Glass Versus Steel - Choosing a Hot Rod's Right Body

Fiberglass versus steel bodies. A few decades ago, this wouldn’t have been an issue among street rodders. Original steel bodies were easier to find, and reproduction bodies were still a novelty.

Times have changed. To drive an original sheetmetal car is no longer the norm, but a rare distinction. Repro ’glass bodies have improved in quality and are accepted as valid street rodding material. But there is still something that makes a steel body, even a reproduction, a bragging point in our hobby. We asked some prominent body manufacturers and rod builders about the pros and cons of ’glass and steel. As we expected, we got a variety of opinions. Manufacturers promote the advantages of their own products but back up their ideas with valid reasoning. How you choose is a matter of which reasoning best suits your taste and your budget.

Desirability

One of the biggest things going for steel bodies is the brag factor. There is some measure of pride in being able to say that your rod is the original steel body. Even repro steel bodies are sometimes perceived as somehow being more genuine because, like the originals, they are steel.

The fiberglass body industry has had a bad rep to overcome. Fiberglass repros were once regarded as low-quality knock-offs or as cheesy kit cars. Unfortunately, some still may be, but for the most part, bodies from the leading manufacturers are first-class products and offer a good alternative to original or repro steel.

In many cases, today’s high-quality fiberglass bodies are better than originals, due to the ability of modern manufacturers to correct potential original engineering flaws. Also, the quality of many bodies makes them virtually indistinguishable from steel cars. Shop carefully and ’glass can be a smart way of achieving your goal of driving a street rod.

Availability

“There’s nothing like a nice original steel solid ’32 three-window, but good luck finding any these days,” observes Darren Bond at Gibbon Fiberglass. It used to be that primo original bodies were always popping up in farmers’ barns, but those farmers wised up, sold those cars for big money, and are living on their yachts now. Virgin steel has either been hot rodded by somebody else or has rusted into the earth. Finding a survivor typically means spending a lot of time and money repairing or replacing any remaining sheetmetal. Buying a ready-to-go reproduction may be the solution for people who are eager to hit the street.

The advantage of original bodies is that, whatever you want to build, there is a possibility that you’ll find one. Go the repro route and you’re limited to what’s on the market. This may also be the deciding factor in the ’glass versus steel debate. Deuce roadsters are available in steel from Real Steel, Rod Bods, and Brookville, but for something like a ’39 Ford repro body, fiberglass is your only option.

As Kenny from Brookville points out, if steel is the first choice of rodders seeking a true replica, fiberglass may be a better choice for those with more radical tastes. Many ’glass bodies are design extensions of traditional bodies. Trying to turn a gennie ’33 into something as wild as the Speedstar is not realistic for a backyard rod builder and would end up costing more than buying one from Rat’s Glass.

Factors such as firewall location, roof styles (chopped or stock), and hinge styles (hidden or stock) will also affect whose repro body you buy.

Budget

For most rodders, availability is not a question of what is on the market, but of what is in their wallet. Every builder we spoke to mentioned cost as the primary reason for selecting a fiberglass body.

“Economics is the biggest factor,” Dan Fink tells us. “A ’glass car will be far less expensive that a steel-bodied car.” Geoff Mitford-Taylor echoes that: “It’s really a budget thing. A first-time builder is going to be conscious of the cost. A steel body is going to add at least 10 grand onto the price, after you consider bodywork and having it painted.”

There is more to budget than just the initial cost. Buy the cheapest body you can, and chances are, you’ll pay in other areas, such as quality or the amount of work required to turn that body into a decent rod.

Resale value is another important budget consideration. A few years down the road, a steel-bodied car is likely to bring a higher price than a ’glass car because of desirability and other factors. Should you get in an accident, though, fiberglass replacement parts are more prevalent than steel.

Characteristics

Fiberglass and steel are extremely different materials with extremely different characteristics. To the experts, these characteristics can help determine which is better for you.

