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@garncarz avatar
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Molto Verboso
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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@garncarz avatar
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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UTC quote
The flywheel woodruff key from my recently purchased '64 Allstate came sheered off. I removed the debris and replaced it with a #267 from Scooter Mercado. I kicked the engine over and ran if for about a minute before starting various repairs. I got to installing a fresh set of points and a condenser and noticed that the new woodruff key had now sheared off, too. Afterwards, I removed the flare nut and circlip holding the flywheel on and gave them a good clean. I did notice that the flywheel's serrated lock washer was missing and replaced that too.

Not sure what is happening here? Am I not installing the key properly? Too much/not enough torque?

Thanks!
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Moderibbit
1980 P200E - "Old Rusty", 1976 ET3 Primavera
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@xantufrog avatar
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UTC quote
The flywheel key is just a guide, and not capable of holding the flywheel in position, so if its sheering the flywheel is not being properly secured - are you using a torque wrench to tighten the flywheel down to spec?
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UTC quote
You need to torque down the flywheel nut to 45 Ft/Lbs.

check the woodruff slots in both crankshaft and flywheel to see if they have been widened. If they are, you have bigger problems and can involve a replacement of crankshaft or flywheel, or both.
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2007 Stella 225
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UTC quote
Before you do this ensure ignition key is off. I would disconnect the spark plug wire also. You can use a sharpie, Dykem, blue layout fluid etc to coat the crankshaft taper end where the flywheel mounts. Leave flywheel key out, install flywheel and try to spin the flywheel on the crankshaft. You can probably try kicking it over a few dozen times. Taper on crankshaft should have marks where flywheel and crankshaft taper are touching. If its not a good fit you need to hand fit them to get a better fit. People use lapping compound etc. The key is just locating the flywheel magnets in the proper spot for ignition timing etc. Taper is supposed to be doing the holding. I've seen posts in here I'll see if I can find pictures.
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@garncarz avatar
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Molto Verboso
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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@garncarz avatar
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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UTC quote
It appears that some debris from the shredded key remained in the slot and when I tried to slide the flywheel on it pushed the new key out. I cleaned out the key slot with a needle file and retorqued to 63 nm. Fingers crossed. Thanks for everyone's help.
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UTC quote
garncarz wrote:
It appears that some debris from the shredded key remained in the slot and when I tried to slide the flywheel on it pushed the new key out. I cleaned out the key slot with a needle file and retorqued to 63 nm. Fingers crossed. Thanks for everyone's help.
I would be careful to not over torque. You are nearly twice the recommended Ft/Lbs.

http://vespamaintenance.com/specs.html
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UTC quote
Christopher_55934 wrote:
Before you do this ensure ignition key is off. I would disconnect the spark plug wire also. You can use a sharpie, Dykem, blue layout fluid etc to coat the crankshaft taper end where the flywheel mounts. Leave flywheel key out, install flywheel and try to spin the flywheel on the crankshaft. You can probably try kicking it over a few dozen times. Taper on crankshaft should have marks where flywheel and crankshaft taper are touching. If its not a good fit you need to hand fit them to get a better fit. People use lapping compound etc. The key is just locating the flywheel magnets in the proper spot for ignition timing etc. Taper is supposed to be doing the holding. I've seen posts in here I'll see if I can find pictures.
this!

if the taper of the crank and/or flywheel got gouged when the key sheared then the holding force will be reduced regardless of how tight you torque it. Really bad high spots on the crank can be taken out with a file, but I always use a fine lapping compound to get a perfect fit.
OP
@garncarz avatar
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Molto Verboso
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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UTC quote
GickSpeed wrote:
I would be careful to not over torque. You are nearly twice the recommended Ft/Lbs.

http://vespamaintenance.com/specs.html
My torque wrench only reads metric. 63nm = 46.5 lb/ft.
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@garncarz avatar
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Molto Verboso
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oopsclunkthud wrote:
this!

if the taper of the crank and/or flywheel got gouged when the key sheared then the holding force will be reduced regardless of how tight you torque it. Really bad high spots on the crank can be taken out with a file, but I always use a fine lapping compound to get a perfect fit.
I chewed up yet another key trying to kickstart.
Forum member supplied image with no explanatory text
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UTC quote
the key is the symptom

take a picture of the crank taper and the inside of the flywheel
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@garncarz avatar
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Molto Verboso
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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UTC quote
More pix. Lots of spatter/high spots on shaft and flywheel.
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
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UTC quote
garncarz wrote:
My torque wrench only reads metric. 63nm = 46.5 lb/ft.
i will stand corrected. you are right there.
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UTC quote
get a sharpie and cover the crank with it. put the flywheel on loosely without the key and spin it on the shaft to see where it is making contact and where it is not.

here is a shot of my rally crank after lapping the vespatronic flywheel to it.
Forum member supplied image with no explanatory text
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bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
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@socalguy avatar
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UTC quote
Listen to oops... the taper of the crank isn't holding against the inner taper of the flywheel. You need to clean up both surfaces to get a tight interference fit. Get some valve grinding compound, put it on the crank, put the flywheel on and give it a dozen turns in both directions. Look for low spots. Repeat as necessary until you have a nice uniform surface.

