With winter showing its ugly face early this year, more than ever, buyers are scrutinizing the available all-wheel-drive systems. Which are the most interesting, efficient, reliable, etc.?
The SH-AWD system debuted in 2005
The RL sedan was the first to get it
The system is now in its fourth generation
Acura offers the SH-AWD (Super Handling All Wheel Drive) system. Let’s see what makes it unique.
20 Years Already
SH-AWD first appeared in 2005 with the RL sedan. The system was an evolution of all the other AWD technologies previously developed by Honda, whether it was the ATTS (Active Torque Transfer System) on the 1997 Prelude Type SH or the VTM-4 (Variable Torque Management) that equipped the MDX SUV in 2001.
2005 Acura RLThe first used two electronically controlled clutches to send up to 80% of engine torque to the outside wheel during cornering, significantly reducing understeer. With the second, drivers benefited from automatic torque distribution to all four wheels, as needed.
The SH-AWD system combines the advantages of both systems. In fact, it became the first all-wheel-drive system to integrate active torque vectoring (sending more power to the wheel that needs it in real time).
How the SH-AWD System Works
At the heart of the SH-AWD system’s operation is intelligent power management. Up to 70% of engine torque can be directed to the rear wheels, and this force can be fully distributed to a single wheel, left or right. This is achieved through a torque-transfer unit mounted at the front rather than a traditional center differential.
Two hydraulically controlled clutch packs (one for each rear wheel) manage torque distribution. An electric motor powers a hydraulic pump for each pack, enabling precise, rapid power distribution. The system constantly analyzes multiple parameters such as steering angle, lateral forces, wheel rotation speed, yaw rate (left-right rotation), etc. By analyzing this data, the SH-AWD system optimizes torque distribution in real time.
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The system even offers an interesting and unique subtlety: rear-wheel over-acceleration compared to the front wheels. At around 2.7%, this faster rotation allows the rear to dance slightly, which relieves the front wheels of some steering work, improving cornering precision. Simply put, with the rear axle rotating slightly and deliberately, fewer corrections are needed to position the front wheels, reducing the load on them.
Effective Under All Road Conditions
The system is most efficient during winter driving conditions, but it’s effective under all road conditions. It’s especially true in wet conditions, where active distribution to the rear wheels provides better road contact. In heavy snow, as we’ve seen, distribution is optimized between left and right, for constant grip.
And if life takes you off-road, you’ll see that even with one wheel off the ground, grip is maintained, thanks to torque distribution.
In short, if Acura vehicles are known for offering precise, reassuring driving, they largely owe it to the SH-AWD system, now in its fourth generation. Behind the wheel, it truly inspires confidence.
