Abstract: A preassembled, prefilled hydraulic actuator apparatus for a motor vehicle clutch and adapted for connection to a non-integral fluid reservoir. The apparatus comprises a master cylinder having a supply inlet and a working pressure outlet, a slave cylinder having an inlet, a working pressure conduit interconnecting the outlet of the master cylinder and the inlet of the slave cylinder, and a low-pressure supply conduit for connection to a reservoir. In one embodiment, the supply conduit is connected at one end to the master cylinder inlet and the free end of the supply conduit is sealed by a bung partition, a piercing coupling is provided on the free end of the supply conduit, and the coupling is connected to an outlet fitting on a prefilled reservoir which may also serve as the hydraulic fluid source for the brake system of the vehicle.