[Dukedesmo]

I've never noticed the radial exit hole in the clutch end of the shaft but I suppose there should be something or the oil in there would be as old as the bike and eventually get gummed up in the bearing, causing it to seize and defeating the objective.

I've also often wondered why the narrow section of the rod (inside the shaft) is in a 'rough' finish, obviously it doesn't run on anything so doesn't need to be machined smooth so I assumed it was purely a cost thing? but maybe the roughness also encourages the oil to stick to it better, allowing the feed to be more effective?

The 'O' rings sit in the case to stop oil leaking out onto the slave cylinder area (though you'd hardly know if a little leaked) but, presumably also stops chain oil/crud from potentially contaminating the oil?

If you think about if the 'O' rings were in the bore of the shaft then what would stop the pushrod from spinning with it due to the friction? and if it didn't then the 'O' rings would be worn away by the shaft constantly riding on them?

As it is the only contact between shaft and pushrod is through the little bearing which is precisely there to prevent rotation, although there will be a small amount of drag through both it and the accompanying oil seal.

Otherwise the primary drag is from the pressure plate through the bearing so as long as the bearings are good then the rod won't spin. If it does then the slave cylinder won't last long, which is what the Evo slave cylinder bearing was claimed to help in the event of the rod spinning - although I would think that at the point the shaft is spinning the slave's days (even with a bearing) are numbered.

I don't know how common the rod spinning is but Ducati saw fit to put an anti-spin pin/attachment on recent models, so it must happen sometimes? but I'm certain neither of mine spin - if they did then they'd be going at up to 5000 rpm (clutch runs at around half engine speed - depending on primary drive ratio) and I would imagine the slave would start to get very hot, very quickly and wouldn't last long?

For that reason it's worth changing the pressure plate bearing regularly - they're not expensive so good insurance. I've also changed the inner bearing in the shaft on both of mine even though neither was causing any problem, again they are cheap enough and easy to fit (also need the oil seal) but, be warned the old one can be an absolute sod to remove as you can't get a purchase behind it due to the shaft behind it being the same ID as the bearing. The one in my 916 came out fairly easily but on the Monster I had resort to die grinder/small chisel and then pick out the pieces, I soon started to regret starting the job.

Plus, if you do change it be sure to fit the oil seal with the 'lip' pointing inwards (I now use reading glasses when fitting small parts!) or it'll leak oil into the clutch. That said I don't know if wet clutch bikes have the seal as it would be OK, indeed probably preferable to let the oil pass through the clutch?

The oil seal is also the reason that the pushrod should, ideally be removed from the slave end as pulling the 'O' rings through the seal could damage it, so always best to remove the pressure plate from the rod first and then pull the rod out from the left side. It might need some 'persuasion' to separate though and be careful that if you run the engine with no clutch (enjoy the silence on a dry clutch bike!) that unless the rod's in place oil will come out of the shaft.