Mercedes Benz

OFFICIAL PRESS RELEASE

San Diego, USA, Jan 14, 2011

Chassis and braking system: Agile, dynamic, exclusive

The CLS 63 AMG also occupies an exceptional position in the areas of suspension and the braking system. The exclusive combination of AMG RIDE CONTROL sports suspension, electromechanical AMG sports parameter steering and AMG high-performance braking system guarantees a high level of driving dynamics, awe-inspiring agility and at the same time renowned Mercedes comfort on long journeys.


For the CLS 63 AMG, the AMG engineers developed a new AMG RIDE CONTROL sports suspension which is characterised by a high degree of variability. A steel suspension is used at the front, and an all-air suspension system at the rear. This solution guarantees a sensitive response from the front springs while the vehicle is kept at a constant height thanks to the automatic level control system – irrespective of the load. The top-of-the-line AMG model differs from the other CLS variants with its newly developed three-link front suspension with wider track – increased by 24 mm, to 1623 mm, compared with the CLS 500. In conjunction with new hub carriers for more negative camber at the front, this provides much more grip when taking bends at high speed.

Another feature of the AMG RIDE CONTROL sports suspension is the electronically controlled damping system: the system varies the damping characteristics instantly according to the driving situation, road speed and load status, reducing the roll angle of the body. For the driver this means instant, continuously variable adjustment between the greatest possible agility and optimum ride comfort – depending on the driving style and route. The damping can also be individually adjusted by pressing the appropriate button in the AMG DRIVE UNIT. A push of a button is all it takes for the electronics to switch from "Comfort" to "Sport" or "Sport plus." The selected mode is displayed in the AMG instrument cluster.

"Comfort" delivers a sensitive response with soft damping characteristics, while the shock absorber response is an average 40 percent firmer in "Sport". "Sport plus" is ideal for challenging laps on a racetrack: in addition to the higher damping force, this mode comes with specific control algorithms that have been tailor-made for a decidedly sporty driving style on level road surfaces. The driving dynamics of the CLS 63 AMG can be upgraded even further ex factory: exclusive optional extras available from the AMG Performance Studio include a stiffer performance suspension, lightweight forged AMG light-alloy wheels and also a rear axle locking differential with a 40 percent locking action.

Eleven sensors for electronic damper control

The electronic damper control utilises four sensors to permanently monitor the drive and brake torque along with steering angle and lateral acceleration. Four position sensors are also used to determine the ride height and to ascertain the direction of motion. Three acceleration sensors help identify the absolute body roll. Powerful control electronics that interact constantly with the engine and transmission control units instantly adjust the forces at the four shock absorbers.

New axle components and more direct steering

The high-grade axle components, made for the most part from aluminium, are further evidence of the painstakingly redesigned AMG RIDE CONTROL sports suspension. New steering knuckles, wishbones, torque strut bearings and head bearings at the front provide extra stability and improved road contact. A weight-optimised, thicker tubular stabiliser reduces body roll on fast S-shaped bends. The rear suspension has also been substantially reworked in the interests of enhanced handling stability: new track rods, push-pull rods and far more rigid mountings for the subframe – on which the rear axle is mounted – translate into enhanced dynamics when cornering. The AMG-specific kinematics and the new elastokinematics on both axles also noticeably increase precision during cornering – a solution that has already proven itself on the C 63 AMG.

New, more direct electromechanical steering ratio

This is complemented by the newly developed electromechanical AMG sports parameter steering: with a steering ratio (14:1) which is 22 percent more direct than that of other CLS models, and in conjunction with the variable power assistance which adapts according to the suspension mode, it provides for decidedly agile handling when cornering. In addition, the electromechanical AMG sports parameter steering also makes an important contribution to efficiency, since the steering assist function only requires power when the driver actually steers. Compared with the previous model with regular hydraulic power steering, this enables savings of up to 0.3 litre/7 g CO2 per 100 km (NEDC combined) to be achieved.

In the new steering system the steering gear and the supporting servo-motor form a single compact unit and are mounted as previously on an extremely rigid and low-weight integral support frame, made of high-strength steel, which is positioned in front of the wheel's centre line. The high-performance control unit processes a variety of parameters captured by the sensors – including vehicle speed, steering angle, steering angle speed, lateral acceleration and also understeer/oversteer characteristics – and in a split second calculates the forces which the driver needs to input into the steering in different driving situations – from parking to high-speed motorway driving. Active damping enhances the feeling of safety when driving straight ahead at high speed.

AMG-specific solutions for enhanced steering precision and driving dynamics

An AMG-specific solution has been implemented in the form of the fixed, programmed power assistance characteristics. In suspension mode "C", the AMG sports parameter steering has a comfortable feel, providing a higher level of steering assistance. In "S+" mode, on the other hand, the driver will discern reduced steering assistance – which tends to result in a better road feel. This in turn results in enhanced response and steering precision. Another AMG exclusive is the interaction between the new steering and the 3-stage ESP®: the driver will feel if the vehicle starts to understeer thanks to a defined superposition of a steering moment earlier than with a regular power steering system. In "ESP SPORT" and "ESP OFF", the special control algorithm helps the driver to achieve a cleaner side-slip angle.

In addition to more precise steering and a more comfortable feel at the wheel,
the new electric power steering offers a range of additional advantages. Power assistance remains available when the engine is stationary, for example – whereby an algorithm ensures that the combustion engine is not prompted to start up in ECO start/stop mode when the driver is merely moving the steering wheel while the vehicle is at a standstill. The new steering system has also enabled implementation of the "Active Park Assist" automatic parking function and relieves the strain on the driver on road surfaces which slope away towards the kerb.

