PS - apologies for the “Thread drift”
This is from the adventureriders forum regarding the V100 clutch.
'Anyway, regarding the V100’s clunk. The V100’s and Stelvio’s wet clutch is designed different than any other wet clutch I’ve ever seen. On every other wet clutch the primary gear reduction is between the crankshaft and the outer clutch basket. This allows the whole clutch assembly to rotate substantially slower than the engine is turning. In a normal wet clutch the inner clutch hub is connected to the transmission input shaft.
Moto Guzzi, or Aprillia, designed the V100’s clutch the opposite of a normal wet clutch. The clutch’s inner hub is attached to a shaft that’s connected directly to the crankshaft. So the entire clutch assembly spins at the same speed as the engine. The primary gear reduction is between the outer clutch basket and the transmission input shaft. The reason why that horrible clunk occurs when shifting from neutral to first is because 1, the whole clutch assembly is spinning at 1500 RPMs at idle as there is no primary gear reduction between the engine and the clutch. And 2, the heavy part of the clutch assembly, the outer clutch basket and all steel clutch plates that are locked into the basket, act as a small flywheel that comes to an instantaneous stop when the transmission is shifted into first. The only way to stop the dreaded clunk when shifting from neutral to first while the bike is running, is for the bike to be rolling forward when shifting it into first, which is a bit impractical. On my V100 Mandello, I normally shift the bike into first when the engine is stopped, pull in the clutch, then start the bike. No more clunk. When I come to stops while riding, I simply keep the bike running in first gear and hold the clutch lever in. Once again no clunk, but I think my left forearm might eventually look like Popeye’s.’
I am no expert,but this would seem to explain the reason for the dreaded clunk.
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Thanks, @Stromcat, that’s a very informative account. Stuff like that makes this forum a great place.
What an interesting design cock-up, though!
I would love to know Aprillias/Guzzis reasons for doing this.
Well, this is an interesting thread for a non-techy like me. I do have the quick shifter fitted to my Stelvio and on the first couple of rides I did wonder why I’d bothered. Clutchless gear changes were nothing like as smooth as I’d experienced on several BMWs and my most recent Multistrada V2S. And I was also wondering what the little warning light in the bottom right corner of the dash was telling me. Then I read my owners manual which advises against changing gear without using the clutch at lower engine speeds - and the warning light appears to tell me when it is safe to use the quick shifter. That situation is, perhaps, not ideal and not what I’m used to - but I bought my Stelvio precisely to get away from what I was used to. So I’ll view that as part of the charm and character of my new bike and get used to it.
What I don’t think I’ll get used to, though, is the enormous clunk and lurch when selecting first gear from standstill. That isn’t charming or characterful, and I think it could actually be dangerous in some circumstances. In my naivety I had imagined that the problem is caused by too high a tickover speed - around 1500 rpm in my case - and that a dealer could make a simple adjustment to rectify it. Having read all the thread above it appears that it might not be just a simple adjustment.
Yes, I’m disappointed and concerned about the problem. But, no, it wouldn’t make me think about changing my bike. There has to be a solution (and that may be just miles on the clock as I’m only at about 1300 so far).
I’ll keep following the comments of those more techy than me here.
Err…there is no “gearbox oil” because it’s a unit engine.