Mercedes finds cause of gearbox failures

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Mercedes F1 chief technical officer James Allison is confident that his technical team has found the root cause of the German-Anglo squad’s recent gearbox failures and can make the necessary changes to avoid its reappearance.

Mercedes experienced technical issues with its gearbox over the last race weekends. Lewis Hamilton had to start the Austrian GP with a new gearbox while Valtteri Bottas got a new unit for the following race weekend at Silverstone. Both unscheduled changes triggered grid penalties.

The team’s engineers found damages to the gearbox after the Azerbaijan GP and were analyzing whether the units could survive the coming races. However, as the risk of a retirement would have been too high, the team decided for a change. F1 gearboxes has to complete six consecutive races.

James Allison, technical director of Mercedes, disclosed his team was too aggressive with its latest gearbox solution as it sought desperately for the tiniest of improvement in the fierce battle with Ferrari. Mercedes will revert to a less aggressive and therefore less risky gearbox for the coming races.

“In the old days, you’d be in a gear, then you’d be out of a gear and then you’d be in another gear and you’d just lose drive all the time that the gears were in transit from one to the other,” he is quoted by

“In a seamless shift you are in one gear and then the next one takes over instantly - so there isn’t a loss of drive. However, if you imagine the gearbox, when you are shifting up, it’s spinning at a high speed in a lower gear, then you want to upshift the box, all that rotating inertia has to slow down to meet the next gear."

"So seamless though it is, there is still an amount of spinning stuff that needs to be slowed down to meet the next gear,” concluded Allison.

Why to use seamless gearbox?

Formula One has been using seamless gearboxes for many years. The seamless technology meant a huge step forward at its inception and drivers instantly gained around two-three tenths depending on the nature of the given track.

Engineers started looking for ways for “seamless” gear changes because they recognized the valuable time lost while changes from one gear to the next one. Because of the speed of the differential, the power has to be interrupted while the dogs disengage from one set of gears and bind with the next.

Those interruptions were not only a problem because power wasn't being sent to the wheels, the aero drag is so great that the car is actually decelerating. Formula One cars produce much higher drag then street production cars.

Other series and even production cars started exploring the benefits of seamless gearboxes. MotoGP saw the first use of it in 2013 when the Honda MotoGP Team introduced it.