17 Apr
As the hardened stuff changes dimensions somewhat anyway I put the big sprocket on the lathe and ground the under-size (I left a couple thou in there) internals to proper size for the bearings and the seal. The outside diameter was ground to correct size as well to make the seal run smooth and easy
So its all concentric to less than a thou.
Next step was to grind the front sprocket internally to a tight fit on the shaft. Took half the day to do all the grinding but it feels so good when all is tight and fits as desired.
After putting the bearings in and securing them with a circlip I pressed the rubber seal into the rear sprocket. Then the whole assembly of front and rear sprocket connected with the chain was pushed on the shafts. Front sprocket is tight on shaft and needed to be pulled home the last 1/8" completely with the big nut and a couple spacers - nice. Then I fitted the inner Bronze disc over the rear gear pin and tightened it up.
Next step was warming the internally nickel plated and ground rear gear pinion in boiling water. Had it in there for 1/2 hour to make sure it will go fully home over that long shaft. First attempt worked perfectly - all dimensions correct - it slid almost home, getting tight within the last 1/16". Hurried to fit a couple spacers to pull it fully home.
So to try if everything is correct I fitted the chain tensioner and turned the cranks - all spins nice and free without tight spots - I guess we have a good bottom end now.