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 Post subject: Sloppy Front suspension
PostPosted: Mon May 14, 2012 7:10 am 
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Joined: Wed Jan 05, 2011 7:48 am
Posts: 15
Location: Copenhagen, Denmark
model: 900 SS
year: 1990
My fork seems very tired. I changed the oil in it over the winter. But it does not seem to have helped. When I drive over bumps, the fork goes into the bottom at a not very pleasant way. And I think that perhaps there is not enough oil in it. I poured 500ml in each leg, as prescribed in a workshop manual.

But are not really happy with the outcome :banghead:
My Ducati running with a Marzocchi fork.

Can anyone help me?

-Simon

Pictures of my bike:

Image


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 Post subject: Re: Sloppy Front suspension
PostPosted: Mon May 14, 2012 8:21 pm 
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paso grand pooh-bah
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Joined: Sat Sep 03, 2005 12:00 am
Posts: 1318
Location: SF Bay Area
model: 750 Sport
year: 1990
Nice bike. One of the few/ rare 900 SS I see.
The forks, as best I can deduce, are basically the same as the one on the 750 Sport, the M1BB. 40mm fork tubes. While not a horrible fork, there also wasn't much praise heaped on it. Fairly basic, and no adjustment to speak of. The good thing, (or bad thing) is those forks are pretty special that they fit your bike and are set up for 17" front wheel and 4 piston calipers. Good reasons to make them work better.

First of is to take them apart to see what you have inside of them. If the damper rods are disconnected or broken, then its pretty plain what you need to do. Fork springs can also break, giving you very little spring force.

One alternative is to go to some aftermarket stuff. Top of my list is the Ricor folks that do make a product for a 40mm fork. Could be your fastest/cheapest way forward. http://store.ricorshocks.com/


Of course there is the matter of just setting the forks up in the first place.
1. proper fork spring rate
2. sag / preload (on your bike, thats adding preload shims)
3. Damping adjustment (which on that fork, is changing the weight of the oil)

Search the web for some good technical papers on what you should do.

Remember:
- Only one change at time - so you know the cause and effect.
- Take lots of notes. What was the set up, and how does it feel and ride?
- Take your time
- Do the back as well as the front. ( as stiff shock in back will make the front feel soft, and visa versa)
- Find someone who knows what they are doing to help


If all else fails. Take it to a good suspension shop. I live in the SF Bay area, so I have about 3-4 good choices, but in more rural areas, you may find a good shop hard to find.

Can you tell us a bit more about your bike.
- What weight fork oil did you use?
- What is your sag set at currently?
- How much do you weigh?
- Do you know what the fork spring rate is?
- Have you taken the forks apart already?

Cheers, Phil

_________________
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


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 Post subject: Re: Sloppy Front suspension
PostPosted: Tue May 15, 2012 6:53 am 
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Joined: Wed Jan 05, 2011 7:48 am
Posts: 15
Location: Copenhagen, Denmark
model: 900 SS
year: 1990
ducinthebay wrote:


Can you tell us a bit more about your bike.
- What weight fork oil did you use?
- What is your sag set at currently?
- How much do you weigh?
- Do you know what the fork spring rate is?
- Have you taken the forks apart already?

Cheers, Phil


I've used Shell Advance Fork 15(15w) oil in the fork. I haven't had the fork disasembled. My weight is 96Kg :D

A little history of my duc :)

In 1995, my dad and one of his good friend went to italy and bought the bike. My dads friend, had wanted that kind of duc since it came on the market in 1989, but the one he found in Denmark had a too high price tag. When it finally came to denmark, he parked in his garage and forgot all about it, due to the birth of his two kids. In 1998 he died of a heart attack, in 2009 I was helping cleaning the garage and we uncovered the long forgotten Ducati :lol: The wife to my fathers friend, told me that if i wanted to have it, it was my bike. I took the bike home, to my fathers workshop, and first i thought of selling it, but keeped it. In Denmark you have to pay registrations tax, if you want to have license plates on a imported bike - the tax was 30.000 Danish Kroner = 5500 $ :banghead:

Something funny about my bike, it has Fabio Taglioni autograf on the tank :)

Some more pictures:

Image
Image


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 Post subject: Re: Sloppy Front suspension
PostPosted: Tue May 15, 2012 9:29 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5272
Location: southern Germany
model: 750 Paso
year: 1987
Quote:
Remember:
- Only one change at time - so you know the cause and effect.
- Take lots of notes. What was the set up, and how does it feel and ride?
- Take your time
- Do the back as well as the front. ( as stiff shock in back will make the front feel soft, and visa versa)
- Find someone who knows what they are doing to help

:thumbup:

A sad story your bike has, but it`s nice to see it`s in a good home now.
I find it strange that a fork is too soft. Most complaints on old Ducatis is it`s too hard and not very sensitive.
In case you disassemble the fork check if there are the metal spacers on top of the spring that give it a preload.
If changing the fork oil it`s always better to measure the airgap between oil and the top edge than filling it up with a measuring cup.

G.


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 Post subject: Re: Sloppy Front suspension
PostPosted: Tue May 15, 2012 10:34 am 
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Joined: Wed Jan 05, 2011 7:48 am
Posts: 15
Location: Copenhagen, Denmark
model: 900 SS
year: 1990
It has had a sad childhod :-P But now things are different, and actually i drive "her" 65km each day to work :)

Sometime ago i stubbled over this photo on another duc forum:

Image

It looks like, it have been equieped with the front and rear suspension from a SuperSport 91-98 :)
Is this something that could be done, without needing a whole lot of special solutions ?

The reason why i ask, is that i know where there is SuperSport from 1995 - where the engine is a dead, i'v been offered the bike to a small amount of $ :mrgreen:


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 Post subject: Re: Sloppy Front suspension
PostPosted: Tue May 15, 2012 2:38 pm 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5272
Location: southern Germany
model: 750 Paso
year: 1987
Swingarm and fork of that bike are from a 900SSie 2002-2005. The older SSs didn`t have a swingarm with that shape and chain adjuster and they also had 40mm calipers instead of those with 65mm mounting.

G.


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 Post subject: Re: Sloppy Front suspension
PostPosted: Tue May 15, 2012 3:52 pm 
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paso grand pooh-bah
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Joined: Sat Sep 03, 2005 12:00 am
Posts: 1318
Location: SF Bay Area
model: 750 Sport
year: 1990
SimonT-Dk wrote:
It looks like, it have been equieped with the front and rear suspension from a SuperSport 91-98 :)
Is this something that could be done, without needing a whole lot of special solutions ?

The reason why i ask, is that i know where there is SuperSport from 1995 - where the engine is a dead, i'v been offered the bike to a small amount of $ :mrgreen:


Yes, putting a front end from an SS or Monster will work fine. The easiest way is to get the entire front end. While you may be able to use your front wheel, the axle size may be different. Search the posts on 17" wheels and you will find some Sports with SS front ends on them, including a blog from Loud Bikes. Modern suspension is a lovely upgrade.

There are plenty on this list that would be interested in your front end, as it has the 17" wheel.

The rear shock may need to be upgraded also, which you can get from the SS. Fits the Sport just fine.

Cheers,
Phil

_________________
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


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