- 1engine
- 2 - Manual transmission
- 3 - Front axle drive/differential
- 4 - Drive shafts/front suspension
- 5 - cardan shaft
- 6 - Haldex clutch
- 7 - rear axle drive bevel gears
- 8 - rear axle differential
- 9 - drive shafts
Warning: Arrows point in the direction of travel.
The all-wheel drive model of the AUDI A3 is equipped with permanent all-wheel drive. The following elements are additionally required for rear wheel drive:
The power take-off unit from the manual transmission of the front axle to ensure the transmission of motion to the cardan shaft, which connects the manual transmission to the rear differential. From the differential of the rear axle, the motion is transmitted through the drive shafts to the rear wheels.
To accommodate the rear axle differential, the all-wheel drive AUDI A3 has a double wishbone rear suspension and a two-piece fuel tank.
To equalize the different speeds of the front and rear axles in all-wheel drive vehicles and to distribute torque depending on driving conditions between the front and rear axles, a Haldex clutch is used, mounted on the rear axle differential.
The Haldex clutch is an electronically controlled, hydraulically actuated disc clutch. Depending on the signals from various sensors, such as the engine control unit and ABS, the Haldex clutch control unit regulates the engagement of the rear axle. The all-wheel drive control system recognizes the cause of the slippage of the individual wheels and the different wheel speeds and distributes the torque between the front and rear wheels accordingly. The rear axle can be completely disconnected from the drive, which removes restrictions when towing with the front or rear axles raised. The all-wheel drive model can also be equipped with all electronic and hydraulic systems, such as ABS, EDS, ASR, EBV and ESP.
Towing of 4WD vehicles
All-wheel drive vehicles may be towed no more than 50 km at a speed of no more than 50 km/h. Otherwise, towing must be done on a special transporter by fully loading.
Warning: Do not start the engine when towing. General towing instructions are provided in the Introduction.