What would cause a torn clutch drum? RSS V-Twin SE5

[merlot]

A friend rang me... said she lost drive while ryding uphill at 70kph when it went bang then no drive. Thinking it's the pulley (the bike is 2015 RSS with 105,000 kms) I flatbed it home and start looking.... The engine runs, I selected first (with a click not a clunk) but can still spin the pulley easily (belt off) with no drive.... So I pulled the clutch side and found a torn clutch hub..... I will look further today, but my question is: what do you think caused this.... my thoughts are debris in the gearbox jamming the gears (dont know what else to think...at first I thought a snapped mainshaft but that's ok... Also, how far can I go into the gearbox without removing the engine... I hope to be able to see inside the gearbox after I pull the remains of the hub out, even if I need to buy a scope..... I don't want to replace the clutch (if I can source one) then find the cause is still there..... I was thinking it could also have jammed on the engine side... if the drive gears jammed, then the rear wheel would tear the hub before the centrifugal clutch had time to disengage..... all help gratefully received... TIA...... Russ update..i have now purchased workshop manual

[PMK]

Looks like fatigue failure. Typically if the gearbox on a motorcycle locks up, the clutch does not break like that. Also, if the gearbox did fail, and lock up to break that clutch inner hub, the rider would have immediately felt the sudden stoppage.

My guess is simple metal fatigue over time, ultimately cracking completely around the inner hub.

[merlot]

Thanks for reply PMK..... Yes, she felt no stoppage, just no drive. I was able to prove all gears from back wheel to clutch hub centre and all smooth so really relieved, I wasn't looking forward to a gearbox repair. Parts are ordered and should be up and running by mid next week (so happy to have parts available in these times of freight logistics). I told her she needs a t-shirt or badge "I stuffed a Spyder". I thought "metal fatigue" when I saw it but the transmission was always in the back of my mind. I suppose it's the luck of the draw, I have known the 990 to do twice the Kms of this one and she rides fairly sedately... She has had some chatter on takeoff, but tries to warm it up when cold starts, so that may be contributing factor... It might pay V-Twin owners to factor in a hub change during their winter layup if their mileage is getting up there... Its fairly simple with some advice.... Thanks again... Russ

[PMK]

Clutch chatter can trash an inner and out basket, plus fibre plates.

Very likely the outer basket is stressed also. Downside of those failing is the tab breaks off and destroys a lot as it spins about. Also contaminates the oil with metal particles.

Inner and outer clutch baskets should be replaced. Unless needed for wear or overheating, plates should be ok.

[merlot]

yes...have ordered both inner and outer....real nuisance as i couldnt draw the outer basket without removing the clutch cover...ah well,its better than doing a gearbox

[KX5062]

Do you think you got all of the debris out? That looks like a lot loose metal could be floating around inside the engine, which could be catastrophic.

[hypurone]

And are we sure she is using a proper "motorcycle wet clutch" type oil in it? If not, this will cause the "chatter" previously mentioned and if left unchecked.... Also, the 990's need to avoid anything with the SL (??) rating in the oil IIRC....

[missouriboy]

Is the operator aware that RPM should be maintained at a minimum 3,200? And to always downshift before going below that reading?

I understood this to be the approximate RPM to reach full clutch lock-up, and that excessive cruising with slippage occurring would cause premature clutch wear.

Anyhow, that's how I ran mine, but I only had it for half that many miles...