A bevel with no shim needed?

[Bevel bob]

My bottom bevel (on the crank) is still slack with no shim , the ground faces meet perfectly and the crank shims are on the drive side, so what gives??The only answer I have is that the bevels are very worn?? Or perhaps the main bearing is not seated or facing the wrong way?

[DewCatTea-Bob]

" the crank shims are on the drive side, so what gives?? "

____ So you're saying that you have ALL your crankshaft-shims placed on it's primary-gear side, (and none at all on it's right-side?) ?
Did you 'mike' the exact width of the original right-side crankcase main-bearing and compare that with your replacement main-bearing's exact width (to make sure they were both exactly the same)?


DUCATIly,
-Bob

[Eldert]

Hi Bob
why did you put all crankshims on the drive side ?? was that to centralise the rod in de sleeve bore ?
if you put a shim on the r.h. side your crank will move over and the problem with the bevelsgear might be solved

Eldert

P.S. put in the gear that drives the oil pump before you tighten the nut for the bottom bevelgear for the final time

[Bevel bob]

Thanks guys, silly me, just following the book, should know by now what a lot of rubbish it is. I will transfer a 10 thou shim over.Had problem with the crank radius not letting the shims sit against the crank cheek,need to open out the bore of the shims otherwise crank float develops quickly.--------Later!! No don't like the thin shim against the crank,think I will get the back of the bevel gear ground down by 5 or6 thou, what do you think?-----later, that didn't work either! the problem is that due to the gasket on the housing being too thick(or the big shim above the bearings too thin)the bearings and bevel assembly as a unit can move up and down in the bushing . The shim and gasket are not availiable in different thicknesses.The only way i can resolve this is to tap the whole caboodle up against the shim and housing and then shim the bevels snug which stops any movement,this seems to work,but is not the ideal answer.

[DewCatTea-Bob]

" think I will get the back of the bevel gear ground down by 5 or6 thou, what do you think? "

____ Well b.Bob, I had been waiting for your reply to my first post (to clarify the details of your issue), before making any suggestions,, because you seemed to indicate that the meshing of the two bevel-gears was still sloppy even though their common 45degree-plane was properly aligned & exactly flush.(?)
__ As you should understand, the pair of bevel-gears should both FREELY mesh without any slop at all, AND, also do so while their common-plane is exactly matched -(flush)!!
So in your case where the crankshaft bevel-gear SEEMS to need to be pulled inward (by re-shimming the crankshaft), to eliminate the left-over gear-play slop (between the bevel-pair),, if the common-plane of the pair of bevel-gears is indeed already perfectly flush, then after moving the crankshaft's bevel-gear inward any at all, THEN the pair will no longer be flushly-aligned as they should be! _ And that would then mean that in order to CORRECTLY eliminate the remaining play/slop which you've ran into, you'd have to maintain your flush-alignment of the bevel-pair's common-plane by, not just moving the crankshaft's bevel-gear inward, but ALSO shim the other bevel-gear downward, as well ! _ Please realize that this would be the case ONLY if the common-plane of the pair of bevel-gears is indeed already EXACTLY flushly-aligned (and ya still have some gear-play/mesh-slop) !
Hopefully, your bevel-pair really isn't already exactly flushly-aligned, and thus you will then likely only need to re-shim just one bevel-gear or the other (in order to eliminate the play-slop and also obtain perfectly matched bevel-alignment at the same time) !
____ Many wanta-be DUKE-mechanics don't realize that when either the right-side crankcase main-bearing, (or the right-side camshaft support-bearing) is replaced, that the replacement bearing's races should be miked in order to be sure that they're EXACTLY the same width as the races of the bearing being replaced,, cuz if they're not, then re-shimming is likely going to be required in order to maintain the original bevel-gear alignment which was set at the factory ! _ (This is also the case with the replacement of the bearings which support the bevel-shafts !)
__ Since you have likely replaced all related bearings, then ya have to expect that realignment of the bevel-gears is going to very likely be needed ! _ So keeping notes of how your replacement-bearings compare to the originals, can help ya keep track of the exact shimming-work which will be required. _ Otherwise, you'll have to do a fair amount of playing-around with all the shimming in order to get it all reset just-right !

____ To address your above question, I advise against grinding-down your crankshaft bevel-gear's back-face, especially by that small amount. _ Because if you take-off just a little too much, then you'll have a very hard-time getting any shim to exactly make-up the exact difference which you may then need !
I would not risk trying any grinding unless I had a replacement set of bevel-gears laying around with no other use for them !
If any related grinding-work is to be attempted, it should be done with precision and with very well planed-out amounts ! _ But there really shouldn't be any need for any such grinding.


DUCATIly,
-Bob

[Bevel bob]

Hi Dew catea Bob, I suspect that this problem is common, and that the only thing holding the bevels in mesh on lots of singles is the tightness of the bearings in the bushing as the thick gasket sets now supplied mean that the housing does not bear down on the shim which holds the bearings down within the steel bush,This is probably why my bearings were shot.Mine are all now closely shimmed and ground faces meet perfectly however if i was to remove the crank bevel it would be possible to tap down the whole bevel assembly including bearings by about 6 thou within the steel bushing.Perhaps someone should get some thicker shims made.