Carbon Fiber Wheels: Does Your Z06 or ZR1 Need Them?
Does your C8 Z06/ZR1 really need carbon fiber wheels?
This story was first published in the March 2024 issue of Vette Vues Magazine.
A big shout-out to Thomas Edison and Union Carbide!
Carbon Fiber is, without a doubt, the darling material for today’s performance cars. We explored the amazing history of carbon fiber in the May 2019 issue of Vette Vues. The story dates back to Thomas Edison in 1879 when the great inventor was searching for a workable filament for his electric light bulb project. U.S. Navy ships used the same basic filaments into the 1960s because they were stronger and more resistant to vibration than tungsten. “Strength” is the most important part.
Union Carbide physicist Roger Bacon is credited with the first carbon fiber experiments in 1956. Using an elaborate process, Bacon created carbon fiber “whiskers”. These whiskers were 1/10th the diameter of a human hair that you could bend and kink, but they weren’t brittle. He called these long filaments the “perfect graphite.” Steel has a tensile strength of 1-2 Gigapascals (GPa); Bacon’s fibers had a tensile strength of 20 GPa. Later development brought the carbon fiber’s strength up to 200 Gpa.
The applications of carbon fiber are almost endless
Once carbon fiber went into production, the scope of applications was astounding: boat hulls, water filters, antennas, electromagnetic shields, military and commercial aircraft, and eventually automotive parts. In 1981, the racing world was skeptical when McLaren built a Formula 1 car with a carbon fiber monocoque tub. Many drivers refused to drive the car, thinking that the car was brittle and would shatter in a crash. As fate would have it, the car was in a severe crash, with the driver walking away. Analysis showed that if the car had a standard aluminum tub, the crash would have been fatal. Overnight, Formula 1 was changed forever.
The 1992 Stingray III concept car was built with a carbon fiber tub, but you couldn’t see it. Gradually, small carbon fiber parts were integrated into production cars. But when race cars started using clear-coated carbon fiber spoilers, wings, splitters, ground effects, and eventually body panels, people started noticing the cool look of exposed carbon fiber weave. The hood of the 2004 Commemorative Edition Z06 was the first automotive use of carbon fiber on an exterior body panel. The hood had unique hood stripes, and between two of the stripes, the carbon fiber weave was visible.
From there, carbon fiber started showing up on Corvettes, other performance cars, and in the aftermarket world. It was only a matter of time before wheel manufacturers learned how to make high-performance wheels. For racing, it all came down to the reduction of unsprung mass.
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Why is this important for modern high-performance cars?
Unsprung mass is everything that sits on a car’s suspension. Everything that rotates and actuates is unsprung mass. In the early days of sports cars, what wasn’t “rubber” was steel. Gradually, builders integrated aluminum, magnesium, titanium, and fiberglass to save weight; a lighter race car was a faster race car. In terms of unsprung mass, the C4 was a quantum leap in development with computer-designed, lightweight suspension components, brake calipers, and wheels. Every successive generation has been engineered with lighter unsprung mass components. Carbon fiber wheels are the next step to what could be a mostly carbon fiber C9 Corvette.
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Let’s look at the C8 Z06’s optional carbon fiber wheels.
Harlan Charles has described the C8 Z06 as a “race car you can drive on the street”. For race cars, when it comes to wheels, size matters. We’ll start by comparing the sizes of the stock C8 and C8 Z06 wheels.
Standard C8 wheels:
Front: 19” x 8.5” forged aluminum, with 245/35ZR19 Michelin Pilot Sport ALS, or Pilot Sport 4S tires on Z51.
Rear: 20” x 11”, shod 305/30ZR20 Michelin Pilot Sport ALS (Pilot Sport 4S on Z51)
Standard C8 Z06 wheels:
Front: 20” x 10” forged aluminum & carbon fiber, with 275/30ZR20 Michelin Pilot Sport 4 S ZP or Pilot Sport Cup 2 R tires.
Front: 21” x 13” forged aluminum & carbon fiber, with 345/25ZR21 Michelin Pilot Sport 4 S ZP or Pilot Sport Cup 2 R tires.
Despite the larger mass of the Z06 wheels, the total weight reduction of all four wheels is 41 pounds, approximately 10 pounds per corner. The reduced weight of the wheels and ceramic rotors improves acceleration and braking because there is less inertia per corner.
The C8 Z06 is a concerto of large and small weight savings and improved strength. Each element might seem small, but remember the math axiom, “The whole is greater than the sum of its parts”. In other words, it all adds up.
Let’s talk about cost
Carbon fiber looks like “the future”, is five times lighter than steel, 50% lighter than aluminum, and is totally high-tech. But it ain’t cheap. Since the 2024 Commemorative Edition Z06, extensive use of carbon fiber has been limited to the Z06 and ZR1 Corvettes. The 2009 ZR1 had a carbon fiber hood, front fenders, fixed roof panel, roof bow, front splitter, side skirts, and a 638-horsepower supercharged engine. The base 2009 Corvette cost $47,895; the ZR1 cost $103,300! The price included the jewel-like supercharged LS9 engine.
