2009 Audi TTS

The Chassis

The front suspension of the TTS, with a track of 1,555 millimeters (61.22 in), adheres to a design principle that has already proved highly effective: a McPherson structure with triangular lower wishbones. The pivot bearings, the subframe and the wishbones are made from aluminum. This measure has cut the unsprung weight of the transverse links alone by 2.5 kilograms (5.51 lb). To increase the rigidity, the subframe is bolted to the body at six points. The level of servo assistance for the rack-and-pinion steering falls as the speed rises; its characteristics have been adapted to the dynamic overall character of the TTS.

Because the electromechanical system does not tap the power supply when the car is driving in a straight line, in contrast to hydraulic power steering, it operates very efficiently and saves an average of 0.2 liters of fuel per 100 kilometers. With its precise, analytical operating principle, the steering provides good road feedback yet exhibits minimal sensitivity to excitation from the road surface. Its ratio of 16.9:1 gives it a sporty character.

The four-link rear suspension has a track width of 1,546 millimeters (60.87 in). Its design principle offers major benefits in terms of driving dynamics, because it separates the cushioning of longitudinal and transverse forces. The longitudinal links absorb the driveline and braking forces, and their relatively soft mounts permit good ride comfort. On the other hand, the three wishbones per wheel – the spring link, the upper wishbone and the tie rod – are attached very rigidly to the subframe, benefiting the handling characteristics.

All links are made from high-strength steel grades. Separate coil springs and dampers provide vertical support.

The Audi TTS comes as standard with 18-inch cast aluminum wheels that sport the five-arm parallel-spoke S design and are shod with 245/40-size tires as standard. For winter driving, the same size wheels are available with winter tires or with 17-inch tires that are compatible with snow chains. A number of other wheel variants are optionally available, including an exclusive 19-inch cast aluminum wheel designed by quattro GmbH.

The large wheels conceal high-performance sport brakes. The ventilated disks on the front wheels measure 340 millimeters (25.67 in) in diameter and 310 mm (13.39 in) at the rear. The brake calipers are painted black, with special TTS badges at the front. Their sport brake pads guarantee high friction.

Audi magnetic ride – crisp and versatile

The TTS rolls off the production line equipped with yet another high-tech solution — the Audi magnetic ride adaptive suspension system. Circulating inside the damper pistons is a special fluid containing minute magnetic particles. When an electrical voltage is applied, the oil’s flow properties change the characteristics of the suspension.

Audi magnetic ride works adaptively, meaning that it adjusts automatically to suit the prevailing conditions. The driver can select one of two suspension settings. In “Normal” mode, when oil viscosity is high, the TTS offers a well-balanced, comfortable ride. In the “Sport” setting, meaning low viscosity, the TTS harnesses all of the potential of its sports suspension – which lowers the body by 10 millimeters (0.39 in.) – to deliver uncompromisingly dynamic handling.

The Audi generates non-stop fun at the wheel as it speeds around corners like a go-cart with absolute crispness and precision, seemingly glued to the road. Any body roll is suppressed from the moment the vehicle starts to turn. The steering becomes more responsive and direct, and selective bracing of the wheels makes the self-steering more neutral.

For sport enthusiasts: two-stage ESP

The ESP electronic stabilization program is optimized for dynamic driving. A brief press of a button at lower speeds – e.g. when driving on snow chains – is all it takes to increase wheel slip. When the button is pressed longer, the TTS driver enters a second, sporty operating plane in which the ESP permits controlled sideslip angles. The brakes intervene somewhat later than in normal operation and the engine manipulation is suppressed.

The elastokinematic behavior of the chassis links on the TTS has been slightly modified compared with the basic technical configuration; sporty springs hold the body ten millimeters (0.39 in) lower. This built-for-fun Audi is equipped with the high-tech Audi magnetic ride as standard – the shock absorbers’ electronic control resolves the conflict between comfort and drivability.

The shock absorber pistons contain a synthetic hydrocarbon fluid in which microscopically small magnetic particles measuring between three and ten microns (a micron is one-thousandth of a millimeter) are enclosed. When voltage is applied to a coil, a magnetic field is created in which the alignment of the particles changes.

They arrange themselves transversely to the direction of flow of the fluid, thus inhibiting its flow through the piston channels. This alters the damping characteristic within a matter of milliseconds, much faster than is possible with conventional adaptive dampers.

The magnetic ride system’s control unit constantly monitors the properties of the road surface and the driver’s style, adjusting the response accordingly. The driver can change between the Normal and Sport modes at the touch of a button. In Normal mode, when the fluid is able to flow readily, the TTS offers a wellbalanced, comfortable ride. In the Sport mode it is uncompromisingly crisp, hugging the road; any hint of body roll is nipped in the bud. The steering response becomes even more precise and specific stabilization of each wheel imparts even more neutrality to the self-steering behavior.

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