One of my posts on page 2 of this account talks about the fitting of the swinging arm bearings. Having made the top hat bushes and worked out how to fit the bearings I was able to fit the swinging arm temporarily to the engine plates. With the gearbox in place, that enabled me to work out the chain line for the rear hub.
The first job was to make spacers to centralise the hub. This isn't as easy as it sounds because the hub incorporates a rubber shock absorber which is squeezed slightly to fit. You don't want this loose, nor do you want to spring the swinging arm legs outwards so a certain amount of trial and error was needed. The swinging arm legs are not symmetrical by the way with the one on the right angled further outwards than the one on the left.
I knew the hubs were Grimeca and was lucky enough to buy one brand new form RGM Norton via Ebay. This was almost the last of a batch they had made in the 1980s and was powder coated black. Over the years in storage though, the powder coating had largely come loose so it had to be removed. Naturally, those bits which hadn't come loose were an absolute swine to remove. The hub lacked only one thing - the brake operating lever. Maybe it was fashionable to break these whilst falling off your Norton. I managed to buy no fewer than 3 incompatible brake operating levers before finally buying a complete spare brake plate from the USA which happened to have the lever fitted. Some careful measurements from the gearbox sprocket and engine plates enabled me to determine how much to machine off the drive end of the hub for a correct chain line. Then I could make the sprocket fit by enlarging the hole in its centre by a boring bar in the lathe.
Quite what the spoke lengths should be or the head angles were a little uncertain, as was the angle for the hole in the dimple on the rim. Having found a formula on the internet for bicycle spokes I had some idea what was needed but decided to ask the experts at Central Wheel Company. The man on the counter took one look at the hub and said "You need a rim and spokes for an early 1970s Ducati." So that was how I found out the original fitment for the rear hub.
I had bought the front wheel complete at a Stafford Show but the spokes were corroded so I took one out to find its dimensions so that Central Wheel could make me a set. To my surprise, the ever helpful man on the counter told me that a new rim was completely unnecessary and that the old one would polish up well. He was entirely right and deserves great credit for giving such a good impression of the company. I fully recommend Central Wheel Company as a result.
As ever, I built the wheels myself and I am pleased to say that they trued up well enough.