Bodykits: Fiberglass vs Polyurethane

[delta6]

(I was researching and this is what I found so I decided to share it with you guys).

Body kits, as you well know, exist in various price levels. The variation in price usually has more to do with materials, manufacturing methods, and scale. A few years ago, body kits imported directly from Japan carried a certain cache that domestically produced kits could only emulate. You should understand that this is automotive fashion, and more exclusive body kits (much like a designer’s more exclusive dresses) simply cost more to get into the small volume manufacturing of some of these Japanese body kits afforded excellent quality with what was essentially a handlaid fiberglass construction process. Given the small manufacturing capacity, there simply weren’t that many of them on the road. In other words, there are people who cough up inordinate amounts of money to have, in effect, the dress that no else is wearing to the ball. In the process, they make their cars look like something out of an anime cartoon and remove the expensive kit two years later after the Kit Car people come to ask how they did that to a VW Type I.

Handlaying fiberglass involves laying sheets of cloth into a mold and soaking the sheets with a resin to produce the desired shape and that later hardens the sheets of fabric into a solid. As body kits grew in popularity and the visionaries in power saw that greater units could be sold to help reduce price (and increase profits), fiberglass started being sprayed from a chopper gun rather than being handlaid. This proved to be far quicker, but yielded a finished piece that was less flexible, less resistant to impact and more prone to fitment misalignments. Even larger volume production involves the use of molded polyurethane, whose greatest expense to produce rests in the expensive tooling required to mold such pieces. A urethane body component allows the greatest durability and flexibility and is actually the material used by original equipment manufactures (OEM) for bumper covers and factory sill or ground effects.

Urethane body components are the most resistant to driveway impacts and curb scrapes. Unlike fiberglass components, which are usually gel-coated and ready to paint, urethane body components require mixtures of adhesive agents to be mixed into paint for it to properly adhere. Usually paint jobs done on polyurethane do not adhere as well as on fiberglass, so they are more prone to cracking and chipping. Because of the ease with which fiberglass can be molded and manipulated by hand (and the scale on which it can be done), it is the creative canvas for body effects on a limited production basis. For the time it takes to design and manufacture one kit by hand, several kits can be produced by spraying the fiberglass into the mold. These larger volume manufacturers than pass on their savings on to consumers.

PROs and CONs:
Urethane can be quite flexible in large areas, but in smaller areas, it can rip, snap, puncture or even fold. In those scenarios, the urethane bumper is nearly impossible to repair and is completely ruined. Because of its flexible characteristics, the paint must be added with a flex agent to lessen the chances of the paint to crack, peel and spiderweb. Again, because of its flexible characteristics, it will often sag and droop over time. Heat will accelerate this process, and possibly make it worse over time. The only major advantage of having a urethane kit is when the fitment or mold was bad, it can always be flexed and forced into fitting properly.

Handlayed fiberglass is also very flexible, but not as much as urethane. In heavy impacts, it can crack, but it can always be repaired. Unlike urethane, fiberglass body kits can be repaired no matter how bad the damage is. Since handlayed fiberglass is stiffer than urethane, it doesn’t need a flex agent to be added to the paint. The paint will stick very well and has a much less chance of peeling, crack and spiderweb. Another advantage of a fiberglass kit is that it can also be modified if anyone wants it to be changed. A vent can be added, or removed… holes or mounts for foglights can be added… license plate mounts can also be added or removed. Urethane kits can be forced into a good fitment; however fiberglass kits can not be forced into fitment to the extent that urethane can. Fiberglass kits have a slightly less room for adjustment.

Some will say, “I have a urethane kit, and I can run into a wall and my bumper will still be in once piece!” Although this is true, the paint will be ruined and it will need to be repainted. Painting urethane correctly will cost a little more. A fiberglass kit in the same scenario would need to be repaired and painted. In the end, repairing the fiberglass kit came out spending slightly more. But as I mentioned above, if the urethane bumper received any permanent damage, it would be completely ruined. There is no such thing as permanent damage for a fiberglass kit.