Clutch Assembly Interchangeability?

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guzzijon
Posts: 62
Joined: Wed Mar 07, 2012 12:55 am

Clutch Assembly Interchangeability?

Postby guzzijon » Mon Apr 16, 2012 12:56 am

I got another bad surprise when I opened up the Scrambler and saw what looks like the result of someone not having the right tool for the job:

Image

I suspect from what I've been able to find in books and online that all Ducati single clutch assemblies are the same but I wanted to post here and make sure before I buy something that won't fit. There's a clutch assembly on eBay right now from a '72 350, will that work on my '63 250?

or does anyone here have a spare clutch hub they would like to sell? Thanks for any info you guys can give me!
1963 (early) 250 Scrambler project
1964 250 Monza project
1981 Moto Guzzi Monza
1983 Moto Guzzi LeMans III

graeme
Posts: 1006
Joined: Sun Mar 25, 2012 12:00 am
Location: Tasmania Australia

Re: Clutch Assembly Interchangeability?

Postby graeme » Mon Apr 16, 2012 2:03 am

Hi John,
I am pretty sure all the wide case clutch hubs are the same but the "supposedly matched" (to the clutch hub) pinion gear is larger on 450's giving higher gear ratios.
Not sure what size the matched pinion gear is on 350's.

graeme
Posts: 1006
Joined: Sun Mar 25, 2012 12:00 am
Location: Tasmania Australia

Re: Clutch Assembly Interchangeability?

Postby graeme » Mon Apr 16, 2012 2:13 am

450 = 27 teeth
250 = 24 teeth
350 ?

graeme

Eldert
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Location: Hazerswoude Rijndijk Netherlands

Re: Clutch Assembly Interchangeability?

Postby Eldert » Mon Apr 16, 2012 7:09 am

a 250 has a 24 /60 = 2.5 primary ratio , 350 and 450 have a 57 /27 = 2.11 ratio

the 250 is made out of brittle cast iron . 350 /450 is made out of better material

you can exchange clutch housings no problem but you have to use your own gear on the crank
Ducati matched that gear to the crankcases , they had undersize gears for as the machining of the bearing bores was a little of

Eldert
Last edited by Eldert on Mon Apr 16, 2012 5:54 pm, edited 4 times in total.

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

Re: Clutch Assembly Interchangeability?

Postby DewCatTea-Bob » Mon Apr 16, 2012 10:32 am

By: guzzijon...
" I suspect from what I've been able to find in books and online that all Ducati single clutch assemblies are the same "

____ NOT true ! ...
The later-200's driven primary-gear is the same as the 250's except the clutch-basket holds only 6 pairs of plates,, while the 350/450-basket holds the same number of plates (as the 7-pairs of a 250), THAT version (of driven-p.gear) is smaller and thus will not work with your 250's stock 24t drive-gear.
__ Also, 250 n-c & 250 w-c primary-gear sets are interchangeable (since they're the same).


" There's a clutch assembly on eBay right now from a '72 350, will that work on my '63 250? "

____ Certainly not without also the 350's 27t drive-gear !


" or does anyone here have a spare clutch hub they would like to sell? "

____ I probably have a spare 250 clutch-drum/basket,, but, instead of replacing the one you already have currently installed, you could instead simply bust-off the basket-lief that's 180-degrees opposite of the lief-ear that's already gone, so as to (roughly) rebalance-out that clutch-drum (well enough). _ Doing-so may seem like making the basket even worse,, but actually, I assure you that it will then still operate & do it's job just as well as a stock-basket with all of it's lief-ears still intact.


Dukaddy-DUKEs,
-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

guzzijon
Posts: 62
Joined: Wed Mar 07, 2012 12:55 am

Re: Clutch Assembly Interchangeability?

Postby guzzijon » Mon Apr 16, 2012 3:11 pm

Thanks for the information everyone. There is already a second tab/lief/ear broken off, but it is not quite 180 degrees across from the one pictured. It's one tab/lief/ear counter-clockwise from the one that is 180 degrees opposite. Do you think that will work in terms of balance? Thanks!
1963 (early) 250 Scrambler project
1964 250 Monza project
1981 Moto Guzzi Monza
1983 Moto Guzzi LeMans III

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

Necessity of Clutch-basket Balance

Postby DewCatTea-Bob » Mon Apr 16, 2012 5:46 pm

" There is already a second tab/lief/ear broken off, but it is not quite 180 degrees across from the one pictured. It's one tab/lief/ear counter-clockwise from the one that is 180 degrees opposite. "

____ Sorry, I hadn't looked closely enough before to notice that a second basket-ear/tab was also broken-off. _ While it's not too uncommon to find a 250-basket with only one of it's ear-tabs broken-away, I've never seen one still in use with two missing (which were not directly opposite one-another).
However, if you find that your clutch still operates well enough as it's meant to, then it could probably continue-on being used as it is.


