View Full Version : Making Fiberglass Repairs and Shapes

12-05-2007, 02:35 AM
Ok doods, its been a while since I have contributed anything other than OT stuff. I have been sooper busy with work, but I was able to eek out some airplane work this summer. It involves fixing some holes in my cowl and making some new shapes for air inlets and outlets. All stuff that is directly applicable to cars.

Lets get started.

Here is the cowl. Unfortunately, I did not snap any picts before I started, but you can still see the holes I covered with glass. The new oblong shaped holes of for the new exhaust exits. As you can see, I have hacked this thing up pretty good over the years trying new stuff.


Here you can see how I made the oil cooler inlet ducts. A "block" was sanded to shape as a pink piece of foam and then smoothed with molding clay. I used spray on adhesive to temporarily attach the foam to the cowl. Used plastic tape or carnuba wax as a mold release so the resin would not stick to the cowl. Here is the rough part before trimming and re-attaching. The rear air exit duct was made in much the same way.


Drill a few reference holes, remove it, take the foam and clay out and trim it to shape. Glue and rivet it back into place. No its not perfect yet, you clean it up with micro balloon filler or bondo.


I needed to make a little more room for the exhaust pipes and oil lines. I put the cowl back on and continued to cut more big holes in the cowl until the thing would go back on without hitting anything. Next I used artistic judgment to place molding clay over the big holes. Smooth it to shape and wax. Repeated the same process as with the inlet. Drill reference holes, remove, trim excess and rivet the new pieces in place.



Much sanding and filling later, you can't really see that there were any other holes.



Off to the airport for a couple of proving flights. She rocked, time for paint.

Much more sanding and filling later, plus paint.


Final product on the day of the race this summer.


One thing I will add. If you are going to take on a composite project, its much easier to use a good epoxy like West Systems than the cheap polyester crap from Walmart. Its quite a bit more expensive, but the results are much better. Plus you have a working time of many hours instead of minutes. It also actually gets fully hard when it cures.

Anyway, hope this helps. I have a few more projects I can go through if anyone is interested.

12-05-2007, 05:24 AM
Looks awesome man. I like to see other people workin with fiber glass. It super fun and rewarding.

You ever use US composites stuff? How did you like it?

12-05-2007, 02:07 PM
I have not but a buddy of mine has. He did not report any issues. I use West Systems since I can buy it locally. Saves the Hazmat shipping fees.

12-05-2007, 08:43 PM
yea thats why i used the US composites but other than that I haven't tried anyothers. The US composites is so smoothe and finsishes so much better than cheapo brands. It was so easy to tell which stuff was the US composites and what was the cheapo stuff when I was learnin bodywork on my car. definately important to buy good stuff to work with.