woodruff key

L

lavy

New member
Hi anyone know the size of woodruff key to go on the end of crankshaft on a laverda 125 Lesmo or where to find this out and to ontain one thanks lavy
 
Lavy, just go to any place that sells Woodruff keys (any half decent hardware or small engine repair shop) and pick out 3 or 4 that are just a bit thicker than the slot on the crank, but with different radii of curvature. Then get ready to spend an afternoon with a few beers and maybe a mate or two in the shed with a selection of flat files. Very carefully file one of the keys to the right width, fit it into the slot on the crank, and see if the flywheel will fit. If it doesn't, file a smidgin (a good archaic Anglo-Saxon word there) off the top, and keep trying until the flywheel just fits on, and then you're done! While you should try to have the key fit as closely as possible to the profile of the hole in the crank, it doesn't matter if the curvature is not quite exactly the same as the original, it's just a locating pin. The crank and flywheel tapers and the torque on the nut are what really hold the flywheel in place.
If you get too loose (with the filing, not the tinnies :D), just start again. The things are almost free to buy. A belt sander can help, I use a 3/8" hand-held pneumatic one myself, very handy little tool. Worst thing that will happen is you will lose a tiny bit of skin off a couple of fingertips  :o. If this is a problem for you you're on the wrong forum  8).

Ken

PS DO NOT try to use an angle grinder or a bench grinder. You WILL hurt yourself and lose the Woodruff key as well.
 
Look out for a cheese head skrew with a suitable head to fit into the groove.
Find something suitable,cut off head,cut in half,de burr - job done
Andy
 
THANKS FOR REPLYS THOUGHT ABOUT MAKING ONE , BUT DOES IT NEED TO BE HARDENED STEEL ETC TO AVOID RISK OF IT  BEEING SHEERED OFF  ??
 
Further comment on Phil's advice. You don't want woodruff keys to be made out of stuff that's harder than the shaft and rotor (flywheel or gear or whatever). If the nut works loose and the taper loses its grip, it's better that the key shears off rather than having it rattle around knocking chunks out of the shaft and rotor.
 
Have been known to make one out of a washer, to hold the flywheel on to the end of the crank on a Yam DT175. Didn't have much choice, distinct lack of engineering shops in the New Guinea Highlands in the seventies.
 
Why not just buy one from a dealer. Readily available.
Then you know it's fit for purpose.
Not against the idea of making one but if you have no means to do this then it's a lower risk option.
 
lavy said:
thats why i asked for the size at the start of this thread so i could just order one ?
Click to expand...

Pretty sure the dealer will know the size if you tell him where it is for.
 
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