I am working on a GT 40 replica. The car had a bad windshield that was taken out several years ago. It is time to install the new windshield, and the roof line has saged and needs to be built up to meet the glass. The bottom corners support the glass and the gaps are significant. Across the top the gap for the tray is 1″ to .75″, the side tray is off by .2-.3″, and the center of the bottom edge is off by .5″. In Kevin’s 3 part series on filler he says not to use filler for more that .25″. All the old paint has been removed down to the gel coat on the tray and half of the roof. My question is two part.
1. Should all the buildup be done with fiberglass cloth and mat(biaxial) and then filler for shaping to fit? The tray area will not be seen. Would filler be OK for the bottom area?
2. Can the repair be done over the gel coat or do I have to sand down to fiberglass to start the repair?