Ok fought through the rain down to the shed yesterday - tried as best I could to implement Max's idea, which did seem to me the best solution to whats a tricky problem.
All seemed to go well - very glad I had those cobalt drill bits as regular HSS really just stinks at drilling into steel. The only tricky aspect was which of the 3 pieces that need to be drilled to do first? The disc carrier is easy as you'd slot it into the hub and do those together. But you also have the big cover/giant washer bit, which goes under the disc carrier & a large bolt is screwed into the engine shaft to hold it all in place.
The tricky aspect is that all 3 parts have to be in the right position relative to each other & most importantly CENTRED on the screw hole in the engine shaft. The only perfect way to do this would have been to bolt all on and then turn mower on side and drill through all 3 together - haha which had I owned the right drill might have been easier than what I ended up doing. Bearing in mind in total there was about 16mm of decent steel to drill through .....so on the side would have been hard.
All was i did on a crappy drill press, lined them up by hand best i could. In the end i was a lil off centre, so had to widen the centre hole in the big cover/giant washer a bit with a round file so that I could screw everything on - as I couldn't get the threads to bit initially. As a spacer below the shaft i used a large nut that when I rounded the corners off it fitted into the hub very snuggly, around 10mm or so in height.
Seems to have in total gotten me the 10-12mm lower on the effective blade height relative to the deck vs original - so SHOULD allow me to cut at same height I prefer but not have the deck dragging as badly.
Images attached show the lower position on the shaft of the hub (the shiny metal is effectively the lower amount gained). The bolts holding the hub, disc carrier and big washer all together. The position of the blades relative to the rear of the deck and also the front of the deck.
Big thanks to Max for the idea and others for their assistance. Will report back on how it goes.
