1975 Chevrolet Corvette Race Car - Fast Line Around The Learning Curve

John Greenwood's Outrageous C3 Corvette Racer

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John Greenwood's "wide body" C3 Corvette racer, seen here on top of the Corkscrew at Laguna Seca during the IMSA Camel GT race there in early 1975.

It was a car that could do over 220 miles an hour on the back stretch at Daytona, then drift through the high-banked turns like a World of Outlaws car, fully under control. The "Spirit of Sebring" Corvettes built by John Greenwood in the mid-'70s represented a high water mark in the design and construction of road-racing Corvettes. These were the last cars that he built using the production C3 Corvette frame; his later cars were full-tube-chassis ones.

It was, in Greenwood's words, the wildest production-based road racer to date, much less the wildest production-based one ever. "Without a doubt, the #75 car was, for me, the most fun, biggest rush, and biggest reward for doing all that kind of stuff, of any car that we ever did," Greenwood says from his Apopka, Florida Corvette store, Greenwood Corvettes. "That was THE car...that car was a bad boy!"

Back in the spring of 1975, we saw the #75 "Spirit of Sebring" Vette in action at Laguna Seca, in an IMSA Camel GT Challenge race. As Greenwood recalls, that race was as much a test/research-and-development session as it was a competition against the factory Porsches and BMWs in the field. "We didn't do well there," he says. "There was a learning curve with the car." Once he took the fast line on that curve, Greenwood wound up with a car that ran up front in both IMSA Camel GT and Trans Am-and scored three wins in Trans Am, leading to that series' 1975 championship.

Greenwood's foray into road racing followed a successful career street-racing W-engined Chevys (Impalas and Corvettes) on Woodward Avenue outside Detroit. Turning to road racing in the late '60s, after initial success at the club level starting at Waterford Hills, Greenwood took his Corvette racing operation nationwide, winning two consecutive Sports Car Club of America (SCCA) A/Production National Championships in 1970-71.

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It wasn't just to cover the extra-wide Goodyear racing tires that the Greenwood Vette's bodywork was as wide as it was. Thanks to Zora Arkus-Duntov's input, those plus-size body panels increase down force at speed.

A sponsorship deal with BFGoodrich in '72 resulted in his first highly-modified Vette racers, called the "swing-arm cars" by Greenwood, which he ran in IMSA's Camel GT Challenge and SCCA's Trans-Am Series in 1972 and '73 (scoring three Trans-Am wins in '73) wearing ZL1 flares over their shaved BFG Radial T/As. His next race cars after the swing-arm cars, were to be progressions, while still wearing BFG's regular-production tires.

Troubles with Goodrich's production-derived tires--when they switched from 60-series to 50-series ones to race on in '73--led to on-track problems, and the BFG program ended after that season. But that didn't stop Greenwood from getting design, fabrication and technical help for his next C3 race cars.

It started at a test session on the big oval at central Ohio's Transportation Research Center (TRC). "At the time, I was getting more and more associated with Zora Arkus-Duntov," Greenwood recalls. "He and I sat down and talked, and I said, 'I want to build the most highly-modified platform car.'" Nothing brought out the best in Zora like a challenge-especially one involving Corvettes, as Greenwood witnessed. "As I'm sitting there talking to Zora, we're sitting on a curb and I'm telling him what I'm doing, and he's talking about the body work, and he wanted to make this wide body with the fender flares angling up. He just kept going with his hands, and explains to me how he wanted to make the fenders and bodywork on the car." And, so was born the concept of using wider bodywork to create downforce.

Greenwood's new racing Corvette turned out to have as much state-of-the-art Chevy and GM help as a privateer could dream of back then, as GM's corporate racing ban didn't end for another decade. "We came up with a deal where they ended up designing the body that was on the car at GM, at Chevrolet's Advanced Styling studio," says Greenwood, who also notes the contribution that future-GM Styling boss Jerry Palmer (and its then-current chief, Bill Mitchell) made at the time, as well as Randy Wittine's. "They made some temporary 'tools' (body tooling), and gave me the first tools. We made a deal where we would go ahead and produce the parts, for any Corvette person who wanted to use them. The parts ended up being homologated for FIA, so we could run them at LeMans (or in any other FIA-sanctioned races). [Zora] ended up having the clay model done, and they made the parts." Also, those wide-body parts got GM factory part numbers, and were listed in the Chevrolet Power service manual (along with stuff like LS7 crate engines and bare ZL1 blocks) for Chevy racers that was released in the mid-'70s.

