Bottom bevel bearings.

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Bevel bob
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Re: Bottom bevel bearings.

Postby Bevel bob » Mon Apr 26, 2010 8:55 am

Your right Clymer did get the crank clearance right, still plenty of BS to avoid in there.Got the upper outer race and spacer out easily, lower outer race is inhabiting the spacer area and wont come out ,have to rig up a press or threaded puller.There is a small curved plate fixed with screws behind the kickstart, its pretty chewed at one end,is this normal?.

dsmess
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Re: Bottom bevel bearings.

Postby dsmess » Mon Apr 26, 2010 2:49 pm

The angular bearings should be used in pairs...for a couple of reasons. If you use an angular combined with a standard type in the lower bevel spacer, and set a preload using the 'snug shim' you are putting an axial load on the standard bearing as well. Also I believe there are reflected axial forces in both directions as the engine is accelerated and deaccelerated. I'm not sure what you mean about the upper bearing...if you mean the self centering one at the top of the shaft. I think it is used to avoid binding because of any misalignment of the long shaft. Machining tolerances add up!

Here are the angular bearings:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... K:MEWAX:IT

I got a couple of them from him a couple months ago for a Mach 1 engine. They are not exactly selling like hot cakes.

Scott

Bevel bob
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Re: Bottom bevel bearings.

Postby Bevel bob » Mon Apr 26, 2010 5:27 pm

Hi Scott,The bearings are as you say,I am trying to decide whether they should appose each other or work together against the thrust which is mostly upwards.

DewCatTea-Bob
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Re: Bottom bevel bearings.

Postby DewCatTea-Bob » Mon Apr 26, 2010 5:51 pm

" I lost confidence in Clymer when I read tighten the clutch nut to 700-850 foot -Ibs, "

____ I'd guess that's meant to be 'inch-pounds', or more likely 'cm-kg.s' (which is almost the same as 'in-lb.s') !?


" Also tappet clearances for Mach 1 inlet 9.8 thou ex 16 thou?. "

____ I have a copy of the ' FIRST EDITION , Fourth Printing July 1979 ' issue of the Clymer-manual... It states those same incorrect valve-clearances on it's page 65 !
The correct factory-clearances for those models which use the Mach-I cam, are:
.15mm (.006") for intake and .3mm (.012") for exhaust !
However, I'm sure that .004" in. & .008" ex. would work okay, (but I wouldn't go any tighter!).


" I'm also having to question everything I find in this motor, certainly can't put bearings
"back the same way they came out"! "

____ What are you quoting, exactly?
It would be quite helpful if you'd let us know the issue & page of any info you've found within your Clymer-manual !


" The bottom bevel was shimmed far to tight which is likely why the bearings were worn out and nut loose. "

____ Such improper bevel-gear shimming is a very common-problem whenever most any non-DUCATI mechanics screw-around with DUKEs ! _ I never trust anyone other than myself to get such work done exactly right ! _ Either loose or too tight is bad-news ! _ But the secondary concern is proper-alignment, which is also very quite important !
__ That you realize all the things that you do, I'm sure that YOU could do a much better, if not perfect, job !


" There is a small curved plate fixed with screws behind the kickstart, its pretty chewed at one end,is this normal?. "

____ Not real sure of exactly what you're actually referring to but, if you mean the k.s.gear's lifter-plate (which is held against the motor-case wall by two flat-head slot-screws), then that small plate should have just slight wear on it's slanted lifting-surface only !
If that's not the "plate" which you're meaning to refer to, then please let us know what other part that the plate question looks to make contact with.


DUKE-Cheers,
DCT-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob

DewCatTea-Bob
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Re: Bottom bevel bearings.

Postby DewCatTea-Bob » Mon Apr 26, 2010 6:20 pm

" I am trying to decide whether they should appose each other or work together against the thrust which is mostly upwards. "

____ Apparently you didn't read (or didn't understand) all of my earlier (extended) posting...
__ The stock-type bearings are meant to work back-to-back !
YOUR alternate-thought would be reasonable only if there was also another spacer which connects the inner-races of the two stock-bearings (just as the stock-spacer connects the outer-races of those two bearings) !
So you need to make sure that the stock-type bearings are installed back-to-back, as opposed to facing front-to-front. - (With the presumption that the inner-race cannot be pushed-out through & past the 'back' side of the bearing.)


