Mercedes details reasons for Bottas' botched pitstop

Mercedes says a "misplaced" wheel gun caused Valtteri Bottas' lengthy pitstop on lap 31 of last Sunday's Bahrain GP.

Bottas' hopes of joining the fight up front between his teammate Lewis Hamilton and Red Bull's Max Verstappen was as good as crushed when the Finn endured a mid-race 10.9s tyre change.

The Mercedes driver was not at fault however, with his right front gun man lacking just a bit of precision in his all-important task, technical director James Allison explained in the Brackley squad's post-race debrief on YouTube.

"When the car came into the pit-stop box, Valtteri came in very neatly, positioned the car neatly and well, which is always a help for the pit crew," said the always eloquent Allison.

"But sadly one of the gun men went onto the wheel, started to disengage the nut, loosened the nut but then started to withdraw the wheel gun just a little bit too soon before the nut had spun off its thread, and because it was still offering some resistance at that point, as he withdrew the wheel gun, the socket on the wheel gun started to disengage from the nut and then started to spin round.

"We call it machining the nut because it starts to chip away at the edges of the nut and destroy the nut, a bit like when you are using a screwdriver and you don’t have it lined up properly, and you start to sort of damage the screwdriver slot.

"So, as he pulled away, the gun machined away at the nut and it didn’t actually come off its mountings," added the Mercedes tech boss.

"He went back in to deal with it but the gun recognises, or is designed to recognise, when it has done a ‘gunning-off’ action and it automatically shuttles the gun so that it is then in ‘doing-up’ mode.

"And so when he went back on to finish the job of taking the wheel nut off, the gun is now in ‘doing-up’ mode and instead of undoing the nut, it is doing it up again and the subsequent sort of follow-on mess of that is what causes something which is normally a beautiful two-second pit stop, causes it to then collapse into something that haemorrhages lap time and seconds in the pit lane.

"But all of it was caused by that initial misplacing of the wheel gun, machining the nut as the wheel gun came off."

• Read also: Wolff says team had no strategy to help frustrated Bottas

Despite the pitstop set back, the second in three races for Mercedes, Bottas kept his fighting spirit turned on despite his slim chances of catching up with the leading dueling duo of Hamilton and Verstappen.

"I mean, I knew that after the long pit-stop, when you lose 10 seconds or something like that, in a close battle against Max and Lewis, it’s going to be hard to regain that – but of course you don’t think about things negatively," commented the Finn after his race.

"You try to keep pushing and try to make the most out of the situation – but there wasn’t really many things happening, so it was a bit lonely. Lonely race after that."

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