Mercedes conducts ‘autopsy’ on Bottas’ Monaco wheel nut

Mercedes is conducting a thorough investigation on the wheel nut that ended Valtteri Bottas’ race in the Monaco Grand Prix -- after it had to wait more than two days to remove it.

The right-front wheel would not come off when Bottas made his one and only pit stop on Sunday, with Mercedes saying it had machined the wheel nut onto the axle.

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The team confirmed that the car arrived back in Brackley late on Monday and the wheel was finally removed at 10 a.m. Tuesday morning, with motorsport strategy director James Vowles saying there are things that can be learned from the offending item.

“We did certain steps in Monaco to try and remove it -- some during the pit stop, also some just afterwards -- ultimately there we concluded that to remove that nut we were going to need some fairly heavy equipment and specialist equipment and that would be better done here in the factory,” Vowles said.

“More so, it allows us an opportunity to do an autopsy on it to understand really how that nut was worn and gather some clues to allow us to do a better job going forward in the future. As a result of that we left the wheel on the car and packaged the car back into the truck to bring it back here directly.”

Vowles says the whole issue was caused by the angle at which the wheel gun made contact with the wheel nut, so the work will focus on how to prevent such a result in future.

“The gun is an incredibly powerful gun, such that you can actually see the mechanics having to restrain themselves holding themselves to the ground, otherwise they get rotated with it at the same time. It’s an impact force and what happens is the nut typically loosens in four or five impacts against it -- a hammering action.

“Now, what happened is we came on slightly angled, so when the socket was connected to the nut, it slightly angled relative to it and as a result of that, instead of distributing the load across all of the nut, it was across a small section and that tore the metal clean off. In fact, all of the metal was now removed from the nut.

“As a result of that, the nut was in place and we were unable to remove it. That’s a brief overview of what happened. Clearly, it’s a circumstance that cost Valtteri dearly and cost the team dearly and one that we are going to put steps in place to mitigate.”