Bevel question

[lloydy1]

Hi, having lined up the bottom bevel and shimming so they are align, (See pictures). Rotating the crank seems quite firm is the word I can describe it as. To say binding would not be correct, but I am a little unsure if I have them meshed a little to tight. Can anyone tell me please, should the crank rotate by hand without feeling that you need a little help from a spanner on the end of the crank?

[Bevel bob]

If the crank rotated freely before the bevels fitted there should be no change after fitting . I would like to see/feel the smallest perceptible play and rotate about six crank revolutions to check .

[lloydy1]

If the crank rotated freely before the bevels fitted there should be no change after fitting . I would like to see/feel the smallest perceptible play and rotate about six crank revolutions to check .

Hi Bob, It is a little stiffer to rotate now than it was, so I have the backlash incorrect I feel. I will have to split it again and reduce the shims under the bevel gear.

Thanks for your advice. Dave

[Bevel bob]

Don't feel bad about it. Lost count of the number of times mine came apart!.

[LaceyDucati]

Dave

The crank should be free to turn. There should be no perceivable play at the tightest spot in the rotations, but there should be no perceivable tightness in the feel either. Any other play throughout the rotations you just have to live with and generally is no more than a few thou, which is fine. Just one thing, did you align the bevels at the ground marks? This is the only part of the bevels which will probably align, assuming you have a matched set. If the ground patch doesn't look matched then things get even more time consuming

Other things: Ensure the shaft is shimmed snug under the circlip. When correct the shaft should spin free and there should be no play in the bearings. At this point you should just be able to turn the top shim under the circlip with your fingers. Ensure the lower bevel cap is holding the bearing housing firmly in place and the housing cannot move. Lastly, only finally check the bevels with all screws and nuts fully tight, as the final tightening can make a difference.

Happy shimming

Nigel

[DewCatTea-Bob]

[quote= lloydy1 ...
" having lined up the bottom bevel and shimming so they are align, Rotating the crank seems quite firm is the word I can describe it as. To say binding would not be correct, but I am a little unsure if I have them meshed a little to tight. Can anyone tell me please, should the crank rotate by hand without feeling that you need a little help from a spanner on the end of the crank? "

____ Firstly, thanks for a better than average & well comprehendibly worded-explanation of your inquiry-issue !
__ I'd have to check-it-out in person to be sure but, it seems that you have the bevel-pair mesh-setting adjusted TOO tightly ! _ And leaving it set too tight would EAT power, (not to mention gear-teeth life) !
With that bevel-pair set properly adjusted, the crankshaft then ought-to STILL be able to rotate just (about) as easily by hand as when it's bevel-gear is-not yet even installed in it's place.
__ The matched bevel-pair setting should have their mesh-alignment adjusted & finally set so that their grind-mark patch-areas will be completely 'FLUSH' -(smoothly-leveled & totally-flat without any perceptible notch-step detectable between the two flatly-ground grind-spots of their grind-mark patch-areas) ! _ (And a 'matched' bevel-pair should show all their corresponding minute scratch-marks [within the factory grind-spot/patch] all aligned-up when meshed-together [after their timing-dots have been set aligned].)
__ It seems fairly likely that solving your overly tight meshing-issue, would simply require an addition of a minimally-thick spacer-shim placed behind the crankshaft bevel-gear.
Is it possible that you've (since tear-down) lost one such minimal-size thin-shim somehow ? - As the thinnest shims may possibly come-off stuck-together unnoticed along-with any other thicker shim, and-so sometime then-after may've later become lost during a clean-up procedure or other handling-task.
Another possible reason for such unexpected change in bevel-gear clearance, could be due-to a change of the crankshaft-shimming within the crankcases, or replaced main-bearings (with slightly differing thickness than that of the previous bearing-races).
In this particular case, with the clearance having become tighter,, assuming that ALL the involved shimming has been kept exactly just as it was when disassembled, then it's quite likely that a new pair of main-bearings were installed in the crankcase, and the one supporting the right-side of the crankshaft just happens to be a couple thousandths or-so thicker (than the main-bearing races which got replaced), thus leading to causing the bevel-pair to mesh more tightly (by the same amount).



