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Doctor, I've got no pulse!
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<blockquote data-quote="69ST" data-source="post: 184338" data-attributes="member: 5"><p>I've seen guys destroy parts due to a stubborn flywheel. The worst was a recent video of a flywheel & crank being destroyed in the process. Who would've imagined that was possible? Prior to that, the collateral damage award went to the guy who broke-off the end of a Nice crankshaft(!). IMO, none of this destruction is necessary. I rebuilt the aforementioned Nice 110, the flywheel was easily removed from the broken crank. With the 72cc motor, shown in the video...the "jump the shark" moment is pretty obvious; but, in all fairness, my view is a bit jaded since I've been wrenching on small engines for 50 years now.</p><p></p><p>The missing element is heat. Heating the flange, quickly, has never failed me yet. All it takes is a garden-variety propane torch, some care in aiming the heat (keeping it away from the crankshaft) and working quickly enough so that conduction doesn't undo your efforts by transferring heat energy to the crankshaft snout. (This same "trick" also work wonders on oil spinner cover/throwout bearing flange screws & stator screws.) Tapered holes respond well to rapid warming and, really, temps in the 200F range should be plenty. In a worst-case situation, a flywheel stuck like nothing I've yet encountered firsthand, I'd snug the flywheel puller as tightly as one would dare (stopping short of damaging the crank), then applying propane torch persuasion to the flange area. I expect that the puller will lose a little tension in the process, from thermal expansion...that can be used to your advantage, by retorquing the puller. When clearances tighten, as the metal parts cool, more pulling force would be applied. A few heating/cooling cycles should be sufficient to break a stubborn mechanical bond. Having said all of that, I seriously doubt you'll have to deal with anything remotely resembling this. The slightest bit of movement, along the crank snout, and the flywheel will lose its grip rapidly.</p></blockquote><p></p>
[QUOTE="69ST, post: 184338, member: 5"] I've seen guys destroy parts due to a stubborn flywheel. The worst was a recent video of a flywheel & crank being destroyed in the process. Who would've imagined that was possible? Prior to that, the collateral damage award went to the guy who broke-off the end of a Nice crankshaft(!). IMO, none of this destruction is necessary. I rebuilt the aforementioned Nice 110, the flywheel was easily removed from the broken crank. With the 72cc motor, shown in the video...the "jump the shark" moment is pretty obvious; but, in all fairness, my view is a bit jaded since I've been wrenching on small engines for 50 years now. The missing element is heat. Heating the flange, quickly, has never failed me yet. All it takes is a garden-variety propane torch, some care in aiming the heat (keeping it away from the crankshaft) and working quickly enough so that conduction doesn't undo your efforts by transferring heat energy to the crankshaft snout. (This same "trick" also work wonders on oil spinner cover/throwout bearing flange screws & stator screws.) Tapered holes respond well to rapid warming and, really, temps in the 200F range should be plenty. In a worst-case situation, a flywheel stuck like nothing I've yet encountered firsthand, I'd snug the flywheel puller as tightly as one would dare (stopping short of damaging the crank), then applying propane torch persuasion to the flange area. I expect that the puller will lose a little tension in the process, from thermal expansion...that can be used to your advantage, by retorquing the puller. When clearances tighten, as the metal parts cool, more pulling force would be applied. A few heating/cooling cycles should be sufficient to break a stubborn mechanical bond. Having said all of that, I seriously doubt you'll have to deal with anything remotely resembling this. The slightest bit of movement, along the crank snout, and the flywheel will lose its grip rapidly. [/QUOTE]
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Doctor, I've got no pulse!
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