Purpose Of The System
The SMG II combines the six-speed manual gearbox (S6S420G) of the E46 M3 with computer controlled electrohydraulic clutch and gear change operation. The driver is provided with the accuracy of manual gear selection, the convenience of automated shifting and the speed and adaptability of driver-adjusted computer control. See Fig 1 . Using technology developed for the BMW/Williams Formula 1 car, the SMG II with DRIVELOGIC adapts the speed, accuracy and control of the race cars electrohydraulic shifting to the M3.
Features of the SMG II include:
- Two operating modes: Manual, shift lever or the steering wheel mounted paddle switches are used to make gear changes. (S-Mode) Automatic: gear selection and shifting provided by the SMG II. (A-Mode).
- DRIVELOGIC control to adjust shift programs in the "A" mode or shift dynamics in the S Mode.
- Light weight and elimination of torque convertor when compared to an Automatic Transmission.
- Same basic 6 speed gear box design as non-SMG II equipped M3.
- Elimination of clutch pedal.
- Adaptable based on engine torque and speed.
The SMG II system is consists of the following components:
- Basic Gearbox (S6S420G, Getrag type D).
- SMG II Control Unit (Siemens).
- SMG CAN Bus.
- DME Control Unit (MSS54).
- Hydraulic unit and solenoids.
- Gearbox Actuator.
- Clutch Slave Cylinder with PLCD (Permanent Linear Contactless Displacement).
- Shift Lever Module with Shift Lock.
- Steering Wheel Paddle mounted switches.
- DRIVELOGIC Control.
- Display in instrument cluster.
- DSC control unit.
- SAC dry single disc clutch. See Fig 2 .
The standard basic gearbox (S6S420G), as used in the M3, is transformed into a sequential gearbox with the addition of a hydraulic unit and shift assembly, a special clutch slave cylinder and a new shift-lever module. See Fig 3 .