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View Full Version : key sheared 3 times!



tommygunnz
12-19-2009, 11:11 PM
I sheared my 3rd counter balencer key tonight,the motors recently broke in,I put a new crank and main bearings in too.Ill put a new key in and I can ride hard for a day I actually smoked my buddies banshee 3 times in a row on the street today and it didn't break but a while later....I'm wondering when I tapped the crank into the case with a rubber mallet if it took the crank out of spec but its not like I was pounding the hell out of it,does anyone have a pointer I want to cover bases before pulling the crank out to see if its out of spec

headache
12-20-2009, 10:09 AM
i would visually look at the slot in the crank where the key fits in and make sure it isn't too loose or wore. that will cause the key to shear off easily. Other than that are you sure that you are getting the nut tight enough? on one of my old blasters i wasn't getting the flywheel key tight enough and they kept shearing off. I had to get a better impact wrench than what i had... If that doesn't work it sounds like your goin to have to pull the crank and check it between centers. I put a rod on a 87 LT crank a few years back and could only get it to about .0025" runout. And it ran fine with no noticeable vibration. In fact its still running... I know that everyone says it should be .001" but you know...

tommygunnz
12-20-2009, 11:59 AM
Originally posted by headache
i would visually look at the slot in the crank where the key fits in and make sure it isn't too loose or wore. that will cause the key to shear off easily. Other than that are you sure that you are getting the nut tight enough? on one of my old blasters i wasn't getting the flywheel key tight enough and they kept shearing off. I had to get a better impact wrench than what i had... If that doesn't work it sounds like your goin to have to pull the crank and check it between centers. I put a rod on a 87 LT crank a few years back and could only get it to about .0025" runout. And it ran fine with no noticeable vibration. In fact its still running... I know that everyone says it should be .001" but you know... I tightened the nut on the counter balencer with a penny in the gears and a socket wrench Im scarred Im gonna strip it I got it what feels to me to be tight and Im by far not weak,I never had a issue like this with my built 270R(120 over).I really like this LT even more than I imagened I do now espesially since Im burning my boys banshee which is far from stock:devil: so needless to say,Im stickin it out but would you impact that nut on?

headache
12-20-2009, 02:35 PM
ok i got confused for a minute. Your talking about the key on the balancer right? That nut is supposed to be torqued to 65 to 80 ft. pounds. I would definetly impact it on. The good thing about using an impact is that it delivers the fast blows and doesn't really try to twist on the gears and nut as much as doing it by hand with a ratchet. which will kinda pull on that key as your tightening it. Does that make sense? If you still have problems you might have to get a new balancer or maybe the bearing could be bad causing it to vibrate and shear the key. I dunno this is tricky.. Hope you get it!

tommygunnz
12-20-2009, 03:37 PM
Originally posted by headache
ok i got confused for a minute. Your talking about the key on the balancer right? That nut is supposed to be torqued to 65 to 80 ft. pounds. I would definetly impact it on. The good thing about using an impact is that it delivers the fast blows and doesn't really try to twist on the gears and nut as much as doing it by hand with a ratchet. which will kinda pull on that key as your tightening it. Does that make sense? If you still have problems you might have to get a new balancer or maybe the bearing could be bad causing it to vibrate and shear the key. I dunno this is tricky.. Hope you get it! thanks Im gonna take the counter balancer out and check the bearings out(I think theyre ok),and Im gonna impact that nut on this time even though the nut is tight after the key breaks,if that doesnt do it Im either gonna get a new balencer shaft or pull the (new)crank out and have it checked.Its so disapointing the key keeps breaking the power its making is very pleasing if only my bike wasnt so nice looking and looked like just another neglected LT it would suprise the **** out of people!Any way,thats what Im gonna do :cuss:

headache
01-02-2010, 09:00 PM
hey did you get this thing fixed?

tommygunnz
01-02-2010, 10:20 PM
Yeah a socket wrench and penny in the gear wasn't enough I had to impact it on she's screamin now like she should:D