Author Topic: Crankshaft side play/shims etc  (Read 3948 times)

Offline RichardL

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Re: Crankshaft side play/shims etc
« Reply #120 on: 24.08. 2018 21:19 »
Almost shy to ask a shim question here, having read so much on it, written so much on it, and been given so much good advice. Nonetheless, I don't recall this question being asked by me or anyone else, and if it has, there is too much info to sift through to find it. 

Question is: Should we target an allowance for the minimum amount of side play before installing shims? I want to tell my machinist to dress the face of the new T.S. bushing so the crank is not locked up when the cases are assembled. I don't think it would be good if the play (without shims) was, say, 0.004".  That would mean the shim (or shim stack) might be just 2-3 thou thick. Arguments for specially machined thick shims seem to support the notion that such a thin shim, by itself, is a recipe for shim destruction. ("Well, Richard, if you get your bearing on right, tight to the web and with the shim sandwiched between and (maybe) Loctited, the shim should be fine, you dummy."  Then I say, "Well, yes it should, so why bother with custom-made thick shims?")

Going back to my original question in the recent rebirth of this topic. 

I've removed the old two-piece bushing to find that its flange is 0.011" thicker than my new solid phosphor bronze bushing. So, asking if the machinist can skim the bush to create minimum side play seems a moot point.

Richard L.

Any thoughts?

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

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Re: Crankshaft side play/shims etc
« Reply #121 on: 24.08. 2018 21:43 »
G'day Richard.
That's a good example of why shimming needs to be done. With after market parts coming from all parts of the globe there's bound to be differences.
If the old one was thicker in the thrust flange tan std I wonder what the PO did to the cases or crank to make it fit (grind thrust face of crank, counter bore the case etc).
Looks like it's back to shims for you.
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Offline RichardL

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Re: Crankshaft side play/shims etc
« Reply #122 on: 24.08. 2018 22:43 »
Well, I'd planned on shimming anyway. Thrust face of crank and landing at case look unmolested

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.