Flange attachment

You've shaped your nose and/or scuttle to fit your chassis and powerplant, and now it's time to mount the flanges. If you've never worked with fiberglass reinforced plastic (FRP, commonly known as "fiberglass" to the laiety) before, this is a great first FRP project because it's pretty near impossible to screw this one up. Here's a quick and easy way to do the job.

You'll need:

—an ounce of polyester (or epoxy or vinylester) resin. It will probably come with…

—some MEKP (methyl ethyl ketone peroxide) catalyst for the above (see specific instructions for the epoxy you're using, if you're using epoxy resin)

—a pair of latex gloves (available in boxes of 100 from pro paint suppliers, Harbor Freight etc, or mooch a couple from a beauty salon)

—eye protection, preferably safety goggles or a face sheild but safety glasses at the minimum. You really don't want to get this stuff in your eyes.

—a couple small brushes

—a couple small paper cups

—a popsicle stick

—some 2" wide masking tape

—a well ventilated workspace, with a couple/few layers of newspaper over anything you want to stay nice

We'll use a nose (which we'll call the "part") as our example; the scuttle works the same way. We'll do the left flange here; the right isn't much different.

Step 1: Mask the outside of the part to 2" from the edge, so if you dribble you won't be scraping hardened resins off the pretty side of the part. The flange is the long L-shaped (in cross section) object at the bottom of the photo.

Step 3: Put one of the fiberglass mat strips (not listed in the "You'll need" part of these instructions because Kinetic supplied them; they're in the bag with the flanges) where the flange will mount…

Aha! You're wondering what happened to Step 2. Step 2 is where you sand the gloss off where the mat is laid, both on the part and on the side of the flange. 80 grit sandpaper works fine; you want to get some "tooth" for the resin to adhere to, plus sanding will remove any slight surface impurities that might hamper a good bond. In the photo above, you can see that the mat is on a spot that looks frosty rather than shiny; that's because I already did Step 2.

Step 4: Put the flange on top of the mat. You can see on this example there's a red felt penned "L" on the bottom of the flange, about mid-flange, and a red arrow forward of the L. You can also see how sanding the side of the flange has made it a frosty opaque instead of a glossy clear. Also note the flange is placed forward of the recess for the hood (hey, we're in America), as needed to make it fit flush against the side of the nose.

Step 5a: Tape the bottom of the flange to the edge of the part, leaving half the tape overhanging…

Step 5b: …then tape the overhanging tape to the outside of the part. This positions the flange precisely, with the proper spacing for the mat between the flange and the part, and the tape makes a handy hinge for the next step.

Step 6: Flop the flange over so the mat is exposed. Temporarily remove the mat. Note that against the blue background of the tape, it is easy to see the felt pen markings on the flange.

Step 7: Put on your gloves and goggles. Put half an ounce of resin in one of the paper cups. Bathroom-size Dixie cups work well for this, You don't actually need half an ounce, but it's hard to measure much less than that. Add 10 drops of catalyst (8 drops if it's a hot day) and stir it well with a popicle stick or whatever. Wet both the part and the bonding surface of the flange, you'll know you didn't miss a spot because wetting the surfaces makes them clear and glossy again.

Step 8: Lay the mat in place and wet it out with the resin. It too will become clear. If there are bubbles under the mat, poke them out with the tip of the brush; jab the bubbles toward the edge of the mat. You don't have to rush through this part of the job, you have about 15 minutes before the resin starts to gel.

Step 9: The reverse of Step 6; flop the flange back on top of the mat. You can see if there are any bubbles between the mat and the flange, and if so, deal with them by tilting the flange back and fluffing up the mat in the low spots (you can use the brush to move the fibers of the mat around; after a couple of minutes the binder that holds the dry mat together will dissolve in the resin and the mat will become a bunch of fibers flying in loose formation rather than an object in its own right.

If you've done a neat job so far, you can tape the flange down firmly—not surprisingly, masking tape won't stick to wet resin—or put some weights on it (pocket change is good). Let the part rest somewhere warm for an hour (70 degrees f. or so) or until the resin isn't sticky any more, and then pull off the masking tape; the resin will be firm but not yet hard and drips (if any) will be easy to remove with a razor blade. Then flip the part over and do the other flange on the other side (use a new brush and cup). In a day, the part will be cured and ready to install on your car.



•Neatness counts. Anything you touch with catalised resin will be permanently hard tomorrow. This includes your clothes, your tools, the walls, the floor…but it's not hard to be neat on a small job like this. I did this flange with a camera in my left hand (see photos above) and didn't get any on the camera. However, accidents happen, and if you're going to do lots of fiberglassing in your career you'll want to sacrifice a set of old clothes to the resin gods.

•Polyester resin is available in small quantities at most big box hardware stores (e.g. Lowe's, Home Depot) for about $10 a pint or $15 a quart, including catalyst. Keep the can sealed after you're done with the flanges and it will last for years. If you're buying all your fiberglass parts from ouside vendors (me me pick me!) that resin will be all you'll need for the whole car. If you're designing and fabricating your own parts (which is fun but time consuming, and if you're only building one car it'll be more expensive than buying the parts outright) you'll need lots of resin and lots of other stuff but that's another story (if there's interest I'll do another how-to on creating your own parts). We don't include resin or catalyst with our parts because the hazmat shipping surcharge on an ounce (the resin is flammable and the catalyst will oxidise dang near anything) is more than the purchase price of a quart.

•You can clean your resin tools with acetone, but on a job like this I don't bother. Your tools in this case are two brushes and a popsicle stick (or other sacrificial stirring device) and it's easier—and probably cheaper, and probably better for the planet—to toss them than to clean them. Once the resin has cured, it's a solid plastic and pretty benign, but as long as it's liquid (which includes being liquid dissolved in acetone) it's a hazardous waste.

•I wouldn't do fiberglass fabrication without eye protection any more than I'd grind metal without eye protection. I used to when I was young, and I didn't wear gloves either, but the list of dumb things I used to do is long and distinguished and I know better now…and now, so do you.

IMPORTANT NOTE: Do <not> use the flanges as attachment points. The flanges that fit against the frame rails are there to eliminate edge gaps and give the part something to sit on while it's being attached. Attach the part to the chassis with fasteners that penetrate the part itself, fasteners such as bolts or Dzus fasteners. We are making new molds that will produce much narrower flanges, which should eliminate that temptation. Weight is the enemy of these cars, and to make flanges robust enough to serve as "hidden mounts" they would have to be made heavier and would need a greater bonding surface.