Mercedes explain issue behind Valtteri Bottas' race-ruining pit stop

Valtteri Bottas pit stop in Bahrain Grand Prix — Photo: © LAT Images

Mercedes

Mercedes explain issue behind Bottas' race-ruining pit stop

A problem with the wheel gun wrecked Bottas' Bahrain GP

Ian Parkes

Thursday 1 April 2021 12:00

Mercedes has explained the fine margins that exist around a pit stop that ultimately wrecked Valtteri Bottas' Bahrain Grand Prix.

When the Finn made his second stop at the end of lap 30 in Sunday's race there remained a slender chance he could challenge team-mate Lewis Hamilton and Max Verstappen in his Red Bull for the victory.

But then a split-second fault led to Bottas remaining stationary for 10.9secs, which dropped him out of contention and resulted in him finishing over 37 seconds adrift of race-winner Hamilton.

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Outlining the nuances of how a planned two-second stop can go all wrong in the blink of an eye, Mercedes technical director James Allison said: "When the car came into the pit stop box, Valtteri came in very neatly, positioned the car neatly, which is always a help for the pit crew.

"But sadly one of the gunmen 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.

"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.

"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.

"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."

Describing what unfolds as a "follow-on mess", Allison added: "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.”

Immediately after the race, Bottas bemoaned what he felt was a "defensive" strategy from Mercedes, only for team principal Toto Wolff to explain the team had no other options on the table to thrust him back in contention.