RALLY CROSS PROJECT

Rally Cross has the added difficulty of being a competition raced in two completely different kinds of surface. This is what makes it more difficult to adjust a suspension because of two completely different working conditions.

We were lucky to meet Ludo Helven and his team when we were looking for a chance to test our system. Ludo's enthusiasm was contagious, and we started to work in this project in the fall of 2003.

Ludo's car uses McPerson struts front and rear McPerson is the choice for many car manufacturers as one of the best packaging solutions, but for racing this rises some design challenges. For us it was the first time we were building anything else than just a hydraulic cylinder as a wheel suspension element, so we had to design and manufacture from zero a self-guided McPerson strut.

The installation of this system required a complete analysis of the car. We had to carefully measure the vehicle dynamic characteristics such as roll and pitch inertias, so our system could be properly tuned from the beginning. As with our other race projects, we seeked the optimal damping rate that would maximize tire adherence in all conditions. Fortunately for us, the suspension rates of this car were familiar to us. We had been analyzing other rally cars and we knew some of the choices made by rally drivers. Still, the needs in the tarmac areas required enough under steer to gain rear grip that would help to transmit the 500hp onto the road.

The first tests went really well. The test driver preferred a stiffer suspension to gain stability, since it amazingly did not impair the behavior in the off-road areas.

We are now looking for the next tests with some eagerness.

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