Technical data

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quattro®/quattro® with sports differential
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 goes
to the front axle, 60% to 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 more
feel for the road and thus increased safety.
The optional quattro with sports 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 sports 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 electro-hydraulic
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.
48
Why only use two wheels
when a car has four?
The quattro® permanent all-wheel drive.
A7_S7_Fas18_2012_03.indd 48 23.04.12 13:13