A supercharger clutch system has a clutch housing (52) in which a clutch pack (84) is disposed to transmit torque from an input, such as a pulley (66), to one of the timing gears (58). The clutch pack (84) is disposed within a cage (92), having a spring seat member (98) adjacent thereto. A set of springs (104) biases the seat member and the clutch cage (92) to engage the clutch pack (84). On the opposite side, axially, of the clutch pack there is a piston (76) including a portion (80) surrounding the clutch cage (92) and engaging the seat member (98). The piston (76) and the clutch housing (52) define a pressure chamber (106) which, when pressurized, causes movement of the piston in a direction compressing the springs (104) and disengaging the clutch pack. The invention provides a method of controlling the clutch system by means of an electrohydraulic valve (110) which can communicate the pressure chamber (106) to either high pressure (112) or low pressure (132). The valve (110) is controlled by sensing throttle position (141) and modifying a command signal (130) to a coil (126) of the valve (110) in response to the throttle position (141), so that the rate of clutch engagement may be modulated in response to throttle position.