Preliminary data on woodruff key failures
Posted February 26, 2003 - 04:11 AM
Posted February 26, 2003 - 04:14 AM
You seem to want to get others worked up. There is no need to blow this into a bigger deal than it already isn't. Again I ask "Do you have a custom pot stirring stick?"
Posted February 26, 2003 - 08:04 AM
The manual started out at 50 lbs. Someone at the factory thought 61 lbs would solve the problem. So all manuals were updated with the paste-overs. Then between Japan and the USA someone else decided 47 lbs was the correct setting???
Posted February 26, 2003 - 04:21 PM
I've talked to the dealer service manager and someone at Yamaha, both assured me not to worry about it. I've only been worried about this because this is my first new bike and I read all the stories about the valves on CRF450's last year. I know how Honda has always been absolutely loyal to their customers on new models, often after warranties expire, but they dropped the ball on the CRF. I've been afraid that Yamaha could do the same about our flywheel keys.
But - they haven't before, and it's not expected that they will this time. I predict that my WR will be fixed permanently when I pick it up. If it's not, I'll give them time to work it out.
Besides, there's still three feet of ice and snow on the trails. Not like I can ride anything right now anyways.
Posted February 26, 2003 - 06:12 PM
Posted February 26, 2003 - 06:34 PM
Posted February 26, 2003 - 09:09 PM
Posted February 27, 2003 - 03:30 AM
Posted February 27, 2003 - 05:54 AM
Posted February 27, 2003 - 09:01 AM
Posted February 27, 2003 - 12:19 PM
Posted February 27, 2003 - 12:40 PM
Posted February 27, 2003 - 12:55 PM
Posted February 27, 2003 - 04:14 PM
Do you realize that the woodruff key is there for only alignment so the timing is correct? If you do not see that, the discussion cannot go any further on that issue. The key holds no forces.
A shearing woodruff key is a by-product of the taper between the flywheel and crankshaft not holding the rotational forces at work.
What could cause that?
1. The torque on the nut is not enough to force the tapers to a respective position on each other such that the frictional forces between the tapers are enough to withstand the other forces at work.
2. Too much torque, to the extend that the tapers are being distorted. (not likely with the rumors of an air line being pinched)
3. The tapers are not fitting properly (angles are off). This could be as minor as tooling gone bad or as major as the taper angle not being adequate.
What are the remedies for incorrect taper fit?
A. Lapping the 2 tapers together with lapping compound.
B. Replacing parts; ie flywheel or crankshaft.
Another question must be asked, what is creating forces so great as to break the holding force of the tapers?
Possibilities: (running low on this one, anyone?)
2. Too strong of a starter
3. Flywheel too heavy
4. Backfiring and the starter only turning one way
A. Change the jetting, the Canadian model does run stock jetting that is richer, that might be a start.
a. Seems there has been some problems with twisting the throttle just a little to get it to start with the e-button. Some have backfired after this, Yamaha says this is a no no. Starter jet might be something to look at like utvols had suggested. 72 seems to be what he had used, again weather would play a big role in how all bike start around the country this time of year.
B. Don’t use starter, not likely, most of us bought the bike for that convenience however there could be something to the idea that someone mentioned that KTM recommend only using the starter when the bike has warmed up. The starter is small (weight reduction, agreed) and therefore can’t turn the bike over like a swift kick can especially when it is cold. (KTM claim is just a thought, not substantiated at all.)
C. The flywheel is different from the YZ450 but I have heard 2 different stories, does anybody know the scoup on this? I have read the flywheel is heavier another article says its just larger in diameter.
D. This is a new and interesting observation, Wrench let us know what you find out with this.
Since I am tired of speculation in the wildest sense, here is what I see as a logical way to approach the issue.
I am wondering what kind of stats we would find from the persons that have richer jetting, lapped their flywheel, torqued the nut, loosened and retorqued to 47 ft-lbs. (assuming 47 ft lbs is correct) Can anyone comment on this?
Posted February 27, 2003 - 04:31 PM
what part of the VIN# ?
Posted February 27, 2003 - 05:25 PM
Posted February 27, 2003 - 07:29 PM