Suspension: Dedicated to dynamism

Mar 5, 2015
The chassis of the CLA Shooting Brake features a McPherson front axle and multi-link independent rear suspension. Three control arms and one trailing arm per wheel manage the incoming forces. This means that longitudinal and lateral dynamics are independent of one another. The Direct-Steer system is standard in all versions.
Specific to the CLA is the elastic de-coupling of the rear axle carrier. The measures include rubber bushes vulcanised onto the stabiliser, plus elastomer coatings for the coil springs, which facilitate effective noise de-coupling between the body and rear axle.
The connection between the shock absorber and the body is via an aluminium bearing at the top, which through its cardanically soft mount contributes to a reduction in friction in the damper and therefore to an improvement in response. The wheel carriers and spring control arms are made of aluminium to reduce the unsprung masses.
These four chassis and suspension set-ups are available:
  • Comfort suspension
  • Lowered comfort suspension (standard in conjunction with Urban)
  • Lowered sports suspension (standard in conjunction with AMG Line). Through the tauter configuration of the springs and damping the sports suspension facilitates a sportier driving style without any great loss of comfort.
  • Sports suspension engineered by AMG. This suspension is also lowered and it is characterised by an independently developed AMG front and rear axle. In addition it includes larger-dimensioned stabilisers for high lateral acceleration and a reduced tendency to roll (standard for the CLA 250 Sport 4MATIC)
In the case of the lowered suspension variants the body is 15 mm lower at the front axle and 10 mm lower at the rear axle. For no extra charge the Urban design and equipment line is also available on request with the comfort suspension, and likewise the AMG Line is alternatively available with the lowered comfort suspension.
Irrespective of the chassis, all CLA models (except the CLA 250 Sport) are fitted with the Sports Direct Steer system. Compared to conventional systems, this electromechanical power steering provides better feedback to the driver and makes an important contribution to the vehicle's overall efficiency, as the servo assistance only requires energy when the vehicle is actually being steered. It also allows various steering assistance functions that are initiated by the ESP® control unit. These include countersteering when the vehicle oversteers, steering corrections when braking on surfaces with different levels of grip, reducing the effects of front-wheel drive on the steering and compensation of cross-winds and road camber. The CLA 250 Sport includes the AMG speed-sensitive sports steering from the CLA 45 AMG.
With all engines the CLA features disc brakes all round. The floating callipers on the rear axle as well as the brake booster are made of aluminium. An especially convenient feature is the HOLD function familiar from the larger model series: when stopping, for example at traffic lights, the driver merely has to press the brake pedal slightly more firmly once to keep the brake engaged until moving off again. The brake is released automatically when the driver steps on the accelerator. In versions with manual transmission the Hill-Start Assist function is able automatically to prevent the vehicle from rolling back unintentionally when moving off on an uphill slope.
The CLA is equipped with an electric parking brake, which operates by means of actuator motors acting on the callipers of the rear axle. The parking brake is activated via a button under the light switch on the left of the dashboard, freeing up space on the centre console where the handbrake lever would normally be. If the button is pressed when travelling faster than 4 km/h, the parking brake functions as an emergency brake: all four wheel brakes are activated by the ESP® hydraulic unit. In conjunction with the 7G-DCT automatic transmission, the parking brake offers a particularly convenient mode of functioning: when the driver accelerates sufficiently after fastening his seat belt, the parking brake is released automatically.