Fork oil grade 1980 SD 38mm Marzocchis

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PAUL FINN
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Fork oil grade 1980 SD 38mm Marzocchis

Post by PAUL FINN » Wed Aug 31, 2011 11:28 pm

Hi i understand oils have evolved in 30 years. Can i get a recomendation for fork oil for my bike. Standard forks used for club runs and social rides.
Cheers Finny

DaleMclean
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Post by DaleMclean » Thu Sep 01, 2011 1:22 pm

Auto trans fluid and double the amount recommended is what i have run for years
I survived :-)

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Post by BevHevSteve » Thu Sep 01, 2011 2:08 pm

DaleMclean wrote:Auto trans fluid and double the amount recommended is what i have run for years
euuuuhhh. :shock: totally light fluid, compensating for its lack of viscosity by doubling up on the volume, not what i consider good advice.

:arrow: Depending on your weight, MOTUL 5 wt up to their 10 wt fork fluid works at the recommended levels.
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Post by Sir Duke Sam » Sun Sep 04, 2011 1:51 am

How much per tube as I'm about to change my fluid as well?
TNX

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Craig in France
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Post by Craig in France » Sun Sep 04, 2011 4:20 am

Sir Duke Sam wrote:How much per tube as I'm about to change my fluid as well?
185cc.
EDIT: But see my later posting below.

BTW:
Information such as this can be readily obtained by consulting the owner's manual and/or the workshop manual on Steve's site, http://www.bevelheaven.com/ , section 'Manuals Index'.
Last edited by Craig in France on Wed Sep 14, 2011 10:01 am, edited 1 time in total.

notanumber
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Post by notanumber » Thu Sep 08, 2011 7:10 am

The amount shown in the 'Data Index' here is 210cc for the SD ...
FWIW my own (limited but recent) SS experience is that 10W is significantly too light; 230cc/20W seems fine, as recommended in Stephen Eke's 'Ducati Tuning' book.
Any opinions/'facts' to do with old Ducatis do seem highly variable ...

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Post by Craig in France » Wed Sep 14, 2011 10:01 am

notanumber wrote:The amount shown in the 'Data Index' here is 210cc for the SD. FWIW, my own (limited but recent) SS experience is that 10W is significantly too light; 230cc/20W seems fine, as recommended in Stephen Eke's 'Ducati Tuning' book. Any opinions/'facts' to do with old Ducatis do seem highly variable ...
Thanks for this, notanumber and Sir Duke Sam. Interesting - your postings have made me go and have a closer look, starting with what Ducati said at the time. Beginning with weight …

Weight/type
Each of the 3 editions that I have of the Ducati Workshop Manual for the SD say 25 (the reference is found in the relevant page of the ‘Vehicle Overhauling’ section.)

However, the three SD Owner's Manuals that I have offer different advice according to which edition you look in. So the July '77 (2nd Edition) manual says 25; but the June '79 (3rd Edition), as well as the SSD manual (July ‘79), says ATF. *

However, that said, like Steve A., I don’t like ATF. It may start off ok, but I find it quickly deteriorates. Personally, I’m currently using a 10-30 synthetic fork oil.

Quantity
Wherever I look, I can only find 185cc referenced in any of the SD Workshop or Owner's Manuals. Which was why I gave this in my earlier reply. And is what I’m currently using.

But your experience makes me begin to have some doubts. I wonder whether the information was simply repeated from manual to manual, possibly, for example, not taking into account the switch from Cerianis to Marzocchis.

Certainly for the MHR with similar, albeit not the same, 38mm Marzocchis, the amount given in the Workshop Manual is 220cc (250cc when the fork is fully stripped). And, similarly, my Laverda RGS Corsa, which also uses 38mm Marzocchis, takes 300cc per leg - a whopping 60% difference over the 185cc specified for the SD. Which seems weird …

So I can well believe that your 230cc may be nearer the mark. Maybe I should go experiment with a bit more fork oil ...

Btw, the amounts given in the Bevel Heaven Data section, purporting to be from Phil at Road and Race, are very similar to what Mick Walker lists in Appendix 5 of his “Ducati Twins Restoration”.

Ciao

Craig

* I guess this might reflect the change from Cerianis to Marzocchis; but it's impossible to tell since the illustration of which models the later manual covers shows bikes with both Cerianis and Marzocchis.

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Post by Vince » Thu Sep 15, 2011 12:22 am

My take is working on volume is counterproductive,what is needed is the oil hight with the springs out and the fork bottomed,this air gap is what becomes the bottoming resistance.Good suspendion to me is using just about 90% of the travel over bumps but still having some travel avalable when the fork bottoms under brakes into bumpy corners.I use 140mm oil hight as a starting point,then with a cable tie on the fork I go for a good test and see what travel I am using and adjust the oil hight to use as much travel as I required.I am using 7.5wt as I like it plush,anywhere worth riding and not being hasseled is by definition bumpy as in OZ.BTW Race Tech emulators help 100%.

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Post by radecal » Thu Oct 06, 2011 6:46 am

Hi Vince,
Interested in how you fitted and set up the Race Tech emulators.
What forks are they in?
RAD

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Post by BevHevSteve » Thu Oct 06, 2011 8:56 am

Hi Bob [RAD] have a look at this LAVERDA site where the author show and describes what is needed to happen in our forks [38mm] to install the emulators. It is very well shown.

http://www.laverdamania.net/emulatorgb.htm

Also, here is the specific emulator kit needed, I keep them in stock $170
https://store.bevelheaven.com/Chassis-S ... ani-Forks/
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Post by radecal » Fri Oct 07, 2011 2:29 am

Thanks Steve.
I haven't fitted the fork spring kits I got from you yet but was about to start when I saw this. Have you tried putting the progressive spring kits in with the emulator kits on a set of forks?
Be interested to find out what they are like (and any pitfalls before I start).
RAD

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Post by BevHevSteve » Fri Oct 07, 2011 6:24 am

The fork spring kit you got from me is a dual rate kit with adjustable crossover, not 'progressive' meaning each fork leg gets 2 springs. A stiff one and a soft one. Each has it's own job. Much better than 1 progressive wound spring.

Having used emulators in my racebike with a works spring kit I can tell you that the emulators do smooth things out and are well worth the effort to install.
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Post by Craig in France » Fri Oct 07, 2011 10:29 am

Hi Bob,

If you do go ahead with fiitting a set of emulators, I'd be very appreciative if you can take some photos and do a write-up on how it goes!

It's something I've thought of doing, but haven't yet got round to (despite Doug Holme & Chris Pitt's excellent write-up that Steve pointed you to).

Cheers

Craig

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Post by radecal » Sun Oct 09, 2011 4:37 am

No wukkas Craig.
Just hope I can figure out the machining bits from their diagrams. If it works like Steve says. I'll have a half a dozen bikes to do so should be able to get it right (hopefully) by then!

Steve, not sure you answered my question after my misunderstanding of what I got from you (shows how much time I have had to look at things!).
Are you saying that the emulators will work with the twin spring kit I got from you or do I have to go with single springs?
RAD

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Post by BevHevSteve » Sun Oct 09, 2011 8:22 am

Bob, the works dual rate fork spring kit is in my opinion the best spring kit available for 38mm Marzocchi and Ceriani forks, and is especially helpful in our bevel drives. The emulators take the damping part of the forks to another level. Yes, emulators are a good addition to our fork spring kit.
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