The Gretz kit comes with a steel mast predrilled for attach screws and nut plates, a joggled doubler for the wing skin, and a spacer plate. It does not include the optional angle to tie the doubler to the rib.
The first step is to lay out and drill the fastener holes per the included drawing on three sides. The upper fastener holes locations in the kit drawing are not used (pre-drilled) as they are match drilled from the existing spar flange/skin holes. The rest of the holes are all “new” for this installation. For the angle, I used a scrap fuel tank z-bracket that I messed up. For some reason I had already cut off one of the flanges so it was ready to go other than cutting it to length. I drilled four #30 holes in one leg for attaching to the wing rib.
The doubler needs to be aligned on the spar flange to pick up the existing holes and spaced appropriately for the optional angle that ties in the rib. The doubler is then match drilled from the spar flange. The lower outboard skin is then clecoed onto the wing and the skin is back drilled through the holes on the doubler (#40 & #19 for the #8 screws).