DUKE-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob

Bevel bob
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Re: Bottom bevel bearings.

Postby Bevel bob » Mon Apr 26, 2010 9:07 pm

Thanks Bob,so the lower bearing of the pair resists the bevel axial upward load on its own and the upper one resists any knocks from the tower shaft and provides radial support.Both the bearings are angular contact type(FAG steel cage) approx £20 the pair,

DewCatTea-Bob
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Re: Bottom bevel bearings.

Postby DewCatTea-Bob » Mon Apr 26, 2010 9:47 pm

____ Okay Scott, it seems that you were addressing my earlier (extended) posting, and so I assume that I ought to clarify it's points somewhat.


" If you use an angular combined with a standard type in the lower bevel spacer, and set a preload using the 'snug shim' you are putting an axial load on the standard bearing as well. "

____ That fact would be very quite true Scott ! _ Providing that anyone ever goes-ahead & tries-out doing your idea of preloading that particular bearing-combo, (by using slightly thicker than needed shimming under the clip-retainer.) _ However if that were ever to be done, then the very small pressure that the clip could possibly help cause to be exerted vertically/axially, would be so very well within the range of a standard-bearing's axial load-handling, that it would not be a real concern ! - (As the C-slots in the races of standard-bearings can handle axial-loads up to 25% of their rated radial-load capability !)
__ I guess I ought to point-out here, that the particular bearing-combo which I've suggested would not require any such "preload". _ But perhaps I'm overlooking some reason (other than the one obvious reason), for including the slight pre-load (when using the stock-type pair of "angular" bearings)? _ But I'm really doubting that !
__ When I replaced the pair of stock-bearings (for the lower-bevelshaft) in my own project-motor, I chose to use two of the special (self-aligning) bearings -(same as stock for the upper-bevelshaft). _ I've only suggested that the UPPER bearing (for the lower-bevelshaft) COULD be a standard-type bearing, because it's cheaper and would be okay to use there (only in combination with the suggested special-bearing, of course !).
__ If it weren't for the extra added expense of that type of special-bearing, I'm quite sure that Ducati would've chosen to use that same special-bearing at all three locations (and not just at the top-location on the upper-bevelshaft). _ (We all realize that choices for any bearing at any location, are always of course determined by need vs. expense !)


" Also I believe there are reflected axial forces in both directions as the engine is accelerated and deaccelerated. "

____ While such pressure-reversal as that is no doubt true in the case of the helical primary-gears (attempting to move the crankshaft side-to-side through the inner-races of the crankcase's main-bearings), such is not the case within the drive-line for the overhead-camshaft, as THAT shaft has no alternate drive-line which also reaches through to the road-surface forcing it to alter any pressure against the crankshaft during changes between acceleration & deceleration !
And if you might have meant that the valve-springs could provide a similar force effect, then in that case, it's also not possible,, for two separate reasons... First, the special -(dual-row & self-aligning) bearing on the upper-bevelshaft should prevent any vertical/axial pressures from passing through it (toward the lower-bevelshaft),, and second, the upper-bevelshaft does not make any vertical-contact with the lower-bevelshaft anyhow, (as there's at least a 1mm-gap between the two separate shaft tip-ends & butts)!
__ The only other possible way (I can think of) that any possible sort of notable reverse-pressure could be exerted upon the crankshaft from the bevel-shaft drive-line system, would be when the engine's RPMs are suddenly drastically reduced from a high RPM-range... Thus allowing the relatively insignificant rotational-momentum -('flywheel-effect') of the spinning bevel-shafts themselves, to torque (through the lower bevel-gears) against the crankshaft. _ And it seems so very quite doubtful that Ducati had ever figured that the type of angular-bearing which they chose for the upper-position (of the lower-bevelshaft), would really be actually required to handle that particular (minor) instance ! _ (That thought seems laughable!)


