The secret to the handling of Vauxhall’s 155mph Astra VXR hot hatch is a German-made Drexler limited-slip differential that’s said to be the first of its kind employed in a production front-wheel-drive road car.
The diff employs circular plates that lock to prevent the 276bhp VXR from spinning away power in corners and over cambers when driving hard. Plate-type diffs have been used in motorsport in front-drive cars since the 1960s, but they usually work with an aggressive action and are difficult to drive.
However, Vauxhall says the Drexler Motorsport unit is very easy to drive. “There is very little snatching of the wheel,” says VXR boss Volker Strycek, a former touring car racer. “We are tuning it so you can hardly feel the operation.”
Strycek has also driven front-drive cars that use torque-sensing front diffs, such as the Ford Focus RS, and says the VXR has much nicer steering. Also helping to reduce torque steer is the VXR’s HiPerStrut front suspension, which decouples the front wheels from the steering axis.
Strycek will personally be pounding the VXR around the Nürburgring from next month as Vauxhall enters the final development phase of the Astra VXR project ahead of its launch this summer.
According to project chief Uli Pfeffer, the new VXR is a big improvement over the outgoing car with more power and performance, a better ride and improved grip.
He says the new bodyshell is 40 per cent torsionally stiffer, which makes for a better platform for the suspension. The FlexRide active dampers also have a wider operating range that allows a comfortable everyday ride quality but much better track performance.
The standard springs are 30 per cent stiffer and the front anti-roll bar has been uprated by five per cent compared with that of the GTC on which the VXR is based. The rear axle is also stiffened. In VXR ‘Race’ mode, the chassis is said to be 50 to 60 per cent stiffer.