pre load: How tight ?

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stian buksa
Cucciolo - the Lil Pup
Posts: 20
Joined: Mon Oct 12, 2009 10:50 am

pre load: How tight ?

Post by stian buksa » Tue Aug 16, 2011 6:26 pm

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 ?

Stian

Den
Mach 3
Posts: 89
Joined: Fri Apr 09, 2004 5:02 pm
Location: Florida, USA

Post by Den » Fri Aug 19, 2011 5:36 am

Try calling or emailing Phil at roadrace@connect.net.au for advice.
He has some experience with roundcase bevels.


phil hitchcock
road and race
2 bon mace close
berkeley vale nsw 2261
australia
ph/fax 0243884211
international 61243884211
www.roadandrace.com.au
NOTE NEW EMAIL ADDRESS
roadrace@connect.net.au

bobnorton
860 GT / GTS
Posts: 280
Joined: Wed Jan 16, 2008 2:18 am
Location: bromley kent

Post by bobnorton » Fri Aug 19, 2011 8:39 pm

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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