Audi A5 and S5 Cabriolet: The Suspension
The Audi A5 Cabriolet leads its class in all relevant sporty criteria steering response, stability and agility yet it provides a very smooth ride The reason for these strengths is the exemplary body stiffness and the cleanly balanced distribution of axle loads. The front axle is located far forward in the front section a condition made possible by an unusual solution: The differential is mounted in front of the clutch or torque converter.
The suspension design is also technologically advanced. The front wheels are mounted on a five-link axle that can respond separately to the longitudinal and lateral forces acting upon it. Bearings are stiff in the lateral direction for sporty precision and soft and supple in the longitudinal direction. All major components of the front and rear suspensions are made of aluminum, which reduces the unsprung masses.
The auxiliary frame for the front axle and the engine is rigidly bolted to the front section of the car. The high rigidity facilitates the spontaneous generation of steering force. The steering box, mounted low and far forward, transmits the steering commands directly to the wheels.
The hydraulic rack-and-pinion steering with its 16:1 ratio is sporty and direct, providing a precise and finely differentiated connection with the road. A regulated vane-type pump also provides just the right amount of hydraulic energy for the respective operating point. The speed-dependent servotronic is standard with the V6 engines and the 211 hp 2.0 TFSI.
Compact and capable: the rear axle The rear-wheel suspension of the Audi A5 Cabriolet is a self-tracking trapezoidal link suspension and is identical in the front-wheel drive and quattro versions. It is also mounted onto an auxiliary frame and is very compact for added space in the trunk. The springs and shock absorbers the latter with small supplemental springs are mounted separately on the wheel carriers, a solution that enabled the developers to combine high ride comfort with sporty precision.
Audi also delivers the A5 Cabriolet with a sport suspension. Two variants are available a somewhat tauter configuration and an S line sport suspension that lowers the body by 10 millimeters.
The Audi A5 Cabriolet rides on 7.5 J x 17 forged alloy wheels sporting a classic six-arm design. The tires including the winter tires are in a sporty 225/50 format. Individualists can choose from three additional 17-inch wheels, two 18-inch wheels and one 8.5 J x 19 wheel. quattro GmbH also supplies additional 18-inch, 19-inch and even 20-inch wheels, the latter shod with 265/30 wide tires.
Behind the large wheels of the A5 Cabriolet are large brakes that can be very precisely metered. Both 2.0 TFSI models have 314 millimeter (12.36 in) disks up front and 300 millimeter (11.81 in) disks at the rear. The ventilated front disks are designed for maximum heat dissipation: The two halves of the disk are connected by hundreds of small metal cubes, between which a high volume of cooling air can flow in a very short period of time.
The V6 versions of the new Audi A5 Cabriolet are equipped with brakes featuring 320 millimeter (12.60 in) disks. A composite construction was chosen for the calipers: nodular cast iron is used in areas requiring high strength. The piston housing of aluminum dissipates the heat very well. The lightweight brake calipers are extremely stiff; the aluminum disks and cover plates are also unusually light.
Even more driving enjoyment: Audi drive select One high-end technology that helps the A5 Cabriolet outpace its competitors is the Audi drive select driving dynamics system. It provides the driver with access to all of the technical components relevant to driving dynamics via buttons on the center console, and enables the driver to switch between three modes comfort, auto and dynamic to vary their function. If the MMI navigation plus operating system is present, a fourth mode in which the driver can compose his or her own custom settings from a large number of parameters is also available.
Audi drive select influences the engines throttle response characteristic, the shift points of the seven-speed S tronic and multitronic transmissions as well as the boost of the servotronic steering. Because of the modular system layout, the customer can order one or more of three additional technologies: the sport differential, adaptive shock absorber control or dynamic steering.
A fast controller plays the lead role in electronic shock absorber control. It continuously analyzes the signals received from 14 sensors and calculates the optimal damping per wheel in extremely short intervals (1,000 times per second).
The CDC (continuous damping control) shock absorbers include electromagnetically actuated valves. They control the flow of hydraulic fluid between the inner and the outer tubes. A large cross-section provides a soft damping characteristic, and a small cross-section provides a hard damping characteristic.
The dynamic steering is another high-end technology from Audi its superposition gear modifies the steering ratio as a function of driving speed. It is integrated into the steering column and combined with an electric motor. As a harmonic drive it is compact and light. It operates without any play and is therefore extremely precise, with low friction. It can transmit very high torques and operates at a high level of efficiency.
Audi dynamic steering can vary its steering ratio by nearly 100 percent in response to both the vehicle speed and the Audi drive select mode in use. The transitions are continuous and undetectable. The system is very direct when parking, and boost is also very high. At moderate highway speeds, the system becomes less direct and provides less power assist. At top speeds, an indirect steering ratio and low level of power assist facilitate steady tracking.
The dynamic steering system cooperates closely with ESP in the vehicle dynamics and safety areas. It relieves the burden on the electronic stabilization program for the simple reason that a steering correction can be performed faster than the time needed by the brake system to build up pressure at the individual wheels. It thus eliminates many braking operations and the driving becomes faster and more flowing.
Dynamic steering counteracts both oversteer as a result of load changes and understeer. It also provides valuable assistance when braking on surfaces with various coefficients of friction.
The equipment, specifications, and prices stated herein refer to the model range offered for sale in Germany. Subject to change without notice; errors and omissions excepted.
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