag. Using a Rockwell snowmobile engine, all the air was sucked from underneath the car creating a low pressure area; the 2J was literally sucked to the ground. The two cylinder engine was installed on top of the gearbox and the air was blown out the back by two large fans. The area was sealed off by lexan skirts that were connected to the suspension to keep them attached to the ground at all time.

There was more to the mid-engined Chaparrals than just the fancy aerodynamics; the chassis, suspension and engine were usually on the cutting edge as well. Looking for a balance between light weight and rigidity, Hall used moncoque designs for his chassis constructed of either fiberglass or aluminium. For the 2J, he used aluminium, which offered a bit more rigidity, required due to the higher cornering speeds and heavier weight. The car was also considerably wider than its predecessors to prevent the two-wheel cornering antics of the 2H. The big-block Chevrolet engine was of an all-alloy construction and displaced well in excess of seven litres. The fuel injected 680 bhp unit was mated to a Chaparral developed 3-speed automatic gearbox.

Courtesy of the company's many past innovations, the introduction of the Chaparral 2J was highly anticipated. Despite not being completely ready, Hall rushed the car's debut to prevent other teams from stealing his idea. He hired F1 World Champion Jackie Stewart for the occasion and he was immediately on the pace. He set the fastest lap, but was forced to retire with boiling brake fluid. By that time the Rockwell engine had already failed, which would remain the 2J's Achilles heel for the remainder of the season. Chaparral skipped three races to further develop the car and at their return, Vic Elford promptly placed the white machine on pole, with a margin of more than a second over the McLaren of Denny Hulme. At the start Elford was passed by the two Works McLarens because of the automatic gearbox, but within two laps he had gotten by both and took off into the distance. Sadly the fan-engine started to act up again and due to pitting several times, the 2J eventually finished the race in sixth.

While the new Chaparral had not won a race yet, the other teams realized that once it was made reliable, there was nothing stopping the innovative racer. Instead of trying to adopt the sucker system themselves, the teams started to complain. They figured that the spinning fans were in fact moving aerodynamic devices. At the season's final race, the controversy reached a peak and the 2J was banned, despite a final attempt by Hall to convince the sport's governing body that the sucker system was perfectly legal. Elford was allowed to compete in the final race and he gave the car a fitting final outing by putting it on pole again, 2.2 seconds clear of the rest. Sadly the fan motor broke once again in the middle of a very high speed corner. With no suction, the car lost almost all grip, but fortunately Elford managed to keep the car out of the wall.

Tired from fighting with the authorities, Hall closed his racing shop and stayed away from racing for most of the decade. He had a new car on the drawing boards that used a Venturi system to create a low pressure area under the car without having to use fans. In 1977 a very similar design was introduced by Lotus in Formula 1, which heralded the arrival of the ground effects era. The fans also made an appearance in F1 on a Brabham, which managed to score a victory before it was also banned. Not much later Chaparral Cars entered Indy racing and in the 2K, Johnny Rutherford won the 1980 Indy 500. Jim Hall will however be forever remembered for his ground-breaking Can-Am cars and the 2J remains as his finest design and one of the most controversial racing cars ever constructed. It greatly influenced designers for years to come and its resemblance between with the 1980s Group C racing cars is striking.

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  Article Image gallery (15) Chassis (1) Specifications User Comments (2)