Suspension: Comfortable and sporty gliding

Jun 23, 2014
The S-Class Coupé features the enhanced full-support AIRMATIC air suspension with continuously variable damping control as standard. The rear-wheel-drive versions herald the introduction of a world first in the shape of the curve tilting function, which is part of MAGIC BODY CONTROL and also includes the innovative ROAD SURFACE SCAN. The latter enables the Coupé to detect road surface undulations in advance.
The front axle features four-link suspension. Its key characteristics include two individual links (torque strut and spring link) in the lower link plane. The transversely situated forged-aluminium spring link carries the spring strut. The anti-roll bar is connected directly on the steering knuckle, while the forward-sloping torque strut is made of forged aluminium.
A wishbone located high above the lower link plane performs further wheel location functions. This link is also made of forged aluminium, as is the steering knuckle which connects the upper and lower link planes. The fourth link is the track rod which forms part of the rack-and-pinion steering system. The transversely situated steering gear is located in front of the wheel's centre.
The arrangement and design of the wheel location components offer favourable characteristics for the axle kinematics: the kingpin inclination is close to the wheel centre. This provides for large longitudinal force leverage, thus minimising sensitivity to tyre imbalances and fluctuations in braking force.
The lower front axle components, the steering gear and the engine mounts are linked with an assembly carrier. This integral carrier, made from high-strength sheet aluminium, is directly bolted to the body.
Due to the unsurpassed wheel location qualities, the S-Class Coupé features a multi-link rear suspension attached to an aluminium subframe. Consistent lightweight construction minimises the weight of the unsprung masses. Four of the five wheel-locating links are made of forged aluminium, as is the hub carrier. The spring link that carries the spring strut is made of single-ply sheet aluminium. In the standard configuration, the rear axle with air suspension features a torsion-bar stabiliser which is directly connected to the rear axle carrier.
AIRMATIC: enhanced comfort and driving dynamics
The standard-fit full air suspension system AIRMATIC with continuously adaptive damping control allows the spring travel to be maintained whatever the vehicle load, by means of continuous level adjustment. The basic level of the S-Class Coupés is 10 mm lower than that of the S-Class Saloon. The vehicle level is lowered by a further 10 mm when driving at higher speed. Aerodynamic drag is reduced, and handling stability is improved by the car's low centre of gravity. A switch on the centre console allows the driver to select from two different damper configurations: "Sport" and "Comfort".
The AIRMATIC system with continuously variable damping control that featured on the preceding model has been modified in many respects: new air suspension bellows with reduced breakaway torque make for even better ride comfort as they do not stiffen as much at low amplitudes and larger frequencies. The spring travel on the rear axle has been increased, thus improving absorption capacity if excitation is high. To further reduce tyre noise, the air suspension struts on the rear axle are decoupled from the body.
In the lower control panel on the centre console, the driver can select a 40 mm higher vehicle level if the road surface is poor or when negotiating a tricky garage entrance, for example.
Further improvements have likewise been made to the adaptive damping system. This fully automatic, electronically controlled system adjusts the shock absorbers at each wheel as required. As before, the single-tube shock absorbers are equipped with a valve each for the compression and rebound stage, while there is a new feature in the shape of continuous damping adjustment. This means that the optimum operating point can be selected every time based on various data such as acceleration, vehicle level or vehicle speed. A button on the centre console allows the driver to select a sportier setting as an alternative to the comfort-oriented default setting.
Steering: Electro-mechanical Direct-Steer system and steering assistance
The new S-Class Coupé comes with an electro-mechanical Direct-Steer system as standard. As well as a more precise and also more comfortable steering experience, the steering system has a major impact on overall efficiency, since it only requires energy when the vehicle is actually being steered.
In the new steering system, the steering gear and the supporting servomotor form a single compact unit and are mounted on an extremely rigid and low-weight integral support frame made of aluminium which is positioned in front of the wheel's centreline. The steering gear is designed as a Direct-Steer system, which means that the steering ratio becomes noticeably more direct as the steering angle increases. This enhances the vehicle's handling and agility substantially.
The steering assistance function can help to stabilise the vehicle. An assisting steering wheel torque is determined depending on the driving conditions, and a corresponding steering impulse is triggered.
The function never overrules the driver, but instead indicates the direction in which to steer to stabilise the vehicle. In the event of oversteer, the steering assistance system prompts the driver to countersteer using the steering wheel until the vehicle has stabilised again.
If the vehicle is braked on a road surface with different friction (µ-split) on the left and right, this generates a yawing impulse which turns the vehicle in the direction of the higher friction. The steering assistance system prompts the driver to turn the steering wheel in the appropriate direction to compensate for the yaw caused by the different friction.
