JUNE 29, 1998
McLaren's contractive suspension system
Motor racing historians will remember that Bianchi is one of two Belgian brothers who raced with some success in the 1960s, although his late brother Grand Prix driver Lucien Bianchi - who was killed in 1969 while testing an Alfa Romeo sportscar at Le Mans - is better-known.
Bianchi tested an Alpine F1 prototype back in the late 1960s but his career was cut short by a dreadful accident at Le Mans in 1968 when he was racing a Renault sportscar. He suffered serious burns but recovered to start up an engineering business, specializing in advanced suspension designs.
Bianchi has been involved in research with McLaren in recent years although the current suspension being used by the team does not appear to be the same as his design, although McLaren is so protective of the system that it is difficult to know exactly what is involved.
Our sources, however, suggest that similar systems are to be found on the McLaren F1 cars and on the Mercedes-Benz GT sportscars.
Contractive suspension is a revolutionary concept which is claimed to be dramatically more efficient than traditional linear and variable rate suspensions. These systems are, in effect, a compromise between the need to absorb vertical shocks and to avoid pitch and roll movement. The best compromise has traditionally been spring/damper units which are linked side-to-side by anti-roll bars. The new contractive suspension does away with the need for anti-roll bars as it separates the compression of a spring from the rebound, making each wheel more independent. The rebound is made less dramatic by the use of a second spring which is used in opposition to the main one. The compression travel uses only the main spring stiffness, while rebound travel uses the sum of the stiffness of the two springs, which means that the rebound is around three times stiffer.
In practical terms this means that the cars ride bumps in a much more stable fashion which in turn increases the efficiency of the car to give better braking, better exploitation of the tires and improved traction over bumps. It also lowers the centre of gravity under lateral and longitudinal acceleration.
The system can be modified to suit different surfaces by changes to the static position of the car with different spring combinations.
We believe that rival teams are already working on such systems although the fact that the McLaren system has been so easy to hide has made it very difficult for rivals to get a clear picture of how the systems work. McLaren has complained several times to other teams, having found spies inside its garage trying to spot the secret of the suspension.