Audi A5 Sportback: handling and active
safety (4/7 >)
- The five-door A5 Sportback benefits from a high body stiffness with
balanced distribution of axle load. As in the rest of the A5 series, the
front axle is moved far to the front.
The differential is mounted directly behind the
longitudinally installed engine and thus in front of the clutch or torque
converter. The battery was moved to the luggage compartment for better
All major components of the front and rear suspensions
are made of aluminium, reducing the unsprung masses.
Materials in the
body structure, legend (top to down): standard steels,
high-strength steels, higher-strength steels,
maximum-strength steels, maximum-strength steels (hot
The front wheels are mounted on a five-link axle that
can absorb separately 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.
The front axle and the engine are fastened to an
auxiliary frame that is bolted to the front section of the car.
chassis and drivetrain, front-wheel drive (AWD
The rear suspension is identical in the
front-wheel-drive and quattro versions. The self-tracking, trapezoidal
link rear suspension is also mounted on an auxiliary frame. The springs
and shock absorbers – the latter with small supplemental stop springs
– are mounted separately on the wheel carriers, to combine ride comfort
with sporty precision.
An optional sport suspension is available in three
variants: a tauter setup with or without controlled dampers and an S line
sports suspension that lowers the body by 10 millimetres (0.39 in).
The 2.0 TDI and the 2.0 TFSI with 132 kW (180 hp) get
314-millimetre (12.36 in) ventilated front discs and 300-millimetre (11.81
in) discs at the rear.
To enhance heat dissipation in the front discs, two
friction rings are connected by hundreds of small metal cubes through
which a high volume of cooling air can flow.
aerodynamic underbody for air flow optimization.
With the V6 engines and the 2.0 TFSI with 155 kW (211
hp), the front discs diameter is 320 millimetres (12.6 in), with calipers
made of a composite material. The piston housing is made of aluminium,
better for weight and heat dissipation.
The standard, six-spoke 7.5 J x 17 forged alloy wheels
come with 225/50 tires. Two additional 17-inch wheels, four 18-inch
wheels, one of which in an A5 Sportback-specific design, and three 19-inch
wheels are available as options.
The top of the line is a 9 J x 20, seven twin-spoke
cast wheel shod with 265/30 tires. All versions are equipped with a tire
pressure monitoring display.
The front-wheel-drive versions of the A5 Sportback come
standard with the latest generation of the ESP stabilization program from
the A5 Coupé and Cabriolet, now including a new electronic differential
lock, which works like a mechanical locking differential, preventing
understeer and improving traction.
The new function aims to improve the driving dynamics
through curves, under load and on both wet and dry road surfaces, giving a
more precise steering reaction and greater track stability, improving also
reaction in corners so that the car can be steered with less steering
These results are achieved through sophisticated
software in the ESP. As soon as the electronics detect that the load on
the inside wheel of the powered front axle is reduced too much and the
wheel loses traction, it initiates brief, controlled braking. This
redirects the excess torque to the outside wheel, which due to the greater
dynamic wheel load is capable of delivering more power to the road.
The optional Audi drive select system is another active
safety equipment available for the A5 Sportback, enabling the driver to
access all of the technical components relevant to driving dynamics and
vary their function by switching between “comfort,” “auto” and “dynamic”
modes. A fourth “individual” mode is available with the MMI
navigation system, enabling the driver to customise his / her settings
from a large number of parameters.
Audi drive select influences the:
- engine’s throttle response characteristic,
- shift points of the seven-speed S tronic,
- boost of the servotronic steering.
Consequently, the Audi drive select system needs to be
combined with at least one of three other technologies: the sport
differential, adaptive shock absorber control or dynamic steering.
The electronic shock absorber control system uses CDC
(continuous damping control) shock absorbers. Their electromagnetically
actuated valves control the flow of hydraulic fluid between the inner and
the outer tubes by opening orifices of different sizes. A large
cross-section provides a soft damping characteristic, and a small
cross-section provides a taut characteristic. A fast controller
continuously analyzes the signals received from 14 sensors and calculates
the optimal damping per wheel in extremely short intervals (1,000 times
The rack-and-pinion steering features a sporty and
direct 16.1:1 ratio. The system’s regulated vane pump provides hydraulic
assistance according to driving conditions. The speed-sensitive
servotronic is standard with the 2.0 TFSI with 155 kW (211 hp) and the V6.
The optional dynamic steering system (opposite) varies
the steering ratio by nearly 100 percent as a function of driving speed
and the mode specified by the Audi drive
select system. It uses a superposition gear integrated into the
steering column and driven by an electric motor.
At low speeds, the system is very direct and boost is
also very high, which makes parking easier. 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 works together with the ESP
stabilization program. Because it can make steering corrections in less
time than the brake system needs to build up pressure at the wheels, it
reduces the number of braking actions. Dynamic steering counters oversteer
caused by load changes as well as understeer, and also provides assistance
when braking on surfaces with different coefficients of friction.