Steve, Did you just split the bonnet, or did you cut out a center section to accommodate the width of the piano hinge?
Steve, do you have a fore and aft brace from nose piece to firewall? How did you separate the main bonnet section from the nose, what sort of tool did you use?
After separating the bonnet from the front cowl, I made two slow and careful cuts about .375" apart with a fine tooth jigsaw to accommodate the piano hinge, as you surmised. I cut perhaps .010 inside my marked cutting lines, then finished off the edges with a file, stroking away from the paintwork. By using a couple of layers of painters tape to protect the outer surface of the bonnet I avoided any exterior paintwork except for touching up the cut edges with a brush.
The hinge was pre-drilled for fasteners, which helps immensely in locating the holes. I added 10-32 thread nut-serts to the hinge, btw. I started with drilling the center hole on each side first, inserted the screw, then drilled the next one, inserted the screw, and so on. Because the bonnet has a slight curvature I think this is imperative to ensure you get the spacing correct.
Separating the bonnet and cowl is easy, just a few bolts. The trickiest part of the project was removing the partial bulkhead at the front of the bonnet that bolts to the cowl. This bulkhead was both edge
and plug welded to the bonnet. Took me about 4 hours with a small pistol grip air grinder and 2" disc to grind away 'just enough' of the welds to allow separation without gouging the alloy bonnet itself. Fortunately I have become a very skilled grinder over the years, facilitated by being a poor to mediocre welder. The inner surface of the bonnet was wet sanded and prepped with self etching primer, which I decided to leave as is as I like the contrast, and it can always be painted later on.
There is no fore/aft brace to the front cowl, the mounting braces I made fasten to the front body mounts adequately locate the cowl. And nothing holds the bonnet on except the original 4 Dzus fasteners! That was not the original plan, but after hundreds of miles of testing, I've decided to leave it alone. The body lacing around the perimeter of the bonnet is essential to minimize vibration and and movement.
