Why does clutch fluid turn black so soon. - Page 3 - Ducati.ms - The Ultimate Ducati Forum
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post #21 of 38 (permalink) Old Sep 1st, 2017, 8:12 am
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Got the stock reservoir and mine is turning a little dark, probably time for a flush
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post #22 of 38 (permalink) Old Sep 9th, 2017, 9:20 am
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Is there any benefit other then asthetics for replacing the stock fluid reservoirs ?
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post #23 of 38 (permalink) Old Sep 9th, 2017, 11:58 am
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Is there any benefit other then asthetics for replacing the stock fluid reservoirs ?
no
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post #24 of 38 (permalink) Old May 31st, 2018, 6:05 am
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Originally Posted by Bartubis99 View Post
Tricklidz had the right answer... Fluid going black is the fried slave cylinder seal, other symptom is that your clutch bite point moves closer to the bar as you ride... After about 10 miles of town riding (I.e lots of clutch usage) it's virtually at the bar, yet if you leave the bike overnight, the biting point returns to normal when your first start the bike... The problem is the bearing on the clutch pressure plate. Over time the dry clutch wears and dust is created which gets into the bearing causing it to seize... Once that happens the the push rod spins with the clutch, this is turns spins the slave cylinder... Which gives rise to the two effect described earlier; namely black residue in the fluid (from the fried seal) and loss of clutch power when the spinning slave cylinder causes the fluid to boil. When it cools and condenses, clutch power is restored. Solution is to replace the bearing (a simple fix and costs about £10)
This is exact symptoms on my 1098. Rebuild master, oberon slave, no oil leak. After several miles in the city clutch gradually collapses and wont work anymore. Interesting is that if i pump pump pump clutch lever, function is restored and work for several minutes. Fluid also going dark in one day.

Now question is how I know in which condition is slave cylinder if rod spinning inside?
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post #25 of 38 (permalink) Old May 31st, 2018, 7:14 am
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It may be that if stack height isnít correct, if itís low, that there may not be enough clearance for the rod and itís squeezed between the slave and pressure plate , causing it to spin. This also may reduce throw out bearing life.

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post #26 of 38 (permalink) Old May 31st, 2018, 9:01 am
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Originally Posted by slhaggard View Post
The fluid is in a closed loop. It should not produce any crud. Maybe try completely flushing out the line with new fluid and wiping out the reservoir. Also, check to make sure your slave cylinder does not have any leaks or bad seals which is pretty common. Good luck!

Looking at drawings I see two o-rings on the slave output shaft... are those the seals that go or are the seals integral to the slave cylinder. I replaced the fluid in my clutch and have tried to get the air out, I never get more than a day before the lever feel goes back to very soft.

Started abruptly last friday during a long ride... been fighting with it since. Weird thing is it's not losing fluid or dripping outside the bike anywhere.

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post #27 of 38 (permalink) Old May 31st, 2018, 9:14 am
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I have noted that some of the newer slaves have a cut out across the piston, also have seen new replacement clutch push rods that have a pin crosswise on the slave end.
My summation is that the pin fits into the cut out on the piston, and that keeps the rod from spinning if the T/O bearing starts sticking.
Have not tries this combo to see what happens, when I replaced the rod on my S4, I drove the pin out since my slave would not accommodate it.
When I changed the slave on Woody's S4, the slave had the cut out, but he had old style push rod, so again, could not confirm my assumption.

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post #28 of 38 (permalink) Old May 31st, 2018, 11:12 am
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There's lot's of theories about why the clutch fluid turns black on a Ducati. Do a post search ó the question goes back 15 years, but never resolved satisfactorily. All the hearsay answers are partial and left untested. Kind of like an oil thread.
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post #29 of 38 (permalink) Old May 31st, 2018, 11:15 am
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Quote:
Originally Posted by DaveK View Post
I never get more than a day before the lever feel goes back to very soft.

Started abruptly last friday during a long ride... been fighting with it since. Weird thing is it's not losing fluid or dripping outside the bike anywhere.
Same problem? Same answer.
https://www.ducati.ms/forums/241-tech...ml#post6869298
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post #30 of 38 (permalink) Old May 31st, 2018, 12:11 pm
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Originally Posted by Strega View Post
Possible... was planning to vacuum bleed the whole damned thing but I'm getting air through the bleeder valve threads so I needed to pick up some teflon tape to tighten up the vacuum.

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