GKN Automotive’s Senior Vice President of Engineering & Technology, Dr Ray Kuczera, discusses how the Ford Focus RS AWD system has taken drivelines into new territory.
The new Ford Focus RS uses a GKN all-wheel drive (AWD) system with a Twinster twin-clutch system. This was not the first application of the technology – the Range Rover Evoque had already proven Twinster off-road and in production – but the Focus RS took it into new territory, revealing how much power torque vectoring could deliver to a brand’s marketing.
Twinster can apply torque to one or both wheels independently, enabling dynamic torque vectoring functions across a vehicle’s entire speed range. The Twinster in the Focus RS uses new gearing ratios that deliver more torque to the rear wheels. When AWD is engaged, the Twinster drives the rear wheels faster than the front. Read the original news release.
Over-speeding the rear wheels alters the way the car feels and handles. In curves, the Twinster makes the vehicle turn in more sharply, responding more immediately to the driver’s inputs. And in Ford’s drift mode, the AWD system delivers even more torque to the rear axle, delivering enough torque to the rear wheels for the RS to achieve a controlled “drift” through corners.
GKN Automotive’s software contains a unique subsystem that modifies the torque controls in ways that make it easier to induce on-throttle over-steer and then maintain side-slip angle while counter steering. Creating the desired yaw behaviour is a combination of calibration changes that modify the level of torque applied, how quickly it gets applied, and how much difference is created between the inner and outer rear wheels.
Until the Focus RS, most vehicles used the brake system to achieve a kind of simple vectoring effect. The way the RS uses Twinster to deliver purer performance and feel put a spotlight on the difference fully dynamic torque vectoring offers.
AWD is becoming the driveline of choice for performance cars. It is just the most effective way of putting power onto the road. The Focus RS used GKN Automotive technology to demonstrate vividly to consumers how innovative drivelines are rewriting the rules.
Unsurprisingly, there is now a lot of interest in pairing Twinster with our eDrive systems. We believe the legacy of the Focus RS could be a new generation of hybrid vehicles that use torque vectoring to unlock their full potential.