I'm shearing Woodruff Keys... looking for help

yamaslut

yamaslut

kill it
Location
Daytona Beach, Florida
ok, I'm about to take up walking.... my ski f^cking hates me or something...

I have sheared 3 Woodruff Keys today and I am not getting why... I just rebuilt my motor and everything is kosher except the flywheel is creating havoc w/ my crank.. What would cause this to happen??? It's like there are Gremlins crawling around my ski destroying things...


  • the motor spins freely
  • the flywheel seats properly
  • the bolt is tightened w/ a impact wrench, no locktight I used anti-seize
  • the bendix is free flowing and spins out
  • starter is brand new OEM
  • no binding anywhere, I can spin crank by hand w/ plugs removed
anyone????
 
Crab

Crab

thanks darin...noswad!
Location
Seattle
yamaslut said:
ok, I'm about to take up walking.... my ski f^cking hates me or something...

I have sheared 3 Woodruff Keys today and I am not getting why... I just rebuilt my motor and everything is kosher except the flywheel is creating havoc w/ my crank.. What would cause this to happen??? It's like there are Gremlins crawling around my ski destroying things...


  • the motor spins freely
  • the flywheel seats properly
  • the bolt is tightened w/ a impact wrench, no locktight I used anti-seize
  • the bendix is free flowing and spins out
  • starter is brand new OEM
  • no binding anywhere, I can spin crank by hand w/ plugs removed
anyone????
Click to expand...
you probably need to lapp it, check with a magic marker and see how they mesh, should rub the black off evenly everywhere.
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Check that the bolt goes in all the way.
Torque it to 70ftlbs (torque wrench!)

Also, make sure both mating surfaces are clean.


PS: I know the OEM spec is 51 ftlbs. Many builders will tell you to go 70ftlbs, as does MSD & RAD.
 
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djkorn1

djkorn1

kidkornfilms
Site Supporter
Location
Cleveland Ohio
....put some garlic in your engine compartment to ward off evil.

and break that sucker in nice and slow in some flat water....for 1/2 tank of gas.
 
SuperJETT

SuperJETT

So long and thanks for all the fish
Location
none
norcal ex said:
I was having this problem.. take some 600 grit and "lap" the crank and flywheel
Click to expand...

I use valve grinding compound, works great, just have to clean it up well after. Put a little on the inside of the flywheel, put it on without the key and spin the flywheel by hand to lap them.
 
BruceSki

BruceSki

Formerly Motoman25
Location
Long Island
Matt_E said:
Check that the bolt goes in all the way.
Torque it to 70ftlbs (torque wrench!)

Also, make sure both mating surfaces are clean.


PS: I know the OEM spec is 51 ftlbs. Many builders will tell you to go 70ftlbs, as does MSD & RAD.
Click to expand...


TBM told me 75 foot pounds... ive put at least 20 hrs since then and havent had a problem. except my bendix misses the flywheel sometimes... but i think thats another issue
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
The woodruff key doesn't really matter its only job is to hold the flywheel in position while you tighten down the flywheel.After you tighten it down the taper holds the flywheel on,if the tapers do not match up correctly than it can shear the keyway.
 
Crab

Crab

thanks darin...noswad!
Location
Seattle
Shonuff said:
How do you tell if the taper matches?

It the flywheel new to you, Nick?
Click to expand...
Clean both halves then wipe down with a magic marker on the crank. Push flywheel on where the key would be and rock back and forth while applying pressure. On removal look to see the contact areas, it should be obvious if it needs to be lapped.
 
Q

QuickMick

Guest
SuperJETT said:
I use valve grinding compound, works great, just have to clean it up well after. Put a little on the inside of the flywheel, put it on without the key and spin the flywheel by hand to lap them.
Click to expand...

Even if this guy hates couch riders, do as he states. Valve LAPPING compound on the snout and install flywheel spin about 10 times. Remove and clean it up good, then put some machinest bluing or black magic marker on both the crank and the ID of the flywheel. spin it about 2-3 times with even pressure and remove to check your mating surface.
 
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SUPERTUNE

SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
Alway use the correct tools...torque wrench to 70 lbs, never use an impact wrench for installing, removal only. I have never needed to LAP a flywheel to the cranksnout on a Yamaha engine, (just a fine file and 280 paper to sand out an occasional nick) yes, I did it to old 440/550's back in the day because they did like to gall the taper from using no rev limiter and the flywheels weighed a ton.
 
GDFL

GDFL

Location
Melbourne, FL
I did have to use a washer once because the threads didn't go deep enough in the crank for the bolt to seat properly. The bolt was tight, but the head of the bolt wasn't holding the flywheel. Maybe look into that.
 
BruceSki

BruceSki

Formerly Motoman25
Location
Long Island
is it possible a flywheel bolt might need to be a replacement item?

maybe they stretch after installation/removal many times.

:shrug:

j/w on this one i have nothing to back it up with
 
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