Abstract: A flexible coupling system to connect two substantially axially aligned shafts, comprises coupling members mountable on the ends of each of the shafts with each coupling member having a drive face for engagement with the opposed drive face of the other coupling member to provide a torque transmitting connection. Each coupling member has a tubular extension extending away from the drive face with an inner axial surface engageable over the shaft and a distal end. A locking ring engageable with the distal end of each coupling member is provided. Each distal end and each locking ring are formed with one of an axially extending annular eccentric projection and an axially extending eccentric shoulder. The shoulder and projection are rotatable to interengage and lock with each other in an interference fit to lock the coupling members on the shaft.