Quattro: description, features, and operating principle

Quattro: description, features, and operating principle

Quattro is a permanent all-wheel drive system which has been installed on Audi cars with transverse engine layouts. It first appeared in 1980. Today it is offered as standard or as an option for most Audi models. Quattro makes it possible to improve a vehicle’s off-road capability on cross-country terrain and improve its dynamics.

How Quattro works

The key components of the system are:

  • A gearbox: it adjusts the engine torque according to the selected driving mode and transfers the torque to other parts of the transmission.
  • A transfer case with a central differential: it distributes the engine torque between the front and rear axles.
  • Drive gears: they increase the torque transferred to the wheels.
  • Cross-axle differentials: they distribute the torque between the left and right wheels.
  • A drive shaft: it connects the transfer case and the rear drive gear.
  • The front drive shaft: it transfers the torque from the transfer case to the front main gear.

Most Audi models use a Torsen or crown gear self-locking differential as the central differential. In normal driving conditions, the engine torque is distributed between the front and rear axles at a ratio of 40:60. If a wheel starts to slip, most of the torque is transferred to the axle which has better traction. The torque ratio between the front and rear axles can be, for example, 15:85, 20:80, 80:20, 70:30, or 75:25.

Quattro features

System generation Differential type Production year Audi models equipped with this system
Inter-axle Rear axle Front axle
I Open with mechanical lock-up Open with mechanical lock-up Open without lock-up 1981 Quattro 85; 80 B2; Coupé 81, 85
II Symmetrical, self-locking Torsen Т-1 1988 100 C3 44, 44Q; 80 B4 8C2, 8C5; 90 B3 89, 89Q, 8A; S2 B4; A6 C4 4A5
III Symmetrical, Self-locking Torsen Т-1 1988 V8 441, 442, 4C2, 4C8
IV Open with electronic lock-up 1995 A4 B5 8D5; A6 C5 4B5; A8 D3 4E2, 4E8
V Asymmetrical,self-locking Torsen Т-3 2006 RS4 B7 8ED; S6 C6 4FH
VI Asymmetrical, self-locking, crown gear 2010 RS5 8T; A7 4A, 4G

Typical Quattro malfunctions

  • Differential gears wear out quickly.
  • Universal-joint crosses can be damaged due to driving on rough roads.
  • ABS sensor failure causes the electronic differential lock to malfunction.

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