{"id":500190,"date":"2022-11-15T14:40:46","date_gmt":"2022-11-15T22:40:46","guid":{"rendered":"https:\/\/sportscardigest.com\/?p=137727"},"modified":"2024-12-27T13:00:03","modified_gmt":"2024-12-27T13:00:03","slug":"the-astonishing-chaparral-2j","status":"publish","type":"post","link":"https:\/\/www.supercars.net\/blog\/the-astonishing-chaparral-2j\/","title":{"rendered":"1970 Chaparral 2J – Astonishing"},"content":{"rendered":"

\"\"<\/a>At Watkins Glen they said, \u201cIt looks like the box it came in.\u201d 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.<\/p>\n

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-earned status of the Wizard Technician of Group 7 racing. In the rest of the 1970 Can-Am season it revealed phenomenal pace.<\/p>\n

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In mid-1970 Jim Hall looked at the birdie from the cockpit of his latest creation, the Chaparral 2J. The result of a combined effort between Chaparral cars and Chevrolet R&D, the 2J was the innovative elixir that Hall needed after his troubled Can-Am seasons of 1968 and \u201869. Looking, as one commentator said, \u201clike the box it came in,\u201d the 2J introduced suction ground effects to automobile racing.<\/figcaption><\/figure>\n

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\u2019s secretive R&D Department had been closely cooperating on the building, testing and even racing of advanced sports-racing cars.<\/p>\n

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Shown, as at left, at Midland\u2019s Rattlesnake Raceway prior to its racing debut, the 2J was sucked against the road surface by two extractor fans mounted at its extreme rear. Hall\u2019s 2J was a much-improved (by Chaparral) evolution of a crude test vehicle built by Chevrolet R&D to explore this radical concept.<\/figcaption><\/figure>\n

The 2J\u2019s 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\u2019s Vasa Ni\u0107in applied for a patent on it on December 29, 1925.<\/p>\n

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A diagram explained the concept of the Chaparral 2J. Driven at a constant speed of some 5,000 rpm by a separate engine, the twin 17-inch fans at the rear extracted air from an enclosed area of the 2J extending from the rear of the front wheels all the way to the extreme tail. At the side and rear, skirts made of tough GE Lexan plastic ensured that the suction was highly effective by staying close to the road surface.<\/figcaption><\/figure>\n

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 \u201cground effect\u201d racing cars but these were a decade in the future, while the basis of the 2J was created in the winter of 1968.<\/p>\n

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The front end of the 2J Chaparral was shaped to divert as much air as possible up over the top of the vehicle and around its sides. Front air inlets were for the engine-cooling radiator and ducts to the front brakes. Slotted inlets on both sides of the rollover bar ingested induction air for the engine.<\/figcaption><\/figure>\n

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 \u201cunfair advantage.\u201d During 1968, engineers in Chevrolet\u2019s Research and Development Department seized on suction downforce as a radical breakthrough that could revitalize their activities under new chief Charlie Simmons.<\/p>\n

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, R&D engineer Paul Van Valkenburgh said, \u201cSimmons gave Don Gates all the draftsmen, technicians and budget he needed to have it ready for the next racing season.\u201d<\/p>\n

Gates, the brainy engineer who had won Simmons\u2019 approval, concentrated on the suction system of Chevy\u2019s \u201cSuspension Test Vehicle\u201d 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.<\/p>\n

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The central section of the Chaparral 2J was a deep and rugged aluminum monocoque tub. It used front suspension similar to that of the 2H and rear suspension adapted from the 2G. That the suspension geometries provided anti-dive and anti-squat was particularly useful for the 2J, which needed to ride as flat and level as possible to maintain its ground-effect skirts in close proximity to the road.<\/figcaption><\/figure>\n

The STV\u2019s fundamental monocoque structure was very deep through its center because that portion, initially unpainted, was a major load-bearing section. Hatches in its sides met the rules requiring doors. Longerons extending rearward from the monocoque embraced the Chaparral-prepared Chevrolet V-8, an aluminum engine of 7.6 liters and 680 bhp driving through a Chevy-built transmission combining a torque converter with three gears forward that were shifted without a clutch.<\/p>\n

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The Chaparral 2H carried over Chevrolet’s torque-converter transmission with a three-gear dog-clutch box. Perched atop this was the engine that drove the extractor fans, a two-cylinder two-stroke air-cooled JLO engine usually found in snowmobiles. Disc brakes were internally ventilated.<\/figcaption><\/figure>\n

