SMC Redefines Clutch Sprockets
From 1956 to 1995, kart racing clutches utilized a traditional setup of bushings or needle bearings, and sprockets welded to a steel cover. In 1995, SMC revolutionized the design by connecting a steel sprocket to an aluminum drum without welding. This innovation improved heat transfer, which helped lower the temperature of friction materials during racing. The secondary benefit was cost reduction, which allowed racers to replace only the sprockets, not the entire sprocket/drum assembly, to adjust gear ratios.
In 2024, SMC advanced the design by creating a 10-tooth sprocket for the inboard side of the clutch—previously, the smallest sprocket had 11 teeth. This new sprocket features a ball bearing, replacing the traditional needle roller bearing. This same ball bearing is now also used in larger sprockets. Compared to needle roller bearings, ball bearings offer superior performance in racing environments, where speed, efficiency, load flexibility (radial, axial, or moment loads), and resistance to contamination are crucial. Ball bearings reduce friction and enhance durability, making them ideal for high-performance applications.
The 2024 REV3 sprocket is slightly wider than its 1995 predecessor and now features three ears instead of two to distribute stresses in the drum better. REV3 sprockets, paired with the new 12-slot drums, are fully interchangeable with older SMC drum and sprocket setups. Additionally, the REV3 sprockets, when paired with the new 8-slot drums, are compatible with other popular clutch brands, including Bully, Gator, Viper, Orange Crush, N-Gage, EGO, El Diablo, GoldiLocks, The Touch, Pulse, and more.