Seven gears, four drive modes, double-declutching and Race Start function – the power transfer promises superb emotion and pure driving pleasure. At the same time, the AMG SPEEDSHIFT MCT 7-speed sports transmission contributes substantially to reducing fuel consumption.
The AMG SPEEDSHIFT MCT 7-speed sports transmission is an innovative power transfer system that made its debut in the high-performance SL 63 AMG Roadster in 2008. It combines the sporty, direct and agile feedback of a manual transmission and the maximum convenience of an automatic transmission. Fitted with seven speeds, four drive modes, a double-declutching and Race Start function, the AMG SPEEDSHIFT MCT 7‑speed sports transmission offers superb versatility. MCT stands for Multi-Clutch Technology and only employs clutch elements to perform gearshifts.
A wet start-up clutch, which runs in an oil bath, replaces the conventional torque converter. Thanks to its low rotational inertia, the transmission responds instantaneously and dynamically without the losses typical of a torque converter transmission – thereby helping to save fuel. The AMG sports transmission also impresses with its low weight of just 80 kilograms, which has been made possible through the use of lightweight magnesium for the transmission housing. Vibrations are effectively eliminated by a new, two-stage torsion damper, with resulting benefits in perceived passenger comfort.
Consumption-optimised drive mode “C” (Controlled Efficiency)
During development the AMG engineers paid special attention to the new drive mode “C” (Controlled Efficiency). The emphasis was on delivering minimum engine speed coupled with a reduced number of gearshifts in all driving situations. When moving off in “C”, the MCT transmission always selects second gear and shifts decidedly early to next higher gears if the driving style permits. At 60 km/h for instance, sixth gear will already be engaged – not only improving fuel consumption but noise levels, too. Controlled Efficiency also means convenient gearshifts and a “soft” accelerator response set-up for outstandingly smooth power transfer.
The powerful electronic control unit and the integrated 80 MHz processor ensure spontaneous downshifts at the same time – say when approaching traffic lights or if the driver suddenly needs power for dynamic acceleration.
Drive modes “S”, “S+” and “M” for even more driving pleasure and dynamism
The engine and transmission come across as much more agile in the “S” (Sport) mode. Accelerator pedal movements trigger a more direct traction response, making the downshifts more spontaneous. The engine speed is allowed to reach a higher level in each gear, while the gearshifts are around 25 percent faster than in “C”. Turning the rotary switch in the AMG DRIVE UNIT a notch further to the right activates “S+” mode. Sport plus shifts the gears another 25 percent faster than in “S”. The same applies to the manual shift mode “M”. In “S+” and “M” modes, gearshifts at full throttle take just 100 milliseconds.
The engine management system partially suppresses cylinders in “S”, “S+” and “M” modes: precisely interrupting ignition and injection under full load for brief periods leads to even faster gearshifts than before. The highly emotional vocals are an appealing side effect of this lightning-fast process.
Ultra-fast, spontaneous multiple downshifts are another forte of the AMG SPEEDSHIFT MCT 7-speed sports transmission. For instance, kickdown lets you move straight from seventh down to fourth gear or from fifth to second. In the Sport, Sport plus and Manual modes the automatic double-declutching function is active. Every manual or automatic downshift is accompanied by precisely metered double-declutching – from “S” through “S+” to “M” incrementally. And this not only adds to the driver’s emotional experience: the load-free downshift minimises load-change reactions, which pays dividends particularly when braking into a bend on the racetrack and also enhances safety in the wet or on ice.
In manual “M” mode the driver also benefits from the high torque of the V8 engine, as there is no automatic downshift under full load and kickdown; the transmission remains steadfastly in the selected gear. Moreover, the AMG MCT sports transmission does not perform an automatic upshift in manual mode when the rev limit is reached. In “M” mode the AMG instrument cluster displays the current gear and alerts the driver to the need for an upshift just before the needle reaches the red zone. This means that a particularly sporty driver can use the superior performance potential to its fullest extent. When approaching the lower rev limit, e.g. when braking the vehicle, there is an automatic downshift to the next lower gear.
AMG DRIVE UNIT with Race Start function
The AMG DRIVE UNIT is the central control unit for the AMG SPEEDSHIFT MCT 7-speed sports transmission and all driving dynamics functions. The driver can change gears either using the new AMG E-SELECT selector lever or via the AMG steering-wheel shift paddles. On the left next to the selector lever is the electronic rotary switch to select the four drive modes including activation of the Race Start function. Underneath are three buttons for additional functions: the first controls the ESP® function, the second the AMG RIDE CONTROL sports suspension. The third adorned with AMG lettering is used to store the personal set-up. Briefly pressing the AMG button brings up the configuration options, whilst holding down the button allows you to program the required set-ups – this is confirmed by an acoustic signal. The current settings may be viewed in the AMG instrument cluster by pressing the AMG button at any time.
The Race Start function delivers maximum dynamism: while the vehicle is at a standstill, the driver needs to activate the ESP® sports function and press the brake pedal with their left foot. Having preselected the Race Start program using the rotary switch, a confirmation message comes up on the AMG central display. The driver then simply needs to confirm the Race Start function by pulling the “Up” shift paddle once, fully depressing the accelerator and taking his foot off the brake. The optimum start-up engine speed is set fully automatically and the E 63 AMG accelerates away with flawless traction – all the way up to top speed, if so required. The driver does not need to shift gear manually; the AMG transmission changes gear with lightning-fast shift times.
Source: Daimler AG