BMW Dual Mass Flywheel - LuK 21207640733 135i, 135is, 335i, 335i GT xDrive, 335i xDrive, & more

OE replacement dual mass flywheel, acts as a mounting point for the pressure plate

A flywheel serves two important functions. Firstly, the flywheel is a rotating mechanical device that stores rotational energy. It helps maintain engine rotation in between ignition cycles. Secondly, the flywheel is the friction surface for the clutch disc and a mounting point for the pressure plate.

A dual mass flywheel is a special flywheel that has an inner and outer mass. The inner mass is coupled to the engines mass moment of inertia while the outer mass is coupled to the transmissions moment of inertia. The inner and outer mas are lined by a spring/damping system which reduces drive train vibration and allows for smooth clutch engagement and disengagement.

As a dual mass flywheel ages it can develop an issue with the damping system which can cause severe vibrations. For this reason FCP recommends replacing your dual mass flywheels with every clutch service.