BMW SMG / SMG-II / SMG III
automated-manual · longitudinal · 1996–2010
Also known as: smg, smg-ii, smg ii, smg iii, sequential manual gearbox, getrag smg, smg-iii
BMW's Sequential Manual Gearbox — in the E46 3 Series, E60 5 Series, E63 6 Series and E85 Z4.
It is a manual gearbox with a hydraulic actuator on it, which is what people find strange about it and what the name says plainly. There is no torque converter, so it does not creep; the clutch is a real clutch and wears like one; and the lurch on a slow change is the robot doing what a driver's left foot would do more smoothly.
The failure that defines it is the hydraulic pump and its accumulator. The pump runs on demand, the accumulator holds pressure between operations, and when either fails the car refuses to select a gear and shows a warning — usually intermittently first, and often after standing overnight. It is a very well-known fault with a well-known remedy, and it is not the clutch.
A pump that runs constantly rather than in short bursts is the accumulator, and that is audible from outside the car with the door open — one of the few faults in this catalogue with a diagnosis you can hear.
A clutch replacement must be followed by a bleed and an adaptation reset. Without it the car judders from rest and changes badly, which is exactly the complaint the work was meant to fix.
It is not the DCT that replaced it. BMW's later dual-clutch has two clutches, no single-clutch pause, and entirely different faults.
SMG and SMG-II are six-speeds; SMG III in the E60 M5 and E63 M6 is a seven. That last one is a different gearbox with a different pump and a different failure pattern, and it is the one most owners arrive asking about.
Cars fitted with this gearbox
4 generations. Only where a source names the model and the generation together — a gearbox is documented as a product far more often than as a fitment, so this list is deliberately shorter than the truth.
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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