The years that followed World War II began the 'Roadster Era' at Indianapolis, characterized by lower, wider, offset-driveline cars. It was both exciting and dangerous, with drivers earning driving duties by demonstrating bravery, skill, and tenacity while driving their spring and midget cars on tracks from coast to coast. The chassis designs were unique, and varied from builder to builder, demonstrating creativity, talent, and ingenuity. Among the most famous of these were powered by Offenhauser's four-cylinder engines.
Immediately following World War II, A.J. Watson built his first track car for CRA Hot Rod races, but ultimately became disinterested in driving. He visited Indianapolis over the years as both a builder and mechanic, until 1954, when he was hired as the chief mechanic for John Zink Jr. Bob Swiekert drove Zink's Kurtis KK500C Roadster modified by Watson to victory in the 1955 Indy 500, securing Watson's place on the team. For the 1956 Indy 500, Watson built the first true Watson Indianapolis Roadster for Zink. It shed the conventional Kurtis-derived design, in favor of a more lightweight approach, with a narrower chassis and devoid of any unnecessary steel or bracing. Copious amounts of lightweight 4130 Chromoly tubing were used, and the driveline parts were formed from magnesium, with sheet magnesium used for body panels. Rather than placing the Offy powerplant 36 degrees to the right, he mounted it upright, which allowed for increased left-side weight bias and easier maintenance. The entire package weighed a mere 1,640 pounds, a full 220 pounds less than the winning Kurtis of the previous year.
With Pat Flaherty assigned driving duties, the car handily won the 500. Watson would continue to build another 22 roadsters, with some refinements and design work being performed by Larry Shinoda, of Corvette fame. Watson Roadsters would win the Indianapolis 500 six times in just nine years.
by Dan Vaughan