Mercedes will be unable to remove the front-right wheel nut from Valtteri Bottas’ Monaco Grand Prix race car until it returns to the team’s UK factory this week.
Bottas was running in second position before he stopped for a scheduled tyre change mid-race, only for Mercedes to struggle to remove the tyre. It later revealed the wheel nut had been machined to the axle by the wheel gun used by its pit crew.
Mercedes technical director James Allison revealed the car left Monte Carlo with the wheel nut still attached.
“We eventually didn’t get the wheel off, it is sat in our garage with the wheel still on it,” Allison said after the race.
“It will have to be ground off, get a Dremel [tool] out and painfully slice through the remnants of the wheel nut. We will do that back at the factory.”
Allison explained how the issue had occurred at the pit-stop.
“If we don’t quite get the pitstop gun cleanly on the nut, then it can chip away at the driving faces of the nut,” Allison said.
“We call it machining the nut. It is a bit like when you take a Phillips head screwdriver, and you don’t get it squarely in the cross of the screwdriver.
“You start to round off the driving face of the screwdriver slots, and then you just simply can’t take the screw out of whatever it is you are trying to take it out of because you have no longer got the driving faces.
“A very similar thing happens with our pitstop nuts if the gun starts spinning and chipping off the driving faces of the wheelnut.
“Given the power of the gun, you can end up with no driving face and you just machine the nut down to a place where there is nothing left to grab a hold of, and that is what we had today.”
The issue forced Bottas to retire from the race. With Bottas’ teammate Lewis Hamilton finishing seventh, and Red Bull pair Max Verstappen and Sergio Perez finishing first and fourth respectively, Mercedes has relinquished the lead of the drivers’ and constructors’ championships.