Flywheel shearing off woodruff key.

[macawman]

Having an issue with the crankshaft woodruff key being shared off by the flywheel on my 56 Johnson 10 horse. When the key is inserted in the crankshaft slot, it only protrudes about 1/16th inch which is less than half the depth of the slots in the timing Cam and flywheel. Is the OEM version of this key "taller" then a standard, off-the-shelf 1/8th inch woodruff key?

 

[nccatfisher]

Having an issue with the crankshaft woodruff key being shared off by the flywheel on my 56 Johnson 10 horse. When the key is inserted in the crankshaft slot, it only protrudes about 1/16th inch which is less than half the depth of the slots in the timing Cam and flywheel. Is the OEM version of this key "taller" then a standard, off-the-shelf 1/8th inch woodruff key?

If my memory serves me correct those keys are bigger because they are aluminum. I am guessing you are putting a standard steel key in there which is a bad idea in the first place. You need to go with the correct fit (OEM) because if it doesn't even the slightest rock on that flywheel along with causing it to sheer will also cause erratic timing.

 

[MrGiggles]

In theory the key is only there for assembly. The flywheel taper is supposed to hold them together.

Make sure the crank and flywheel are clean, dry, and torqued correctly. I've also heard of people lapping the flywheel to the crankshaft using valve grinding compound.

 

[Pappy]

The key is indeed just a locator.
Both tapers should be absolutely clean and fit together almost perfectly. There should be no fretting anywhere that is left over from the key shearing. The key should be a steel key.
Lapping the flywheel to the crank can be done but keep in mind the compound may get into the upper crankcase seal and destroy it.
Tapers should be wiped with laquer thinner or acetone and be bone dry and clean prior to assembly.
Proper torque should be sourced and applied.
If your engine is out of time or the plug wires are reversed the engine may kick back hard enough to shear a flywheel key. You may want to check.
No lock washer beneath the nut. Not needed.

 

[macawman]

When installing the flywheel, should I tap it with a rubber mallet to make sure it is firemly seated before torquing?

 

[Pappy]

no.

 

[macawman]

Thanks for the input, guys. Most helpful, as always.