Tech Talk: FRP (Fiberglass) vs Blended Materials for Aftermarket Body Kits

24 Sep

We get this question ALL the time – what is the ‘right’ material to select when buying aftermarket body parts? There are a range of materials that manufacturers use. Several higher end manufacturers, mainly in the Japanese realm, offer several of their products in both FRP as well as a blended, or hybrid material. FRP stands for Fiberglass Reinforced Plastic. This term is tossed around alot in the aftermarket aero world. It’s a bit of a catch all term, that generally describes a range of composites (parts made by mixing various materials together). Without getting boring, there are differences among “FRP” blends. Not only do the materials mixed together vary, so do the epoxy types used to hold them together. Since a fiberglass part is only as good as the quality of the mold used to produce it, that is why you see such a huge variation in pricing among parts that on their surface look similar. This is an area where you get what you pay for. For ease of terminology, I will stick to using the generic term “FRP”, but I am specifically referring to the better-branded/manufactured stuff out there, since that is what I am most familiar with. FRP has many fantastic properties. It is extremely strong relative (especially) relative to it’s weight (it’s light), it can be molded into many complex shapes, it is easily repaired should it get damaged, and it’s able to be produced at relatively low costs. FRP really has no downsides in and of itself, it is a terrific material for these type of parts. Some will say that urethane is ALWAYS better, and it’s simply not the case. Urethane molds are extremely expensive to produce, which is why you rarely see aftermarket aero parts offered in the material to begin with. When you do, they tend to be extremely heavy relative to their FRP counterparts. Urethane is extremely durable, mainly because it has so much tensile strength, but should it be damaged via impact, it’s very difficult (and often impossible), to repair. Most times when it suffers such an impact, it has to be replaced. Fiberglass on the otherhand can literally be decimated – shattered into multiple chunks after an impact, but joined back together relatively easily. Serviceability is a big benefit of FRP parts. Another issue with aftermarket urethane, that is often overlooked, is longevity. Depending on where in the world you live, the urethane can break down over the course of time, due to environmental conditions. This process can cause the urethane to lose its shape and literally deform. As this happens, its aesthetic value and its durability both suffer.

In the last 10 years (give or take), we’ve seen variations of fiberglass hit the market. These are components use a combination of different man made materials (urethane, various plastics, etc) added into the “FRP” mixture, and sealed with a different type of epoxy. The purpose of this type of material was to bridge the gap between the aftermarket urethane parts and the OEM plastic/urethane level parts. These blended, or hybrid materials are more flexible vs their straight FRP counterparts, but not as flexible as a full urethane part. In the case of manufacturers like INGS and CWest, their blended materials have the added bonus of requiring much less prep time before they are ready for paint. This type of manufacturing is more expensive to do, so only a handful of worthwhile companies offer it. Several try (mostly knockoff firms), and succeed to varying degrees. In many cases I have seen, while the material itself is generally quite good, in the interest the mold quality suffers. Molds are used for longer than they should be, or simply are inaccurate in the first place. This results in unwanted gaps when installed, or parts that are too long, too short, and require significant prep work in order to actually install on the car. Prep work is expensive, generally charged per hour, and can quickly make the ‘savings’ vs the genuine article disappear. While the hybrid/blended parts are slightly heavier than their FRP counterparts, they are nowhere near the level of a urethane part. Somewhere on the order of 5% or so heavier.

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