The New Audi A3
Published: 16th June 2003
Quattro Permanent Four-Wheel-Drive
- Like its predecessor and the Audi TT quattro, the Audi A3 quattro features a hydraulic multi-plate clutch designed for Audi models with transversely mounted engines, which varies the distribution of power to the front and rear wheels
- Fitted between the driveshaft and the rear differential, the multiplate clutch uses a package of plates running in an oil bath within the clutch housing, which can be pressed together by controlled hydraulic power, providing a variable lock between the front and rear axle
- Electronically controlled, the system responds instantaneously to any change in traction. With its own oil supply featuring two axialpiston pumps quickly building up pressure, the clutch is able to intervene as required with a difference in rotating angles of only 450 between the front and rear axle
- Power is distributed as a function of mechanical conditions, using both hydraulic and electronic signals. A data link provided by a CANbus electronic data line registers and evaluates a wide range of data fed in by other sensors and control units
- The electronic "brain" uses information such as wheel and engine speed, road speed and engine torque, and controls clutch pressure and the additional power required for the particular driving situation accordingly
- Front-mounted engine and multi-plate clutch at the rear benefits overall weight distribution, maximising handling stability
- quattro permanent four-wheel drive will be allied to the 3.2-litre petrol and 2.0 TDI engines
- New A3 features further improved McPherson strut front suspension and new four-arm independent suspension at the rear
- Handling stability and control benefits from longer wheel base and also from relatively firm spring settings, combined with efficient shock absorption and moderate tuning of the roll bars. Damping effect is geared in each version of the new A3 to the different weight of the car and its axle loads
- New four-arm rear suspension design combines compact dimensions with low weight and, in particular, dynamic driving qualities. Functional separation of longitudinal and side forces provides a high standard of lateral rigidity for optimum dynamics and driving safety and makes the suspension relatively soft lengthwise to improve the standard of roll comfort
- On each side the axle incorporates a wheel subframe with a wheel bearing, two track control arms at the bottom, one track control arm at the top and a longitudinal control arm. The three track control arms are connected to the body of the car by the axle subframe. This structure on the front-wheel drive A3 is made of extra-strong steel tubes and plates and is bolted firmly to the body, forming a complete unit helping to save weight and reinforce the rear end of the car
- The rear axle subframe on quattro models also accommodates the final drive and is made of aluminium to reduce weight even further
- Twin-sleeve gas pressure dampers are fitted directly next to the wheels, helping to maximise load space in the luggage compartment. Rear anti-roll bar is mounted on extra-firm rubber/metal bearings fitted to the axle subframe, efficiently reducing body movement and transmission of lateral forces
- Front suspension is by McPherson struts with wishbones below. The subframe is bolted directly on to the chassis of the car, and the crossbars and track control arm mounts are now made of aluminium, reducing weight by 1.5 kilos compared with previous A3
- Anti-roll bar is mounted directly on the spring strut, helping to improve its response and allowing the engineers to make the whole unit more compact than before, saving a further 1.6 kilos compared with previous A3
- Front track control arm mount is extra-stiff to provide stable side support. Rear track control arm mount has a non-linear response curve ensuring good ride comfort under minor loads and controlled self-steering behaviour as forces increase
