When somebody mentions a spring, you probably picture a standard coil spring that looks like a steel pigtail. Most motocrossers immediately envision the shock spring on a race bike. A spring, however, is any elastic object that stores energy. A lesser known type of spring is a Belleville washer. Belleville washers are a type of disc-shaped cup with an extremely high tensile strength. Originally developed in the mid-19th century by Julian Belleville, Belleville springs are used in a variety of environments where a heavy load bearing ability is required. Belleville springs can be made in a wide range of sizes (from very small washers to very large discs). Their shape resembles a shallow soup bowl with the bottom cut out, and they are generally made from tempered steel to stand up to immense pressure. Because of their construction, Belleville springs distribute weight evenly around their circumference. As a result, they can be used to hold substantial loads and are highly useful in areas subject to thermal expansion, vibration and high bolt loads—all of which describe a motorcycle clutch. The Belleville washer clutch spring is a creative idea (although old hands will remember that Maico used Belleville washers in their clutches decades ago). Hinson recognized certain advantages of the Belleville design over the traditional coil spring-equipped clutch, and they have actually been using this type of spring in their slipper clutches for about four years. The Belleville washer distributes the load around the radius of the pressure plate (as opposed multiple individual springs arranged in a circle). Additionally, traditional coil springs tend to bow out or bend over to the side when com- pressed. This flexing results in friction (rubbing) against the sides of the pressure plate as the clutch disengages. It was Roger DeCoster who first registered complaints about the rubbing issue, and the concerns of “The Man” were enough of a catalyst for Hinson to continue devel- opment on their Single Spring (SS) Belleville washer clutch. Much of Hinson’s early development and durability testing was done on quads, which have very similar engines, but are under increased loads because of their extra weight and bigger tire footprints. Currently, Hinson has pro riders running the all-new SS (Single Spring) clutch for durability testing.