Hyperco drag racing springs are cold-wound from preheattreated SAE 9254 chrome silicon wire.Optimum wire diameter is selected for the ndividual design- without compromise. After coiling, the closed ends are ground,and the spring is thermally stress relieved, pre-set and shot-peened. Completed springs are magnafluxed, inspected, epoxy powder coated and checked for dimensions,trueness and rate. Hyperco then tests eachcoil for actual rate and etches the rate permanently into the spring. Hypercoils strict manufacturing tolerances assure the racer of springs within a tolerance range of +/- 2%- most being within 1%!