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Discussion Starter #1
My 916 with 16k on it has begun to get hard to shift down into 1st and 2nd when hot. Have new slave and have cleaned lubed the transfer pin going to the clutch. Any comments?
 

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Discussion Starter #3
OK didn't think of that - I have always run Mob 1 15-50
 

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If it only happens when hot...or gets progressively worse the hotter it gets ...and then resolves after cooling...need to bleed the clutch hydraulics more thoroughly; contaminated fluid will also cause this as the absorbed water gets heated by the engine and vaporizes.
 

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If it only happens when hot...or gets progressively worse the hotter it gets ...and then resolves after cooling...need to bleed the clutch hydraulics more thoroughly; contaminated fluid will also cause this as the absorbed water gets heated by the engine and vaporizes.
That's exactly what it is doing - better explanation than mine, thank you. I think my slave's seals are shot and are letting air or whatever into the system.
 

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I had the problem just from using non-racing grade hydraulic fluid...or not changing the fluid on a regular basis. I would start the bike up in the pits without issue...then head out onto the track, and during the session the ability to shift cleanly would deteriorate. I would have to come in before the session was over and after cooling in the pits the problem would resolve.
 

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Discussion Starter #7
Rob - I just checked my log and I won't embarass myself by telling you how long that fluid has been in there. I thought I bled it when I had the problem but the log says otherwise!
Rob
 

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If it only happens when hot...or gets progressively worse the hotter it gets ...and then resolves after cooling...need to bleed the clutch hydraulics more thoroughly; contaminated fluid will also cause this as the absorbed water gets heated by the engine and vaporizes.
You may also want to check the bearing in the pressure plate to make sure it is spinning freely... If it gets a little sticky it can spin the entire push rod, which can generate a pretty good deal of heat in the clutch slave and the fluid as well (not to mention destroying the o-rings on the push rod).... once it's hot any h20 that has been absorbed into the fluid will essentially "boil" and air bubbles will be inevitable...
 

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Discussion Starter #9
I presume I have to dismantle the clutch to check the bearing?
 

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I presume I have to dismantle the clutch to check the bearing?
No... you can see the bearing in the pressure plate without dismantling it. Just remove the clutch cover and watch the pressure plate while the engine is running. You will be able to see the bushing on the end of the pushrod and if it's spinning that would indicate the pressure plate bearing has some stiction.
 

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No... you can see the bearing in the pressure plate without dismantling it. Just remove the clutch cover and watch the pressure plate while the engine is running. You will be able to see the bushing on the end of the pushrod and if it's spinning that would indicate the pressure plate bearing has some stiction.

Coming to the conversation late,

I have been chasing the same demon on my 998. I have bleed and changed fluid several times as well as went to the Oberon Slave. I can se the pushrod spin a little bit while in neutral on the stand with the clutch not pulled in. Once pulled in, the spinning stops. Also my fluid goes black after the first ride on new juice. Is my bearing the culprit?

Thanks!
t_bare
 

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Coming to the conversation late,

I have been chasing the same demon on my 998. I have bleed and changed fluid several times as well as went to the Oberon Slave. I can se the pushrod spin a little bit while in neutral on the stand with the clutch not pulled in. Once pulled in, the spinning stops. Also my fluid goes black after the first ride on new juice. Is my bearing the culprit?

Thanks!
t_bare
It could be, I have had to replace the slave cylinder twice already, first one was with a ducati performance unit that went bad after about 2000 miles, then I went with the oberon. I also replaced the throwout bearing on the clutch pressure plate at the same time. This seems to have resolved the issue, but I believe that it may be slowly coming back.

Mine also spins slowly with the clutch engaged, and stops when the clutch is disengaged (clutch lever pulled in). the throwout bearing itself even when new does not seem to rotate all that freely, and feels a little tight, so the pushrod seems to spin a little bit...

why did they make a pushrod that can spin if there's a throwout bearing? I really don't want to have to replace the slave cylinder again...

If they put a little keyway or something on the pushrod to prevent it from spinning....

edit: I recall seeing a japanese slave cylinder unit on the forum that has a bearing in the slave cylinder so that the seals don't get fried when the clutch pushrod spins.... but it's pricey...
 
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