Power transmission: All-wheel drive for perfect dynamics

Feb 8, 2013
  • Performance-oriented AMG 4MATIC all-wheel drive
  • Compact all-wheel drive entailing additional weight of only around 70 kilograms
  • AMG SPEEDSHIFT MCT 7-speed sports transmission for personal set-up
  • Standard-fit ECO start/stop function helps to save fuel
  • 3-stage ESP® with "SPORT Handling" mode
The AMG SPEEDSHIFT 7-speed sports transmission and the new, performance-oriented AMG 4MATIC all-wheel drive complement the AMG 5.5-litre V8 biturbo engine to perfection. These two high-tech systems raise the driving dynamics of the E 63 AMG to a new, unprecedented level.
The performance-oriented AMG 4MATIC all-wheel drive is optionally available for the E 63 AMG rated at 410 kW (557 hp). The E 63 AMG S with 430 kW (585 hp) engine comes with all-wheel drive as standard. The technical basis is provided by a transfer case for the additional power take-off to the driven front axle. This transfer case is integrated compactly into the AMG SPEEDSHIFT MCT 7-speed sports transmission and requires virtually no additional installation space. The torque is transmitted from the power take-off via a propeller shaft to the front axle. Power transmission from the front-axle differential to the front-left drive shaft is effected via an intermediate shaft which passes through an encapsulated shaft duct in the engine oil pan. The compact design results in additional weight of only around 70 kilograms.
In contrast to the series production vehicles, on the E-Class all-wheel drive models the engine torque is distributed to the front and rear axles at a ratio of 33 to 67 percent. This clearly rear-biased power distribution provides for signature AMG high driving dynamics and superlative driving enjoyment. The 3-stage ESP® has been tailored specifically to the permanent all-wheel drive system. In "SPORT Handling" mode, ESP® Curve Dynamic Assist performs selective braking intervention on individual wheels in the interests of high agility, thereby avoiding understeering when turning and cornering. In bends, specific brief braking of the inner rear wheel results in defined cornering of the vehicle.
The 3-stage ESP® system offers three individual control strategies at the push of a button: the ESP® button on the AMG DRIVE UNIT enables the driver to choose between the stages "ON", "SPORT Handling" mode and "OFF" – the display in the AMG instrument cluster indicates the currently active state. In "ESP ON" mode, the system initiates braking intervention on one or more wheels and reduces the engine torque on detecting that the operating conditions are becoming unstable. In "SPORT Handling" mode, the intervention thresholds in response to over- or understeering and the accompanying engine torque intervention allow higher levels of driving dynamics and corresponding drift angles. This provides for considerably enhanced driving enjoyment. Pressing the ESP® button longer activates "ESP OFF". This mode avoids reducing the engine torque in the interests of greater driving dynamics and even more fun at the wheel. "ESP OFF" should only be used by experienced drivers on cordoned-off race tracks. In both "SPORT Handling" mode and "ESP OFF", all the ESP® safety functions are available when braking.
Enhanced driving safety on wet or wintry road surfaces
The AMG 4MATIC all-wheel drive also enhances driving safety and grip on wet or wintry road surfaces. Optimum traction is guaranteed by a multi-disk clutch with a locking effect of 50 Newton metres which exploits the frictional connection potential of all four wheels to the full on snow and ice in particular. This set-up enables high levels of traction by harnessing the dynamic shift in axle load toward the rear that occurs during acceleration to deliver more drive torque to the rear wheels.
All control system interventions go virtually unnoticed, yet drivers still know straight away if they are driving near the limit, as a yellow warning symbol will flash in the AMG instrument cluster. This serves as a clear prompt to adapt the driving style to the road conditions.
E 63 AMG S-Model with differential lock on the rear axle
The E 63 AMG S sees Mercedes-AMG going one step further. True to AMG's "Driving Performance" brand claim, a mechanical differential lock is fitted on the rear axle of the most powerful E-Class model. This high-tech package results in a further increase in traction, ultimately leading to even greater driving dynamics and enhanced driving enjoyment, especially on the race track.
Exclusive AMG SPEEDSHIFT MCT 7-speed sports transmission
RACESTART, double-declutching function, seven gears, four transmission modes and stop/start function: the AMG SPEEDSHIFT MCT 7-speed sports transmission in the E 63 AMG combines extreme emotional appeal, maximum driving pleasure and optimum economy. The transmission boasts a thrilling combination of unique options which no other automotive manufacturer is able to offer in this format.
