pre load: How tight ?

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stian buksa
Cucciolo - the Lil Pup
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pre load: How tight ?

Post by stian buksa »

I've found two methods of finding the correct amount of crankshaft pre-load described on this forum:

"The generally accepted preload on the cranks is .05-.10mm[.002"-.004"] You should feel some drag but the crank should fall on its own when the heavy part of the flywheel is up" - wdietz186

"To do it right you will want to measure the crank end float with a dial indicator. Measure the end float and then add an extra 0.004"." - Den

Do the amount of pre-load using the two different methods end up as the same ?

Or to say it another way: How tight will the crank be using the "dial indicator method" ?

I have adjusted the end float twice, using the first method, but it ends up loose after a few thousand kms. The first time I used the smaller diameter shims which didn't work well because the base was a little concave, but now it is loose again

I'm afraid to put too much pre-load as this will stress the engine too much I guess ?


Mach 3
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Post by Den »

Try calling or emailing Phil at [email protected] for advice.
He has some experience with roundcase bevels.

phil hitchcock
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Post by bobnorton »

Don't know if its the same but on the singles there is a tiny radius on the crank that stops the shim meeting the crank face fully,this soon wears out the shim, i openned out the shim to clear this .

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