Moisture is the enemy of steel, and rust is a problem for anybody living in the snowbelt or near the ocean. On the other hand, fiberglass is impervious to corrosion. “Heat is the worst enemy of fiberglass,” says Darren Bond at Gibbon. “Fiberglass cures with heat, not with time.”

John Steele at JPS Motorsports builds a lot of ’glass rods and sport car replicas. According to John, “Heat can reshape the ’glass before you get it, even if the mold is good. I’ve seen pieces that were perfect out of the mold and when they shipped, but go out of shape all of a sudden.”

As Bond explains, “Once the ’glass hits a higher temperature, it will ‘turn * green’ as they say, becoming more pliable and releasing some of the styrene and chemicals in the ’glass, leaving kind of an orange-peel effect in the gelcoat.”

For Steele, this pliability can be an advantage. “Fiberglass is plastic but it does not have a memory. If you apply heat, like sunlight, or apply pressure like weight, you can actually shape it and it will keep a permanent shape. You can even reshape it in the sun if you have to.”

“Steel is ductile, meaning that it moves and stays without breaking,” Karl Wescott explains. “Steel will bend and stay bent. ’Glass is not ductile, but is flexible. It will bend without cracking or breaking up to a point.” Hal Hanneman at Hanneman Fiberglass silently demonstrated this principle by walking over to a ’glass roadster body in his shop and giving the quarter-panel a solid karate kick with no damage. Impressive.

Working With the Material

If you’re not going to be doing the bodywork on your rod, working with the material is not an issue for you. Otherwise, there are some things to consider. According to Kenny at Brookville, “Working on a steel car is a lot less messy than working on a ’glass car. The average guy can weld and file on steel. Not everyone can mix and lay fiberglass to patch a ’glass car.”

John Steele works with both. “For me, it’s easier to fit fiberglass, because you can build it up or cut it down easily. But if you’re not experienced with ’glass work, it’s easier to repair a mistake in metal. You just cut a new piece, weld it in, grind it down, use a little finish material, and you’re done.”

“It’s no fun to grind, it’s itchy, and the smell’s not the best, but ’glass is a little easier to work with,” says Darren at Gibbon. “If the lines are off, it requires as much bodywork to fix a steel car as it would if you had a poor-quality ’glass body. Steel and Bondo are not two of a kind, whereas with fiberglass the characteristics and raw materials are very similar to Bondo. If properly done, it adheres to the fiberglass and will not come off like it will on a steel car. The gelcoat will tell you where it’s high or low, which makes ’glass good for beginner bodymen.”

’Glass and Steel in Combo

Unless you are building a street rod from scratch, you may not need to buy a complete new body, and could build up an existing body with aftermarket reproduction components. Perhaps you’re starting with an original body and only need to replace the hood and decklid, fenders and running boards, or a couple quarter-panels. Adding ’glass fenders to an otherwise steel car is a typical option. Of course, this requires doing some investigating ahead of time to find out how well an aftermarket part will fit with other original parts.

Steel replacement parts are a very good way of repairing worn-out original sheetmetal. Brookville was in the replacement body panel business for more than a decade before introducing its Model A body. Since its parts are created as exact reproductions with stock mounting points, repair and replacement is generally a straightforward job.

Jay at Early Iron has had a lot of success making new steel panels work on original cars and has used repro steel subrails on original-bodied coupes. Some modifications have been required, but he finds it a lot easier than having to fabricate parts.

Confused Yet?

Not knowing you, we can’t give you a definitive answer as to whether your next street rod body should be original steel, repro steel, or fiberglass. Perhaps we’ve given you some criteria for answering the question for yourself.

Talk to as many rod owners as you can about what type of body they built and whether or not they were happy with the results. Study the car features in R&C, paying attention to which bodies are prominent. Go to street rod events where these companies have booths set up and talk to the representatives there. As virtually every expert told us, rodders can have fun at many levels and any body style can be built into an outstanding street rod. Select the body that will provide the greatest fun for you and you will have made the right decision.