Check for Damaged Components

All following checking procedures have to be carried out at installed dual mass flywheel. For visual check at vehicle very bright light and a additional bright and small pocket lamp is necessary. Damages like grease on primary flywheel and loose ore missing balance weights cannot be checked at installed condition. During visual check material alteration can be stated which eliminate a further operating suitability.

For comparison different damages at dual mass flywheel with the corresponding further procedure are presented here.

1. Inspect plain bearing (1) for damages.
   Fig 1: Plain Bearing

   Courtesy of GENERAL MOTORS COMPANY
   NOTE: In case of mechanical damages at plain bearing the dual mass flywheel has to be replaced.

   Dependent of the manufacturer damages can be detected through ventilation openings of secondary flywheel. Parts of the bearing (1) are detached or lie loose around the bearing bolt.

2. Inspect toothed ring (1) for damages.
   Fig 2: Toothed Ring

   Courtesy of GENERAL MOTORS COMPANY
   NOTE: Light abrasion on frontal areas of teeth is allowed. If problems occur during starting the engine the dual mass flywheel has to be replaced.

   The toothed ring is needed to start the engine. Through a lot of starting procedures and/or an incorrect engaging starter signs of abrasion can occur on teeth of the toothed ring. The profile of damages can reach from only low signs of abrasion up to heavy material removal. The installation of a pulse-generator ring depends on the manufacturer.

   The image shows signs of abrasion and mechanical damages at toothed ring (1), they occur through abrasion due to a lot of starting procedures. In this case the dual mass flywheel has to be replaced.

3. Inspect tilt clearance.
   Fig 3: Inspecting Tilt Clearance

   Courtesy of GENERAL MOTORS COMPANY
   NOTE: The check must be carried out only by hand without any tools.

   At dual mass flywheel the additional-mass ring looms over the gap between primary and secondary flywheel. It is not possible to carry out just a visual check.

4. Embrace dual mass flywheel and apply thumbs onto the outer radius of secondary flywheel.
   Fig 4: Tilt Clearance Height

   Courtesy of GENERAL MOTORS COMPANY
   NOTE: An absolute clear measurement is not possible with this check due to the different applied forces of the several workshop employees during the check.
5. Apply pressure onto the secondary flywheel alternating on upper, lower, left and right side

   During the tilt clearance check a functional metal rattling noise may occur.

   If tilt clearance is higher than 3 mm (MUST be measured, DO NOT make an estimation) (1) the dual mass flywheel has to be replaced.

6. Inspect clearance angle (1).
   Fig 5: Tilt Clearance Angle

   Courtesy of GENERAL MOTORS COMPANY

   Before the inspection of the clearance angle the dual mass flywheel should be rotated several times clockwise and anti-clockwise to receive a feeling for the resistance of the springs. In addition unusual loud clicking noise or possible rattle, crunch, grinding noise can be sounded out during rotating the dual mass flywheel.

   If the rotation of the flywheel is impossible the flywheel is defective and has to be replaced.

   The clearance angle is the angle (1) about the secondary and the primary flywheel can be turned light against each other. Thereby the flange wings are moved in the duct of the bowed springs without adjoining the bowed springs. Dictated by functional factors the clearance angle is up to 8 teeth.

   Is the secondary flywheel rotated beyond this point the bowed springs in the duct are moved to spring arrestor in the primary flywheel/cover. Now the both spring are tensioned.

   Fig 6: Rotating Secondary Flywheel Anti-Clockwise

   Courtesy of GENERAL MOTORS COMPANY
   • Rotate secondary flywheel anti-clockwise (arrow) until the elastic counterforce (spring force) is clear noticeable.
   • Release secondary flywheel slowly until the bowed springs are relaxed, so no counterforce acts onto the springs.
   Fig 7: Releasing Secondary Flywheel

   Courtesy of GENERAL MOTORS COMPANY
   • Mark position with a vertical line by a white pencil on secondary flywheel (1) and on toothed ring for starter (2).
   • Rotate secondary flywheel clockwise until the elastic counterforce is clear noticeable.
   • Release secondary flywheel slowly until the bowed springs are relaxed.
   Fig 8: Mark On Flywheel And Toothed Ring For Starter

   Courtesy of GENERAL MOTORS COMPANY
   • Apply new marking on secondary flywheel (1) on the height of the marking on the toothed ring for starter (3).
   • Count amount of teeth on toothed ring for starter from marked tooth up to the height of the first marking on secondary flywheel (2). Dictated by functional factors up to 8 teeth are allowed.
7. ALWAYS replace the engine flywheel if following conditions are given:
   • The difference exceeds the amount of 8 teeth.
   • The dual mass flywheel cannot be rotated.
   • During rotating the dual mass flywheel a hard metallic arrestor is audible or noticeable.