Six Star Magazine Six Star Magazine Autumn 2007 | Página 5

NEWS

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safety update

Subaru Celebrates 35 Years of Symmetrical All-Wheel Drive

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In 1972, when most automobile manufacturers were shifting their focus
from rear-wheel drive to front-wheel drive technology, Subaru was already
way ahead of the game.
At the time, the company’s engineers realized that distributing power
to four wheels instead of just two – regardless of whether they’re
the front or the back wheels – could create more predictable handling and
improved safety in all weather conditions. It would take most of the industry
about 30 years to arrive at this same conclusion.
Starting with a blank sheet of paper, the engineers designed a simple all-wheel drive (AWD) layout
that is still used to this day: a drivetrain that uses a horizontally-opposed engine in front, connected
to a front differential, then a transmission, a transfer case and a rear differential.
All of these components were arranged symmetrically along the centreline of the vehicle, thereby
inspiring the term “Subaru Symmetrical All-Wheel Drive”.
Since that time, many refinements have been made to this AWD system – refinements that have
kept Subaru at the very forefront of design and engineering. What follows is a brief overview of the
major developments that took place along a 35-year path of leadership.
1972-1986 – All Subaru vehicles are front-wheel drive
with on-demand AWD. A lever or switch (depending
on the model) is used to engage the rear wheels for
more traction.
1987 – The Subaru XT6 and the RX are the first
vehicles with a full-time AWD transmission. A manual
transmission with an open centre differential distributes
torque evenly between the front and rear wheels
(50/50) and is locked with the touch of a switch.
1988 – The 4-speed Electronic
Automatic Transmission (4EAT),
the first true Subaru AWD
transmission featuring
computer-controlled
torque transfer to the rear
wheels, is introduced. The
system will maintain power
distribution between front
and rear wheels at 60% / 40%
using input from throttle
sensor, vehicle speed and
wheel slippage.
1989 – The first
Subaru Legacy brings
improved versions
of the manual
and automatic
transmissions. A
new AWD manual
transmission equipped
with a viscous-coupling
centre differential eliminates
the need for the driver to lock

(Not all 2008MY vehicles have been tested to date.)

5-Star Crash Rating‡
National Highway Traffic Safety Administration’s (NHTSA’s)
New Car Assessment Program (2008 Model Year)

Top Safety Pick*
Insurance Institute for Highway Safety
(2007 Model Year)

Good Rating†
Frontal, Side & Rear
Insurance Institute for Highway Safety
(2007 Model Year)

the differential manually. The 4EAT features a revised
AWD electronically-controlled multi-plate transfer clutch
that better controls torque transfer to the rear wheels.
1995 – Subaru leaves the front-wheel drive arena to
focus on AWD exclusively.
2000-2001 – The automatic transmission in the
Subaru WRX and H6 engine brings Variable Torque
Distribution (VTD) to Canada. This system uses
planetary gears as opposed to a transfer
clutch to transfer torque to the wheels;
torque split is set at 45/55 for
more sporty driving.
2003 – The 6-speed manual
transmission debuts in the
Subaru WRX STI. With its
Driver Controlled Centre
Differential (DCCD), the driver
can choose the torque split
manually or allow the computer to
do all the work automatically. A
true wonder of automotive
engineering.
2004 – The 5-speed
Electronic Automatic
Transmission with
SPORTSHIFT™
(5EAT SS) is introduced
featuring VTD and the
ability for drivers to
choose between three
different drive modes –
Economy, Sport and
SPORTSHIFT™.

So, after 35 years of evolution and continuous refinement, Subaru now has an AWD system
suited to every driver’s needs. The multi-plate transfer clutch system is front-wheel drive biased
for safety and predictability, while the 6-speed DCCD manual transmission used in the STI
makes every trip a thrilling one. This approach translates into a better experience behind the
wheel for every driver in all kinds of driving conditions.

5-Star Crash Rating‡
National Highway Traffic Safety Administration’s (NHTSA’s)
New Car As ͕