How the Speedshift Dual Clutch Transmission on the Mercedes-AMG GT Works

The 7 speed, dual-clutch transmission has been developed for the Mercedes-AMG GT by German supplier Magna PT (formerly Getrag). It has been used in supercars such as the SLS AMG, Ferrari California, the popular 458 Italia, the F12 Berlinetta and the second-generation Ford GT.

In the Mercedes-AMG GT, the transmission is placed in a rear transaxle configuration, serving as the car’s transmission, rear differential, and rear-axle, all in a single assembly.

Connecting this assembly to the V8 engine in a single, fixed unit is done with the use of a torque tube. Inside, a carbon fiber drive shaft spins at the same speed as the engine.

At only 8.6 pounds (3.9 kilograms), the torque tube is similar in weight and structural design as the drive shaft on race cars. The transmission is also fitted with a centrifugal pendulum placed into the two-mass flywheel that eliminates oscillations and vibrations.

Due to this configuration and the technologies it uses, the car achieves an ideal 47% front and 53% rear weight distribution which dramatically improves the car stability and handling.

This marvelous feat of engineering functions as two transmissions built into one, each equipped with an electronically controlled clutch. One of the transmissions engages and disengages the odd numbered gears and the other does the same with the even numbered gears.

Since the gear sets are independent the control system can pre-engage the next gear, prior to the shift. For example, if the car is driving in fourth gear, the fifth is pre-engaged.

The upshift occurs in less than 100 milliseconds after interacting with the paddle shifter, when one clutch disengages and the other engages.

To achieve reverse gear without the use of an added shaft that would have created extra weight and extend the overall design of the transmission, the Speedshift DCT 7 intelligently engages a combination of gears two, reverse, thee and one. With the use of all available shafts, the car can be maneuvered backwards.

The first gear has a higher ratio on the AMG GT while the seventh gear and the final drive gave lower ratios. This helps achieve a very spontaneous and agile acceleration, supplies instant response to gas pedal movements, and offers increased shift performance and response time.

There are three pre-installed drive programs to enjoy on standard AMG GTs: "C" (Comfort), "S" (Sport), "S+" (Sport Plus). A fourth “I” (Individual), customizable program is also available.

The high-end models like the AMG GT S, GT C and AMG GT R also have a “RACE” drive program available, which adapts shifting dynamics of the dual-clutch transmission to the requirements of a racetrack.

The AMG Speedshift DCT 7G is still one of the quickest, most agile transmission ever made and although the German constructor, Magna PT has shifted focus on the development of the eight-speed dual-clutch transmission 8DCL900, it will remain a timeless piece of automotive technology in cars such as the Mercedes-AMG GT.