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Extra-wide body panels were made from molds pulled off of a full-size clay model in Chevrolet's Advanced Styling studio, with design input by Jerry Palmer, Randy Wittine, and Zora Arkus-Duntov.

Underneath, Greenwood's new race car got plenty of big-name attention, too. "Bob Riley designed the chassis and suspension, and the fabricator was Ron Fornier, who was with Penske when their Camaro dominated Trans Am with Mark Donahue driving," says Greenwood. "Riley and Fornier worked real close together building those platforms, and I worked with Riley on what I wanted to the point where we ended up using the C3 spindles." Greenwood says the FIA's rules-which SCCA and IMSA followed then-- specified that they had to use production Corvette items like spindles, A-arms, and all geometry points. "We literally stretched all those rules-it cost me twice as much to build the #75 and #76 wide-body cars than it did to build the [later] tube-chassis cars!"

One planned feature of the new car didn't make it on until later: cross-ram fuel injection. "My plan was to come out with this platform, chassis and suspension AND cross-ram injection, with the BFGoodrich tires," Greenwood notes. "I didn't get it done in time for the BFGoodrich deal because of the second-year tire change caused so many problems with the other car, that there wasn't any reason to throw any more speed, or horsepower and all that to the tires."

The result? Greenwood remembers it like it rolled out of his shop yesterday. "That is the most outrageous modified Production-based car that anybody has done! The car would go 230-235 miles per hour-it would enter the banking at Daytona at 221 miles an hour, and I didn't lift at all!"

Before its successful runs came the early races and the problems attendant to an all-new car. "We ran into header problems at the first race at Road Atlanta. It was actually some really 'tricky' headers that Jere Stahl built for us. He'll tell you what we learned right there changed the way he did everything from then on-and he was the guy building Penske's headers, and everybody else's."

Once the car was sorted out, it ran up front, and stayed there in many a race. That led to three Trans Am wins in 1975, at Pocono, Portland, and Nelson Ledges, plus enough other up-front finishes to give him the '75 Trans Am title, while being a factor in the IMSA Camel GT title chase-no matter who drove it. "Milt Minter was a contender, and I was not," Greenwood says. " I told him, I'll let you run my car, because its last race was the November '74 race at Daytona. The championship was between him and Peter Gregg-whoever finished higher in that race won the championship. I put the new cross-ram injection on-I finally got one machined and built, and on the car-and Milt opts to run Kaiser's Porsche, because he had a better chance to finish in the position he needed to beat Gregg to win the championship. I take the #75 car, and I had it working good! We stomped everybody-I won, Milt was third and Peter second, so he (Gregg) won the IMSA championship."

But, in 1976, early bad luck led to a crash. "The next year, the car went to the Daytona 24 Hour. I brought in other drivers, and one of them stepped off the apron going into the tri-oval, and totaled the car. We did re-build it, while we were bringing out another car, and ran it at Sebring. It qualified on the pole again."

Soon after, it was sold to Dr. Juan Olivera, an orthopedic surgeon. Unfortunately, he died in a dirt-bike crash not long after he bought it, and the wide-body C3's history took it to Germany, where it was raced with success. However, after the '80s, the car's history gets hazy, and Greenwood says he doesn't know where it is right now.

But it's a car that Greenwood would like to restore, to the same configuration it was in when he raced it. One big reason: Its "user-friendliness." "When I drove it at Daytona, we'd go down the back straight and enter the banking at 221 miles an hour, and drift it," he recalls fondly. "I'd say we were 30 degrees out. Everybody who was up in the sky lounges at the time told me about the angle the car was on. It was actually under control that way. That car was 'user-friendly'! All my other cars, I did the same thing with all of them."

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