AC Cobra: The truth behind the legend

Carroll Shelby dreamed of building an American sports car. It wasn't a daydream, but an actual dream he had at night. He awoke and wrote down the name of the car so he wouldn't forget it–Cobra. As he later conceived it, the chassis was to be built in Japan, be clothed with a fiberglass body fabricated in Southern California, and be powered by a small-block Chevy V8.

While he'd been a world-class race car driver (he won the 1959 Le Mans 24-Hour, for Aston Martin), when he retired Shelby had virtually no money; what he did have was the gift to sell himself, which he had done with startling results most of his adult life. While a chicken farmer in his native Texas, he convinced wealthy sportsmen that he could not only drive their expensive toys (exotic Ferrari and Maserati sports cars) but win races, a promise on which he delivered with such frequency that it earned him a place on the famed Aston Martin team. The problem was his weak heart, which led to his early retirement, as a driver. Without an income, and having settled in Southern California, Shelby convinced the brass at the Goodyear Tire and Rubber Company in Akron, Ohio that he was the ideal businessman to manage their race tire distributorship in Southern California. With this business as his base, he approached General Motors about financing his dream of building a fiberglas sports car powered by their small-block Chevy V8. They already had such a fiberglass sports car in the highly successful Chevrolet Corvette and weren't interested.

Undeterred, Shelby next turned his attention to England, where AC Cars had just lost their engine deal with Bristol Motors. The AC "Ace" as it was called, was a proven winner on England's club circuit: a small, lightweight sports car, clothed in a handsome aluminum body. All the car needed was an engine. To make a deal, what Shelby needed was an engine of similar power and dimensions of the Chevy V8. As fate would have it, the Ford Motor Company had just introduced a small-block V8 of its own, and was planning a return to motor racing. Thus, when Shelby arrived in Dearborn, he found a receptive audience in Ford's executive suite. The only question was, would Shelby's sports car be quick enough to beat the famed Corvette? Shelby assured them it would. Next a meeting was arranged with AC Cars and several Ford engineers about mating a Ford V8 with the "Ace" sports car. The engine fit without problem, and the resulting car–now dubbed the Cobra-Ford–was decidedly quick. But the prewar leaf-spring suspension and brakes needed to be beefed up, if the car was to be a consistent winner. This was done once the car was shipped to Southern California. Fitted with extra-wide 15-inch Goodyear Blue Streak racing tires, all that remained was flaring out the fenders to clear the muscular tires. With Ford covering cost overruns, the car went into limited production, and as Shelby said it would, beat GM's Corvette handily, and went on to win races around the world.

If you're looking for a book about the Cobra-Ford saga, "AC Cobra: The truth behind the Anglo-American legend", by Rinsey Mills, will do nicely. I found the history of the original AC "Ace" particularly fascinating. The subsequent story of how AC cars, Carroll Shelby, and the Ford Motor Company got together is better known perhaps, but I enjoyed the author’s telling, which is from England’s point of view (i.e., Shelby's role is played down). Whether or not it’s the real "truth behind the Anglo-American legend” is another matter, but more about that in a moment. Particularly interesting is the story of how the actual chassis was developed over the years, and how it was assembled during the AC Cobra years (lots of revealing photos). I was also interested to learn that the chassis was constructed at the AC factory in Thames-Ditton, while the labor-intensive aluminum bodies were hand-formed by several outside suppliers. A portion of the book covers by serial number the race history of several Cobras. About 998 Ford-Cobras were built in all.

The problem is with the chapter entitled: “Mk II: Coil-Spring chassis and larger engine.” This is about the final version of the Cobra, the Mark II, powered by a big-block 427 Ford V8 (the idea was not Shelby's but Ford's). Here, the author takes some liberties without having spoken with the principles at Ford who designed the modern coil-spring suspension. He writes: “In the publicity material that Shelby produced for the new model great play is made of the almost revolutionary sounding chassis, with the suspension completely designed at Ford using its state-of-the art computer, with a good deal of input from Ford suspension wizard Klaus Arning. Computers at that time were most certainly not what they are today and Ford’s lumbering dinosaur, as it would appear today, would most certainly not have waved a magic wand over design proceedings as suggested.”

No, indeed. But had the author interviewed computer whiz-kid Chuck Carrig, who wrote the computer program in 1963, or knew anything about Klaus Arning’s patented anti-dive/anti-squat independent suspension, or of engineer Bob Negstad, who converted Arning’s ideas into hardware, he would have known how Arning's innovative suspension was mated to the AC frame rails. The details are covered in two articles I wrote for RACECAR ENGINEERING. The first, published in the October 2007 issue, entitled “The Program Maker,” about Chuck Carrig, the computer programer who developed the software, and of how the program actually worked. The Ford computer did not design suspensions, but it did calculate suspension geometry. Its very first application was to the 1964 Ford GT40, two years ahead of the Cobra Mk II. The second story, published in the October 2008 issue, entitled “Independent Thinker,” is about Klaus Arning, the suspensions guru at Ford who developed the anti-dive/anti-squat suspension as employed on the Cobra Mk II. How was it done? With Ford engineer Bob Negstad stationed at the AC factory in England, exchanging data over the wires with Arning at Ford's Dearborn headquarters. It wasn’t easy getting Arning’s advanced suspension to fit AC’s primitive frame rails, but through their trans-Atlantic connection, coupled with output from Ford’s computer, they got the job done.

Unfortunately, the Cobra-Ford Mk II was not as successful as Ford's brass had hoped, and only 260 Mk IIs were actually built, before Shelby's plant was shuttered, and a unique era in the annals of international road racing passed into history.

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