After driving my car for 300 plus miles, I found gravel in the cockpit area behind the seats where my rear tires were picking it up and it was making it through gaps in my rear inner fender wells. I had planned to install inner fender liners but had not gotten to it. Some builders have installed custom bent aluminum panels to enclose the inner fender wells.
After looking at my inner wheel wells, it was obvious the gravel was coming from the gap where the rear cowl lip on the cockpit tub is supposed to seal against the cowl area on the body and also on the bottom of the fender area. There is a "D" gasket that was glued to the lip on the cockpit tub to proved the sealing. In the area around the fender area, the lip deviated from the contour of the fender and was no where close to sealing. Big gap right into the cockpit.
I decided to fix the cockpit tub cowl lip so it conformed to the fender contour and sealed properly. In the picture below, I cut the lip in Area 1 and spaced it about 1/2" with foam pieces to the fender contour. I then fiberglassed the triangular piece that resulted in cutting the lip. The picture is after I glued in some high density polyurethane foam and contoured it with an angle die grinder with sanding disk. Just a matter of applying fiberglass matte and resin over the area. I used 4 layers of matte and resin. Now the "D" gasket (you can see it in the picture where I pulled it out) will fit the 1/2" gap and seal as it is supposed to.
While I was at it, instead of custom cutting/bending some aluminum panels to fill the inner fender liners, I decided to just fill the gaps with the same foam, fiberglass matte and resin. Those are shown in Areas 2 and 3. I only attached the new fiberglass to the existing fiberglass of the cockpits tub. I masked off where the new fiberglass contact the metal seat post or frame. Also where the cockpit tub meet the body. This will allow the fiberglass to flex a bit when the frame flexes. Again, 4 layers of matte and resin as I found this results in about 1/8" thick fiberglass composite patch.
After applying the fiberglass, I coated everything with rattle can truck bed liner. Matched the existing coating pretty well although the texture is not as aggressive. Applied a large bead of black silicone to all the joints.
The final result is shown in the picture below.
Just a different approach to filling the gaps and sealing the rear inner fender wells. Seems to have worked well. No more gravel in the cockpit area.