Abstract: A rotational torque transmission unit in which the input and output shafts are isolated from each other and may be selectively coupled through a lubricated one-way clutch, the one-way clutch having an outer race in the form of a cylindrical cup mounted on the output shaft and an inner race assembly carrying clutch members slidably engaging the input shaft and translatable thereon between a first position on the input shaft within the cylindrical cup and a second position on the input shaft remote from the cylindrical cup, the cylindrical cup being provided with an outwardly flaring conical member to guide the clutch members into the cylindrical cup from the second position on the input shaft.