Mini has developed an all-new 7-speed Steptronic automatic double clutch transmission for its range of convertible, three-door and five-door hatch models.
Designed to enable upward gearshifts without torque interruption, while the pedal is pressed down the transmission control sets the shift points precisely to ensure a continuous increase in speed. This is thanks to the combination of two partial transmissions in a single housing.
The core element of the system consists of two oil-cooled wet clutches: one of these is responsible for the even transmission ratios while the other is for the uneven ratios. During travel, one of the two clutches is open and the other is closed. The parallel opening and closing of the clutches makes acceleration and deceleration maneuvers faster and smoother.
To enable appropriate gear selection, the electronic control system permanently analyzes numerous data points, including the accelerator position, engine speed, road speed and driving mode. As a result, if acceleration has to be unexpectedly interrupted, the double clutch transmission takes no more than a fraction of second to make the next gear down available instead of the next gear up.
Like a conventional converter system, the double clutch transmission also offers a crawl function that enables smooth set-off without needing the driver to touch the accelerator pedal.