What am i into here?

[opposedtwin]

This is the magneto of my newly acquired FD-11. Looks like the woodruff key is sheared? Haven’t ever had a problem like this. How is the flywheel turning the crank shaft if the key is sheared? Because it is turning the crank.

The motor has no spark and so i was planning to test the coils, clean things up, etc.

Will i have to crack the case and go all the way down to remove the remains of the key? How should i proceed here?

Thanks,
Scott

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[chris-p]

Yup sheared. Take the mag plate off. Should be able to get the remains of the key out then, and install new.

The key does not drive flywheel, the friction between the tapers does after torqueing to spec. The key simply aligns them, nothing else.

Should not be too bad a fix.

You likely did not have spark, since the flywheel had altered its orientation on the crank.

[opposedtwin]

Oh! Well that may be good news for the magneto then! Ok, took off the plate and the remains of the key came right out. Would dan gane have a new key? I’ll email him tomorrow.

Also, there are some very small scratches on the taper of the flywheel. Should i worry about them?

[chris-p]

Small scratches I would not worry about. You could dress them (valve grinding compound) to ensure a good seat.

[opposedtwin]

The underside of the ignition plate is pretty wet with oil, and the top side is a bit moist and dirty too. Likely i’ll be getting a chance to use that new seal puller i purchased from Richard about a month ago, eh?

[RICHARD A. WHITE]

🙂

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[Mumbles]

Just go down to your hardware store or auto supply and pick up a proper size key. Like Chris said, it’s not special and it doesn’t drive anything, only aligns the flywheel.

I had a running motor in once which had a piece of a nail aligning the flywheel instead of a Woodruff key. I don’t know for sure how long it had been in there but I bet it was quite a few years.

[outbdnut2]

I had a key shear on a 35 HP RD two years ago. The hardware store keys that big were all too thick. I found a piece of scrap steel the right thickness and cut a chunk out of a corner with a hack saw, then held it with a pliers and shaped it on a bench grinder – worked fine! Yeah it was a bit of messing around, but I got it running without ordering and waiting for a part, and it’s still going strong.
Dave

[Anonymous]

Aren’t flywheel keys a softer metal than regular woodruff keys?

[amuller]

Flywheel keys rarely shear if the mating surfaces are clean, dry, fit together properly, and are properly torqued. In this case, since it did shear, I’d lap the crank taper to the flywheel. It only takes a few minutes, usually. The procedure is in Chrysler manuals.

[Author]

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