N15 gearbox a bit notchy or clunky, seeking advice

After working on a '71 Commando and riding it around (the widow's bike I sold for her), I found that its gearbox was a good deal smoother on the downshift from 3-2, and 2-1 vs my N15. I tend not to downshift much and just roll to a stop to avoid crunching gears, but it has me thinking.

I did a full rebuild of my N15's gearbox with all new bearings and bushings, and it is 'OK', but is a bit of a crash box on those 3-2 and 2-1 downshifts. I remember fiddling with the two camplate spindle screws at the front of the box, which seemed to have an effect on the actuation while on the bench, but I couldn't figure out what to do besides tighten them down to prevent leaks. From memory, it seemed that if I backed them off a bit, shifting got easier, but I never found any info that they were adjustable.

I've also tried to figure out how to lessen the clutch pull, it's quite stiff. Maybe related? Perhaps not a gearbox issue at all except that memory of bench-shifting sticks in my mind. I run 90W gear oil that meets the specs I found in the manual, picked it up from West Marine. The Commando's fluid seemed to be a slurry of ATF and gear oil, I flushed and used the same gear oil and it was A-OK.

As to the hard clutch pull, there are two different methods to ease it in this thread: https://www.accessnorton.com/NortonCommando/heinz-kegler-some-memories.26033/#post-452535 Both developed by Heinz Kegler. The outer basket method looks doable with what is available to the average person. With the riders of Norton generally getting older, it would be good if Andover Norton offered these for the older model Nortons. The Commando can be made to have an easy pull by adjusting the stack height

franko said:

As to the hard clutch pull, there are two different methods to ease it in this thread: https://www.accessnorton.com/NortonCommando/heinz-kegler-some-memories.26033/#post-452535 Both developed by Heinz Kegler. The outer basket method looks doable with what is available to the average person. With the riders of Norton generally getting older, it would be good if Andover Norton offered these for the older model Nortons. The Commando can be made to have an easy pull by adjusting the stack height

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Thanks will check it out. I'm reading up on threads, loose or bent selector / tired spring perhaps, clutch drag maybe. I think more likely the spring than anything, not sure if I replaced it, will check receipts. I've lubed the cable and adjusted, the clutch actuation is fine and I don't think there's too much drag. I have good grip strength and XL hands so the effort isn't so much a bother for me, but my lily-livered 20y/o son who has tiny hands complains about it LOL. I'd like to fit dogleg levers to both brake and clutch but that's a hunting expedition as my setup is a parts-bin special.

OK, an update. The clutch is a bit better after cleaning, adjusting, and lubing. I'm not going to do surgery or modify it with special parts, for various reasons. I can live with it.

As for the camplate spindle screw issue, I either (1) back the bottom-most screw out about 1/2 turn and the gearbox action is light, but I get an oil leak, or (2) tighten it and the leak stops, but the action becomes stiff. I used the correct washers, screws, and o-rings (part #s 20, 21, 22). All I can think of is to pull it out and slip on a slightly thicker washer, or add a thin one. Removal of that screw is tedious, but doable; putting it back in will be no fun at all. I expect I'll have to finagle it from below with a racheting box-end, and something to apply pressure until the threads catch.