Michael Schumacher’s retirement at Chinese Grand Prix – What exactly happens when a wheel nut is loose?

It was a heartbreak for seven-time world champion Michael Schumacher when he retired after his first pitstop in China – he was running in 2^nd position before the pitstop. It would have hurt even more to see his younger teammate win the first race for Mercedes and that too by a mammoth 20-second margin.

When Michael made his pitstop, there was a delay by the mechanics on the front right in taking off the wheel. By the time they had put on a new tyre, the other three had already been fitted onto the axles. The right front wheel had just been mounted on the axle and the pitstop lights went green. The mechanic was not able to tighten the wheel and Michael set off from the pits.

Before corner six, he felt some vibration in his front right and had to retire the car to prevent further damage or a serious accident when he saw the wheel very loosely fitted.

Many of us would have had the same question in our mind that if the wheel is not tightened, how does it not come off immediately as it happens when something is not bolted.

The hub which holds the wheel and is connected to the suspension, consists of a wheel retention system. There is a clip present which flicks when the wheel is passed onto the hub. The regulations state that the clip has the function of holding the wheel nut if it is not tightened fully. This wheel retention system helps in holding the wheel to the car for a short distance/time. If the drivers doesn’t stop even after he seeing the wobbling wheel, after some time the retention system will give away and the wheel will come off.

This clip thus helps in preventing any major accident from happening – especially if the wheel comes off when the car is in the pitlane.