Ferrari and Mercedes reveal cause for their Monaco failure

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Both Scuderia Ferrari and Mercedes endured disastrous technical issues in deciding stages of the Monaco Grand Prix weekend with Ferrari’s pole-sitter Charles Leclerc unable to start his home race while Mercedes’ Valtteri Bottas forced to retire with a wheel nut issue.

The Monaco Grand Prix could have hardly ended in a more catastrophic way for the reigning world champion team after Lewis Hamilton was struggling for sheer pace all weekend long and ended up only in P7 in the 67th running in the Principality following a series of strategic mistakes from the Brackley-based outfit while Valtteri Bottas was sidelined with a wheel nut issue.

Mercedes’ Technical Director James Allison indicated that the issue was down to a human error as the mechanic did not manage to get the gun cleanly on the nut.

“We eventually didn't get the wheel off. It's sat in our garage with the wheels still on it. It will have to be ground off, get a Dremel out [a rotary tool] and painfully slice through the remnants of the wheel nut. We'll do that back at the factory.

“It was a more extreme repeat of the thing we've talked about in public before, which is if we don't quite get the pit stop gun cleanly on the nut, then it can chip away at the driving faces of the nut – we call it machining the nut,” he added.

Allison said that there was no way to get the wheel off after the driving face of the nut got damaged.

“It's a little bit like when you take a Phillips head screwdriver and you don't get it squarely in the cross of the screwdriver and 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're trying to take it out of, because you've no longer got the driving faces.

“If the gun starts spinning and chipping off the driving faces of the wheel nut, then in quite short order, given the violence and the power of the gun, you can end up with no driving faces and you've just machined the nut down to a place where there's nothing left to grab hold of. And that's what we had today,” Allison concluded.

Ferrari endured different fortunes at Monaco. While the Scuderia was looking strong from the first practice on Thursday, the weekend ended with mixed emotions for the Italian team.

Both Carlos Sainz and Charles Leclerc were comfortably in the leading pack across the whole weekend, capitalizing on the SF21’s marvellous low-speed corner performance and self-confidence over the Circuit de Monaco’s unforgiving high kerbs.

Ferrari looked to be in contention for the pole position when Leclerc posted the weekend’s fastest lap time in the all-important Q3 session. However, the Monegasque lost control of his car and clipped the barrier at the exit of the Swimming Pool on his last flying lap, breaking his suspension before cannoning into the wall.

He kept his pole position and the team was able to repair his damaged Ferrari. The team found itself in a big dilemma over the gearbox, but following an in-depth analysis, it decided to keep the unit for the race.

However, the Monegasque encountered an issue at Turn 6 on his installation lap when he left the garage to take his place on the grid. The 23-year-old was unable to start his home race.

While Team Principal Mattia Binotto suggested after the race that the issue was unrelated to the Saturday crash, the team confirmed to that the analysis carried out at the Maranello base showed a crack in the driveshaft hub was the real cause for the reliability problem.

The team had only a limited time to check the car between the qualifying session and the race due to the parc ferme rules, and did not check the left hub as it was on the opposite side of the SF21 to the crash. The Maranello-based outfit suggested that it will revise the processes regarding checking components in the future.