Hi TJD, A few in this & RAT group have mentioned how wear in the spider of cush hub can effect clutch operation, both drag & slip. This is besides the well know notching of the grooves in basket & hub.
2 thoughts. First the Norton
has large dogs similar to Triumph 5 speed, your bike has spline type dogs, so they will never feel the same. Secondly, don't overlook how much wear in cush hub spider effects clutch operation & drag. I'm still learning about how much wear is too much...
I recently had personal experience with this. I've done a lot of clutches with very good results. But the spider & grooves were ok, minimal wear. On my '73 Tiger I've had Hyde 7 plate for a long time. I cover 5k a year so I've learned a few things, but have much more to learn. So I installed 7 plate & cush hub rubbers, 650 springs. All was well for a long time. Then I was getting clack from clutch & some drag. I found rubbers deteriorated & notches in grooves. I replace rubbers, filed grooves smooth, which widened them a fair amount. New Hyde 7 plate. Spider had a fair amount of wear... But all worked fairly good. Not perfect, but was very acceptable. Covered 7k more miles like this & the clack started again. Sounded like bad rubbers. I decided to let it for a while. Some hundreds of miles latter I noticed the clatter starting as well as the clack. Observing this for a few hundred miles & attempting to diagnose noisy very slowly got worse.
I did rubbers again. This time the wear on spider arms was very bad. The wear on back plate of cush hub was very bad. The total gap of the basket thrust washer was
.038" + with new thrust washer! The chain didn't measure very bad on bench, but tensioner had a lot of arch. Tension was verified good often & I could not see rub marks from chain. With new rubbers the hard clack was gone, but the horrible rattle remained. I covered another 60-100 miles attempting to get a definitive diagnosis. No luck. Oil pressure of motor tested good. Noise sounded like right from clutch exactly. Pulling lever or putting into gear no change. Made rattle riding or standing still, but hot motor only. Cold, no noise. Noise came gradually during warm up.
I will not throw parts at bike! However there comes a time when I must do something as an educated guess. All the parts in primary had some wear to very bad wear.
I decided to replace everything except crank sprocket, I mean everything. It fixed the noise 100%. The most shocking part to me was how much difference new cush hub & basket made. This time used Aerco 7 plate, with all smooth steel plates. (Do not roughen the smooth steel plates with 7 plate kits. Always soak friction plates with oil before install with 7 plate kits). Trust me on this.
As I said I've installed several 7 plate kits on used baskets & hubs so had a good baseline of what to expect. However, this was the first time I did with all new parts. The 7 plate kits work really, really good with used parts, but with the new hard parts it's shocking at how well it works. Not a hint of drag, even smoking hot. Pulling lever 1 full second gives silent engagement into 1st. Hot shifting trans fully heat soaked after 70 miles is the best it's ever been. So far I'm feeling really good about the Aerco clutch.
Keep in mind still it's a Triumph, not Norton
, but it's the best a Triumph will get.