ok, this evening a dismantled the wishbones again, as I needed to flip the chassis over to gain access to the underside.

I spent an hour and a half painstakingly grinding off the chequers from my floor panel. I made it from a sheet of 2mm chequerplate, but for it to sit flat and seal against the bottom of the chassis, I had to remove the chequers where the 2 meet. It's not safe to do this with a grinding wheel, as the aluminium builds up in the stone, clogs it, expands and the stone may explode! So the safer way to abrade aluminium is to use a flap wheel or disc. These break up easily as you use them and cannot be clogged by the ground aluminium.

I actually went through 5 flap discs to do it, my hands are stinging and my ears are ringing but it will all be worth it in the end.

After this, I flipped the chassis over (which is getting harder - it's getting heavier all the time!) and clamped the floor panel on flat and marked out the lines to drill the rivet holes along.

All in all one very productive evening.