Meeke rates Finland as his best yet
Briton took third-place-finish on gravel
How to: Change to an asphalt set-up
After six rallies on gravel, the WRC switches to the all-asphalt ADAC Rallye Deutschland this week, and conditions that require some serious set-up tweaks to the World Rally Cars.
But with manufacturer teams limited to just six chassis per season for their two crews, there is no chance of building a specific body shell for the WRC’s three tarmac rounds. Instead, teams use the same basic car all season but swap a number of components to make it more suited to a race track than a gravel track.
Didier Clément, Citroen Racing chief operations engineer, explained the differences between his gravel and asphalt specification DS3 World Rally Cars:
Suspension. “The main difference is that the asphalt car is lower all round by around 100mm. The suspension is much stiffer too, with shorter, narrower springs and thicker anti roll bars. We also reduce the amount of suspension travel because while on gravel you need longer travel to absorb the bumps and maintain traction, it’s not a problem on asphalt. We also fit lighter weight components, including shock absorbers, suspension arms and tie-rods.”
Protection and diffs. “Because the road surface is smoother, we remove a lot of the car’s under chassis protection. The aluminium shield under the engine stays, but to save weight we take off most of the plastic protection that usually protects the chassis from big stones and gravel. We also adjust the mechanical differentials, making them more aggressive to optimise the balance of the car on asphalt.”
Brakes. “On asphalt the car has much more grip than on loose surfaces, and the style of braking is later and more aggressive. To cope, we increase the diameter of the front discs from the 300mm gravel units to 355mm. We also fit water-cooled callipers on the front. We are able to water cool the rears too, but Kris and Mads are very smooth on the brakes and we don’t need the extra cooling. We also fit a different master cylinder that makes the brake pedal much stiffer. The drivers prefer this sort of pedal feel for tarmac.”
Wheels and tyres. “These are bigger on the asphalt spec car. On gravel rallies the usual is a 15-inch wheel with 215mm wide tyre. In Germany we’ll use 18-inch wheels with 235mm wide Michelins.”
