The driving members consist of the flywheel and the pressure plate. Both of these surfaces are machined to a smooth finish to produce little or no vibration or noise upon clutch engagement. The pressure plate is fitted inside the pressure plate cover and is not serviceable. If the pressure plate appears excessively worn or damaged upon inspection, the pressure plate and cover must be replaced as an assembly. The flywheel can be removed and machined if necessary. When removing the engine flywheel during clutch service, an index mark (reference mark) should be made in relation to its position on the engine crankshaft. If this precaution is not observed, an engine imbalance may result.