Carbon Components

Constructing carbon fiber parts for your project car.

By Steve Temple

Photos by Nate Johnson and Stephani Lofthouse

It’s the new black — literally. That dark fabric known as carbon fiber, found on everything from stealth fighters to tennis rackets, is a popular upgrade for project cars as well.

Not all carbon fiber is created equal, of course, and we’re not talking about the vinyl wrap that’s basically a photo of carbon fiber. How can you tell the difference?

Parts subject to higher loads, such as this adjustable front splitter, are made with an epoxy resin cured in an autoclave.

This mold for a gauge-face pod is coated with an orange tooling gelcoat. Nate Johnson says that before layup, it should have a perfectly smooth surface. It’s coated with a high-temp, mold-release carnauba wax buffed to a smooth finish, followed by a layer of clear gelcoat that will serve as a UV-protector on the completed part.

The vinyl ester resin used by Factory Five Racing is a DCPD blend for lower emissions, along with greater flexibility and impact resistance. The typical ratio of MEK catalyst added to the resin is 2 percent by volume, but that can vary slightly depending on the climate and time of year. Dry summer weather requires only 1.5 percent, while in damp winter weather, the ratio might run as high as 3 percent.

A throwaway brush is used to apply the catalyzed resin to the mold. If you’re doing several parts, the brush can be stored in acetone to prevent it from getting hard but usually only for a day or less.

“If it looks 100 percent perfect, it’s not real carbon fiber,” points out Nate Johnson, operations manager for Factory Five Racing. He notes that the loose weave of carbon fiber is a challenge to keep lined up evenly, no matter how carefully you handle it. He’s worked at Factory Five for more than two decades and knows his way around resins and composite materials of all types.

So we leaned on him for some additional tips about laying up carbon fiber parts, such as the gauge-face pod shown here. Other items done in-house include canards, trim covers and covers for roll bars.

The resin needs to be applied with a light touch but in liberal amounts for full saturation. Excess resin will be rolled out later.

Next, chopped matte goes over the saturated carbon fiber and is wetted out with resin as well. The matte adds thickness to the laminate since the carbon fiber is more for its cosmetic appearance in this particular application.

The wetted-out fibers need to sit untouched for a couple minutes in order for the resin to breakdown the binders, softening the fabric and matte so they conform to the contours of the mold. Then, a roller is used to squeeze out the resin-rich laminate.

After about an hour or so, the exothermic reaction cools off and the resin hardens so it’s no longer sticky. Grab the edge of the excess cloth to pop the part out of the mold.

Again, the carbon fiber weave needs careful placement in the mold to prevent any distortion.

Here’s how the finished surface looks right out of the mold, but some extra work is still needed.

An air or body saw trims off the excess cloth. If the edge is not clearly obvious, overlay the part with a template in order to mark a cutting line.

The completed part is now ready to be installed.

A dual-action sander with 80-grit paper smooths off the rough edges.

More stressed items, such as splitters that have to handle heavy loads in terms of downforce, are outsourced to a company that makes aftermarket parts for Aston Martin. These performance parts require high-strength epoxy resin and autoclaving to maintain their integrity.

Even so, Factory Five’s in-house items are still fairly strong, as they use a marine-grade vinyl ester resin rather than conventional polyester resin. And chopped matte serves as reinforcement as we’ll see.

Should you tackle this sort of job on your own? “It’s not a rookie move,” Nate advises. But there’s enough detail here to determine whether you’d want to make your parts or simply purchase them. Either way, you’ll get a car that’s right in style with the new black.