" Do you think that will work in terms of balance? "

____ While your clutch-basket's current arrangement is STILL off-balance,, the way it currently is, it's balance is still somewhat better than with only one ear-tab missing.
Your basket's balance COULD be brought-back nearer to normal by busting-off still another ear-tab (also 180 opposite from the "second" one missing) as well,, but THAT may not be a worthwhile trade-off, as that (smaller) improvement in balance would be relatively minor in exchange for the additional loss of the function provided by the basket-tabs. _ So unless you've noticed some odd lower frequency vibs (2.5-times less than engine-revs), I wouldn't suggest busting-off the two additional basket-tabs required to get the complete balance back to normal.
I'd suggest that you leave the situation as it is until you have another reason to tear-down & remove the clutch, that way you'll have more time to find replacement parts.
__ It always seems that Duke-parts such as the clutch-basket become listed on eBay somewhat grouped together, time-wise...
Relatively long periods will pass-by without seeing any listed,, then all in a month's time, several will become listed.
And people who have their motor apart waiting to acquire the part will bid fairly high on the listing that's ending soonest, which then takes the winner (willing to bid rather high) off the market, and thus-then leaves the remaining listings easier to win cheaper !
For such an example, I've seen a 350-clutch sell for about 75-bucks, with the second eBay-listing going for about 50, and I-myself then won the last listing (uncontested!) for only 10-bucks !
So it can pay to not have yourself in a position of WAITING-on the part ya think ya need, and instead pick-it-up when it just happens to come-by-your-way (so to speak).
BTW, if you win that 350-clutch, I'd be willing to trade a 250-basket for it. _ But be smart, always bid (for something you want on eBay) NOT BEFORE the last 20-seconds of the listing,, otherwise you'll likely just help cause whoever the winner turns-out to be, to end-up paying MORE !!


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

Rick
Posts: 340
Joined: Thu Nov 11, 2010 1:12 am
Location: Northern Plains, USA

Re: Clutch Assembly Interchangeability?

Postby Rick » Mon Apr 16, 2012 6:09 pm

As a stopgap solution, until you find a replacement, you could get it closer to balanced by drilling holes in the remaining tabs, it was a common racing modification- the 'Blueprint For Power' shows it, here:
http://www.motoscrubs.com/Ducati_Engine ... eprint.gif
Letting the basket spin freely on a shaft and removing/drilling material could get you fairly close, depending on how much time you wanted to spend on it.
I've seen some deeply notched baskets, but never tabs sheared off like yours- I doubt if the clutch plates broke your basket- someone was probably pounding or prying on it. As Eldert said, it's cast iron- you can see the coarse texture where it broke- I think the steel assemblies had narrower gears also.
Rick

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

Necessity of Clutch-basket Balance

Postby DewCatTea-Bob » Mon Apr 16, 2012 6:59 pm

" until you find a replacement, you could get it closer to balanced by drilling holes in the remaining tabs, "

____ Rick is right of-course, ya COULD drill some holes in a couple of the tabs (most opposite the lighter side),, but I didn't bother to mention that fix because I figure the possible resulting improvement (even if then PERFECTLY-balanced) would not really be worth the trouble cuz once the basket is removed (to do the drilling-work), it may as well then be gone-ahead & replaced (likely more economically if your time & labor much counts).


Dukaddy-DUKEs,
-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

guzzijon
Posts: 62
Joined: Wed Mar 07, 2012 12:55 am

Re: Clutch Assembly Interchangeability?

Postby guzzijon » Mon Apr 16, 2012 7:43 pm

Thanks for all the feedback and ideas. One thing to keep in mind is that I will likely be tearing this thing down to the last nut and bolt anyway. This is due to the fact that previous owners left it outside to rot and rust for years and years and due to all the evidence of ham-fisted "mechanics" working on it in the past - stripped exhaust nut threads in the cylinder head, broken off clutch hub tabs, missing piston rings, the list I'm sure will go on and on as we dig further into it. Good thing I have a lot of patience and I'm in no big hurry. :)
1963 (early) 250 Scrambler project
1964 250 Monza project
1981 Moto Guzzi Monza
1983 Moto Guzzi LeMans III


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