Korean GP: McLaren rules out Jenson Button gearbox issue

The Briton complained of gearbox trouble during the Suzuka race, with the team initially suspecting that the matter was related to an overheating sensor.

A thorough investigation by McLaren after the race confirmed that there was indeed nothing wrong with the actual gearbox.

So although McLaren has the option of using a fresh gearbox from this weekend, because the unit it used in Japan was a 'replacement', it has decided to stay with the old one.

"We could have done a new box, but we will keep the Japan one," said McLaren technical director Paddy Lowe.

Speaking about the exact cause of the problems that Button encountered, Lowe said: "One corner had overheated quite badly due, we think, to a blockage [probably caused by rubber debris].

"We always get the highest temperature in the pitstop anyway with the lack of cooling and heat soak, and there is an item in there which is a HIU [Hub Interface Unit] - which is a small computer used to process local sensors.

"That had overheated in the pitstop, so for a couple of laps after the pitstop, before it had cooled down again, it was issuing erroneous signals.

"This caused slightly less than optimal shifts. But there was no impact on the mechanical side of the box."