AMG 7-speed sports transmission wins Popular Science Magazine award

Muamer Hodzic November 13, 2008

The well-known American technical magazine “Popular Science” has made an award to the newly developed AMG SPEEDSHIFT MCT 7-speed sports transmission. During the “Best of what’s new Awards”, the innovative power transfer of the SL 63 AMG high-performance Roadster achieved first place in the “Automotive” category.

The AMG SPEEDSHIFT MCT 7-speed sports transmission was able to claim victory in the hotly contested “Automotive” category. According to the editors of Popular Science, this AMG transmission represents “important and revolutionary technological progress”. Popular Science has presented its sought-after “Best of what’s new Awards” annually in eleven categories since 1987. A total of 100 products enter the final selection. The results are published in the December edition, which traditionally has the largest circulation. Popular Science is the world’s most widely-read science and technology magazine, with an average readership of 6.8 million each month.

The AMGSPEEDSHIFT MCT 7-speed sports transmission is a newly developed and unique power transfer unit that is used exclusively in the new Mercedes-Benz SL 63 AMG. It combines the best of both worlds: the sporty, direct and agile responsiveness of a manual transmission and the maximum comfort of an automatic transmission. Equipped with seven gears, four driving modes, a double-declutch function and a RACE START function, the AMG SPEEDSHIFT MCT 7-speed sports transmission excels with previously unattained flexibility. MCT stands for Multi-Clutch Technology, and indicates that gearchanges are executed solely by the clutch components.

No interruption in tractive power and four driving modes

The centrepiece of the AMG SPEEDSHIFT MCT 7-speed sports transmission is the wet start-off clutch, which operates in a sump and replaces the previous torque converter. Thanks to its low rotational inertia, this transmission is extremely responsive and dynamic, with movements of the accelerator immediately translated into motive power. Equipped with four driving modes, the transmission shifts the gears with no interruption in tractive power and provides tailor-made shift strategies for maximum driving pleasure. In “C” mode the gearchanges are comfort-oriented, with “soft” accelerator mapping for extremely smooth progress. In “S” mode the engine and transmission respond much more immediately, with more revs in each gear and faster downshifts. Gearshifts are also around 20 percent faster than in “C”. Changing to driving mode “S+” shortens this time by a further 20 percent, while “M” provides the most sporty mode of all: now the 6.3-litre AMGV8-engine responds more sharply, and the transmission shifts the gears 10 percent faster – corresponding to a 50 reduction versus “C” mode. In “M” mode the gearchanges take only 100 milliseconds.

Particularly fast and responsive multiple downshifts are another major attribute of the AMG MCT sports transmission. Kickdown alows the driver to change from seventh directly to fourth gear, for example, or from fifth to second gear. In driving modes “S” (Sport), “S+” (Sport plus) and “M” (Manual) the automatic double-declutch function is active. This is not only a benefit in terms of the driver’s emotional experience: the practically load-free downshifts minimise any load-change responses, which has an extremely positive effect when braking into bends on the racetrack.

AMG DRIVE UNIT with innovative RACE START function

The central control unit for the AMG SPEEDSHIFT MCT 7-speed sports transmission and all the dynamic functions is the AMG DRIVE UNIT. The electronic rotary switch for selection of the driving modes, including activation of the innovative RACE START function, is located to the left of the shift lever. Below this there are three keys for other functions: the first controls the ESP® system, the second the ABC suspension and the third, which bears AMGlettering, enables the driver to store the selected driving mode and the suspension setup. Briefly depressing the AMG key displays the configuration options, and longer pressure saves the preferred setups to memory.

The RACE START function opens up new dimensions in driving dynamics: it enables the driver of the SL 63 AMG to summon up the maximum acceleration potential while ensuring the best possible traction for the drive wheels. The optimal start-off engine speed is set fully automatically to give the SL 63 AMG the fastest possible acceleration – if required even to maximum speed. The driver does not need to perform manual gearshifts, as the AMG transmission changes the gears with the shortest possible shift times.

Most powerful roadster in its class with 386 kW/525 hp

Emotional performance courtesy of a technological masterpiece: the Mercedes-Benz SL 63 AMG. This high-performance roadster is powered by the 6.3-litre AMGV8-engine developing 386 kW/525 hp and 630 newton metres – which makes it the most powerful model with a naturally aspirated V8-engine in its class. The SL 63 AMG accelerates from 0 to 100 km/h in 4.6 seconds and has an (electronically limited) top speed of 250 km/h. Its unique combination of a high-revving concept and a large displacement represents the best of both worlds: high torque at low engine speeds combined with flexibility to set the pulse racing – a maximum of 7200 rpm is possible.

The AMG eight-cylinder engine features a wealth of technology adopted from motor sports: this includes the lightweight, particularly rigid closed-deck crankcase and cylinder walls with revolutionary LDS coating, as well as valve gear designed for high engine speeds with bucket-type tappets in the cylinder heads. Together with the variable intake manifold with two integrated throttle flaps, the flow-optimised intake and exhaust ducts ensure perfect cylinder charging and a high output.

This dynamic drive package is ideally matched by the suspension of the SL 63 AMG. The AMGsports suspension based on Active Body Control has been refined, and now features not only a new damper configuration but also completely revised elasto-kinematics. In the interests of greater agility and shorter braking distances, the front axle bearings, spring links and the radius rod , as well as individual strut bearings at the rear axle, have been reconfigured. Together with the improved, speed-sensitive power steering this makes the SL 63 AMG more directly responsive, with extremely precise, linear self-steering characteristics. The AMGsports suspension based on Active Body Control also allows a personal suspension setup. At the touch of a button either sporty characteristics with reduced roll angles and a stiff suspension setup, or a comfort-oriented setting for a high level of long-distance comfort can be selected.

The 3-stage ESP® with sports function is also unique. This system offers three different control settings, and is a logical further development of the AMG ESP® philosophy. Using the ESP® key in the AMG DRIVE UNIT, the driver is able to choose between three modes – “ESP ON”, “ESP SPORT” and “ESP OFF” – and the currently active mode is shown in the central display of the AMG instrument cluster.

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