Just before the Monaco GP start, Charles Leclerc reported a failure in the reconnaissance lap to the grid, Ferrari decided to not start the race as they would have run out of time to fix the problem and be ready to start.
Starting with this failure would have been incredibly difficult to drive and a high risk of a race retirement.
Ferrari did a full investigation the following day at Maranello to find the problem on Leclerc´s car, detecting that the left driveshaft hub was broken. The driveshaft translates the mechanical energy of the engine and power unit into drive for the rear wheels, the hub is the driveshaft part that delivers the motion to the rear wheels.
The driveshaft hub was indeed damaged in the qualifying crash.
The team explained that a detailed check on the left driveshaft hub was not made, as they focus more on the damaged part of the car (the right side in this case). One of the main concerns for the team after the qualifying crash was a damaged gearbox, meaning a five-place grid drop if replaced and handing pole position to Max Verstappen.
Ferrari´s data showed everything was fine when Leclerc left the pits but the problem showed at turn 6 when the driver felt it.
"It is difficult because it is at home and it is not every day we have the chance to be in such a good place, but it is part of motorsport.” Leclerc said after the race.
Binotto explained that the driveshaft hub would have failed even with a new gearbox.
"It's more important really to understand why we didn't detect a problem on the car. The problem was not there when he left the garage, so the problem started to appear in turn six.”
The team said they will now revise and improve its processes in the events of a crash to ensure the car is in good condition.