Overlap Shifting

During the transition of overlap, the clutches run through a slip zone. The torque is gradually transferred from the clutch that is releasing to the clutch that is engaging. The new gear engages the moment the torque level exceeds that of the first clutch. This is described as overlap. If the overlap is correct, (zero overlap) the engaging clutch takes over as much torque as the disengaging clutch releases. The result is a seemingly unnoticed shift of the best quality. See Fig 1 and Fig 2 .

Fig 1: Identifying Overlap Shifting (Clutch 1 Engaged)

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 2: Identifying Overlap Shifting (Clutch 1 Disengaged)

Courtesy of BMW OF NORTH AMERICA, INC.