A two-part flywheel for a vehicle internal combustion engine has a primary mass (2) secured to the engine crankshaft (4) and a secondary mass (3) mounted on the primary mass (2) with a torsion spring device (10) between them. A clutch pressure plate (12) is attached to the secondary mass (3) and a driven clutch plate (16) interposed between the pressure plate and the secondary mass. In order to simplify automated assembly of the pressure plate (12) on the flywheel, a locking means (21) is provided to prevent relative rotation of the masses (2, 3) during assembly, the locking means being released subsequently to allow rotation. The locking means may be released automatically by attachment of the pressure plate (12). <IMAGE>
