Technician Handbook ! 302 Manual Transmissions & Transaxles Flywheel The flywheel is connected to the engine’s crankshaft. A flywheel is very similar to a brake rotor in appearance. It is a large metal disc that stores and releases energy pulses from the crankshaft. It drives the clutch by providing a friction surface for the clutch disc. In addition, the flywheel provides a mounting surface for the clutch cover, and also dissipates heat. Pilot Bearing A pilot bearing supports the engine side of the input shaft. The pilot bearing used on Toyota vehicles is a ball bearing located in a bore in the end of the crankshaft. The pilot bearing only turns when the clutch is disengaged.
Flywheel Inspection The flywheel must have a flat surface to prevent chatter, and the proper surface finish to provide the necessary coefficient of friction. Because the wear of the friction surface is usually concave, a new flat clutch disc will not seat completely against a worn flywheel. This can cause premature clutch wear, chatter or even clutch disc failure. Grooves, heat checks, and warping can occur if there is excessive slippage. The flywheel should be checked for excessive runout if there is vibration or an odd wear pattern at the hub of the disc or clutch cover release levers. If runout is out of spec or visual damage is present, replace the flywheel. Technical Training 9