New gearbox challenge in 2008

After having developed gearboxes that are as accurate as Swiss watches the engineers are taking on a new challenge in 2008: to make them last four grands prix! The Renault team members at Enstone will take the challenge this winter.

The images transmitted by the on-board cameras during grand prix no longer even raise an eyebrow. Twenty years ago they would have had engineers hopping around like demented rabbits! On the screen the cars can be seen lined up on the grid waiting for the lights to go out. When the start is given, the 22 drivers let in the clutch on the steering wheel and press the paddle with their right hand at regular intervals. Each pressure and the car changes up a gear. The driver’s foot mashes the accelerator to the floor. His hands do not leave the steering wheel. In the first corner his left hand is busy; the pressure is accompanied by a quick jab on the accelerator as he downshifts. The scenario is replayed several times per lap, up to 53 times in Monaco which is the highest value of the season. The semi-automatic gearbox caused a major shift in the technological landscape when it appeared in the paddock a little over fifteen years ago.

Nigel Mansell used the first modern semi-automatic gearbox in the history of F1 in the 1989 Brazilian Grand Prix on the Ferrari 640. This type of transmission provided a concrete answer to a problem that was as old as the hills: each time the clutch is disengaged and then reengaged is a period when the power of the engine is not being transmitted to the track. The Scuderia bet on lightning-fast changes to gain several seconds over a race distance, a significant amount. The system invaded the paddock after a difficult debut due to sorting out problems with the hydraulic linkage. The appearance of semi-automatic gearboxes also modified F1 driving techniques in depth. It led to the generalisation of left-foot braking, the disappearance of the clutch pedal and in addition, the driver could keep both his hands on the wheel. It also played a major role in making engines more reliable preventing over-revving or clutch damage. In short, it revolutionised F1.

The system has evolved in the past fifteen years. It is now 100% reliable and is an integral part of F1 technology. Over the last two years it has befitted from some radical developments. The seamless shift, the concept of a gearbox that does not break the torque curve, is the engineers’ latest plaything. The aim as always is to eliminate the slightest power loss in the acceleration phase. The top teams have been using this technology for several months, and they reckon that it gives them a gain of 0.2 to 0.3 seconds per lap compared to conventional transmission. These new generation gearboxes do not tolerate approximation. Their programmes are extremely complex, and the slightest grain of sand in this high-precision mechanism has serious consequences.

The gearbox also plays a determining role in the car’s balance. The complete rear suspension is mounted on its casing: wishbone mounting points, rocker arms and dampers. It must have maximum torsional and flexing stiffness. In addition, as the transmission is at the rear of the car it plays an important role in weight distribution. While the engineers try to reduce its weight to the minimum by using titanium or carbon fibre housings, they affix ballast to its base. The shape of the diffuser also depends on the size of the gearbox. The crushable zone in carbon takes up more and more space at the end of the housings. It absorbs a large amount of energy in the case of a rear-end impact. So today the role of the gearbox is not just for changing speeds.

In 2008, the Federation is pursuing its cost-cutting measures and will oblige the teams to use the same transmission for four consecutive races. In case of an unforeseen change the driver whose car had been worked on will go back five positions on the grid. To ensure that the regulations are respected the gearboxes will be sealed by the FIA. Only the gears can be changed and the replacement parts must be identical. In addition, the teams will have to prove that these have been damaged to be able to put in new ones. It is a question of refining reliability without penalising gearchange speeds. Enstone is getting down to this challenge this winter.

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