'Disastra' Spec 1: Simplify, Add Lightness
Whilst seriously capable on the street, the Astra H VXR has a few key areas that would benefit from improvement when it comes to dedicated track duties.
Within hours of picking up our car, we set about tearing weight out of it – starting with the interior. Clubman class regulations mandate that the midline of the interior – the dashboard and door cards – remains intact to retain a ‘road car look’, whereas the floor and ceiling are free to be stripped.
Out came the headlining, carpets, sound deadening and airbags. The heavy and luxurious VXR leather seats were stripped out and a Safety Devices half-cage took the place of the rear bench. Lightweight seats and harnesses went up front.
Next, we turned our attention to the exhaust – the regular system was too restrictive for track duties. It stifled the turbocharged engine and couldn’t be heard through the heavy insulation of a racing helmet. Critically, this meant the engine wasn’t providing any aural feedback to the driver. We resolved these issues with a 3” turbo-back system with a single rear silencer. As proven on our dyno, the exhaust upgrade released some extra horsepower from the engine and gave the VXR a musical note that’s loud enough to hear through the helmet, but without failing circuit noise tests.
The chassis was next to receive upgrades – we beefed up the engine and gearbox mounts, fitted uprated springs and shocks, and fitted Whiteline’s adjustable rear anti-roll bar. The upgraded anti-roll bar allows for quick adjustments to fine-tune the car’s turn-in and handling balance and is extremely effective at adapting the car’s handling to weather and tyre conditions.Additional touches throughout the car – removing the rear window washer, cutting away brackets and so on, helped drive the weight further down. As class regulations stipulate that all original body panels must be retained, again to keep the ‘road car’ connection, obvious weight-savers like composite panels weren’t a route we could go down, so we had to get creative with where to cut weight.
The Vauxhall's factory-spec M32 gearbox was next to receive some love - although it had to remain largely original to satisfy Clubman rules. We fitted Gizfab’s breather tank, which helps the gearbox stay cooler while on track.
When running on standard power, it’s essential to be able to maximise time spent on the throttle, which means shortening braking distances. Our VXR uses grooved disc brakes, racing brake fluid, braided brake lines and Ferodo DS2500 pads to provide its stopping power.
What does the future hold after Time Attack’s 2017 summer break? Watch this space for 'Disastra' Spec 2…Halfway through the season, armed with our VXR in a mild trackday / ‘fast road’ specification, we’ve punched well above our weight, regularly finishing on the podium and leading sessions, and defeating larger, more established teams.