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There was some discussion a week or two ago about fiberglass fenders and I have been meaning to reply. It is kind of slow today at work...so here goes. Most, if not all, aftermarket/specialty fiberglass auto parts are molded in single sided molds. That is they make a female mold from the original part and then spray chopped fiberglass and resin into the mold to make the part. The mold is relatively inexpensive and the composite materials are quite cheap. There is a good deal of labor involved but not too bad. The problem is that there is poor, at best, control of the thickness of the part and the inside surface of the part is not very good. The one part (floorpan) that I have from Fiber Innovations is made this way and the thickness varies by more than 300%! You also don't get the best strength form this process. You might only end up with 18-30% glass fiber (the strong part of the composite) and the rest resin. Structural composites typically start at 40% and go up to 65% fiber content. Low strength composites are fine for fenders and such, but I would not wnat to rely on them for structure(floorpans). For these parts you want better control and more fiber...but that is another subject. The other problem with this technique is that you can not mold undercuts or return flanges. The part would be stuck in the mold. To accomplish this you have to invest in much better and more sophisticated molds that are two sided and multi-piece. Lots of $$$$. I agree with Dave Hall...the vents on Square and Fasty rear fenders would be a problem to mold in fiberglass. You really need to design the part for the material and not just do a material substitution. You could probably get a pretty decent vent, but it would require a bunch of hand trimming and finishing. Someone asked if an original fender would be required. That would be the easiest way to get a good part, but you would actually need the whole car. You would need to take the mold off of the fender while it was bolted to the car to ensure that the fender retained the correct shape. You would then have to add the flange details to the mold after unbolting the fender. The molded fiberglass part can not be "flexed" into the correct orientation like the steel part and the steel fender is not rigid enough to guarantee that the fender would be right unless it was bolted to the car. This is probably more information than most of you want so I will stop. If any one is interested in discussing this more p-mail me at: jaranson@the-bridge.net I used to do this for a living at Ford Motor Company and still enjoy the topic. Love to help out anyone interested in doing fiberglass work and am planning on some of it for my own Fasty.... Later, John Jaranson (former Ford Research Engineer) '71 FI Auto Fasty (Composite "ground effects" in her future) ------------------------------------------------------------------- Search old messages on the Web! Visit http://www.vwtype3.org/list/