Composite body Panels 101 (2024)

Fiberglass, as most people call it, is more accurately described as a composite. Composites date back centuries when people built their homes out of mud mixed with grass. They also used tree saps and other types of natural materials to create early composites. The composites we are most familiar with today came into existence during the industrial revolution and the discovery of petroleum-based plastics.

How It Came To Be

Glass fibers were created by blowing high-pressure air over streaming molten glass. The glass fibers that resulted were made into fiber mat and eventually woven cloth that was then mixed with epoxy or polyester resin and a catalyst to cure it. Much of the development in composites has been spurred on by military, aerospace, and electronics industry research and development.

Besides its great strength to weight ratio, it has many other desirable properties including chemical resistance, moisture resistance, low conductivity (except carbon), and is a good thermal barrier.

One of the earliest and most widely known automotive uses for fiberglass was the body of the Chevrolet Corvette, first produced in 1953. Originally made from fiberglass cloth and resin, the Corvette has kept up with advances in composites over the years.

Chevrolet changed to a less-fiberglass based and thinner, plastic type construction, sheet molded compound, (SMC) and finally to carbon fiber panels for even more weight reduction. The Chevrolet Corvette also used composites in the suspension. In 1981, the Corvette’s transverse, mono-leaf rear spring was changed to a fiberglass composite construction to further save weight.

In the 1960s and 70s, fiberglass kit cars and the iconic Baja Bug were all the rage. We also had the van craze, with its wide fender flares, and roof mounted spoilers. Performance cars of all types had fiberglass hood scoops, air dams, and NACA ducts.

How It IsMade

Full custom body designs like Bruce Meyers’ Manx used a fiberglass body mounted to an existing VW chassis to create a unique automobile. Meyers was certainly an automotive pioneer.

A surfer and boat builder, he knew the properties of fiberglass construction and what it could do. Fiberglass construction allowed him to build his own cars in a small facility with low overhead instead of a huge factory filled with expensive machinery.

The freedom of fiberglass construction allowsyou tocreate complex curves and unique shapes without expensive tooling and the need for huge metal forming presses. The process is to create the final shape you want using foam, wood, bondo, or any other material that can be shaped which is known as the Buck.

The Buck is then coated with fiberglass, with supports added to hold its final shape after curing. Now you have a Mold. The Mold is then used to construct the final panels.

The mold is coated in a release agent so the part does not stick; followed by the first layer of material into the mold called the Gel coat. It is a layer of pure resin that contains the color and allows for a smooth finish on the outside of the part.

The Gel coat is followed with layers of fiberglass cloth that get saturated with resin to give the part its strength when cured. As long as the panels can release from the mold, nearly any shape can be made.

For complicated parts, the molds can be made in several pieces that are bolted together. Once the fiberglass has cured in the mold, the mold can be taken apart and the new piece released.

Carbon Fiber

The process is similar for carbon fiber reinforced panels although many high-tech manufacturers use pressure and heat to cure the panels in conjunction with a catalyst. Carbon fiber uses tiny fibers composed of carbon atoms.

These carbon atoms are bonded together to form microscopic crystals that are mostly aligned parallel to the long axis of the fiber; giving the fibers their strength. The fibers are then heated to a high temperature in an environment free from oxygen to expel most of the non-carbon molecules. This process is called carbonization. Like fiberglass, the carbon fibers can be made into strands and the strands woven into fabric.

Even racecar interior panels that are typically fabricated in aluminum are being replaced by carbon fiber pieces. Carbon fiber has great strength, and is lighter than the aluminum panels they replace; 40 percent lighter in fact.

Another benefit to composite panels is their availability. It takes hours of skilled labor to fabricate the intricate aluminum interior panels used to protect the driver and drivetrain components on a race truck. Once a mold has been created, additional composite parts, that match perfectly, can be reproduced in large quantities.

From Race Course To Street

Composite body panels have become synonymous with racing. Their versatility, light weight, and relative ease of manufacturing, make them valuable to teams that compete in the rougher types of racing where contact and crashes happen often.

