The traction control ban, chapter 1
Since the last test session in Barcelona, the cars have been running without traction control in view of the 2008 season. It is a major revolution for the engineers who were used to setting up the cars in accordance with this system that had become increasingly refined as the years passed. For the drivers too it is a radical change. They will have to rediscover what it means to have an educated right foot, as well as becoming accustomed to adopting a different approach to setting up their cars.
The concept
Over the years since the FIA decided to free up electronics in the mid-nineties, the traction control system had reached a level of sophistication hitherto unknown in the world of the motorcar. This technology was born from something that is difficult for the non-specialist to grasp. To enable a car to go as quickly as possible the tires must have a minimum rate of slippage in relation to the track. In such conditions the vehicle transmits more load than when it slides a lot, or not at all. The rate is around 5 to 6%. To sum up when a car is moving at 100 km/h its rear wheels have to turn at 105 km/h to generate maximum performance. The term traction control best describes this system, because while it does not eliminate wheel spin, it limits it to its optimal value.
Goodbye to a state-of-the-art technology
For years the ING Renault F1 Team’s engineers worked on programming a system that generated the optimal rate of traction for the rear wheels whatever the conditions: straight, corners, grippe or slippery surfaces, high or low track and tire temperatures, high or low down force etc. To do this they created a system that measured the speed of the front wheels’ (which not being driven cannot spin) rotation very accurately. Using this information they were able to deduce the optimal speed of the rear wheels. The next stage was to model mathematically with the help of the equations, the car’s handling, and the type of compound used as well as the track surface. When this information was fed into the ECU it was capable of calculating the amount of traction for each rear wheel at any given moment. The engineers’ trickiest job in this process was to model the tires’ behavior perfectly. The result: when the car was accelerating the on-board electronics let the engine develop its full power until the sensors picked up the first signs of spinning (101% of the speed at the rear in relation to the front wheels). By playing with the engine’s throttle, ignition and injection in pre-defined sequences, the traction control system allowed the wheels to attain 5% slippage and then maintained that figure. In case there was a difference between the slippage on the right or left-hand wheels, it was corrected by acting on the differential. It meant that the driver could press the accelerator as soon as he reached the apex without asking himself any questions. The power that arrived was always perfectly adapted to provide the rear wheels with maximum grip under reacceleration.
And now?
It’s all change in 2008. The link between the driver’s foot on the accelerator and the throttle response must be direct. So it is impossible to play on the power developed by the engine. This new factor will have several consequences. First of all, the drivers will lose a few tenths over a lap and some may have more problems than others mastering their cars. The set-ups will be different and the cars will certainly understeer more than in 2007, as the teams opt for caution and try to avoid spins. Tire wear could also pose a problem in certain conditions. Finally, if a car is badly set-up the lack of traction control will only magnify the problem.