" I will have to split it again and reduce the shims under the bevel gear. "

____ I gather you're meaning the bevel-gear of the OHC.drive-shaft...
However by what I can seem to see detectable within your pix, it appears that THAT bevel-gear is ALREADY slightly over-stepped above being in the 'flush' setting-position (by perhaps near 1.5 to 3 thousandths off-level). _ So rather, it seems you may just need to bring-outward the crankshaft bevel-gear, by adding the thinnest available O-shim behind THAT b.gear, instead. _ Or at-least doing so ought be a step in the righter direction, (as I'm currently thinking).
__ After you're all-done with rather perfect bevel-gear matching-adjustment,, if you then-after bother to provide us with any 'AFTER' pix (to compare with your two posted before-pix), then be sure to rather take your pic.shots with the grind-patch areas of the bevel-teeth meshed. _ As THEN, I should no-longer be able to seem to detect any non-perfectly flush tooth-meshing between the pair of bevel-gears.


Hopeful-Cheers,
-Bob

[lloydy1]

Hi Guys,

I have re-shimmed the bevel to the crank and it is 100% better than it was (Free spinning) now. I have taken some more pictures as requested by Bob.

They are a matching pair, as they are the ones that were fitted before strip down. I have matched the timing dots if this is what you mean Nigel by asking about the ground patch? sorry if I am incorrect in saying about the dots.

Thanks very much for your guidance on this subject. Dave

[LaceyDucati]

Dave

The timing dots are for achieving the correct cam timing. The ground marks I refer to (and described in detail by Bob) are the ground surfaces as can be clearly seen in your middle picture on the bevel shaft gear. There should be a coresponding and matching ground section on the crank gear, These are the surfaces that should be levelled as Bob describes. These ground surfaces are never at the timing dots and are found several teeth round from the dots.

If you need any further assistance you can call me at the workshop in the week and I'll run through it.

Regards Nigel

[DewCatTea-Bob]

[quote= lloydy1 ...
" I have re-shimmed the bevel to the crank and it is 100% better than it was "

____ What shim-thickness/size did you end-up having to add behind the crankshaft-b.gear, in order to achieve your successful* end-result ?
(* Assuming you've also ended-up with NO detectable slop-play lash.)



" I have taken some more pictures as requested by Bob. "

____ Well not quite... as your first/top pic in your first-post is the ONLY-one which happens to have the pic.shot taken with the best angle & lighting to show/indicate that the alignment-level of the teeth of the crankshaft-b.gear were-not quite completely flush with the teeth of the driveshaft-b.gear.
Your new pix, (especially the first/top-one), don't really show how well the teeth-level match-up together.



" They are a matching pair, as they are the ones that were fitted before strip down. " I

____ These-days, ya really can't count on that always being true, with past-owners often assembling a motor using parts from multiple basket-case motors.
the only way to be sure that a bevel-pair is a factory-matched pair, is to mesh the pair together with the timing-dots aligned and then rotate them until the grind-patch areas then come to show that their patch-boarders & grind-scratch marks all match-up & align-up.



" I have matched the timing dots if this is what you mean Nigel by asking about the ground patch? "

____ Now you should better understand exactly what's meant by "ground patch" & grind-patch/area.
Any pic-shots taken of the corresponding bevel-teeth mesh-levels, ought-to be done with the factory-placed grind-patch/areas on both bevel-gears viewed meshed-together (rather than the areas where the timing-dots mesh).
__ You probably don't need to post any more pix.view attempts, as you've now likely solved your bevel-teeth mesh-level issue.
However, others may like to see that the clues (indicating the previous slight level-misalignment), seen in your very-first pic,, have now been completely dispensed with. _ But you probably would have a difficult time duplicating the particular pic.lighting-angle as you happened to have had it in your very-first pic, (as it now seems that you had-not done it that way purposely).


Hopeful-Cheers,
-Bob

[lloydy1]

[quote="LaceyDucati"]Dave
The ground marks I refer to (and described in detail by Bob) are the ground surfaces as can be clearly seen in your middle picture on the bevel shaft gear.

Hi Nigel/Bob, I fully understand what you are saying now. I have placed an order for some more shims from you Nigel, which I will use under the OHC Bevel to withdraw it back up into the bearings. I used 2 x 1.00 under this bevel and I feel it should be around 1.75 total looking at the worn area on the teeth, so it would seem I still have it meshed a little tight.

You are real gentlemen and I appreciate your guidance. Thanks.