The secret of F1 wheels is nuts

The wheels in F1 are perhaps the most old-fashioned looking part of the entire car.

Looking like the hot-hatch wheels on any Friday night high street, clad in high-profile tyres from a previous motoring era, they are distinctive because they appear to have changed little, not lots, over the years.

But, of course, it would be wrong to say nothing has altered about the wheels since F1 began. Here are a few of the innovations that helped keep the sport’s wheels turning…

Light is right

The rims with spokes that early F1 cars drove on were not, technically speaking, wheels.

Rims were welded or riveted on, and the whole thing was made of heavy steel.

In the 1960s, racing wheels were cast from magnesium and aluminium alloys, making everything lighter and changing the look of the sport as well.

But casting is not an ideal process for making wheels. Small bubbles can be trapped when molten metal is poured, and the structure of the metal itself – as seen under a microscope – is weaker than forged metal.

Forged wheels entered F1 in the 1990s. Jordan was persuaded to use forged wheels by the OZ company, while Ferrari shod its cars with BBS units.

Forged wheels are made from heated metal which is compressed in a die, unlike cast wheels, which are created by pouring molten metal into a mould.

F1 was playing catch-up with these innovative wheels but they brought huge benefits.

The forged magnesium wheels were about 20 per cent lighter than their rivals, but just as strong.

This weight saving was critical – as well as adding to the overall weight of a car, heavy wheels are also more difficult to rotate; engines must work harder and performance is lost. That’s why wheel manufacturers are always trying to shave a few more grammes off the weight of a wheel through clever design.

As well as weight considerations, wheels must perform well aerodynamically and, at the same time, help to dissipate heat from the brakes, which can be glowing at 1,000C when maximum stopping power is required.

There’s an added bonus: magnesium wheels handle vibrations better. In fact, their vibration damping properties are about 100 times better than aluminium and 23 times better than steel.

Given how little suspension an F1 car possesses, this is good news for both the car and the driver.

This is nuts

The wheel itself is only part of the challenge.

In F1, races can be won by shaving fractions of a second off pitstop times.

That means the pressure to remove and attach wheels is huge, and the official record for a stop is 1.92seconds, held by Williams Martini and Red Bull.

Unofficially, teams have managed 1.7seconds to change four wheels – that’s 0.85seconds to detach four wheels and get them out of the way, and another 0.85seconds to get four wheels in position and attach them.

The secret to these unbelievable times is a lot of practice coupled with innovative wheel fastenings.

Drive pins on each axle ensure wheels slip on to the hub accurately and first-time.

The wheel nuts are held within the wheels with O-rings or similar devices, rather than being removed completely; there’s no danger of a nut dropping on to the ground, and the nut is partially located on the axle as the wheel is presented.

The nuts, and the wheel guns that attach them, are engineered as carefully as any other element of an F1 car, so that everything fits perfectly.

And there is as little thread as possible – three turns should secure a nut which, despite being so carefully made, will usually be used just once in anger.

Even safety devices have been designed to speed things up. Once upon a time, mechanics pulled a plunger to raise retaining pins from inside the axle; now, the pins spring up automatically when the wheel gun is removed, and are depressed when the gun is reattached.

This has the added benefit of reducing the risk of the pins being accidentally left undeployed.

In the event that these pins fail, wheels are still tethered to the car by a couple of cords made of Zylon, which is claimed to be the world’s strongest synthetic fibre.

There are vents in the nuts?

These wheels may be masterpieces of engineering but they create turbulence, a lot of it.

And, with the 2017 rules mandating wider tyres, this will be even more of a problem.

Wings can do only so much – a much more innovative solution uses the wheel itself to help manage the turbulent air.

Known as a ‘blown front axle’ or ‘blown wheel nuts’, the approach was unveiled by Williams in 2013.

It works by drawing air from the brake ducts on the inner wheels, through a pipe in the axle and out via holes in the wheel nuts.

This new airflow cuts the wake and turbulence around the front tyres, reducing drag by injecting air into the low pressure area behind the front wheels and producing a cleaner flow of air going back over the rest of the car and its various aerodynamic elements.

It helps preserve the powerful air vortexes that flow off the front wing, and seal the gap between the car’s undertray and track – vital for generating downforce and allowing higher cornering speeds.

There is an additional benefit with the blown front axle. Because the axle itself is hollow, it weighs less.

Of course, teams have to be sure it remains strong enough to withstand the hammering it will get in an F1 race, but lightness is king in racing.

So there you have it. At first glance, wheels are as simple a part as you’ll find on an F1 car.

But that simplicity belies the innovative developments that keep F1’s wheels turning.