If you haven't encountered the car below, your first impression is possibly that it's a customized Corvette from, say, 1957. But it's really the first purpose-built road racer from General Motors, and the first Corvette to have a metal body*...magnesium, in this case. And it exists because, for a brief moment in GM's push to sell more Corvettes, engineer Zora Arkus-Duntov convinced management that a serious effort needed to be made to confront the Ferraris, Maseratis and Jaguars cleaning up on the road racing courses of the Sports Car Club of America. In 1956, to attract management's interest, he had taken two mostly stock Corvettes and one modified car to Daytona Speed Week. John Fitch and Betty Skelton had taken 1st and 2nd places in the production sports car category, and Duntov himself had won the division for modified sports cars. This convinced GM brass to green-light the program that resulted in the blue car shown below, XP-64, the Corvette Super Sport. Body design was assigned to Clare MacKichan. Chassis design was another matter...
GM bought a Jaguar D-Type for evaluation, and GM Styling's first approach to coming up with a winner on a tight schedule involved substituting a Chevy V8 for the twin-cam Jaguar six, moving the steering to the left side, and covering the whole thing with, well, GM Styling. At least this approach would've given them the best brakes in racing at that moment. But the Corvette engineering team, led by Duntov, decided that the cut-and-paste approach was unlikely to work. So GM also bought a Mercedes 300SL, and Duntov's team spent a good while studying that car's tubular chassis. In fairly short order they had a design for a road racer with a lightweight tubular chassis, powered by a 283 with Rochester fuel injection. The test mule, first of two cars built, was bodied in fiberglass. It's shown below with Duntov at the wheel...
The engine in the final version of the Super Sport featured aluminum heads and made 310 hp from 283 cubic inches. Suspension was by coil springs all around, with trailing arms locating a De Dion unit at the rear. Brakes were adapted from Chrysler units with twin leading shoes, and outfitted with finned aluminum covers over iron backing plates. Why Duntov's engineers, having originally been instructed to crib a whole Jaguar chassis, had contented themselves with drums instead of discs, is a mystery...
The magnesium-bodied* racer also differed from the fiberglass mule in adopting clamshell-type access in front for the engine and also for the De Dion rear end with its quick-change differential. The D-Type Jag GM had bought featured similar engine access, and the Lotus Elevens entered at Sebring would have the same access front and rear. John Fitch, seen here with Zora Arkus-Duntov, would share driving duties at Sebring in 1957 with Lancia master Piero Taruffi. The finished car shows off Halibrand alloy knock-off wheels. The whole package weighed a tidy 1,850 pounds.
The magnesium-bodied car wound up wearing the regulation chest-high plexiglass windshield in its one and only race outing, at the 1957 Sebring 12 Hours, where Duntov's team brought the fiberglass-bodied test mule as well. Both cars were fast in practice, and when Duntov allowed Maserati pilots Sterling Moss and Juan Manuel Fangio a few courtesy laps in his new car, Fangio broke the lap record on his second time around. He then won the race in the 450S he shared with Jean Behra. Moss and Harry Schell were 2nd in another Maserati, a 300S. The Corvette SS was just shy of two dozen laps when rear suspension woes ended the race for Fitch and Taruffi. This wasn't such a bad start for a brand-new road racer, but GM brass would shortly decide to honor the Automobile Manufacturers Association ban on corporate support of racing, and the Corvette Super Sport program was shelved. The goofy plexiglass roof punctured by the Flash Gordon headrest visible below highlights the conflict between Duntov's engineers and Harley Earl's stylists, and makes one wonder whether GM wasn't more interested in having a zoomy Motorama exhibit than a successful road racer anyway. Ironically, in the very next year Lance Reventlow would figure out how to make a wildly successful road racer with his Chevy-powered Scarabs*, and would depend almost exclusively on LA hot rod culture, as well as on engineers and metal shapers catering to the growing SCCA scene, with no obvious participation from General Motors.
Half a dozen years later, Zora Arkus-Duntov would build a few copies of another lightweight racer, the Corvette Grand Sport, and GM brass would get nervous and cancel the whole business, only to wind up clandestinely supporting Jim Hall's Chaparral team not too much later, in what turned out to be a turbulent decade inside and outside the auto industry. But both these tales of corporate intrigue will need to be saved for another day...
*Footnote: Lance Reventlow's adventures with the Scarab are reviewed in "Timing Is Everything: Reventlow Scarab Saga", in our archives for 6-2-17. For a look at other special Corvettes that happen to have metal bodies, visit our series of posts on Corvettes bodied in Italy by the likes of Pininfarina, Vignale and Scaglietti, starting with "The Italian Jobs: Corvettes in Italian Suits" (2-24-16), followed by "The Italian Jobs Part 2: The Kelly Corvette Was the First Postmodern Car" (2-27-16), "The Italian Jobs Part 3: Another Eurovision Corvette" (3-10-16), and "The Italian Jobs Part 4: Saved From the Crusher" (3-13-16).
Photo Credits:
Top color photo: George Havelka
Top color photo: George Havelka
All other photos: General Motors
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