Formula 1: The wheel nut causes problems

Daniel Reinhard
Formula 1 technology: the wheel nut
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E a wheel nut weighs between 300 and 350 grams . It is made of steel or aluminum. One piece costs around 450 euros. But the seemingly simple screws can decide a race. Sebastian Vettel cost a loose wheel nut on the front left axle victory in Melbourne. And Michael Schumacher wrote a zero lap at the GP Malaysia because the wheel nut on the left rear completely loosened. The normal fan asks himself: What can be so difficult about tightening a wheel nut properly?

Extreme forces pull the wheel nut

Sauber - Head of Technology Willy Rampf replies: 'In Formula 1, wheel nuts are a science in themselves. If everything doesn't fit, it can be easy Incidents like Vettel and Schumacher come. ' The rear wheel nuts are particularly critical, as in the Schumacher case. The rear wheel transfers forces in both directions when braking and accelerating. The front wheel only rolls when the driver steps on the gas. The forces are enormous. Formula 1 cars accelerate from zero to 100 km /h in 2.5 seconds. And they brake down from 300 to 60 km /h within 80 meters. The delay is up to five g. That also tugs at the wheel nuts.

Sauber only uses old rims and worn nuts. 'When the bike and the mother are new, complications are almost inevitable,' says Rampf. Both parts must first run in. On a Formula 1 bike, the different cone of the nut and rim is more likely to hold the wheel nut on the hub than the thread itself. If the two components are not yet ground into each other, the hold is lost.

Impact wrench hammer the nuts on the thread

But the reverse phenomenon also happens every now and then. 'We once had a test where we couldn't even bring down a wheel nut with brute force. The expansion of the heat had eaten it into the rim. We had to remove the entire wheel carrier,' says Rampf.

Die Wheels are literally hammered onto the thread of the hub using an impact wrench. There are no torque regulations. The mechanic must feel whether the mother is sitting or not. Better to be too tight than too little. Since the impact wrenches develop higher forces when unscrewing than when tightening, getsas a rule, extremely tightened wheel nuts are also removed again.

Wheel nuts over the limit?

The wheel hubs and threads are extremely thin and long. 'A short thread wouldn't give enough hold,' Rampf dismisses. If a problem occurs at all, then you can imagine it after a hasty pit stop. But Schumacher's bike nut said goodbye ten laps after the start. 'Before the start, we checked the nuts exactly', asserts Mercedes GP -Team boss Ross Brawn.

Now that the wheel nut problems are increasing, the question arises what has changed since last year. The tire changes have become even more important because, after the refueling ban, they now determine the time spent in the pits. Are some teams going over the top when designing their wheel nuts, hubs and rims, only to gain a few tenths of a second when changing tires or to save a few grams with an aluminum nut? 'Well possible,' Rampf suspects. 'This year we only use steel wheel nuts. They are less critical.'


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