my clutch shaft - the definition of fubar

Nov 27, 2013
143
4
18
earth
www.Frankenbikes.com
Here is my clutch shaft, and man, it is ruint.
If you were look up fubar in the dictionary, a picture of my clutch shaft should accompany the definition.
2017-10-04 16.52.36.jpg
I mean look at the woodruff (shear) key slot, look at the threads.

The motor had been a little noisy over the past few days, but worked "fine" on my way to work. Started normally after work, but almost immediately began to act as if the clutch was not engaged. Opened the cover and the nut fell out, washer was chewed, no key.

Anyway, i have a new shaft on the way and hope to put it back together this weekend.

It came out pretty easily, i did not even bother to take the engine off the bike:
covers off both sides
rod and ball (throwout) bearing out of shaft
screw, "flower nut" and clutch plate removed
large punch on the chain sprocket side and a couple of taps with a three pound hammer and out it came.

bearings feel fine so i'm re using them.
gotta find my gear puller to remove the big gear.
prolly gonna put new clutch pads in while it is open.

Looking up info on this site i see I had a similar problem on this bike back in 2011, and i apparently made a "temporary" fix then, ha!

el
 

xseler

Well-Known Member
Apr 14, 2013
2,883
126
63
OKC, OK
Mine did the same thing. The new woodruff key that came with the part felt a 'sloppy' in the groove, so I got a standard size key from the hardware store and filed it to fit the slot and groove (they were actually different sizes!).



I also re-used the bearings which felt fine even after 4 years of use.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
156
63
USA
yes, there are factories that use thin keys and others that use thick keys - makes mix/match a pain

chewing the key is usually because nut was not tight enough and unit was allowed to jerk back and forth on key until it failed

bearings there are sealed on shaft, but check clutch hub bearings and between teeth of bevel gears for small pieces of debris from failed key and chewed shaft
 
Nov 27, 2013
143
4
18
earth
www.Frankenbikes.com
My thoughts exactly: jerk + jerk * dig = fail

and you are correct Crassius, the nut was loose (off!) and the threads on the shaft (chain side) are not just stripped, but destroyed. I'm guessing not tight enough is an understatement.

I will definitely check for debris on "both" sides and the middle as well.

part is due today, hopefully back on it over the weekend
 

xseler

Well-Known Member
Apr 14, 2013
2,883
126
63
OKC, OK
My nut was still tight when I removed the cover.............no different noises, it just failed a block from my house (very lucky on that!). Was a month before the Scarecrow Run. Glad it happened before the event!