Audi A7 Sportback Audi S7 Sportback

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quattro®/quattro® with sport differential
Why only use two wheels
when a car has four?
The quattro® permanent all-wheel drive.
quattro is a permanent all-wheel drive system.
If the wheels on one axle of the vehicle lose
grip on the road and threaten to spin, then the
drive force is transferred to the other axle –
automatically and permanently distributed
through the centre differential. The basic
distribution is 40 : 60 – 40 % of the power comes
from the front axle, 60 % from the rear. The
benefit is better traction during acceleration and
improved safety due to exceptional grip. So much
for the technology. But what makes quattro
unique is really the driving feel. “As if you are
stuck to the road,” some customers say. We put it
like this: quattro gives you a better feel for the
road and thus more safety.
The optional quattro with sport differential
further reinforces this unmistakeable quattro
feeling. Vehicles tend to experience understeer
when steering or driving into corners. This is a
normal physical process: a moving object
opposes a change in direction. The elastic tyres
and the suspension mounts tense up until the new
direction has been adopted. When accelerating
into a corner, the load on the front axle is reduced
and it therefore transfers less lateral force to the
tyres – the vehicle understeers. With the sport
differential on the rear axle, the tendency has
been significantly counteracted. This is because
the quattro rear axle differential has been
extended left and right by a clutch system with
two gear levels. They ensure that the individual
wheels on the rear axle receive different levels of
torque. The clutches are activated by an electrohydraulic
actuator. Depending, for example, on
the steering angle, lateral acceleration, yaw
angle and driving speed, the system calculates
the right distribution of wheel torque for any
driving situation. In this way the power is
specifically channelled to the outer rear wheel
when steering or accelerating into a corner. The
effect: the vehicle is effectively pressed into the
corner by the drive force and follows the angle of
the front wheels. The variable left and right drive
forces also help stabilise the steering and the
usual steering corrections are hardly necessary.