The new steering system also assists with braking on a surface with vastly varying grip (split friction surface). Sensors recognise the impending yaw if the vehicle starts to turn in towards the side of the lane with more grip. Through the superposition of a steering moment the driver receives an impulse to countersteer.

If s/he acts on this signal, the steering moment is withdrawn. Deploying the Steering Assist on split friction surfaces can help to improve both the directional stability and also shorten the braking time.

3-stage ESP® with Sport function

The 3-stage ESP® is also consistently tailored to the superb dynamic qualities of the CLS 63 AMG: the Electronic Stability Program supports three individual control strategies at the push of a button: the ESP® button in the AMG DRIVE UNIT allows the driver to choose between "ESP ON", "ESP SPORT" and "ESP OFF" – with the currently active mode shown in the display of the AMG instrument cluster. In "ESP ON", the onset of handling instability leads to braking intervention at one or more of the wheels, accompanied by a reduction in engine torque.

Briefly pressing the ESP® button activates "ESP SPORT". In this mode the braking intervention to counter oversteer or understeer, as well as the accompanying reduction in engine torque, allows a higher dynamic threshold and, for instance, corresponding drift angles – thereby significantly enhancing driving enjoyment.

Operating the brake pedal restores all the normal ESP® functions. Prolonged pressure on the ESP® button activates "ESP OFF". In the interests of handling dynamics, there is no further reduction in engine torque – with the result that driving enjoyment is increased even further. "ESP OFF" should only be used by experienced drivers on dedicated racetracks. In this mode too, operating the brake pedal restores all the normal functions of ESP®.

The system's traction logic is active in all three ESP® modes. If one of the drive wheels starts to spin, specific brake pressure is applied to virtually create the effect of a mechanical differential lock. This means that the engine power is transferred to the road even more effectively.

New ceramic composite high-performance braking system available as an option

As you would expect from an AMG high-performance car, the new CLS 63 AMG also comes with an ultra-powerful braking system. Internally ventilated and perforated brake discs with a generous 360-millimetre diameter are fitted front and rear. Because of the special stresses they face, the front discs feature composite technology that has been tried and tested in motor racing to help offset the temperature peaks more effectively. Grey-painted brake callipers with white AMG lettering and six-piston (front) and four-piston technology (rear) provide responsive, fade-resistant deceleration and extremely short stopping distances.

AMG ceramic composite high-performance brakes are available as an option and are instantly recognisable thanks to the "AMG Carbon Ceramic" logo on the brake callipers. Thanks to the special materials and production technology used to manufacture the discs from carbon-fibre-reinforced ceramic in a vacuum at 1700 degrees Celsius, the ceramic discs are much harder. This not only increases the service life many times over compared with a grey cast iron disc, but also their resistance to extreme loads and heat. The result is extremely short stopping distances, an exact pressure point and much higher fade resistance even under extreme operating conditions. The larger ceramic discs – front: 402 x 39 millimetres; rear: 360 x 32 millimetres – also feature a composite design and are connected with a floating radial mount to an aluminium bowl.

Compared with the conventional composite brake discs, the ceramic brake discs are around 40 percent lighter. The further reduction in unsprung masses not only boosts driving dynamics and agility but also improves steering response as well as ride comfort and contact characteristics. Six-piston fixed callipers are fitted at the front with a brake lining surface of 2 x 154 cm2; four-piston fixed callipers with a brake lining surface of 2 x 73 cm2 are used at the rear.

Overview of brake data:

Numerous functions of the high-performance braking system enhance comfort and safety. Take the practical HOLD function: if the CLS 63 AMG has come to a stop, the driver simply needs to press the brake pedal a little bit firmer. The vehicle is now held by the brake – even if the driver takes their foot off the brake pedal. This prevents the vehicle from unintentionally rolling forward in stop-and-go traffic or inadvertently rolling back on an uphill slope. The HOLD function is automatically disengaged once the vehicle is driven forward. Another useful feature comes in the shape of the hill-start assist. If the sensor technology detects that the driver has stopped on an incline, the brake pressure is automatically maintained constant for a short period. This means the CLS will not roll back and the driver has sufficient time to switch from the brake to the accelerator pedal without having to use the parking brake.

If the driver suddenly switches from the accelerator to the brake pedal prior to emergency braking, the braking system increases the pressure in the brake lines and applies the pads to the brake discs, so that they can grip instantly with full force when the brake pedal is pressed. The system supports the standard-fit Brake Assist by means of this 'priming'. Further standard features include the brake-drying function, which uses brief braking impulses to ensure the film of water on the brake discs is removed in the wet, thus considerably improving the responsiveness of the brakes.

Weight-optimised "Flow Forming" AMG light-alloy wheels

The newly developed AMG light-alloy wheels make a significant contribution to the dynamic handling of the CLS 63 AMG. As on the SLS AMG, they are produced by the new "flow forming" process. During this production process, hot forming in the area of the rim base makes for a denser material structure, thereby improving long-term durability. This also means that lower wall thicknesses can be achieved. The weight saving of up to 0.8 kg per wheel compared to conventional light-alloy wheels reduces the unsprung masses, further improving the handling dynamics and suspension comfort.

The Coupé is fitted as standard with titanium grey-painted wheels featuring a high-sheen finish and new triple-spoke design. The 9.0 x 19 format front wheels are fitted with 255/35 R 19-size tyres, while the 10 x 19 format rear wheels come with 285/30 R 19-size tyres. Available as an optional extra from the AMG Performance Studio are AMG light-alloy forged wheels in a 5-twin-spoke design and painted in titanium grey with a polished finish. They come with 255/35 R 19 (front) and 285/30 R 19 (rear) wide-base tyres.


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