Crankshaft, is it bent or not??
12-07-2004, 04:32 PM
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Crankshaft, is it bent or not??
I was wondering just how much run out on a crank is considered ok or not ok? Obviously the further out you go the worse it would be. Also, are the standard weedies and chainsaws worse than purpose built plane engines? How much is normal from the factory on say; Brison, ZDZ, Rcs, Fuji etc. etc? thanks
12-07-2004, 05:14 PM
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RE: Crankshaft, is it bent or not??
No runout is good on any engine...More that .002 measured at the end of the taper is too much....ALL cranks theoretically come with 0 runout, but in practice it's not possibe to be perfect, depends on how good your measuring indicator is...Mine is a .0005 Mitutoyo, I get cranks to less that .001 all the time, sometimes less than .0005....The worst new crank I ever saw was out .0025 at the end of the taper..Must have been a Friday afternoon crank..
12-08-2004, 12:46 PM
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RE: Crankshaft, is it bent or not??
Thanks Ralph. How much runout will start to develope vibrations?
By the way, what's it cost to straighten one should the need arise?
By the way, what's it cost to straighten one should the need arise?
12-08-2004, 02:50 PM
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RE: Crankshaft, is it bent or not??
$40 plus shipping..Don't know about the max runout for virbation, I would think anything over .005 would be noticeable...You start to get wobbly prop tips with too much runout....005 at the end of the crank translates to a lot wheh you get all the way out to the end of a 20 inch prop....
12-09-2004, 10:09 AM
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RE: Crankshaft, is it bent or not??
Thanks Ralph;
Is that ($40) with the crank removed or in the engine,or doesn't mattter?
I should probably check all of mine, since most I purchased used. Some I already have and seem ok. I use a machine shop grade dial indicator.
Is that ($40) with the crank removed or in the engine,or doesn't mattter?
I should probably check all of mine, since most I purchased used. Some I already have and seem ok. I use a machine shop grade dial indicator.
