How does subaru symmetrical awd work

VTD for automatic transmissions Recently, the automaker has made a move to switch from standard torque-converter automatic transmissions to continuously variable transmissions CVT for most of its vehicles, but there are a few holdouts. The six-cylinder Legacy, Outback, and Tribeca bearing the 3. In this case, the nominal torque split is a rear-biased default, ditching the viscous center diff in favor of a hydraulic multiplate clutch in combination with a planetary-type center differential.

When slip is detected, based on input from sensors measuring wheel slippage, throttle position, and braking force, the electronically controlled clutch can lock down at front-to-rear split where maximum grip is required. Where the purely mechanical viscous differential is simpler and possibly more flexible, VTD's electronically controlled system has the advantage of being proactive rather than reactive -- shifting torque between the axles more quickly than the mechanical system can.

The hardware is similar to the VTD system described above -- both use electronically controlled multiplate clutches to control torque split -- but the CVT-equipped system defaults to a front-biased nominal torque split.

This system makes use of two center differentials. One is electronically controlled and grants the Subaru's computer fine control over the front-to-rear torque split. The other is a mechanical unit that is capable of reacting more quickly to stimuli than its electronic counterpart.

Drivers benefit, ideally, from the best of both the electronically proactive and mechanically reactive worlds here. How does Subaru's system actually work? Jason Fenske of Engineering Explained is here to tell us just that, and he breaks down how all four of Subaru's all-wheel-drive systems function. That's right, not all AWD systems from Subaru are created equally.

Cars with continuously variable transmissions receive a specific type of system, while those equipped with a manual transmission use a different setup. The first system is the Viscous Center Differential. The second is likely the one most consumers will be acquainted with: the Active Torque Split system. The clutch pack found in the all-wheel-drive system is designed to allow for some slip, but if traction begins to falter on a certain axle, the system locks the clutch pack, applies more pressure, and sends more torque to the wheels that need it.

What makes the second system "active" is the fact the system communicates with other vehicle sensors to understand if a situation requires more torque at a certain wheel. Now, let's get to the sporty stuff. A center differential, clutch pack, and a transmission control module all work in concert—sort of like the Active Torque Split system—to send power to the wheel most in need. The holy grail of Subaru all-wheel-drive systems is, hands down, the Driver Controlled Center Differential system.

It's exclusive to the WRX STI, and it uses a planetary style and mechanical limited-slip differential and an electronic differential. It sends most of the torque to the front wheels, although yes, the rear wheels are always equally driven. An electro-hydraulic multi-plate clutch sends the necessary power from front to rear as needed.

Subaru's performance-oriented models are equipped with variable torque split all-wheel drive. This feature is available on models with turbocharged engines. Torque distribution slightly favors the rear for a sportier feel. Subaru's all-wheel drive system adds an extra dose of confidence in all conditions. It's a key feature for anyone who wants to travel safely at all times, but especially in winter. Service Appointment.