Taken from the Audi website.
Introducing the multi-plate clutch
The task of channelling the massive power of the RS 3 Sportback engine onto the road – whatever the situation – is masterfully handled by the upgraded RS 3 Sportback quattro® drivetrain.
At its heart is The Haldex® clutch, an electronically controlled, hydraulic multi-plate clutch that controls the flow of power between the engine and the gearbox. If a situation calls for it, the clutch redirects a majority of the torque input from the front wheels to the rear wheels. And it does so in a fraction of a second.
quattro®: what it does and how it works
Front-wheel or rear-wheel drive has certainly improved thanks to innovations such as electronic stability programmes, anti-lock brakes and traction control. But two-wheel drive cars will, particularly in extreme circumstances, sometimes exhibit certain (and usually undesirable) characteristics.
Due to the weight of the engine and other assemblies resting on the front axle, front-wheel drive cars tend to be slightly superior to rear-wheel drive cars in the amount of grip they can transmit to the road during wet conditions.
But in a front-wheel drive car, hard cornering or cornering on a slippery road surface can cause understeer: where the car continues forwards even though the wheels are turned.
Conversely, rear-wheel drive cars can suffer from oversteer: the driving wheels deliver more power than the road surface can handle, causing the rear end to slide and the car to travel sideways. This can be quite difficult to control and traction aid systems and electronic stability programmes will engage quite early.
Slippery surfaces
With quattro, drive is distributed to all four wheels permanently in varying amounts, depending on the road conditions and how the car’s being driven; it’s constantly ‘feeling’ how much grip there is for each wheel. If a wheel loses grip, drive is diverted away to wheels that have better contact with the road. All his happens imperceptibly, but it results in a feeling of exceptional composure and control, even in what would ordinarily be potentially dangerous driving conditions.
Cornering
With front-wheel or rear-wheel drive the car is effectively being either pulled or pushed round a bend. Instead, with quattro four-wheel drive, all four wheels work together and drive is delivered to where it’s needed and regulated where it isn’t. This means greater stability, more assured road-holding, enhanced agility and improved steering precision.
