Thanks for your thoughts. I did check the nut for security as I had it all apart. I found out I have an additional plate in there that needs taking out! I really believe it was just luck it hasn't happened before.
If it's a slipper, I believe they do tend to have a friction plate first. However, this will only make it 'quiet' if the basket slots are curved at the bottom. If they're parallel all the way to a flat end, the stack will still be free to oscillate. If the nut is tight and all was well before, what has changed to allow plates to pop off the top of the basket??
The slots are curved, they are a teardrop shape. When the clutch was depressed the first friction plate could be pulled clear of the basket. The plate must have been thrown forward, out and round. Why it hasn't happened before now may be down to luck. Everything else looks just fine. I will have to see what happens longer term. I've left one of the 1.5mm plates out, so the stack is now 36.5mm high. Most of the plain plates are 2mm, there were 2 1.5mm bevelled plates (with the dots), I have now left one of these out. I will see how it goes tomorrow morning.
In that case, a friction plate in first should make it quiet and also drop the effective stack height even more. It's still a bit of a worry what caused this though. Steve R's point is a good one. If the plates weren't pushed off due to a loose centre nut, what did push them off? Could it be that putting a plain plate in first raised the stack height enough to do that ?? How long has it been like that??
A pure guess is centrifugal force pushed it forward, I could pull it quite a way out with the clutch lever pulled. It has been like this for a couple of thousand miles. No, there was a 2mm plate on top.
Here is what the clutch stack look like now... From the top, with the clutch lever pulled in, the first friction plate now does not clear the front of the slot....
It must have displaced the plain plate as well then, surely. Anyway, with one less plate and the friction plate in first, dropping the whole stack down, it should no longer be a problem - as long as that nut really is tight... Have just looked at my own and there's no way that could happen to my clutch. The plates are well inside the basket...
That looks perfect The reduced pre-load should make it feel a little lighter too Just hope the fact it's a slipper doesn't make it critical enough it will start to slip.
Exactly this happened to mine. Many years back I had the clutch replaced by a dealer as part of an insurance repair. First ride out the clutch gradually started to disengage less and less until it wouldn't disengage at all. Thinking it was probably slave cylinder related and as I was close to home I tried to limp it back - until the pressure plate cut through the (carbon) cover and deposited itself, along with the hub & plates into the (new) fairing, the cush rubbers were all over the road. The nut had come completely off, the dealer that repaired it (now defunct) claimed the 'O' ring 'let go'...
Is the clutch lever on its maximum span out ? you will get a little bit more outward movement of the pressure plate before the lever touches the bars that way .
Just out of interest , the nut that works loose on the clutch hub I assume there is no tab washer or locking device on it for this to happen ?
Bloody hell the plot thickens the Haynes manual spec will be for a standard clutch not a slipper, @ChrisDS you say you've got a slipper clutch fitted if it's a ball and ramp type (they nearly all are) then you need to reorder your plates, the first plate in MUST be a friction one the reason for this is if a steel is the first one there's a chance it can slip down behind the drum and lock it up
There is a serrated type of washer but it is a 'long' nut and needs to be ferkin' tight so shouldn't be coming undone and definitely not because the 'O' ring underneath it 'lets go'. I have seen the large star washer/spacer that sits between it and the clutch hub actually eat into the hub, causing that to be loose and able to move out a mm or so though, but even then the nut should remain tight.
Just went for a blast in the sunshine, clutch working VERY well. It feels significantly better, 1.5mm can make quite a difference. Thanks to everyone who helped, I learned a lot and the clutch is another part of the bike I now understand.
