Even if you don’t crash, racing often means dealing with various mechanical issues and part failures. For example, Tyler O’Hara’s rear brakes failed at the 2020 King of the Baggers. And sometimes, these problems happen to road cars, too. Case in point, the wheel nut issue that plagued Mercedes F1 racer Valtteri Bottas at the Monaco Grand Prix.
A rounded wheel nut meant the end of the race for Mercedes F1 driver Valtteri Bottas
Formula 1 cars are significantly different than road cars, but they do have several things in common. Notably, F1 cars have wheels that need to attach securely to the wheel hubs and axles. Road cars achieve this by using multiple lug nuts attached to individual wheel studs. F1 cars, though, have center-lock wheels with a singular wheel nut.
Center-lock wheels with wheel nuts are an evolution of the ‘knock-off’ wire wheels found on many early sports cars, The Drive explains. And they’re not designed to reduce unsprung weight. Rather, a single wheel nut is quicker to remove and reinstall than multiple lug nuts. And considering an F1 pit stop is sometimes less than two seconds long, Car and Driver reports, speed is vital.
That’s why professional racing crews use specialized sockets and wheel guns to get the wheel nuts on and off, Car and Driver explains. At its core, a wheel gun is essentially an impact wrench, only it spins significantly faster and with more force. The ones F1 pit crews use spin at 10,000 RPM with over 2000 lb-ft of torque, The Drive reports. And a spinning piece of metal, whether a saw blade or a wheel nut socket, is a grinding tool waiting to happen.
Valtteri Bottas experienced that firsthand at the 2021 Monaco Grand Prix recently. Normally, the wheel guns’ sockets mesh with the teeth on the F1 car’s wheel nuts, Road & Track explains. Only this time, during a pit stop on Lap 30, that didn’t happen on Bottas’s right front wheel.
Instead, the sprocket and wheel nut were misaligned, and when the socket spun, it sheared the teeth and jammed the nut firmly in place. Mercedes had to ship the car back to the factory to get it off, Autoweek reports.
Regular cars’ wheel and lug nuts can get rounded down or stripped off, too
What Bottas experienced in Monaco is what’s known as a ‘stripped’ or ‘rounded’ wheel nut. As in, the once sharp edges of the nut are rounded down so the socket no longer grips it tightly.
The risk of rounding/stripping lug nuts is one reason why impact drivers and wrenches demand careful use, NAPA explains. Because they spin so quickly, they often wear down the sharp edges, making the nuts more difficult to remove.
Plus, while they make removal easier, impact drivers can also over-tighten the lug nuts and damage the wheel stud threads, Autoblog reports. That happened to me at various tire shops, which lead to several new studs and a predilection for hand tools. Over-tightening can also damage the nuts themselves, which can lead to corrosion. Particularly if the nuts are cheaply designed, as some Ford F-150 owners discovered.
If it happens, how can you fix it?
Preventing wheel nut and lug nut rounding isn’t necessarily difficult. It’s a matter of properly fitting tools and good technique. And if you’re not on a pit crew, you don’t have to remove the nuts quickly. If you’re removing them with an impact driver, go slowly to prevent damage. And the best way to screw the nuts back on is with a torque wrench, Autoblog reports.
But sometimes, you accidentally round off your wheel nut or buy a car with stripped lug nuts. Luckily, there are several ways you can try and remove it.
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The most straightforward method is to use a socket one size smaller attached to a long breaker bar, 1A Auto explains. Whack the socket with a hammer to seat it firmly, then use the breaker bar’s leverage to torque the nut free. You can also use a lug nut extractor socket specifically designed for this purpose, Garage Chief explains.
If that doesn’t work, another option is to use a screwdriver as a chisel to make a notch in the lug nut. Then, using a hammer, tap and twist the screwdriver to rotate the nut. Cycle World had to do something like this with a sheared bolt on a Harley-Davidson Sportster scrambler in Scram Africa.
If none of these methods work, you can try to grind new edges onto the lug or wheel nut with an angle grinder. And if that’s still not enough, the last resort is what Mercedes is doing to Valtteri Bottas’ car: drill it out.
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