Fast forward to 2024, the base model Corvette costs $69,995, and the Z06 starts at $114,395. The two versions of the carbon fiber wheels are the same size as the standard Z06 alloy wheels. The Carbon Flash painted versions cost $11,995, and the Clear Coat (you can see the carbon fiber weave) costs $13,995 and can be ordered without the Z07 option. To reduce the unsprung mass even more, the Z07 gets you: the lighter carbon ceramic brake rotors, and includes Dark Gray Metallic-painted calipers; the Z07 suspension, with Magnetic Selective Ride Control; and Michelin Pilot Sport Cup 2 R ultra-performance tires, for only $8,995.
How the Z06 carbon fiber wheels are made
Chevrolet outsourced the C8 Z06 carbon fiber wheels to Carbon Revolution in Australia. The company made the first ever “production” carbon fiber wheels that were part of the 977-generated Porsche 911 GT3. They also supplied carbon fiber wheels for the Shelby Mustang GT500 and Ford’s GT Supercar.
The C8 Z06 wheels have the distinction of being the widest and tallest carbon fiber wheels ever made by Carbon Revolution and have the highest load capacity of any wheel Carbon Revolution has produced. The company’s 50,000th carbon fiber wheel was the Z06’s big 21” x 13” rear wheel.
Carbon fiber parts in the interior won’t make your C8 faster, but it sure is cool!
The process Carbon Revolution uses is called “High-Pressure Resin Transfer Molding” and starts with a “dry wheel”. Carbon fiber sheets are layered before being heated and pressurized into the design of the wheel. The dry wheel is put into a mold and pressurized to remove any trapped air, after which, the resin is injected into the mold at 700 psi. The extreme pressure creates the heat needed to cure the resin, locking it into place and creating an ultra-light, ultra-strong wheel.
Forming the spokes was the hardest part. The solution was to position the carbon fiber fabric to overlap with one another where the spoke meets the rim. They also use a technique they call the “ski jump”, a solid carbon feature that connects the front and back of the spoke laminate in a diagonal direction. To analyze the completed wheel, Carbon Revolution uses computer-based virtual tools to measure real road conditions.
Carbon fiber wheels go with your carbon fiber aero bits.
Does your C8 Z06 need carbon fiber wheels?
That depends on what you will be using your C8 Z06 for. If the car is a street-only machine, the carbon fiber wheel will be for bragging rights only, especially the clear coat version. In the right light, they sparkle and reflect like black chrome and look extremely cool.
Will it make your Z06 quicker on the street? Not by much that you’d notice. Keep in mind that curb rash and damage from speed bumps, broken pavement, or potholes can’t be repaired. There can also be issues with heat degradation, UV degradation, and replacement availability. If you live where the roads are crummy, you might not want carbon fiber wheels.
If your C8 Z06 is a track car and your driving skills are excellent, the lighter wheels and rotors will yield sharper handling because the suspension dampers and sway bars can rebound from bumps quicker. With less inertia from rotating mass, acceleration and braking should improve track times.
Harlan Charles said it all in one sentence
Harlan’s statement, “The C8 Z06 is a race car you can drive on the street,” was not hyperbole. While the C8 Z06 doesn’t have a full roll cage like the Z06 GT3.R, there’s never been more “race car” built into a Corvette. Ever since the arrival of the C5-R race cars in 1999, Pratt and Miller has been Chevrolet’s de facto “High-Performance, Racing Engineering Division”.
Corvette fans have begged for a “street-track” Corvette for decades. The C5 Z06 was the first volley into that arena. Successive Z06 Corvettes kept raising the standard. The C8 Z06 is way beyond anything Duntov ever imagined when he put together the 1963 Z06 Special Performance Equipment option for his 327 Fuelie Sting Rays.
Birmel Guerrero C9 Concept Rendering.
Where will the carbon fiber revolution take us?
C9 is well on its way in development. Typically, work begins on the next-gen car almost at the same time the new car is introduced. Since 2004, there’s been a clear trend for Corvettes; what was special about the current performance model becomes standard on the next-gen car. The C6 Z06/ZR1 aluminum frame is a great example. The standard C7 has an aluminum frame. I can’t wait to see the details of the C8 ZR1. So I fully expect the basic C9 to have more carbon fiber than ever. Perhaps the entire body, available painted or clear-coated. We might see a carbon fiber monocoque tub-frame and wheels as standard equipment.
The C8 Corvette has been an overwhelming success for Chevrolet and GM. 2023 sales of Corvettes totaled 53,785 units, just 22 units shy of the all-time sales record set in 1979. The car is light years better than when that record was set, and it looked like true “high-performance” was dead. To quote the great philosopher Gomer Pile, “Surprise, surprise, surprise…” – Scott
This story was first published in the March 2024 issue of Vette Vues Magazine.
