There were three SCTA-BNI rules that established the parameters for extending the bodywork. The first rule was the tail section could not be higher than 36" above the ground. The second rule was the tail section could not extend beyond the rear edge of rear tire. The third was the rear wheel had to be completely visible behind a line drawn perpendicular to the ground and through the center of the rear axle.
Since this project involved extending existing panels the new work was laid on a form instead of inside a mold. The forms were relatively easy to construct using flat and angle steel stock for framework and shaping a skin of soft aluminum sheeting that was attached with rivets.
The rule about the length of the tail section was built into this first form however the sides were allowed to crowd the visible wheel rule giving me room to trim right up to the rule after the final shaping was done.
Form being test fitted after it was skinned with aluminum sheeting.
The form was covered with a layer of 3M racing tape to ease removal after the outer layers of glass had been laid. I used blue tape to have visual contrast for the photos but any color could have been used. At this point the bike was covered with protective sheeting so it could be used as a jig.
This picture shows the tail section after the six outer layers have been laid and the form was removed. The tape indicates where I made the first trim cut.
The tail section was then removed and turned upside down and two reinforcing layers were laid on the inside. After the inside cured it was test fitted again and the overhang was marked with tape and trimmed.
This picture shows the finished tail section. Eight layers of fiberglass after final shaping yielded an average thickness of 3/32". This was good because that part of the body is not attached to the frame and needs to be self supporting. The small splotches are 'tiger-hair' that was used to smooth minor irregularities. Notice that you can see a ghost of the old tail section edge.