The original floors for many vintage automobiles were made of wood. This was okay 80 years ago. The 1928-31 Model A Ford used a combination of steel floor pans and some wood up front. The Brookville Roadster 1928-29 Ford roadster body is equipped with very nice steel floor pans and was set up for a rumble seat. Having designed a custom frame / chassis for my 1929 Ford roadster hot rod forced me to remove the entire metal floor. Using a C4 Corvette suspension for the chassis / frame on the 1929 Ford hot rod required a narrower frame / chassis width in the rear. My chassis / frame sits inside of the roadsters body rails at the rear of the hot rod. The original Henry Ford design has the entire body sitting on top of the 1928-31 Model A chassis / frame. This was a good design for the time, as the body also provided strength to the lightly made ladder style chassis / frame. Part of my body modifications necessitated the rear floor cross member to be removed and moved a few inches towards the front of the car. Because of this modification the rear floor pan could not be re-used easily. I did consider making new metal floor pans but did not like the 0.5 inch difference between the height of the floor and the roadsters body frame rails and floor cross members. Wanting a nice flat floor even with the top of the roadsters body frame and floor cross members I thought plywood would work but would seal them with fiber glass. Below are a few pictures of this messy process.
Step 1: After giving this a bit of thought, and having done a fair bit of drywall work in all of the houses I have owned, it made sense to trim the edges of the new 0.5 inch plywood floor cut outs with metal drywall j-mold. It fits perfectly over the plywood edges to seal and provide a nicely finished edge. Small nails were used to tack each piece in place.
Step 2: I decided to use a gray colour pigment made for polyester resin to match the grey primer I have been using on the car. Now it is very important to mix the correct amount of catalyst with the amount of resin to be used. Another consideration is the ambient air temperature in the shop. This means if your shop is very warm you can use less catalyst and if it is on the cool side of things, more catalyst is required. Not enough catalyst will be a disaster as the resin will not ever harden. Too much catalyst will cause the resin to set too fast and get very hot. Only mix enough resin for a time period you can handle. The resin is expensive and you do not want a waste any product. I used plastic bowls from the dollar store to mix up the resin. Using a permanent marker, I marked out a 4 ounce and 8 ounce points. From the local farm supplier or even the drug store, purchase several small syringes. These are great for getting the exact measure of catalyst. I used 2 teaspoons or about 6 cc of catalyst for 8 ounces of resin or gel coat. When I did this, my shop temperature was about 65 degrees f. From the dollar store I also purchased heavy duty rubber gloves, several paint brushes, and small paint rollers. For clean-up I used lacquer thinner. Do this in a well-ventilated area and wear safety glasses. I do not clean my rubber gloves or mixing bowls. Once the resin hardens, the hardened resin just peels off the gloves and breaks away from the plastic bowls. When applying the resin to the fibre glass matt, make sure you work out all of the air bubbles to maximize adhesion to the plywood. This is a very messy and smelly process that cannot be rushed.
Step 3: Once all of the floor boards had the fiber glass matt applied with a good coat of resin, I started to paint on the gel coat. Again, I used a colour pigment in the gel coat and used the same amount of catalyst as I did for the resin. Several coats of gel coat were applied. Eventually, I will sand the bottom side of the floor panels smooth for an even finish. All edges were sanded smooth on my stationary 6 inch belt sander. The entire process to seal the wooden floor panels took several nights out in the shop.
All of the panels fit into my 1929 Ford roadster without any problems. These will all get screwed down with a heat shield and rubber padding applied to the interior to reduce noise and heat. These floor panels will be extremely strong and well-sealed from the elements. A similar technique is use to make light weight but very sturdy cedar strip canoes.