Causes for a sheared woodruff key?

[McDog]

Trying to set up a single channel digital total loss on my superjet today and my LED won't work on the system I got. So I had to guess on the pickup plate placement and use a timing light to time it(which sucks). Ski wouldn't idle so I pulled the flywheel again to check things out....sheared flywheel key clean in half.

THIS SUCKS! I was REALLY hoping to ride this d*** thing tomorrow after a total rebuild over the winter. Not now.:bs2:

Two things:

1. Would a local dealer have these in stock or do I need to order some online? (Note I said some so that I will have extras in case it happens again)

2. What causes this? Did I do something wrong? How do I keep it from happening again?

 

[WFO Speedracer]

Trying to set up a single channel digital total loss on my superjet today and my LED won't work on the system I got. So I had to guess on the pickup plate placement and use a timing light to time it(which sucks). Ski wouldn't idle so I pulled the flywheel again to check things out....sheared flywheel key clean in half.

THIS SUCKS! I was REALLY hoping to ride this d*** thing tomorrow after a total rebuild over the winter. Not now.:bs2:

Two things:

1. Would a local dealer have these in stock or do I need to order some online? (Note I said some so that I will have extras in case it happens again)

2. What causes this? Did I do something wrong? How do I keep it from happening again?

I would say at this point you should seriously consider lapping in your flywheel to the crankshaft taper.Your local dealer should have those in stock it fits everything from 6m6 engines to 1200r's.

 

[McDog]

Would boiling it like MSD suggests help any? Does lapping it just involve slathering it with some sort of compound? Where do I get some?

 

[njfl]

Yes the dealer will have it. It is a common key that they use on most Yamaha watercraft a well as the same one for Banshee quads believe it or not.

I am pretty sure that it happened due to not having the flywheel on all the way (possibly because of interfernce, so like wedo said, make sure the mating surfaces are clean).

 

[SUPERTUNE]

I like a little thin layer of oil on the taper, then torque to 65-70 Ft-Lbs on the flywheel bolt. Did you under torque the bolt? When I have seen them sheered, found out customer used an air impact wrench to put flywheel bolt on...:shock:

 

[McDog]

I bet I did under torque it. :dunce::clown:I just tightened it as tight as I could with a socket wrench since I was expecting to have to take it off again after I checked the timing.

 

[WFO Speedracer]

Dude thats not nearly tight enough.Torque it to spec,blue locktite on the threads,ride it then retorque it.

 

[McDog]

I was just gonna start it and check the timing(not ride it)....then worry about having it torqued down. In retrospect that is pretty stupid. But it seemed logical at the time. Thanks for the help.

 

[kevbo]

You should torque an aluminum hub at operating temp. I torque them to 50lbs at 180F, a little more with charging types. Lapping the taper is not as important with aluminum because it will stretch a lot.