For instance, short-course racers sometimes have to replace their body panels after they’re out on the track. They bring piles of fenders, doors, and hoods to the race track. When you have to replace the roof panel, you know you are having a bad day, but that’s not uncommon.

Instead of deforming like steel, composite panels break away and fly off by design. The body panels get consumed, but the race car is somewhat protected. The composite panels are there to resemble a production vehicle, provide some airflow management, and a place to showcase your team’s color scheme and sponsor logos. Without the body, racecars look like a jungle gym on wheels.

Like most components developed for racing, they eventually trickle down to enthusiast vehicles and even daily drivers. Many prerunner trucks run fiberglass panels for the same reasons racers do. They save weight, make room for bigger tires, accommodate long travel suspensions, and can change the entire look of your vehicle.

Fiberglass seats and dashes are also available. Many manufacturers get involved with style as well as function. It is not uncommon to find fiberglass panels that update the grille and headlights to resemble a newer model design or a completely different vehicle. The Ford Raptor has a distinctive look that is very popular.

Thanks to fiberglass suppliers, you can get those same design cues for your F-150, even for a Ranger. Designs are out there to enhance cooling, duct air to the engine, even to soften some unflattering body lines that came from the manufacturer.

Upgrading Your Vehicle

We just recently added a McNeil Racing, fiberglass hood to Project Storm Trooper, our 2005 GMC Canyon prerunner build. The glass hood shaves pounds of weight, and features a functional cold air scoop and distinctive styling to set it apart.

“All of our products are built by hand, we do not own a chopper gun or cut any corners,” Mike Meadows of McNeil Racing said. “We take an extra step (trade secret) in our manufacturing process to prevent air pockets. We have full-time employees whose sole job is to spend 40 hours a week maintaining and refurbishing our molds. We take pride in providing strong, functional, and good looking products.”

McNeil Racing had an interesting start as Meadows explained. “The owner, Perry McNeil, owned several Kentucky Fried Chicken restaurants in Tijuana before he got into the fiberglass business. He had a single cab long bed Ford Ranger delivery truck that he decided to do a run to Mike’s Sky Ranch in,” Meadows said. “He did some simple modifications to the suspension and the truck handled much better than the Baja bugs he had run in the past. Once he discovered that his Ranger was a good off road vehicle, he threw larger tires on it, and subsequently broke the OEM fenders. That led to him trimming and pulling the factory sheet metal, which eventually led to a full fiberglass version being made. The rest is history!”

The install of the hood did not take long and reused the factory hinges. We did have to install some hood pins to make sure that the hood remained closed. Once the hood was aligned we were able to tighten down the bolts and put the truck back together.

One thing we can attest to is the fact that the added features on the hood actually work. We noticed a slight drop in engine temperatures after the addition of the hood thanks to the scoop that was molded into this design.

Building A Truck

If you are building an older truck, aftermarket fiberglass might be your only option. Why start with expensive, rusty, or damaged fenders when you can get new fiberglass parts that are ready for paint? Autofab offers flared fenders, bedsides, and a dropped hood for the 1965 Ford F-100. How long would it take just to track down all the factory steel parts for a vintage truck like that?

When it comes to the future, FiberwerX is using every bit of technology available to design their latest offerings. With the use of computer-aided design, they can create bold new concepts and even aerodynamically test their ideas in the virtual world.

After settling on a design, the CAD data is downloaded to a CNC mill for machining of the buck. They can create anything they like on the computer and are working with both fiberglass and carbon fiber materials.

They have been making custom bodies for Monster trucks like Bigfoot, short course race trucks, and some of the most striking Trophy Trucks in the desert. On their own Trophy Truck body, they spent time on the computer to make everything as aerodynamic as possible.

When races are won and lost by seconds, every second, and every mile per hour of speed counts. The lighter a vehicle is with fiberglass or carbon fiber panels the more of an edge a driver and team have to win a race. These are very exciting times for racers and enthusiasts when it comes to custom fiberglass body panels.