dpmotorcycles Posted February 5, 2011 Report Share Posted February 5, 2011 Hi, I have read some threads about the woodruff key breaking but I can't see if any one has stated why it happens, does anyone know why the break because mine has broke again. Any advise please Paul Quote Link to comment Share on other sites More sharing options...
martinf Posted February 5, 2011 Report Share Posted February 5, 2011 I was told it's if the flywheel has been removed and not lapped in when replaced. Quote Link to comment Share on other sites More sharing options...
dpmotorcycles Posted February 5, 2011 Author Report Share Posted February 5, 2011 I was told it's if the flywheel has been removed and not lapped in when replaced. What does lapped on mean?? Quote Link to comment Share on other sites More sharing options...
dan williams Posted February 6, 2011 Report Share Posted February 6, 2011 The lapping thing is a bit over rated. It means polishing the flywheel and shaft to a perfect fit. Many theories on what the perfect fit is. Usually the problem is the flywheel nut wasn't tightened properly. Forget the rear brake,jamming something in the wheel,rope in the cylinder methods. Make yourself a proper holding tool and torque to the right setting with a torque wrench and it'll stay put. http://www.trialscentral.com/forums/topic/27287-flywheel-holding-tool-sheared-woodruff/page__view__findpost__p__214657 Quote Link to comment Share on other sites More sharing options...
dpmotorcycles Posted February 6, 2011 Author Report Share Posted February 6, 2011 The lapping thing is a bit over rated. It means polishing the flywheel and shaft to a perfect fit. Many theories on what the perfect fit is. Usually the problem is the flywheel nut wasn't tightened properly. Forget the rear brake,jamming something in the wheel,rope in the cylinder methods. Make yourself a proper holding tool and torque to the right setting with a torque wrench and it'll stay put. http://www.trialscentral.com/forums/topic/27287-flywheel-holding-tool-sheared-woodruff/page__view__findpost__p__214657 Thanks guys, so what I get from this is, I never tightened the nut enough, I knew it would be my fault lol Thanks again Quote Link to comment Share on other sites More sharing options...
breeze Posted February 6, 2011 Report Share Posted February 6, 2011 Hi lapping is not polishing it is lapping! the key does not hold the flywheel on it merely gives you a specific position, the taper is what holds it on and the nut stop it from working loose. You need to ensure the tapers are clean, apply a small film of valve grinding paste to the taper (without the key fitted) put the flywheel onto the crank and with light pressure turn back & forth the flywheel to lap together the mating surfaces, when correct you will find that the flywheel locks to the crank with very little pressure. Clean very carefully the crank & flywheel, refit key, fit flywheel & nut, tighten to correct torque. Quote Link to comment Share on other sites More sharing options...
chewy Posted February 6, 2011 Report Share Posted February 6, 2011 (edited) Hi lapping is not polishing it is lapping! the key does not hold the flywheel on it merely gives you a specific position, the taper is what holds it on and the nut stop it from working loose. You need to ensure the tapers are clean, apply a small film of valve grinding paste to the taper (without the key fitted) put the flywheel onto the crank and with light pressure turn back & forth the flywheel to lap together the mating surfaces, when correct you will find that the flywheel locks to the crank with very little pressure. Clean very carefully the crank & flywheel, refit key, fit flywheel & nut, tighten to correct torque. Here Here it's a pity that the manufacturers cant seem to make these parts properly in the first place, probably spending all thier money on big trucks and world round. Edited February 6, 2011 by chewy Quote Link to comment Share on other sites More sharing options...
dan williams Posted February 6, 2011 Report Share Posted February 6, 2011 I've seen several opinions on here by knowledgeable people about what the proper relationship of the taper of the flywheel vs. crankshaft is. Since I don Quote Link to comment Share on other sites More sharing options...
dpmotorcycles Posted February 6, 2011 Author Report Share Posted February 6, 2011 I've seen several opinions on here by knowledgeable people about what the proper relationship of the taper of the flywheel vs. crankshaft is. Since I don Quote Link to comment Share on other sites More sharing options...
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