Containing the areas where suction was generated was a box-like structure made of 0.25-inch aluminum honeycomb. With no available technology to give it curvature, the result was a laughably slab-sided appearance. Dzus fasteners joined the major panels together and allowed quick access. In all, said Van Valkenburgh, \u201cit was probably the strongest, stiffest racecar chassis that had ever been built.\u201d<\/p>\n

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Stripped of its front and rear body sections, the 2J revealed its deep central aluminum monocoque structure. Its hinged \u201cdoors\u201d met the letter of the Can-Am regulations. Standing behind the car in sunglasses was Cameron Argetsinger, spark plug of road racing at Watkins Glen who had joined Chaparral Cars as a vice president in 1970.<\/figcaption><\/figure>\n

The STV\u2019s suspension was conventional. At the front it had tubular wishbones and coil\/damper assemblies like those of the Chaparral 2H and racing-style linkages like those of the 2E\/G at the rear. Their geometries countered nose-dive on braking and tail squat on acceleration, both of these being activities that would upset the skirt system more than would be convenient.<\/p>\n

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Ducts from the air inlets athwart the cockpit provided fresh ram air to the inlet manifold of the 2J, carried over from the 2H. In the foreground, attached to the rear suspension by a Bowden cable, is the bell-crank linkage that kept the Lexan side skirt close to the ground as the rear of the Chaparral rose and fell over bumps.<\/figcaption><\/figure>\n

An important feature of the STV\u2019s springing was that it was trimmed for ideal geometry at 1.5 inches below the car\u2019s stance with its downforce not running. That was the amount that the car was calculated to be pulled down by suction to its operating height. From that datum line, the springing allowed three inches of travel in both jounce and rebound. To take advantage of its downforce the STV wore the widest wheel rims it could accept and the widest of Firestone\u2019s racing tires. Disc brakes were internally vented for cooling.<\/p>\n

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Jim Hall\u2019s problematic Chaparral 2H.<\/figcaption><\/figure>\n

As the 1969 Can-Am season progressed, the faults of Hall\u2019s Chaparral 2H were found to be many and insoluble. This was not surprising to Chevrolet, which knew that Hall\u2019s personally chosen approach, a car built for maximum speed with little attention to downforce, would not work on the Can-Am circuits.<\/p>\n

Meanwhile, tests of the STV were attracting attention at Chevrolet R&D. \u201cThe first time the auxiliary-motor fan-drive system was fired up,\u201d recalled Van Valkenburgh, \u201cit literally smoked out the engineering lab. It became rather embarrassing to have around\u2026so ridiculously sensational that everyone was talking about it.\u201d In the spring of 1969, Hall asked Don Gates to join his effort to sort out the 2H. Chevrolet decided that as the STV was Gates\u2019s baby, the semi-finished vehicle might as well accompany him to Midland. It was shipped there in September.<\/p>\n

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As originally built by Chevrolet and made whole to run at Rattlesnake, the STV\u2019s rear wheels were exposed, in conventional fashion. Suction was applied over an area that was the width of the car and the length of the body between its wheel arches. Suction fans were mounted low at the sides of the body, flanking the engine and individually driven by small two-stroke motors.<\/p>\n

In tests, beginning in November of 1969, this arrangement did give substantial downforce but the car\u2019s handling was treacherous. \u201cRegardless of how much basic understeer was incorporated with the fans off,\u201d said Paul Van Valkenburgh, \u201cwhen they were turned on the car oversteered uncontrollably. Apparently, the center of downward pressure was too far forward. But in spite of all the problems, with the fans working it was as fast as any other car ever run at Midland.\u201d<\/p>\n

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Among the gauges facing the driver in the cockpit of the 2J was one which told him how much suction was being generated under the car. Tests showed that when suction was lost the Chaparral remained easily controllable. He was also informed about the cylinder-head temperature of the auxiliary engine. As in the 2G the steering wheel was quick-removable for easy entry.<\/figcaption><\/figure>\n

While Jim Hall was increasingly cool to \u201csomeone else\u2019s Can-Am car\u201d the STV found a defender at Midland in Tom Dutton, an engineer-driver who had joined the team during 1969. \u201cPractically everyone else viewed the project with either distrust or malice,\u201d recalled Van Valkenburgh. Dutton was the driver for tests that proved to the sanctioning Sports Car Club of America that the car would not be wildly uncontrollable if or when downforce was lost. The SCCA also judged it acceptable in spite of FIA rules prohibiting \u201cmovable aerodynamic devices\u201d.<\/p>\n