A dynamic character
The Audi Sportback concept show car took the basic architecture and many components of its suspension from the brand’s latest and most successful model family: the very dynamic A4/A5 model series. The dynamic suspension sets standards here, as well, combining precision and dynamism with high stability and superior poise. The suspension mountings, steering, wheels and brakes have been developed for top performance and numerous aluminum components are used to keep unsprung masses to a minimum.
Optimal distribution of weight
The new five-link front suspension makes a major contribution to the car’s dynamic character. By moving the differential further forward and the clutch further back, the design engineers were able to reposition the front axle 154 millimeters (6.06 inches) further forward. The result is an optimal distribution of weight between the front and rear axles.
The front suspension is made up of five links per wheel – a support link and a control arm at the bottom and two control arms at the top. The fifth link – the track rod – connects the steering box and the pivot bearing. All these links are made of forged aluminum, ensuring low unsprung masses, ultra-precise wheel control and a high level of crash safety. The anti-roll bar fabricated from a high-strength tube saves additional weight. The backbone of the rear axle is a subframe with high flexural and torsional rigidity.
If sporty handling is to be combined with a high standard of ride comfort, the unsprung masses must be kept as low as possible. Audi has pursued this approach for all the rear-axle components. The upper control arms and the track rods are of forged aluminum. Their high rigidity ensures that toe and camber angles change very little when dynamic forces act on the wheels.
The CDC (continuous damping control) shock absorbers, similar to those that Audi already uses on the luxury Q7 SUV with air suspension, are twin-tube, gas-filled hydraulic units with an additional external valve and connecting pipe. Their operation can be continuously varied.
An electromagnetically energized, proportional-action valve regulates the flow of hydraulic fluid between the inner and outer damper tubes. A smaller flow cross-section makes the damping characteristic firmer, a larger one makes it softer.
The control unit applies adaptive operating characteristics within the mode the driver has chosen via Audi drive select. It adapts to match the driver’s driving style and the road conditions. Even from the comfort mode, the shock absorbers can be switched in an instant to a firm setting if desired, though not to the absolute limit. They are fitted in conjunction with sports suspension springs, which still provide a good level of ride comfort, even off-road.
The control unit selects the optimum damping force for the current driving situation, for instance firmer damping to prevent body roll and pitch when cornering fast or braking, or lower damping force where the surface under the wheels is hard and uneven.
The show car marks the first time that Audi has used electromechanical steering in a car with a longitudinal engine. Its primary advantage is that, unlike conventional power steering systems, it only consumes energy when actually steering. On average, this means a fuel saving of 0.2 liters per 100 kilometers, depending on driving conditions.
The electromechanical steering of the Audi Sportback concept also enables the coupling with the parking steering assistant for fully automatic steering when parallel parking.
The Audi Sportback concept is equipped with ceramic brakes on all four wheels for effective deceleration even under the most demanding conditions. Compared with conventional steel disks, ceramic brakes not only last four times longer, up to 300,000 kilometers (186,411 miles), but also offer high resistance to fading. The significant reduction in weight also leads to advantages in terms of comfort and handling, thanks to reduced unsprung masses.
On the front axle, 380-millimeter (14.96-inch) ceramic disks are fitted in combination with 21-inch wheels. The rear disks have a diameter of 356 millimeters (14.02 inches). The elaborate cooling duct geometry of the ventilated brake disks ensures optimal cooling of the brake disks. Firm grip on the brake disk is guaranteed at the front by 6-piston monobloc aluminum brake calipers, and at the rear by floating-caliper brakes.