ENGINE TORQUE DISTRIBUTION – DIRECTING THE FLOW OF POWER

In an all-wheel-drive vehicle, engine power can be directed to all four wheels. Subaru Symmetrical AWD differs slightly from model to model in how it directs power to the wheels, depending on its transmission.

MODELS WITH FIVE-SPEED MANUAL TRANSMISSION – CONTINUOUS ALL-WHEEL DRIVE:

A viscous-type locking center differential and limited-slip rear differential help distribute torque – normally configured at a 50/50 split front to rear. If wheel speed differs between front and rear axles, the center and/or rear differentials lock up to help distribute power to the wheels with the most traction.

MODELS WITH FOUR-SPEED AUTOMATIC TRANSMISSIONS – ACTIVE ALL-WHEEL DRIVE:

An electronically controlled variable transfer clutch and limited-slip rear differential distribute power to where traction is needed. Sensors monitor parameters such as wheel slippage, throttle position, and braking to help determine torque distribution and direct it to the wheels with optimum traction.

MODELS WITH FIVE-SPEED AUTOMATIC TRANSMISSION – VARIABLE TORQUE DISTRIBUTION ALL-WHEEL DRIVE:

As with Active All-Wheel Drive, an electronically controlled variable transfer clutch distributes power, but through a planetary-type center differential and a viscous-type limited-slip rear differential. Torque distribution is normally configured at a performance-oriented rear-wheel-biased 45/55 split front to rear. Sensors monitor the same parameters as for Active All-Wheel Drive.

WRX STI, WITH SIX-SPEED MANUAL TRANSMISSION – DRIVER CONTROLLED CENTER DIFFERENTIAL (DCCD) ALL-WHEEL DRIVE:

 The STI uses an electronically managed multi-plate transfer clutch and a mechanical limited-slip differential in conjunction with a planetary-gear-type center differential to control power distribution between the front and rear wheels. Featuring manual and three automatic modes, DCCD is normally configured at a 41/59 split front to rear. Sensors monitor parameters such as wheel slippage, steering angle, throttle position, and braking to help determine torque distribution and direct it to the wheels with optimum traction. DCCD also features a limited-slip helical front and Torsen^® rear differential.

BALANCE FOR CONTROL

For safety sake, drivers don’t want any surprises from their vehicles when they’re on the road. Having a balanced vehicle that delivers power to the wheels with the greatest traction contributes to driving control. At the same time, this is the type of control that makes a Subaru fun to drive, which is demonstrated by the success that Subaru has had in rally and road-racing championships around the world.

Symmetrical AWD provides safe, predictable, fun-to-drive Subaru vehicles.

SUBARU SYMMETRICAL ALL-WHEEL DRIVE Boxer engine. Lightweight, compact, lower center of gravity Linear power flow to all wheels Powertrain balanced left to right Drivetrain engineered as a single unit – not added on		TRUCK-BASED 4-WHEEL DRIVE Requires power to flow through several 90° turns Extra parts, extra weight Often part-time 4WD, requiring driver intervention		ALL-WHEEL DRIVE ADAPTED FROM FRONT-WHEEL DRIVE Requires power to flow through several 90° turns to the rear wheels Often front-wheel drive until wheelspin is detected		ALL-WHEEL DRIVE ADAPTED FROM REAR-WHEEL DRIVE Requires power to flow through several 90° turns Raised center of gravity, extra weight Often rear-wheel drive until wheelspin is detected