Numerical Design of Racecar Suspension Parameters

Even with the rapidly evolving computational tools available today, suspension design remains very much a black art. This is especially true with respect to road cars because there are so many competing design objectives. In a racecar some of these objectives may be neglected. Even still, just concentrating on maximizing road-holding capability remains a formidable task. This paper outlines a procedure for establishing suspension parameters, and includes a computational example that entails spring, damper, and anti-roll bar specification. The procedure is unique in that it not only covers the prerequisite vehicle dynamic equations, but also outlines the process that sequences the design evolution. The racecar design covered in the example is typical of a growing number of small open wheel formula racecars, built specifically for American autocrossing and British hillclimbs. These lightweight racecars, 250-300 kilograms, often employ motorcycle engines producing in excess of 75 kilowatts. The power to weight ratio rivals that of many high level formula racecars. Due to the nature of the application, braking and cornering performance is equally impressive. The model presented embraces the latest trends with respect to racecar vehicle dynamics. Special emphasis, including discussion of theory and analysis, is placed on damper specification.