The sports transmission is exclusive to Mercedes-AMG and combines the sporty, direct and agile responsiveness of a manual transmission with the maximum comfort of an automatic transmission. MCT stands for Multi-Clutch Technology and indicates that only clutch elements are employed to perform gearshifts. A compact 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.
ECO start/stop function fitted as standard
The ECO start/stop function fitted as standard is permanently active in fuel-efficient "Controlled Efficiency" ("C") driving mode. Once the driver comes to a halt, e.g. at a red traffic light or in a traffic jam, the engine is automatically switched off. When the brake pedal is released or the accelerator is depressed, the engine is immediately restarted and the car is able to move off quickly. Intelligent technology guarantees a comfortable and immediate starting procedure: a crankshaft sensor which recognises the direction of rotation registers the rest position of all eight pistons. For an automatic engine start, the cylinder with the most favourable piston position receives an injection of fuel into its combustion chamber. The precise piezo-electric injectors greatly assist this process, as they make particularly fast starts possible.
The engine management system ensures that the engine is only switched off if certain preconditions are met. The starter battery must have sufficient charge, for example, and the engine must be at the necessary operating temperature for efficient emissions control. The same applies to the interior temperature selected by the driver: if this has not yet been reached, the engine is not switched off when the car comes to a stop. The onboard network management system ensures that active audio, telephone or video functions are not interrupted by the start/stop function.
A green "ECO" symbol shows the driver when the start/stop function is active. Should one of the above criteria be preventing activation of the system, this is shown in the central display by the message "Start/stop inactive" and a yellow "ECO" symbol. In the more performance-oriented driving modes "S" (Sport), "S+" (Sport plus) and "M" (Manual), the start/stop function is always deactivated.
Fuel-efficient Controlled Efficiency ("C") drive mode
In adapting the MCT sports transmission to the AMG 5.5-litre V8 biturbo engine, the AMG engineers paid special attention to the new driving mode Controlled Efficiency ("C"). The emphasis was on attaining minimum engine speeds in the highest possible gears for all driving situations. When moving off in "C", the transmission always selects second gear and shifts markedly early to the next-highest gears if the driving style permits. At 60 km/h for instance, sixth gear will already be engaged – improving not only fuel consumption but also noise levels. Thanks to its powerful, readily available torque even at low engine speeds, the AMG V8 biturbo unit is absolutely ideal for this style of driving. Controlled Efficiency also means convenient gearshifts and a "soft" accelerator response set-up for outstandingly smooth power transfer.
Drive modes "S", "S+" and "M" for even greater driving pleasure and dynamism
In addition to Controlled Efficiency ("C"), three transmission modes are available to meet the demands of drivers looking for a more dynamic ride: in "S" (Sport) mode, the engine and transmission take on a much more agile character. 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 in "S" are around 25 percent faster than in "C". Turning the rotary switch on 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 also 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. An appealing side effect of this lightning-fast process is a highly emotional sound in response to every gearshift with wide open throttle.
Ultra-fast, spontaneous multiple downshifts are another forte of the AMG SPEEDSHIFT MCT 7-speed sports transmission. For instance, kickdown allows gearshifts straight from seventh down to fourth gear, or from fifth to second. In the "S", "S+" and "M" driving modes the automatic double-declutching function is active. Every manual or automatic downshift is accompanied by precisely metered double-declutching – with increasing intensity from "S" through "S+" to "M". And this not only adds to the driver's emotional experience: the load-free downshift minimises load-change reactions, which pays particular dividends when braking into bends – and also enhances safety in the wet
or on ice.
No automatic downshifts in manual "M" mode
In manual “M” mode the driver also benefits from the high torque of the V8 biturbo engine, as there is no automatic downshift under full load and kickdown; the transmission remains steadfastly in the selected gear. Moreover, the 7-speed 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 provides the driver with a visual warning of 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.
The powerful electronic transmission control unit with integrated 200 MHz processor controls spontaneous downshifts – when the driver suddenly needs power for dynamic acceleration, for example.
The AMG DRIVE UNIT is the central control unit for the AMG SPEEDSHIFT MCT 7-speed sports transmission and all driving dynamics functions. 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 3-stage ESP®, the second the AMG RIDE CONTROL sports suspension.
The third, bearing AMG lettering, is used to store the personal set-up for transmission programme, suspension mode and 3-stage ESP®. Briefly pressing the AMG button brings up the configuration options, whilst holding down the button allows you to programme the required set-up - this is confirmed by an audible 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 is able to activate SPORT Handling mode and press the brake pedal with his 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 MCT transmission changes gear in lightning-fast shift times.