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The stock fork was a 2002 showa short needle. Even with 43cst at 6click was a little underdamped.
Maybe it was rhe defective one?

A little ot to recap:

2 years ago 32kkm i had to replace worn outer tubes and scratched inners (with nos parts). New ducati bushings, skf seal, all parts cleaned and inspected (including shims, piston bands, cartridge bushings)
Had the forks checked by 2 good suspension shop for sticktion and freeplay. The said its was good.

Last winter 38kkm tired by the crappy stock dual rate spring, by the quick loss of damping and some sticktion i put in an andreani misano cartridge. And found the outer tube wear, worst than the first 30kkm set.?

Angry for that i put the 3rd set of nos outers, inspected and cleaned all.
Replaced upper bushings with nos parts (they have sligtly more clearance than the new ducati part number : 0.08 to 0.10mm installed if i remember).
I've also reshaped the upper bushing land recess to a barrel shape so it can negotiate a out of axis due to the tube flex. Just in case...
Cleaning
981990

981993

Bush landing recess
981991

Backyard lower and upper bush cleance check
981992

981994

The wear mark is located where the bushing work normal condition, not where the lower triple tree is.
But since the second set i've reduced the torque from 20 to 15Nm
 

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In the US there is a 2-3 year range if monsters 2000-2002 where there is a defect in the damper unit and it passes by oil on the low speed rebound. If sprung these units often do need the rebound adjuster wound in more than normal but that is because the oil has another less restrictive path somewhere.

This defect is not in any of the similar damper units I have ever seen from 1991-2006 superbike,monster,supersport,st series with the same design.

When running thinner oils say for better compression damping know that the thinner it is the faster the damping changes with wear. Nothing wrong with that but it will lead to more often changing of oil.

With the lower in the upper can you feel the play?
Where in the travel is the spot lining up with the upper bushing?
i've found the m1000 adj forks to be similar when using the maxima 5. certainly unique among the adj showas, the ss and st ones are much different. is the valving obviously different when you pull them apart? i don't get into them that far.
 

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The stock compression valving has been the same across these forks/models (crap). I have hunted for the source of the leak and assume it is a small spec difference somewhere on the damper rod or rod to cartridge seal. I keep putting off spending the time to find it as I do not see many of these forks anymore.

Have you tried simply running the forks with a different oil?
If I follow you you had 32kkm on the first stock set
then 6000km and now again?
I know you are seeing metal bits and some where but are you only seeing break in of the new parts? I can tell you it is not common to wear out uppers, I probably have changed less than 5 in 20 years doing this full time.
 

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M900sie, M1000ie,s2r1k std rebound setting is 6click (1turn), on the other is 12click.
Maybe the needle is different?
Less diameter or half cone angle?
Stock m900 is quite big: 3mm
Eventually i can measure the cone angle..

On the second set i used silkolene rsf pro 7.5w
Now i use ohlins 1309 19cst as suggested by andreani.
There are a bit less sticktion but i don't know if it is the oil, the new bushing lands or the small spring that don't rub the inside of inner tube.
Sbk forks also use thicker bushings and probably thicker inner tube (less flex).
M900 inner tubes are only 1.65mm thick

Now (third set) the bike has 44kkm??.
1 or 2kkm ago i opened it to revalve.
The finishing was ok.
There are some black powder in the oil. It was not shiny, i hope it was coming from the bĺack derlin spring guide. Maybe the metal bits appear only when the anodizing is completely worn.
My plan was to slight revalve the comp leg before the riding season but now no shops no shims no anodizing check...

The bushing clearance is ok/common?
 

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Bushing wear normally is not a concern unless you see high miles (you qualify on first set), often not enough to require changing. At the point you can feel rocking play between upper and lower -that is considerably more than new. Any time a fork is apart is a good time to inspect them and change if in doubt.

I have used aftermarket bushings- I do not recommend them. In a pinch I will continue to use them. OEM bushiings are simply better made from what I have seen.

Are you sure the upper tube is wearing vs just polishing? Can you get in there with a bore gauge to see how much wear you may be looking at. You will likely always have a point where forces meet and if it lives in that sport long enough I would expect signs of that. What I cannot tell is - Is the wear you are seeing detrimental to the function of the fork?

Obviously the burning up of the oil is telling something (heat) is a issue due to something damping related. This can be improved with a better oil maybe but it may just mask a underlying problem that is the cause (too restrictive oil passage).

The wear in the upper tube is more bushing or spring related. I have seen abnormal wear from a spring that was not guided side loading and rubbing the tube. Watch for preload to spring or washers as well, a spriing guide might keep a spring in check but the washer/spacer above it might not run centered.
 

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Today i was able to find the first set outer:
982046

982047

Better than the second.
On this set the oem bushing were black and a bit worn.

On the second i used new ducati
34911201A, redish teflon with a code stamped inside. Thin teflon an thick metal. Almost perfect after 6kkm

On the third i put a 2004 new old stock ducati, redish teflon, no markings inside, thin metal compared to the new version.

I have to find it and take a picture.

The wear is true, most in the second set, is just not easy to capture it in a picture.
The bore gauge is in my wishlist, i have a large wishlist:ROFLMAO::ROFLMAO:
I can try to check measuring the clearance.
I am not worried about clearance i am worried about metal flacking going around inside the fork.

On the first set it get trapped between lower bushings and inner tube and trashed it with a lot of vertical scratches and seals start to leak..
Tryed to polish the tube but the scratches were too deep.

On the worn second set i cleaned all and rotate the tube. (And put in andreani cartridge)
After 2 or 3 weeks the oil was black and shiny.
When stripped down there was shiny metal trapped in upper, lower and cartridge bushings and also in the piston band.

On the third set the oil was quite clean, with the same cartridge and settings, so oil burning up wasn't the cause

On the first 2 set the oem springs were on the lower part of the fork, no moving parts or washers around the uppers.

Thanks
 

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As promised:
Ducati oem, left to right:
2002, 0.99mm thick
2004, 0.96mm thick
2018, 1.00mm thick
982066

982067

982068


2002 was in the first set
2004 was in an new old stock like the one in the third set
2018 was in the second set

It make some sense?
 

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Discussion Starter #28
Hey everyone. OP here. :)

Finally got around to starting the rebuild of the first fork yesterday.

As this is my first time, I wanted to ask: is the "bronze" collar that wraps around the bottom end of the outer slider supposed to unseat?

While I was driving the seal in (Using the MotionPro tool) that collar kept popping off. I was finally able to get everything to seat by having a friend hold and steady the inner slider, while I simultaneously gripped the bottom of that collar and drove the seal down and in.

The relative ease with which it popped off (and back on) was concerning to me.
982192
 

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Discussion Starter #30
Thank you, @belter.

I was thinking, "Oh, cripes... now what have I done."

The fact that it all went together relatively easily after holding the bottom of that collar with a deathtrap has given me visions of my forks coming apart on the freeway...

[Does every newbie fork rebuilder visualize that???]
 
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