Questions Mark 3.

[elmoi11]

Hello everyone, I would like you to help me with any questions about this model.

The Mark 3 wide crankcase models made from 1968 onwards apparently had the same 31,5 millimeter front forks as the older 175, 200, 250 narrow crankcase.

Are they really identical, are they interchangeable?

On some website I have read that in the Mark 3 model, they were longer.
But they look the same to me.

Thanks and sorry for the bad translation.

[Ventodue]

It's always worth checking the parts books for this kinda thing. IME, Ducati were rigorous in their parts numbering.

So:
Narrow case 250 Mark 3 (and also Monza, SCR and GT after engine number 87422): 0621.37.100 (31.5mm forks, Ducati brand).

Wide case 250 and 350 Mark 3 (and Desmo): 0687.37.103 (31.5mm forks, Ducati brand).

So already we know the complete units were not the same. To find out just how they were different, you need to compare the list of individual components ...
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To explain the Ducati parts system a little. This applies only to the post-1961Type B engines. The earlier Type A engines used a different system.

The first 4 digits are for when the part was first used. It is sometimes possible to relate this - tentatively - to a particular model. So here 0621 would seem to be the 1961 250 Monza; 0687 seems to be the 1968 Mark 3.
The second 2 digits are for where the part is most used. Here, 37 is for the front suspension.
The final 3 digits are for the variation of the part. This can be significant ... or not.

[elmoi11]

Hello Ventodue.

Thank you very much for your answer, and for all the information you have given me, but I only have the maintenance manuals for various Ducati Italia models. But I don't have the parts manuals for any Italian model.

Could you advise me how I can get them, to be able to compare them and find out if there really is any significant difference in the 31.5mm forks of the Mark 3 wide crankcase and the forks of a 31.5mm narrow crankcase 175, 200, Monza, etc.

It would also be interesting, if any Mark3 owner has been able to physically compare them with the other narrow Ducati crankcases.

I have several 31.5mm narrow carter forks. If they really are the same, you could use them to mount them on the wide carter frame. And so I would not have to buy others, (which are surely expensive).

Thanks and apologies again for my bad translation.

[Jon Pegler]

There are no significant differences between the 31.5mm forks on a narrowcase Ducati and the 31.5mm forks on the early widecase Ducatis.
The very earliest 175s and 125s used a slightly different stanchion, with a 30mm diameter at the top, but you are unlikely to come across a set like that.
You can fit the standard 31.5mm foks as a direct replacement, so you do not need to source a different set of forks.
There are lots of minor differences in the component parts, (yokes, top nuts etc.) but nothing to stop you fitting them.

Jon

[Ventodue]

There you are, elmoi11, a perfect answer from Jon!

(Thanks Jon )

[ducwiz]

Hi elmoi11,

.. thank you very much for your answer, and for all the information you have given me, but I only have the maintenance manuals for various Ducati Italia models. But I don't have the parts manuals for any Italian model.

If you are interested, I can send download links by PM for different parts catalogs of wide and narrow case Ducatis, as well as some spanish Mototrans models.

Hans

[Ventodue]

<snip> But I don't have the parts manuals for any Italian model. Could you advise me how I can get them ...

The most common version of the parts list that includes your bike comes in two volumes: one for the engine, the other for all the rest.



For a paper version, both photocopies and originals come up on ebay, Subito etc fairly regularly. Here they are on ebay Italia for example. Just don't pay too much ...

https://www.ebay.it/i/152849353604
https://www.ebay.it/i/153025618132

Or you can buy a pdf version here:
http://www.duc.nu/?model=classics

And on-line, page by page, and free here: http://www.ducatimeccanica.com/parti_di ... /index.htm

And I'm sure other people will have other sources ...

[ducwiz]

Two "free" sources:

As .pdf: https://www.rpw.it/Files/Ducati_MonocilindriciMonoalbero1968-73_5m_CR.pdf

All pages as single .jpg image files: http://www.luke3d.org/bmw/ducatimanual/Parti%20di%20Ricambio.zip

[elmoi11]

Hi Jon.

Thank you very much for the clarification. This is great.
And I am writing to you from Spain, I have several NCs that need restoration and also a 350 WC chassis and WC engine and many parts to complete. With this, the intention is to make a "Mark3" 68-70. A few days ago I bought a coffin deposit, I try to put a photo.
I would be missing some main parts like the seat, side boxes, fenders, etc. It would also be interesting to have some empty carters (Mark3 WC), I think the numbering should be between 6xxx and 9xxx.
But little by little, they are difficult to find and expensive.

"Ventodue" thanks again for the sources.

Also thanks "Ducwiz" I sent you a private.

The engine parts manual is wonderful, to have the link.
I would be missing the "frame" parts manual.

Regards.
Moises.

[ducwiz]

Craig,

the catalog offered on Ducatimeccanica is an older version, I reckon it ~1970/71. I.e. it doesn't contain the electronic ignition components etc.
Seems that the 1973 chassis catalog ("part II" in your photo) quoted by Moises is not available for a free download.

Hans