flywheel stuck!!!

[panasonic]

Some tapers are self holding other are not.

The shallower the angle the more holding power. Think of a drill chuck on a small home drill press..it is held on only with the taper, nothing else. The shaft that the drill chuck is mounted on is held up in the spindle with the taper only.

Milling machine tapers are a steeper angle and must be held in with a draw bar, less they will fall out. (side loads)

Tapers on a flywheel are interference fit, for the following reason: (not all my words, mine in red)

Elastic deformation. When you sock the taper (crank) into the socket (Flywheel) the socket expands a little bit radially and the taper compresses a little--a basic interference fit.

The nut provides the push.

The reason the shallow taper is important is because there is a component of the "interference force" that is pushing the taper back out of the socket. That component is proportional to sine of the angle of the taper, and below 7 degrees that component can be overcome by the friction between the two surfaces.


I don't know the taper angle on a Yamaha engine, but I am willing to bet its less then 7 degrees.

Could be wrong though, that is how we learn.

[panasonic]

Oh ya that is a nice puller, the flywheel got no choice in coming off with that...

[TownsendsFJR1300]

Some tapers are self holding other are not.

The shallower the angle the more holding power. Think of a drill chuck on a small home drill press..it is held on only with the taper, nothing else. The shaft that the drill chuck is mounted on is held up in the spindle with the taper only.

Milling machine tapers are a steeper angle and must be held in with a draw bar, less they will fall out. (side loads)

Tapers on a flywheel are interference fit, for the following reason: (not all my words, mine in red)

Elastic deformation. When you sock the taper (crank) into the socket (Flywheel) the socket expands a little bit radially and the taper compresses a little--a basic interference fit.

The nut provides the push.

The reason the shallow taper is important is because there is a component of the "interference force" that is pushing the taper back out of the socket. That component is proportional to sine of the angle of the taper, and below 7 degrees that component can be overcome by the friction between the two surfaces.


I don't know the taper angle on a Yamaha engine, but I am willing to bet its less then 7 degrees.

Could be wrong though, that is how we learn.

GREAT INFORMATION!

Someones apparently familiar with it..

[fairdeal]

there is a component of the "interference force" that is pushing the taper back out of the socket.

That component is proportional to sine of the angle of the taper,
and below 7 degrees that component can be overcome by the friction between the two surfaces.

sounds right to me...

let me find my slide rule - it's here someplace.....

[TownsendsFJR1300]

Any updates?

[rodbolt17]

the OD and ID tapers are IDENTICAL.
NEVER EVER EVER lube them at reassembly.

well maybe if yiou just like replacing keys.

I typically lap them in place.

at least check the taper fit.

carefully clean all surfaces.
place a #2 pencil mark from top to bottom of the crank taper at three places 120* apart.
place the flywheel with NO key on the crank.
rotate the flywheel 90*.
remove the flywheel .
pencil marks should be gone.
if not lap the tapers.