Torque transmission mechanism

This torque transmission mechanism (A) for an internal combustion engine, adapted to transmit a starting torque from a starter motor to a crankshaft (4) of the internal combustion engine, comprises a ring gear (2) that transmits the starting torque and a one-way clutch (8) disposed between the ring gear (2) and the crankshaft (4). The ring gear (2) comprises a gear side portion (20) to which the starting torque is transmitted from the starter motor via gear mesh, and a flange (22) for attaching the gear side portion (20) to an inner ring (7) of the one-way clutch (8). The gear side portion (20) is made in one piece with the flange (22).