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Shims
Posted: Tue Nov 17, 2009 10:16 pm
by Crashfangio
Does anyone of our members from Australia (Melbourne) know of a good local source of engine shims suitable for a Bevel??
In particular I require a selection of mains shims to set the correct crankshaft end float. It's also possible that others will be needed when I start measuring up the top end, although mains will do for now.
2nd question, is it desirable to keep the mains as one single shim for each side or is acceptable to run two together, only if required.
Finally, I take it that there must be an equal size (and number) of shims on each side in order to keep the crank right in the center of the engine, or does it not matter??
Advice will be greatly appriciated.
David
Posted: Wed Nov 18, 2009 1:22 am
by BEVEL DAVE
You can use 2 if needed but no. is not critical, yes centred is better but not critical either.
I have shims but you will need to let me know what you need. I will see what I have in stock.
Dave.
Posted: Thu Nov 19, 2009 2:10 pm
by rwhc80
David,
you should consider joining the DOCV. Ducati Owners Club Of Vic With a 73 GT it will give you access to use the extensive set of club tools inc the shim kit, along with stacks of reference material. You only attend meetings and club days if it suits you, but the access to the equipment is worth the membership alone.
Cheers
Rick
Posted: Fri Nov 27, 2009 2:12 pm
by Crashfangio
Thanks Dave. I've managed to source the sizes I need through Chris Bullen at Precision Shims here in Melbourne. I have reassembled the bottom end and all seems well thus far.
I have got just on 0.01mm play, which I am happy with considering the mains bearings are original and probley a bit worn. I would prefer just a tiny LITTLE slack rather than the bearings being loaded up. Anyway, it is better than what it was prior to disassembly.
Rick, I checked out the DOCV website and I think they will have my membership in the new year. Thanks for the tip.
Cheers, David.
Posted: Fri Nov 27, 2009 7:02 pm
by rwhc80
David,
Unless I miss understand what you're referring to , be careful !!!
The crank in beveldrive engines should have no endfloat. infact they should have preload due to the angular contact bearings. these bearings are designed to run under load.
Regards
Rick
Posted: Fri Nov 27, 2009 7:31 pm
by wdietz186
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.Remember the cases expand when hot and the bearings are designed to run with some preload.Shoot for .25-.30mm on the trans shafts and shift drum.It is time consuming to get it right but oh so satisfying when you do.
without micrometer
Posted: Wed Jun 09, 2010 3:48 pm
by stian buksa
Any tips to how to measure the crankshaft preload without fancy instruments ?
With 0,50 mm shims i can feel that the crank is a little "loose"
With 0,60 mm its tight, with a minimum of drag
With 0,75 mm its tighter, with more drag
Which one should I go for ?
71 750 roundcase GT
Posted: Thu Jun 10, 2010 12:39 am
by bobnorton
Beware that the shim does not sit against a tiny crank radius or it will get loose in no time .
Re: without micrometer
Posted: Fri Aug 27, 2010 5:56 pm
by Den
stian buksa wrote:Any tips to how to measure the crankshaft preload without fancy instruments ?
With 0,50 mm shims i can feel that the crank is a little "loose"
With 0,60 mm its tight, with a minimum of drag
With 0,75 mm its tighter, with more drag
Which one should I go for ?
71 750 roundcase GT
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".
.
measured pre load: How tight ?
Posted: Thu Aug 18, 2011 9:28 pm
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 ?
Stian
(Also submitted as a new topic in the roundcase section)