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Clutch drag is caused by friction between clutch parts and adjacent components having different rotational speeds when the clutch is released. The root cause of drag is the presence of normal reactions between friction surfaces when the clutch is disengaged. In most cases, especially in multiple disc clutches, these reactions cannot be eliminated but they can and should be minimized by proper design. The major difficulty in dealing with drag problems is associated with the relatively small magnitudes of drag torque in comparison to useful torques carried by the drivetrain. From the history of drag problems, especially in the automotive industry, it appears obvious that the problem of dragging clutches has no single solution. There are many potential sources of friction forces contributing to drag torque. In addition, contributions from particular sources are very small and not necessarily consistent.