Made For Motorsports: Fatigue Testing At CCW

Venture to any track day, any club race, and even a few professional categories, and you’re bound to spot a set of simple CCW wheels. The clean, uncompromising designs denote performance, which is only reinforced by the sheer number of these wheels adorning track-focused automobiles. Everything from Honda S2000s, Porsche 911s, Corvettes, and M3s wear these hoops; they transcend brand-appropriate modifications and speak to the tuner, driver, or racer looking for a dependable wheel package that can withstand punishment at the track.

It’s interesting to note how frequently the footwork of a sports car is overlooked. You’ve heard the same tired spiel about the nuts and bolts mattering more than 0-60 times, but wheels and tires play one of the largest roles when it comes to altering maximum performance. It’s considered low on the list for some, but those who know the shock of a wheel failure or a cracked rim know the value of a thoroughly tested wheel for their track toy.

Not willing to let any bit of performance fail to make it to the pavement, CCW takes every possible performance criteria into consideration when engineering its line of forged performance wheels. Whether its wheels are used for spirited backroad blasts, wheel-to-wheel dicing in a sanctioned event, or just appearing stylish at a meet, they’re all built to exacting standards.

TS-12 wheels dot each corner of the Phoenix Performance Mustang, as driven by SCCA Champion Andrew Aquilante.

CCW’s wheels are built to such a standard across their entire range that the differences between the road-oriented variant of a wheel and a motorsports-oriented wheel aren’t that vast. The racing wheel “opens up the design language to save weight,” says Chris Bovis, Vice President of Marketing and Business Development at CCW. The racing wheels are built with some crucial structural differences—larger pockets, for instance, are included to accept an impact gun and allow for quicker wheel changes. Again, the specific requirements of a given wheel are taken into consideration so only what’s totally necessary is included—every ounce of fat is trimmed.

The Fall-Line M3 wearing CCW’s custom FLM:15 wheels designed specifically for the teams racing needs.

Racing wheels are subjected to severe and specific forces on the track. When designing  wheels for motorsports, CCW considers clubbing apex curbs, dropping wheels off the track, greater levels of ambient temperature, getting squeezed by downforce, and occasionally rubbing with other wheels rotating at speed. This is a relatively short list of demands when compared to the numerous kinds of abuse a road-oriented wheel has to endure, often for a longer period of time. Because of the increased loading and concentrated forces acting on competition wheels, they need to be built to endure real violence, lap after lap, without any deformation.

This wheel is incredibly light for its size and competition, we’ve seen no fatigue or deflection on the wheels – Shea Holbrook, six-time Pirelli World Challenge winner

The C10 model is a common choice for many Pro SCCA and IMSA builders, since it’s made specifically for road-racing competition and punished to ensure its worthiness for the task. The extended back bell and narrow drop center are shaped to accommodate large-diameter performance brakes, which any track-rat-turned-club racer will inevitably consider at some point. The monoblock wheel is forged from 6061-T6 aluminum and passes a 3,000 pounds-per-wheel cornering fatigue test load for 300,000 cycles. 

Additionally, this wheel is shot peened for a 25 percent increase in surface strength, which entails steel shot striking the surface of the wheel with sufficient force to alter the aluminum’s properties. The imparted stress in the material surface aides against crack propagation and other defects from harming the wheel. When having to support a 3,000-pound car that frequently clouts the curbs and occasionally rubs on foreign fenders, that’s a reassuring piece of information to have.

In short, they’re able to handle the demands that a road course will throw at them. Though looks are less important in this form-following-function kind of context, the simplistic appearance plays a role in its motorsport-appeal. The robust, straightforward, frill-free design connotes a sense of focus and strength. Plus, it seems to complement the shapes of most modern vehicles, as evidenced by the Corvette below.

A Z06 wearing a set of simple and effective TS-12 wheels—some of the more popular in SCCA and IMSA racing.

On the street, the appearance of a wheel is more important—but that doesn’t mean the build quality is any less. Contrary to what common sense might suggest, the road-going wheel needs to be stronger in a wider array of situations. Consider the sort of stress potholes place on a wheel, and it makes perfect sense why this is the case. Additionally, the greater weight, regular curbing, uneven surfaces, and longer distances covered are all factors considered during the lengthy engineering process. It’s not an easy life for these aluminum cylinders we tend to overlook.

