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Old 14-Sep-2003, 23:49
thrustercat
 
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More Clutch Problems on my 748...Help!

Hiya Chaps, not a good weekend…I fear that I have, yet again, more clutch problems. I have not owned my 1999 748bp for long and I seem to be having lots of problems in a short space of time. I’m kind of new to DSC and hope that someone can point me in the right direction.

I have noticed that the clutch lever action on my 748 seems to have a little extra play than it should. On looking at some of the comments posted by dukess999 clutch problem ‘Stephen’ mentioned that the slave cylinder could have seized… perhaps this could be my problem?! I know for a fact that the clutch is not slipping.

Even when I have the bike in 1st gear and the clutch lever pulled in (when stood still), I have noticed that I cannot move the bike back and forth in a ‘neutral’ gear state.

I had a 12k service at the end of July by TecMoto, primarily because I had the classic slipping clutch problem. The plates were replaced which solved the problem.

I would be grateful if someone can point me in the right direction, or perhaps help me to diagnose the problem further.

Much appreciated for any help you can provide.



[Edited on 28-9-2003 by thrustercat]

[Edited on 6-10-2003 by thrustercat]
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Old 15-Sep-2003, 00:20
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Jon Jon is offline
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thrustercat. Remove the clutch cover and see how much the pressure plate moves when pulling in the clutch. See if by pumping the lever the plate moves any further. The reason I say this is that once when cleaning out my clutch I managed to let the fluid level drop. Don't ask me how because I've no idea, When came to use the clutch I could feel straight away that all was not well. The lever came all the way back to the bar without any real resistance. Once I bled the system it was fine.
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Old 15-Sep-2003, 17:11
thrustercat
 
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thanks for the advice Jon, I shall bleed the clutch sometime this week, hopefully this will lead to an easy solution.
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Old 18-Sep-2003, 10:37
thrustercat
 
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Right...bled clutch, which took all of 5 minutes. Has the assistance of another pair of hands and now all is working okay - fantastic stuff.
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Old 28-Sep-2003, 13:50
thrustercat
 
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I have bled the clutch a number of times now, and each time I take it for its initial 5mile run the same symptoms occur - excess play in the clutch leaver, less resistance and generally feeling very spongy, until you can bring it to the handlebar with no resistance at all!

I have also noticed that the clutch fluid has turned black \ grey when bleeding?! I don't understand what is causing this - it’s as though the clutch fluid is burning up.

I used dot 5.1 synthetic clutch fluid (not sure if other have had issued using dot 5.1). I have now flushed it and am using dot 4. I have read articles where I have to keep on bleeding, over and over again until it is okay…sounds like an air block somewhere.

I am now getting fed up taking my 8mm spanner, bleeding pot and clutch fluid wherever I go!!

Advice appreciated.
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Old 28-Sep-2003, 14:49
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nelly nelly is offline
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sounds like the seal on the slave cylinder piston has gone.
It's pretty common. Check around the back of the slave cylinder and front sprocket for fluid.
Replacement isn't too difficult. You can use either a new Ducati one or an Evoluzione one. The Evo ones has better seals and cost about £3 more at £18.
I stock the Evo ones.
It's far less common but similar symptons can be had from thes eals in the master cylinder failing to.
The fluid will turn black........."they all do that".
I use 5.1 fluid with no problems, so you're OK there.
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Old 28-Sep-2003, 15:06
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As Nelly says, the problem is probably a dodgy seal which will be causing air to leak into the system (giving you the recurring bleeding problem) and also causing your fluid to turn black.

I've seen Ashley's bike and I don't know if his clutch slave cylinder is a standard one - it has a star shaped pattern on it, with lots of points (almost like a bi-hex socket!) rather than having the Ducati circle/D shape on it... if that helps!
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Old 28-Sep-2003, 16:05
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The cylinder with the star shaped cutout is standard Ducati. It's the later design to alleviate all of the early problems they had, like leaking piston seals
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Old 28-Sep-2003, 16:26
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DSC Member Shazaam! Shazaam! is offline
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If you have not already done so, you can make bleeding much easier if you replace the banjo bolt at the master cylinder line connection with a bleeder-type banjo bolt. The master cylinder area is where most of the air rises to, gets trapped, and cannot be bled out (easily) using the bleed nipple down by the slave unit.



If an inspection doesn't reveal a fluid leak, there's another common problem that mimics having air in the clutch hydraulic system. The clutch pushrod is spinning because the bearing in the pressure plate is not moving freely. This causes the pushrod to move the clutch slave piston back into its bore slightly.

So, when you ride for awhile without using the clutch, when you try to use it, you have to pump the lever a little to first move the cylinder back into position, after which it works normally. Low-pull aftermarket slave units accentuate this problem because a full lever stroke moves the slave cylinder piston a shorter distance than it does the stock unit.

You usually just need to lubricate or replace the pushrod bearing on pressure plate to cure the problem.
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Old 28-Sep-2003, 23:48
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Nice post Shazaam!

I also know that Ashley's just had a new clutch in his bike (like sub 1,000 miles ago) so I doubt it would be the bearing that is failing...
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