Subaru AWD - the Best or average?
2015 Subaru Forester
Symmetrical AWD.....what is it?
We've all heard the marketing Spiel. Anyone with a TV has heard time and again Subaru ads bragging about their "symmetrical AWD" system.
But what exactly is it.....and why is it so "great?"
Subaru's system has established itself as one of the best AWD systems available and it's same basic design has been in use for over 20 years.
Interestingly, Subaru's symmetrical AWD is very unique.
Traditional AWD systems - and 4wd systems for that matter (i.e. from Ford, Jeep, GM, .Etc) rely on a transfer case located just aft of the transmission that has one input drive shaft and two output drive shafts, one of which being off-center in order to drive the front differential.
This can be seen when looking underneath a traditional Jeep or Ford system.
This arrangement forces one front axle half-shaft to be shorter than the other, resulting in what Subaru calls an "asymmetrical" layout.
According to Subaru this layout makes it difficult for the AWD/4wd system to efficiently transfer power from the wheels without traction to the wheels with traction.
Subaru supposedly solves this problem by employing a totally different layout; equal length half-shafts between the left and right axles, both front and rear.
To help split the power between the front and rear drive shafts Subaru's layout uses a viscous center differential for manual transmission models (clutch-pack non-differential for automatic models) located aft of the transmission which keeps the differential output shaft to the front of the vehicle exactly in line with the output shaft going to the rear of the vehicle.
This allows the front differential half-shafts to be of equal length, thus creating a "symmetrical" AWD system. Subaru claims this arrangement allows a faster and more efficient transfer of power to wheels with traction.
Anyone who owns a Jeep or other 4x4 with a traditional transfer case has seen this happen; since the front axle half-shaft on the left (as seen from the driver's seat) is shorter than the one on the right, the left wheel tends to spin first when in 4wd. Similarly, the two wheels that first lose traction are usually the left front and the right rear.
Subaru's system seeks to eliminate this making sure that when appropriating traction to various wheels the AWD system does not have to overcome the "disadvantages" off a traditional system with unequal length half-shafts.
The AWD system is really good. Learn to drive it to take advantage of its strengths and it will pull through many situations.
Momentum is key. The system works best in assisting the driver to maintain momentum when moving through Mud and Snow as well as up-and-over rocks. My system ensures an ALMOST continuous 50/50 split between the front and rear drive shafts. Wheel braking is also included. When one wheel slips the ABS motor kicks in to apply braking force to that wheel to transfer power to the opposite wheel driven by the same differential (as Subaru used to say, from the wheels that slip to the wheels that grip).
I routinely use this car to cross streams to my favorite secluded place and also love to drive snow-covered trails. This crossover goes anywhere that my Liberty goes and does so almost as easily.
Subaru symmetrical AWD used to be the "prince" of AWD systems (Audi' Quattro being the King!) but that was about 20 years ago when most manufacturers offered AWD as a rare and more expensive option.
Fast forward to today whereas Subaru's fiercest competition comes in the likes of Ford's Intelligent AWD, Nissan's Intuitive AWD, and Honda's Real Time AWD, and Subaru has some very fierce competition.
So this begs the question.....does Subaru really have a point when it comes to their "Symmetrical" AWD?.
Subaru's AWD systems are still superior as compared to other vehicles but only by a slim margin. Subaru can still market their Symmetrical AWD (quite well) but they had better focus on other attributes as well so they can dominate the market.