" I'm not sure what you mean about the upper bearing...if you mean the self centering one at the top of the shaft. "

____ Let me clarify some things...
I've tried to keep these things clear by referring to either the 'upper-bevelshaft' OR the 'lower-bevelshaft',, and since the upper-unit has only one bearing while the lower-unit has both an upper and a lower bearing, we must use added wording to help keep thoughts straight & on-track. _ So my wording is always carefully chosen, so as to help keep them from possibly meaning more than one thought. _ (That point being made because if ya don't realize that you're reading carefully chosen wording, [during these days of all the common chat-style writing], then ya can't be as sure that the writer's wording was meant to convey exactly what it seems to be.)
__ Next, I've previously referred to three different types of ball-bearing bearings in this thread (so far), all of which I don't really know the actual official tech-terminology names of...
I've referred to the single bearing of the upper-bevelshaft as a "special" 'dual-row self-aligning' bearing, (which is only one of the "angular" types available).
And I've also referred to the other stock "angular" type pair of bearings (which have L-shaped bearing-races), as used for the lower-bevelshaft. _ (Which I do not disagree ought to be used in pairs, [for the one obvious reason which I've already covered previously].)
And also, I've also referred to the 'standard-type' of ball-bearing bearing, (which I'm sure we're all somewhat familiar with).
__ I still contend that the self-aligning type (as used on the upper-bevelshaft), can be used in-place/instead of the "angular" type stock-bearing that's located in the LOWER position for the lower-bevelshaft,, since that special-bearing properly handles axial-loads, as well as prevents vertical pressures from passing through it IN EITHER DIRECTION !!
The stock-bearing type (on the lower-bevelshaft) can also do those same two jobs BUT, obviously, in just ONE vertical/axial direction only ! _ (Thus the need for two of them.) _ That type of "angular" bearing is made to tolerate loads EQUALLY either radially OR axially,, so that's why I believe that that particular type of stock-bearing is not really needed for handling the normal relatively slight vertical-loads in question for this application.)
__ So anyhow, if the stock (dual-row self-aligning type) bearing, (as used on the upper-bevelshaft), is also used for the lower-position for the lower-bevelshaft, then the upper-bearing (for the lower-bevelshaft) might as well be a standard-bearing !

____ Hope this post clears-up everything which I had meant to convey before.


DUKE-Cheers,
DCT-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob

DewCatTea-Bob
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Re: Bottom bevel bearings.

Postby DewCatTea-Bob » Mon Apr 26, 2010 10:22 pm

" so the lower bearing of the pair resists the bevel axial upward load on its own "

____ That's quite correct ! _ (And in an over-kill manor too!)


" and the upper one resists any knocks from the tower shaft and provides radial support. "

____ As to "radial support", YES! , But as to "knocks" (or other pressures) from the upper-bevelshaft (or anywhere else), I'm not thinking so.
It's just for convenience-sake, as I've meant to convey previously.


" Both the bearings are angular contact type(FAG steel cage) approx £20 the pair, "

____ I'm not surprised that such special bearings cost 15-bucks each, but too bad that you didn't wait & get them for a single-buck -(about 2/3rds-Pound) each, as Scott seems to have found for you !


Hopeful-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob

Bevel bob
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Location: Bromley Kent UK.

Re: Bottom bevel bearings.

Postby Bevel bob » Tue Apr 27, 2010 6:21 am

Hi Bob, The bearings would be a steal at that price! unfortunately they are $10 each plus packing,air frieght,insurance,import tax,etc and still may end up in a ditch!!No its cheaper my way,delivered next day.Better than local specialist at about £50 the pair!!.As to no load from the tower shaft,when my top bevel bearing collapsed it all went south!!

DewCatTea-Bob
Posts: 2897
Joined: Sun Nov 01, 2009 10:53 am
Location: Near SE side of Lake Michigan

Re: Bottom bevel bearings.

Postby DewCatTea-Bob » Tue Apr 27, 2010 2:26 pm

" unfortunately they are $10 each plus packing,air frieght,insurance,import tax,etc "

____ My understanding of that eBay-listing which our good-fellow Scott found, is that for the 10$-US, ya get a batch of 10 bearings ! _ So the 10-bucks is what you'd pay for the pair you need, and you'd also then have 8 bearings left-over (to sell for profit locally!?).


" Better than local specialist at about £50 the pair!! "

____ WOW! _ That would be about $37.50 each ! - (Here in USA, my understanding is that one of your British 'Pounds' is equal to about 1 & 1/2 US-dollars.) _ I don't think that type of bearing is worth THAT much !


" when my top bevel bearing collapsed it all went south!! "

____ Do you mean to say that the special stock-bearing of the UPPER-bevelshaft went bad?
Cuz I myself have never had to replace one of those special type of bearings for any reason (other than being seized-up due to rust, after being left in it's motor outside & neglected) !


DUKE-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob


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