What is the Sequential M Gearbox (SMG)?
In 1997, BMW introduced the Sequential M Gearbox (SMG) as an option on the European-spec E36 M3 in some markets. Using the internals of the Getrag six-speed manual gearbox, SMG employs an electronic clutch operated by a magnetic valve that is triggered by pulling or pushing on the gear lever. Two further valves operate a pair of hydraulic cylinders that electronically engage each gear, thus allowing for shifts to occur in as little as 0.4 seconds. The SMG electronics are integrated with the Siemens engine management system to put the engine and gearbox in synch. The system includes an automatic mode, gear indicator in place of the engine oil temperature gauge below the tachometer, and a flashing upshift light under the M logo in the instrument cluster.
