Automatic Transmission: Notes

The F07 is available exclusively with an automatic transmission. The new transmissions GA8HP45Z and GA8HP70Z will be deployed.

Fig 1: Cutway View Of Automatic Transmission

Courtesy of BMW OF NORTH AMERICA, INC.

Highlights of the new eight speed transmission:

Enhanced gearshift spontaneity
Greater driving and shifting comfort as a result of a closer gear ratio
Higher precision control of the converter lockup clutch at low engine loads
Higher power transmission of the converter lockup clutch
Reduced fuel consumption (-5% to -6%)

The GA8HP45Z and GA8HP70Z are new developments and will gradually replace the established 6-speed automatic transmissions GA6HP19Z TU and GA6HP26Z TU. The overall gear ratio has been increased from 6.04 to 7.07; the gear to gear ratios have are now closer, thus also reducing the differences in speed when shifting gear. The weight of the transmission has been reduced significantly using a plastic oil pan and other light weight components.

The Electronic Transmission Control (EGS) control unit is integrated in the control unit framework of the electronic immobilizer EWS. This provides better protection against theft.

Operation is now exclusively via the electronic gear selector switch (GWS).

Mechanical torsional vibration dampers of the second generation are deployed in the torque converter:

Turbine torsional vibration damper, TTD
Dual-damper torque converter, ZDW. (used on diesel models)

The function and structure of the torque converter are described in the "E70 Automatic transmission" training material available on TIS and ICP.

The vibration isolation reduces the proportion of slip on the converter lockup clutch and enables a larger operating range with the converter lockup clutch closed. This reduces the fuel consumption by 5% to 6% in the consumption cycle (KV01) compared to the TU 6-speed automatic transmission used until now.