923902 Nut, pinion and sprocket shaft

This MCS pinion and sprocket shaft nut is a critical fastener for late Ironhead and early Evo Sportster engines. Featuring a 3/4-20 thread, it is used on the flywheel side to secure the shaft assembly. It serves as a direct replacement for OEM part number 23902-81 and fits late 1981 to 1985 Sportster models. These nuts are essential for maintaining the integrity of the motor's rotating assembly. Having a few spares on the bench is always a good idea during a full teardown, and these are sold as a pack of five to ensure you have what you need. They ensure that your pinion and sprocket shafts remain seated correctly under the vibrations and heat of regular operation.