Symmetrical All Wheel Drive is 40

Symmetrical All Wheel Drive is 40

Subaru celebrates the 40th anniversary of its signature Symmetrical All Wheel Drive system this year and will mark the occasion with a showcase at next month’s Geneva International Motor Show.

All Wheel Drive was introduced in 1972 on the Leone wagon in Japan. In the ensuing years, Fuji Heavy Industries (FHI), the maker of Subaru vehicles, has refined the technology.

Before the end of the decade Subaru was entering international rallies with its AWD Leone models – most notably the Kenyan Safari. A long period of development culminated in World Manufacturer’s Championships with the Impreza in a variety of models in the 1990s and driver’s titles for Colin McRae, Richard Burns and Petter Solberg.

Closer to home Subaru has been the most successful marque in rallying on both sides of the Tasman with multiple drivers and manufacturers awards as well as winning national and international series around the world over the last 25 years, thanks to the mechanical correctness of Symmetrical All Wheel Drive.

Total production* of Subaru AWD vehicles reached 11,782,812 at the end of January 31, 2012 making up nearly 56% of Subaru’s total vehicle sales.

The AWD system provides optimum traction by distributing engine power to all four wheels in a balanced manner.

AWD combines with Subaru’s flat horizontally opposed Boxer engine to produce a perfectly symmetrical power-train and low centre of gravity – the lack of major components sitting either side of the powertrain results in great balance, stability, response – and the driving dynamics for which Subarus are famed.

Continuous research and development over 40 years has refined the AWD technology, making the system ideal for a wide variety of conditions, from rough roads to rain, gravel mud, sand, snow and ice.

The latest technology includes four-wheel traction management, giving accurate grip to all four wheels, all the time.


Variable Torque Distribution (VTD)-AWD: Electronically controlled sporty AWD for enhanced turning performance
A compact AWD system that combines the centre differential with an electronically controlled hydraulic multiple-disc clutch and Limited Slip Differential (LSD) using the planetary gear. The 45:55 front: rear torque distribution is continuously variable, using a multiple disc clutch LSD. Torque distribution is controlled automatically up to an equal 50:50 front: rear ratio to suit road surface conditions, for superb stability. By distributing torque with an emphasis on the rear wheels, turning performance is enhanced, providing aggressive and sporty driving.

Active torque split AWD: Electronically controlled AWD for enhanced fuel efficiency and stability
Subaru’s original electronically controlled Multi Plate Transfer (MPT) adjusts torque distribution to the front and rear wheels in real-time, to suit driving conditions. The system usually distributes torque 60:40 front: rear. It maximizes the benefits of AWD by providing stability and safety, regardless of the driver’s skill in any driving situation.

Viscous centre differential AWD: Mechanical AWD for manual transmissions
The system is a combination of the bevel-gear-type centre differential and the viscous LSD. A 50:50 front: rear torque distribution is set under normal conditions. It delivers stable and sporty driving that always maximizes available traction.

Multi-mode Driver Control Centre Differential AWD: Performance-directed AWD
The electronically controlled DCCD AWD system employs a combination of torque sensing mechanical LSD and electronically controlled LSD. It provides a performance-oriented 41:59 front: rear torque distribution for optimum vehicle dynamics control. The mechanical LSD has a quicker response and activates just before the electronic LSD. While managing large torque, the system demonstrates the highest balance between agility and stability. There is the choice of automatic LSD control modes and manual mode, which the driver can select according to conditions.

*Including the productions of part-time 4WD vehicles

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