They drive like crazed teenagers on a Saturday night-foot to the floor, brakes glowing red hot-bouncing over foot-high curbs with reckless abandon. But don't worry about dinging the wheels on Dad's new car, here in the alternate reality that is Formula One, wheels only get one shot at competitive glory. Thanks to Avus Wheels, we've been favored with a peek behind the curtain in Valencia, Spain, where wheels for the Red Bull, Toro Rosso and McLaren F1 teams are manufactured.
But wait, you say, McLaren wheels wear Enkei logos. True enough, Enkei is McLaren's official supplier. But what F1 story would be complete without a bit of international intrigue? Nearly two decades ago, Sport Styling started importing, distributing and selling aftermarket parts throughout Spain and Portugal. Recently, the company decided to start in-house production of its own premium road wheels, named Avus after the famous German circuit, in part because of concerns about the state of the Italian wheel industry. Avus recruited OZ Wheels' competition department manager, Luigi Lucaora, to oversee the operation. Seems the chair industry isn't the only Italian manufacturing segment stressed by lower cost (and in the case of wheels, certainly lower quality) goods from China.
Meanwhile, Japan's Enkei was seeing explosive growth in OEM alloy wheel sales and all but abandoned the aftermarket because production capacity was strained (some 17 million units last year). But as one of the few companies with the technology to produce the forged blanks Avus needed for its three-piece street wheels, the companies struck a deal. When the new Red Bull/Toro Rosso teams started shopping for a wheel supplier, Lucaora's racing connections and technical savvy helped seal the deal. Avus became the teams' official supplier. Enkei remains the official supplier to McLaren, while Avus supplies technical expertise and responsive small-scale manufacturing, and the Japanese firm supplies the forged magnesium blanks Avus uses to produce its F1 wheels. In addition to this technological agreement, Avus is also Enkei's European distributor for aftermarket wheels.
Meanwhile, Avus has taken data from team engineers (offsets, loads, weight targets, lip shape, hub and drive peg measurements, mounting face and plane, caliper size, etc.) to come up with a preliminary design and run it through an FEM program. The brake caliper determines the shape of the spoke profile-there's only a 2.5 to 3mm clearance-and the team dictates the number of spokes, usually between 10 and 14. The tightest tolerances are at the nut-mating surface-plus or minus 0.3mm-and the hub's titanium-aluminum drive pegs (every team uses a different shape and number) are at plus or minus 0.0013mm. Maximum loads approach around 8000 pounds at maximum downforce and 4g under braking.
The process that ends with a 7.9-pound 12.75x13 front or 13.7x13 rear wheel starts by continuous-casting a piece of magnesium about 20 feet long and roughly the diameter of the finished wheel. The outer layer is machined away to remove any cooling cracks to a diameter of 11.8 inches and the piece is cut into 62-pound chunks. Length won't matter, as a piston driven by 9000 tons of pressure squeezes the blank into the tooling at rates carefully controlled by temperature sensors. Anything over 300 degrees Celsius can seriously weaken the blank.
In this age of CAD-driven rapid prototyping, teams can have a sample in the wind tunnel within 24 hours. Once the OK is given, Avus feeds the data into one of several five-axis milling machines and the manufacturing process begins. When machining is finished, the blanks have lost more than 44 pounds, transformed into wheels weighing around eight pounds. After being cleaned, they are dipped in a fluorescent green solution and X-rayed. Flawed wheels are ditched, the rest head for the paint shop. So precise is the machining that even after adding the valve stem and pressure sensor, nearly all the wheels are perfectly balanced. And though the wheels need to be perfectly round at 300 kph-186 mph or so-the stresses are so closely calculated that at maximum cornering load, given the bending moment across the wheel, the inner lip actually flexes into an oval.
Of course, the devil is in the details. McLaren wants to know the weight of each wheel before and after painting, even though the difference is only 30 grams. When the team went to a new paint scheme, they insisted the wheels already painted be stripped before the new color was applied, rather than suffer a 120-gram weight penalty. While the Red Bull and Toro Rosso wheels use spokes of consistent shape, the McLaren wheel has subtly sculpted spokes, raduised on the inside where the spoke meets the rim with a wider taper at the base.
With only 20mm or so of suspension travel in a current F1 car, according to Lucaora, the tire is an integral part of the suspension and has almost no deformation in the sidewall. Mounting an F1 tire is a difficult thing. McLaren has been experimenting with a 'low lip' design. The shorter 7mm mounting lip allows for longer spokes (the dip in a wheel's cross section is to allow the bead over the rim and a lower lip requires less room) and the team feels the 7mm version works better than the 14mm alternative.
Since wheel/tire combinations are closely figured, Lucaora can't resist telling of a recent near-fiasco. With the unveiling of one car (we won't say whose, where or when, just that it was not Avus-shod) set for the morning and press from around the world gathering, Lucaora received a panicked phone call from an old pit-lane acquaintance. Seems the new wheels showed up just as planned but, despite the best efforts, they refused to accept the new tires. A rudely awakened Avus machinist needed to remove only a couple of millimeters from the lip to save the presentation, and though the wheels were ruined, no one was ever the wiser.
An F1 team will use upwards of 1200 wheels over the course of a season. Teams need to have two dry compounds, intermediate and rain tires ready every weekend, and this is a one-time mounting situation. Despite this seeming bounty, wheels are rarely available, especially those wrapped in super-secret tires. But if you need a gift for the F1 nut in your life, 100 numbered and documented wheels will come back to Avus this year. Though pricing has yet to be determined, if you have to ask... Check out the company website for more information on F1 and the even more brutal world of DTM racing wheels. Or you can just check out the entire line of cast and forged modular street wheels.