The new Porsche 911 GT3 is packed with technology, but one of the most interesting aspects is this active rear-wheel steering.
Active rear-wheel steering/four-wheel steering is perhaps best remembered on the Honda Prelude of the late 1980s. In typical Japanese style, the effects were overly obvious, so I remember the Prelude as curious to drive, but the Honda’s mechanical 4WS system (below) was much vaunted by one of my favourite motoring writers (and noted Porsche hater), LJK Setright. BMW used the system on the 850 CSI, and it is still found on current 5-series.
Porsche patented a form of passive rear-steer on the 928, with its famous Weissach Axle, but active is a whole new ball game, made easier by the introduction of electric power steering. Active rear wheel steering has been added “to achieve higher precision and lateral dynamics”. Depending on the speed, the rear steers in the same or opposite direction of the front wheels, improving stability and agility.
Other new modules to improve dynamics on the 991 GT3 include a fully variable electronically-controlled rear diff lock (sounds very very trick), and the dynamic engine mounts. The 20-inch forged alloy wheels with centre locks are also new.
Based on the light, yet stuff aluminium body of the current 911, the 991 GT3 is 44 millimetres wider than a 911 Carrera S across the rear axle. Porsche says that the fixed rear wing makes a decisive contribution to the ‘exemplary’ aerodynamics of the new 911 GT3, which combines low air resistance with even more power.
That’s about as much as I can say on new 991 GT3 tech until we get some cutaway drawings from Stuttgart – normal service is henceforth resumed! I will blog about the 928’s Weissach axle, as that is quite interesting.