a long lever clutch suitable for racing has a lever arm with the centers of the yoke pivot hole and the pressure plate billet pivot hole in a line parallel with the beam surface of the lever . an opening at the external end of the lever permits the addition of bob weights . this design permits control of the internal centrifugal force so that the excessive pressure is not applied to the pressure plate at high rpm . the clutch can also be modified from the 6 - lever configuration to a 3 - lever mode . replaceable thrust and lever shims are used to reduce clutch wear .