The electro-mechanical steering gear also allows driving assistance systems such as Active Parking Assist incl. PARKTRONIC and DISTRONIC PLUS with Steering Assist to be implemented.
The Coupé is equipped with a electrically height and reach-adjustable steering column including an entry-aid function. The adjustment ranges measured from the basic position of the steering wheel are +/- 25 mm for height and 25 mm/35 mm (fore/aft) for reach.
Brakes: large discs, a wealth of assistance functions
Large, internally ventilated brake discs on the front and rear axle create the technical basis for safe and reliable braking by the electronic brake control system ADAPTIVE BRAKE. Multipiece brake discs have been developed to reduce the unsprung masses. On these discs, the friction ring (made of cast iron) and the brake disc bowl (made of sheet steel) are pressed by toothing. They have a diameter of 370 mm (front) or 360 mm (rear).
An electric parking brake is fitted as standard on the S-Class Coupé. A combined floating brake calliper with an electric parking brake function is used at the rear axle.
With the ADAPTIVE BRAKE, the S-Class Coupé offers a wealth of assistance functions. One example of these is the practical HOLD function: after braking to a standstill, briefly pressing the brake pedal a little further is all that is required to activate this function. The car is then held by the brakes, even if the driver's foot is taken off the brake pedal. The HOLD function is deactivated automatically when the car moves off.
If the driver's foot moves abruptly from the accelerator to the brake pedal before an emergency stop, the brake system increases the pressure in the brake lines and already brings the pads into contact with the brake discs so that maximum braking power is available as soon as the driver hits the brake pedal. This priming of the brakes allows the system to assist the standard-fit Brake Assist system.
ADAPTIVE BRAKE also brings safety benefits in the wet: the system briefly applies the brakes at regular intervals to wipe the film of water from the brake discs and ensure that the brakes are able to perform at their peak. The finely metered brake pulses are imperceptible to the driver. This automatic brake drying function is always activated after a certain period of windscreen wiper operation.
Finally, ADAPTIVE BRAKE assists the driver when starting on an uphill slope. When the sensors detect that the Coupé is stopped on an uphill slope, Hill-Start Assist is activated automatically, briefly holding the brake pressure at a constant level so as to prevent the car from rolling backwards.
ESP® Dynamic Cornering Assist offers improved safety in critical cornering conditions. If the ESP® sensors detect an understeering tendency, the system performs specific braking intervention on the side of the vehicle which is on the inside of the bend. This gives rise to gentle rotary movement of the vehicle around the vertical axis.
Wheels and tyres: up to 20 inches ex factory
The wheels available ex factory range from 18 inches to 20 inches. As standard the S-Class Coupé is fitted with ten-spoke light-alloy wheels: 8J x 18 ET 41 (front) and 8.5J x 18 ET 35.3 (rear) with 245/50 R18 tyres. A number of further 18 and 19-inch wheels and tyres are available as optional extras. The largest wheels available ex factory are five-spoke or multi-spoke light-alloy wheels, size 8.5J x 20 ET 36/36.5 with 245/40 R20 tyres (front) and 9.5J x 20 ET 43.5/44 with 275/35 R20 tyres (rear).
A tyre pressure monitoring system which continuously monitors the pressure in all four tyres is standard equipment, with the data for each wheel shown on the instrument cluster display. During a journey, sensors built into the wheels send out radio signals (433 MHz) with information about the air pressure, tyre temperature and direction of rotation plus an individual identification number to distinguish between the wheels. The system detects newly fitted tyres automatically and assigns them to the correct position on the vehicle. The information about direction of rotation received from the wheel sensors and the different signal strength of the rear wheels positioned closer to the receiving antenna and the front wheels positioned further away are evaluated for the purpose of automatic position detection.
The tyre pressure monitoring system can issue three different warning messages:
  • "Correct tyre pressure" if the tyre inflation pressure drops slightly
  • "Check tyres", including an acoustic signal, if the tyre inflation pressure drops severely
  • "Caution: tyre defect", including an acoustic signal, if the tyre inflation pressure suddenly drops whilst driving.
Since the recommended tyre inflation pressures depend on the tyre size, the vehicle load and the maximum speed, the driver occasionally needs to adjust these pressures. The tyre pressure monitoring system detects these changes automatically in most cases. If the tyre inflation is plausible, the reset tyre pressures are accepted as new setpoints by the system axle by axle after a few minutes of driving. If the tyre inflation is implausible, the driver is prompted to correct the pressures. The driver can calibrate the tyre pressure monitoring system manually using the menu "Service/tyre pressure" to specify the current pressures as new setpoints at the push of a button.
In countries that have adopted the ECE agreement, the "TIREFIT" breakdown kit incl. electrical compressor is specified as standard. Run-flat tyres are provided for vehicles outside of the ECE to ensure continued mobility.
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