Stanley Subaru

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Ellsworth, ME 04605

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How Does Subaru All Wheel Drive Work? | What is All Wheel Drive? 

First we will discuss facts about Subaru Symmetrical All Wheel Drive, then go over each type of All Wheel Drive, and then discuss the advantages of each type. Be sure to check out the video that explains how all wheel drive works at the bottom of the page.

Facts About Subaru Symmetrical All-Wheel Drive:

  • Designed and engineered into all Subaru vehicles from the ground up. (Except the rear wheel drive BRZ sports coupe)
  • Starts with a longitudinally mounted SUBARU BOXER engine with its inherent balance and symmetry.
  • The transmission, front and center differentials are engineered as a single unit--not added on.
  • Power flows in a linear manner to all the wheels.
  • Driveshafts are equal in length, and the entire powertrain is balanced left to right-it is symmetrical.
  • The system automatically provides power and traction to all four wheels.

2012 Model Year Subaru Symmetrical All-Wheel-Drive Diagram

2012 Model Year Subaru Symmetrical All-Wheel-Drive Systems


Continuous All Wheel Drive is standard on Subaru vehicles equipped with a manual transmission. (Except Impreza WRX STI)

How It Works:

  • Three differentials--front, center, and rear--can transfer power to all four wheels and allow all four wheels to turn at different speeds when cornering.
  • Under most conditions, power to the front and rear axles is split evenly-50/50.
  • Should loss of traction control occur at either the front or rear wheels, more power is progressively transferred to the axle with the wheels that have the most grip to help maintain the 50/50 power distribution.


Active All Wheel Drive is either standard or optional on Subaru vehicles equipped with a four- or five-speed electronic automatic transmission as well as the Lineartronic Continuously Variable Transmission.

How It Works:

  • The system is designed to send most of the power to the front wheels.  However, there is always some power going to all four wheels.
  • An electronically controlled clutch pack within the transmission (acting as a center differential) allows the front and rear axles to turn at different speeds when cornering.
  • Since the clutch pack also varies the amount of power sent to the front and rear axles, it acts as both a slip-limiting device and a center differential.
  • Should traction loss occur at either the front or rear wheels, more power is progressively transferred to the axle with the wheels that have the most grip.
  • Power split varies based on electronic inputs measuring different driving conditions.

Variable Torque Distribution (VTD) All Wheel Drive

Variable Torque Distribution All Wheel Drive is a performance-oriented system with more of a rear-wheel bias.  It is standard on all Subaru models equipped with a five-speed electronic automatic transmission.

How It Works:

  • This sophisticated AWD system combines the hardware of both an electronically controlled clutch pack and a planetary gear set center differential.
  • Any changes in vehicle dynamics (such as weight transfer) can affect the front-to-rear power split which is varied via the Transmission Control Module which controls the multi-plate clutch pack.
  • This system works automatically, providing the optimal distribution of engine power for dry, wet and slippery road performance.
  • It provides a 45/55 front-to-rear performance bias.

Variable Torque Distribution (VTD) All Wheel Drive with Driver Controlled Center Differential (DCCD)

VTD All Wheel Drive with Driver Controlled Center Differential (DCCD) is standard only on the Impreza WRX STI. It is an ultra-high-performance system that adds both automatic control (based on multiple vehicle inputs) and manual control (based on driver input) of the center differential.

How It Works:

  • This system starts with a 41/59 front-to-rear power split and has the capability to allow the driver to tailor the system's operation to a particular driving situation.
  • DCCD has two operation modes--automatic and manual.  In the automatic mode, based on electronic input, the computer controls the optimum front-to-rear power split. In manual mode, the driver can progressively vary the power split or even lock the system into a 50/50 split for specific driving conditions.


These All Wheel Drive Systems are available on display in our showroom here at Stanley Subaru. We have examples of each system in 3-D form so that further understanding of the complicated systems can be understood. For more information on the different types of All Wheel Drive systems, ask any one of our highly knowledgeable sales consultants!


Jeanne Dennison
Thank you, I am happy to help. Please let me know if there are any other topics or questions you would like to see addressed. Have a great day! --Jeanne for Stanley Subaru.
Post Follow Up
Philip Marmaros
Regarding the 2014 Forester MT vs. CVT.
I'm still confused about the two systems. Which one would give me the best planted feeling when driving at thuway speeds
Post Follow Up
Paul pius
The information mentioned in it was helpful.Thanks for the info.
Jeanne Dennison
Service Manager and in-house "Stig" Neil Harriman says: "I would answer that both would give the same feeling. If your old school and like to shift manually then go with the 6 speed. Remember though, even with a CVT you can change gear manually with paddle shifters and the CVT gets better gas mileage." 
Dan Lors
Center diff explained well enough to figure out, but what is used in the front and rear diffs to direct torque? Are they open, limited slip, locking, air locker, detroit locker, electronically controlled clutches, etc? Explanations I've read so far only say it is done - I'd like to know how it's done.
Paul Axford
I think you'll find that most modern AWD vehicles have a multi-plate clutch as described but do not use a viscous fluid any more. They are now electrically controlled via a smaller magnetic "slave" clutch driving a ball and ramp mechanism that compresses the main clutch relative to the amount of current. Functionally they are similar to the Subaru "Active" system.
FORESTER xt auto. Fully loaded at back - heavy sand, is it normal that front wheels spin and not rear wheels?
Spencer Patterson King
Hi, Johann,

Because symmetrical all wheel drive shifts power to where the wheels have traction, rear wheels slipping is most likely because of a loss of grip on them. You can turn off traction control if it happens again and see if that helps, but if you've got good tires on a good surface and you're still not getting power to the rear wheels, you may want to get it checked.
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