Commando clutch in Dominator 99 - Oil in Chaincase

Mike.....your oil drip is almost certainly coming from the crankshaft oil seal. Possibly you replaced the old one with one of the cheap fakes on the market or the crankshaft damaged the new one. 

For oil to get from an AMC gearbox to the Primary Cases, in serious quantities, is not easy due to the convoluted route it has to negotiate. It also would need something to pump the oil or oil vapour about which could be the clutch push rod but most unlikely if the correct item is inside the gearbox shaft. 

I would suggest checking out your engine breather and the crankshaft oil seal as the more likely causes of your problem.

My 650 gets a little oil thrown into the primary cases but this is ok by me as it lubes the sides of the belt and helps to stop it grinding away on the pulley keepers.

There must be a reason why Norton used something as odd as a 6 mm rod instead of a  more common 1/4". A silver steel rod needs to be hardened, at least in the ends. I prefer to use two or three rods with a bearing ball or roller between them. I usually have a small amount of grease between the rod parts. Never experienced gearbox oil in the clutch, might be pure luck. An idea would be to check if the tiny ventilating hole in the box is clogged.

I have just removed and dismantled my 650 gearbox in an attempt to cure the whine I was getting  in third gear. This gearbox was built 10 years ago from a crate of bits I bought for £125. Everything in this crate looked usable so I just cleaned  all the gears, bushes and bearings and them put the bits back together. I filled the box with Sythetic Gear Oil and it worked fine apart from the whine.

10 years and 8,000 miles a stuck drain plug and the whine encouraged me to take the box apart and do a major rebuild using an RGM refurb Kit costing £!53. Included in this Kit is a Layshaft roller bearing conversion.

Inside the gearbox there was no wear worth noting apart from the kickstart shaft bush which was near death. This was a pig to get out. In the end I drilled it as thin as possible and then chiselled the remainder out. The big surprises were the replacement 2nd & 3rd gear bushes which actually had more play in them than those they were replacing. 

To get all the ball bearings out of the cases I cooked them in the oven for half an hour and they just dropped out when the cases were turned over. The Sleeve Gear replacement needed thumping to get in its housing and so did the Layshaft outer race. The inner race also needed warming before it would slide onto the Layshaft and then would not slide easiliy into its outer.

I am going to refill the box with Sythetic oil again as it appears to have worked OK, not caused any apprent damage and does not need changing  as often as standard EP90.

What did you do about the loose bushes?, What did RGM say about them?.

According to the blurb, sent with the kit, these two bushes are supposed to be loose both on the shaft and inside the respective gears. I have spoken with other reputed Norton Gearbox rebuilder who suggest that this is correct but the play should not be excessive. The more important chunks being the bush and bearings on the respective ends of the Layshaft. I guess the proof will be when roadtesting.

Comment on 6mm rod. Maybe Norton were all set up with 1/4" drills. A 1/4" rod would jam unless they machined a clearance. Result = 6mm rod. So they procured 6mm ready manufactured. All makes perfect sense.