HELP...Crankshaft sideplay...how much is too much?

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Gents, My '74 850 Commando has about 4k on a full engine rebuild....I am into a swing arm repair that should have been done with the other major stuff. I have begun to remove the primary side.....the rotor is off now and all i need to do is pull the clutch and engine sprocket...BUT I noticed that with the main engine sprocket there is a small amount of side play if I pull out or push in on this end of the crankshaft....I am guessing about 1/16th or an inch maybe a bit more maybe a bit less....would you say this is an acceptable amount of play....it is very tight play, it's not as if I can grab the shaft with my fingertips and get a reaction. Little insight please?
Nortonly Yours,
Eric
 
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Spec is .005" to .015". 1/16" is a lot but there is a school of thought that says the crank centres itself when running so play is not critical! That might be the case but there is some sideload from the pump gears though I wouldn't know if it's enough to load the crank one way or other. However, I would not be happy with that amount of play. See if you can measure it just so you know what you really have. It's possible to get a rough reading with a vernier but should be done with a dial guage.
 
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guys...will get a better measurement tomorrow, but after having a closer look today, maybe I misjudged a line on the metal ruler....seems to be a hair under 1/32nd...
checking for an accurate measurement tomorrow.
thanks,
Eric
 
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Has anyone ever found shims in a factory-built Commando engine?

If the drive sprocket keyway can't damage the oil seal then you'll probably be alright !

The hand is capable of feeling very small movements in this sort of situation. A crank shimmed correctly still gives quite a discernable 'clonk' as it moves. As Ludwig says, the oil pump worm means that this doesn't happen in use (otherwise we'd hear it).
 
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I've seen a half dozen commando engines in the past year - none have had shims. When I asked my Norton guy about shimming, he said its not nearly as important as balance, and he'd never seen shims on an original case - and he's done at least a hundred over the years.

Mine was .016 when I measured it. I left it unshimmed.
 
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