If the keyway is enlarged, it can be repaired with epoxy.

Crank Fix. **Done!
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UTC quote
Yep, you need to lap it in. Just be careful to keep the lapping compound away from the seal, don't use too much.

Sacrificial key? I think this has come up before. I'd like to find or make some flywheel woodruff keys out of tuff plastic or aluminum. It seems likely that they would still do the locating job just fine, but wouldn't trash the crank if the taper lets go.

Your thoughts on this idea, has anybody seen anything like this? I'm reminded of our old 18 HP Evenrude with a brass shear pin on the prop and lots of spares on hand we often used while out crabbing.
Designed to break with no collateral damage so you don't ruin your prop on a damn rock!
Designed to break with no collateral damage so you don't ruin your prop on a damn rock!
OP
@garncarz avatar
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Molto Verboso
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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UTC quote
oopsclunkthud wrote:
get a sharpie and cover the crank with it. put the flywheel on loosely without the key and spin it on the shaft to see where it is making contact and where it is not.

here is a shot of my rally crank after lapping the vespatronic flywheel to it.
Looks like I have almost none of the taper holding. I'll knock down the high spots with a fine file and go get some valve lapping compound.
Forum member supplied image with no explanatory text
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1980 P200E - "Old Rusty", 1976 ET3 Primavera
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@xantufrog avatar
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UTC quote
I would think you'd have SOME rubbing somewhere on it - that almost looks like the thing wasn't seated all the way such that none of the taper was really in contact. But I've not dealt with this knackered taper issue before, so that's just the impression I'm getting, not coming from a place of wisdom on it
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UTC quote
I agree. If the tapers were matching perfectly, there would be virtually no blue left.
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UTC quote
garncarz wrote:
Looks like I have almost none of the taper holding. I'll knock down the high spots with a fine file and go get some valve lapping compound.
Where did it actually touch? What stopped it when torqued down? Maybe it's the wrong flywheel?
OP
@garncarz avatar
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Molto Verboso
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1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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UTC quote
I filed down the obvious high spots and gave it a lapping (not the good kind). There are still a few low spots gouged out by the key on both the shaft and the flywheel, but I think its 90%+. Have a look. The woodruff key is still a little loose, too.

Now, turning the flywheel by hand, without the key, and without the washer and nut, there is enough friction that I can turn the engine over.

Results?
Forum member supplied image with no explanatory text
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bodgemaster
63 GL, 76 Super (x2), 74 Primavera (x2), 79 P200, 06 Fly 150
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bodgemaster
@socalguy avatar
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UTC quote
Looks much better, should hold now. Let's see how the key fits in the slot. The timing could be a degree or so off. You should probably re-check it.
@moto64 avatar
UTC

Molto Verboso
'64 Motovespa 150S (177) , '65 VBB, '66 Allstate SF, '66 180SS
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@moto64 avatar
'64 Motovespa 150S (177) , '65 VBB, '66 Allstate SF, '66 180SS
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UTC quote
Looks good. I'd be inclined to hit it with a finer grit. That looks a bit coarse and might be a bitch getting the flywheel off after it's torqued.
OP
@garncarz avatar
UTC

Molto Verboso
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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Molto Verboso
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UTC quote
Moto64 wrote:
Looks good. I'd be inclined to hit it with a finer grit. That looks a bit coarse and might be a bitch getting the flywheel off after it's torqued.
I used Permatex 80036 Valve Grinding Compound, the back of the package states (Start 120 grit - Finish 220 grit).
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UTC quote
I leave the key OUT , pile on the valve grinding paste onto the crank, put on the flywheel & SPIN that puppy like its a record... keep goin till its nice and smooth... clean the paste off (start-ya-bastard is my preferred cleaner, plus its great to huff a bit of ether when things are going wrong)... put marker pen on crank (as mentioned above), put on flywheel (without key), spin that mofo, & once you take it off there should be no marker pen that's not scraped off... get a WIDER KEY (no chance it should be loose in the crank slot!), & grind it thinner if necessary... check it also fits into the flywheel snugly... put on the shakeproof washer & crank it up.


BTW; I've had one that even though the NUT was tight, there was no tension pushing the flywheel onto the taper, & therefore everything was still loose...
To test; try putting nut on WITHOUT the key in place, tighten it, take plug out, spin motor with drill (14mm socket?) & see IF flywheel spins without motor turning, if not, try it with plug IN (ie under compression) & see what happens... if it spins without the key, then there is something wrong!

Ohh, and remember the shakeproof washer!
Also, remember that the NUT bottoms out on the crank (where it steps out at the end of the thread), so it WILL BE TIGHT even if there is no flywheel on. When it comes to that realisation, either add a 2nd shakeproof washer or a washer.
OP
@garncarz avatar
UTC

Molto Verboso
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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Molto Verboso
@garncarz avatar
1964 Allstate Cruisaire, 2022 Husqvarna Vitpilen 401, 1972 Suzuki T500J
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Location: York, PA (the intellectual center of the universe)
UTC quote
Got the flywheel on and now have a nice tight taper fit with the shaft. I'm learning! Thanks for everyone's help.
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