shearing woodruff keys on vespa

lee's anus is leefungchowOG /

ok, so i've got a ciao with 75cc polini, 13.13, polini small pipe. i've got it started on the stand, and as soon a i rev it up a little, it just shears the woodruff key, so the magneeto comes loose and i am left with an "L" shaped key!!! arg!!!! i have stock variator that tightens down agains the magneeto, but for some reason it keeps jumping off the taper!!! WHY? my magneeto is now pretty fucked up after slipping 2 times and ruining 2 keys, so i'm gonna try a new one with some loctite. any other suggestions on how to keep this bitch tight?

thanks!!!

dean please help. i only have one key left!!!!

love,

lee

its so close to being ready to ride!!!

Re: shearing woodruff keys on vespa

Is the key riding too high for the two tapers to mate right? I know American woodruff keys for puch are just a little too wide but very too high. You can check how the taper is seating by applying a VERY thin film of prussian blue (Checker Auto) on one of the surfaces, put them together, pull apart to see that the dye is evenly spread. Is it possible that the magneto has a different degree taper than the crank. I prattle on because the taper fit concept is sure fire considering the physics and the success of the fitting throughout the mechanical world.

Re: shearing woodruff keys on vespa

After you have checked the taper fit, get a larger woodruff key and dremel it so it just fits on both the crank and the flywheel.

Make sure that it is not so tall that it will not let the tapers come together.

Re: shearing woodruff keys on vespa

lee's anus is leefungchowOG /

two eldest members give the same response. thanks you guys, i hadn't thought of that!!!! i'll give it a shot!!!!!

Re: shearing woodruff keys on vespa

ᴛᴇʀʀʏ ᴅᴇᴀɴ /

also, make sure you have the nut on the end of your saft TIGHT! that one nut holds the entire vespa world together. that thing comes loose, your flywheel can come loose and do what you're describing. do you have the bendy lock washer in there? tighten that nut down tight, smash at least one side of that bendy washer over the nut and you should be ok

Re: shearing woodruff keys on vespa

Use a fucking piston stop!

Re: shearing woodruff keys on vespa

and impact wrench helps tighten things well.

Re: shearing woodruff keys on vespa

ᴛᴇʀʀʏ ᴅᴇᴀɴ /

impact wrench might be overboard in this case, a good tightening with a wrench should be enough

Re: shearing woodruff keys on vespa

it's not overboard. and it seems better to be tightening against the inertial mass of the flywheel/crank rather than loading up the bearings and piston stop when things arent moving. oh and you can adjust the impactness.

Re: shearing woodruff keys on vespa

A piece of rope is a good piston stop and it will squish before a brg will. Use a ratchet with a 12" arm and apply 25 lbs pressure to it via a bathroom scale.

Re: shearing woodruff keys on vespa

ᴛᴇʀʀʏ ᴅᴇᴀɴ /

nah, mat, ive seen many a snapped off vespa crank from over tightening. impact wrench on a vespa crank nut = overboard.

of all the different vespa motors i've ran, and the billions of times i've removed my variator for one reason or another, my trusty crescent wrench has never failed me.

Re: shearing woodruff keys on vespa

crescent wrench? you should at least be using a socket. i know piston stops work, i just hate to think what it's doing to my bearings. maybe you dont care.

and learn to spell my name.

Re: shearing woodruff keys on vespa

ᴛᴇʀʀʏ ᴅᴇᴀɴ /

nah, socket isn't needed, though one could use one if one wanted to. crescent wrench works perfectly. it's a rather large nut, 20mm or something? i forget, but it's large and there is plenty of surface area on the nut for an adjustable wrench.

i don't use a piston stop. i've always done it the way the vespa manual says to do it, by putting a screwdriver into the fan blades on the flywheel to jam it against the frame. and because i'm not over tightening it, it pops right off every time.

Re: shearing woodruff keys on vespa

oil filter wrench and a socket works just fine for me.

Re: shearing woodruff keys on vespa

lee's anus is leefungchowOG /

yes i used a piston stop.

gonna put on a new magneeto with a puch clutch key. overtightening FTW, but not too tight!!!

Re: shearing woodruff keys on vespa

Listen to Dean. He know's his vespa peds.

Re: shearing woodruff keys on vespa

lee's anus is leefungchowOG /

ok i will

DFTW

(dean for the win)

Re: shearing woodruff keys on vespa

ᴛᴇʀʀʏ ᴅᴇᴀɴ /

oh you guys.

Re: shearing woodruff keys on vespa

lee's anus is leefungchowOG /

no YOU!!!

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