To ensure these wheels can withstand most conceivable situations, CCW puts them through abuse that would send a weaker wheel home in pieces. Its in-house cornering-impact load test involves three specific tests: impact testing, radial fatigue testing, and rotary fatigue testing; all of these subject the wheels to real-world forces and strains in a controlled fashion.

Impact Testing

Impact testing, which appears to mimic medieval execution, but is very valuable, replicates situations most wheels will run into in a worst-case-scenario. In this test, CCW use a giant guillotine-like device that’s set to a specific height and weight, and drop it onto the wheel to emulate the shock of striking potholes, bumps, and the like.

Radial Fatigue Testing

Radial fatigue testing is slightly different in that it tries to split the wheel open by applying an exaggerated load on the rim shells. Essentially, a ram pushes the wheel into a floating drum which, in turn, spins the wheel and tire. This process tests the integrity of the wheel by aiming to break the wheel under extreme load.

Rotary Fatigue Testing

The third test is designed to replicate the forces imposed on the wheel during high-speed cornering, and is known as the rotary fatigue test. This is the only test performed without a tire mounted. Laid flat on a turntable, a wheel is secured by locking down the bead seat, and an axle is bolted to the center section. Lateral load is applied to the axle, and thus onto the hub pad, with the intention of testing the wheel center’s integrity by imparting flexing and breaking forces.

Fortunately, CCW is one of the few wheel manufacturers that have all three machines in-house, which allows them to streamline the production process. Though the outside labs are necessary to appease the regulatory bodies at certain stages, depending on the intention of the wheel, they can do the majority of testing in-house.

Shea Holbrook’s Pirelli World Challenge Touring Car-class Honda Accord showing the TS-12’s unique weight-reducing design.

Before all the physical testing abuse, CCW relies on Finite Element Analysis (FEA) to optimize its designs, such as the case with the TS-12. All of the weight removed from the TS-12 had no impact on the deflection or integrity of the wheel; in fact, the TS-12 has less deflection than the heavier wheel it replaced.

The TS-12 R-Spec variant is one of the lightest of the entire CCW lineup. Despite this, they’ve seen no decrease in performance characteristics by any measure: load, number of cycles in rotary or fatigue tests, or deflection. The 18-inch model weighs a mere 18.6 pounds a piece, and the 19-inch model just under 20 pounds. Thanks to trimming the the rollers down to the utmost minimum, the bump-deflection is reduced considerably. It might be an overlooked aspect of building a racing car, but by reducing the unsprung mass, the contact patch remains planted to the road more of the time, reducing the sort of jostling bumps that curbs cause.

Shea Holbrook monstering the curbs in her CCW-shod Accord.

Additionally, it helps trim the curb weight of a racing car. Shea Holbrook, six-time Pirelli World Challenge winner, uses the TS-12 to lighten her 3,050-pound Honda Accord—one of the heaviest touring cars in the field. “This wheel is incredibly light for its size and competition, we’ve seen no fatigue or deflection on the wheels,” she remarks enthusiastically. “We had a fair share of curb fits over the season and not once did we come back with a reported bent TS-12.”

Thanks in-part to her association with CCW, who’ve built a specific set of wheels for her purposes, she’s been able to keep her Accord in touch with a field of Lotuses, M235is, Fits, and other cars half the size of the hefty Accord. It’s truly impressive to see how well this car rotates and still remains compliant over a variety of trying surfaces.

Note just how well Holbrook manages the car through the downhill esses at Miller Motorsports Park. Her car looks so compliant and unflustered; barely deflected by the bumps, turning in crisply with two wheels in the air, and able to trace a very tight line with Craig Stanton eagerly nipping at her heels. It’s a demonstration of automotive acrobatics that will leave a few fans drooling in a stupor, some cheering, and others reaching for their credit card.

About the author

Tommy Parry

Tommy Parry has been racing and writing about racing cars for the past seven years. As an automotive enthusiast from a young age, he worked jobs revolving around cars throughout high school, and tried his hand on the race track on his 20th birthday. After winning his first outdoor kart race, Tommy began working as an apprentice mechanic to amateur racers in the Bay Area to sharpen his mechanical understanding. He has worked as a track day instructor and automotive writer since 2012, and continues to race karts, formula cars, sedans, and rally cars in the San Francisco region.
Read My Articles

Corvette's in your inbox.

Build your own custom newsletter with the content you love from Corvette Online, directly to your inbox, absolutely FREE!

Free WordPress Themes

We will safeguard your e-mail and only send content you request.