M Dct With Drivelogic
M DCT Drivelogic is an innovative seven-speed double-clutch transmission that was specially constructed for the BMW M high-rev engines. The system enables extremely fast gear changes without disruption to tractive force; thus allowing very sporty and comfortable gear changes.
The basis for this is a principle developed in motor sport, whereby two separate drive trains, each with its own clutch, continuously transfer engine power to the rear wheels. One drive is for the even gears and the other for the odd ones. For example, when changing from second to third gear, first the third gear is engaged in the inactive drive train. Next, the clutch for this drive train is closed while, simultaneously, the clutch for the active drive train (working in second gear) is opened. This process takes place in milliseconds.
Both clutches are controlled by an integrated hydraulic module. Dry sump lubrication guarantees reliability and maintenance-free operation. In order to cope with the heat that typically develops in the drive train of a high-performance sports car the engine oil isn’t just cooled via the engine’s cooling water circuit, but also kept at the optimal temperature by an oil/air cooler.
The transmission system is especially designed to complement the high torque and high-rev engine typical of the M vehicles. It is capable of up to 9,000 rpm. The seven gears enable optimal adaptation of the relevant gear ratio to the performance characteristics of the drive train. Gear changes when accelerating are carried out with very small rev intervals. The speed increases at a steady rate after every gear change.
The seven-speed transmission can be controlled either automatically or manually. Gears can be changed using either the paddles on the steering wheel, the shift lever or the automatic mode for even more dynamic comfort. Change gears at high speed, without the clutch and without an interruption in the transmission of power. Both modes allow the driver to set the transmission characteristics according to personal preferences or to suit the route. There are eleven driving settings available on M double-clutch transmission Drivelogic and these can be selected via the Drivelogic button on the centre console. The settings vary according to speed of the gear change and the rev speed at which they are activated. The spectrum runs from extremely sporty to comfortable: on the D5 setting, for highest acceleration, the vehicle only changes to a higher gear just before the engine reaches the maximum number of revolutions. In contrast, on the D1 setting the driver can even pull off in second gear and the clutch becomes very light.
In the Drivelogic’s most sporty setting, the S mode, the dynamic clutch control creates the direct traction known from manual transmission for very dynamic driving styles. The manual transmission also has a Launch Control function (Drivelogic setting S6), which allows the vehicle to pull off at maximum speed from a standing stop, and adjusts the starting rotary speed. The switching point is set so the ideal speed is always available when the engine is started. The regulated Launch Control setting gives the M DCT further M functions, e.g. Stability Clutch Control or Low Speed Assistant.