clutch symptoms

[Marc R]

My clutch lever has to be pulled halfway before it starts to disengage, which is quite a bit of slack. The fluid level is fine. I'm tempted to think some air got in there and it just needs to be bled. But I imagine air would slowly get into the line, it was fine a couple of weeks ago. What's your guess?

Its a Ducati 749 (dry clutch). Thanks in advance.

[butcher bergs]

Air doesn't just "get into the line". It has to be introduced to the system somehow such as defective clutch cylinder seals, a flex line puncture or failure to correctly bleed the system.

How old is the fluid?

[Marc R]

11 months/3200 miles

[butcher bergs]

All seals and connections don't appear to have any leaking?

Yes I read the fluid level is fine but even a small amount of seeping can occur which can introduce air to the system.

What year is the bike? What I'm getting at is, is that 3200 lifetime miles of usage on that clutch cylinder?

[Marc R]

Thanks, this is helpful. I'll need to take a look for any leaks.

It's a 2006 with 9400 miles, original clutch cylinder. Seacoast took care of the service last year (happy with their work); the fluids would have been flushed at 6200 miles.

[Paul_E_D]

It's almost always the slave cylinder failing on a duc... start there.

[butcher bergs]

Yep, check for any seeping. Pull back any and all rubber boots to see.

I don't know if this bike has a remote resevoir. If not also might wanna check the clutch cylinder diaphragm to make sure it is properly sealing between the cylinder housing and the cover....another place for air to get in.

[Marc R]

Thanks guys! Looks like I've got some homework to do.

[NPDCPA]

It could be a lot of things. By the 749's time Ducati had cured the slave cylinder problems of old. My guess is either air in the system or problems with the plates. Is the bike left in the elements? Any grabbiness at take off? Any paint lifting around the slave area?

Start with a good bleed and make sure there is no air at the master end. Leave the bike overnight with a strap on the clutch lever and snap thw lever and twang the clutch line a few times to loosen any stuck bubbles. Often the masters will hold air long after the slave end bleeds clean. If fluid is leaking it will be obvious. Start with a bleed with fresh fluid (Prestone synthetic from Walmart is fine) and report back.

[Degsy]

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Here is the fix.

Open top of clutch master reservoir, use 7mm socket to crack the nut in there. Watch air bubble appear from around the nut. Tighten nut, fill to full line with fluid if needed, refit cover.

Known issue on 749/999.

You are having trouble finding neutral, right?

[Marc R]

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Here is the fix.

Open top of clutch master reservoir, use 7mm socket to crack the nut in there. Watch air bubble appear from around the nut. Tighten nut, fill to full line with fluid if needed, refit cover.

Known issue on 749/999.

You are having trouble finding neutral, right?

This fixed it.
Too bad I had to bring into the shop to learn this. I just picked it up from Seacoast yesterday.

It could be a lot of things. By the 749's time Ducati had cured the slave cylinder problems of old. My guess is either air in the system or problems with the plates. Is the bike left in the elements? Any grabbiness at take off? Any paint lifting around the slave area?

Start with a good bleed and make sure there is no air at the master end. Leave the bike overnight with a strap on the clutch lever and snap thw lever and twang the clutch line a few times to loosen any stuck bubbles. Often the masters will hold air long after the slave end bleeds clean. If fluid is leaking it will be obvious. Start with a bleed with fresh fluid (Prestone synthetic from Walmart is fine) and report back.

Good hunch on the air in the system. I tried Berg's helpful suggestions a week or so ago, and couldn't find a problem (no leaks, slave is clean, bike is kept in the garage). The problem seem to occur suddenly, I was convinced I had a mechanical isssue. Took the bike into Seacoast, they confirmed the clutch plates are fine it only needed the air purged out.

Thanks for the advice!

[Degsy]

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Dammit. I didn't realize the thread was a month old. The 749/999 has a master cylinder blessed, but it is under the reservoir cover. At least you know for next time:-)

[butcher bergs]

My apologies for leading you in the wrong direction. While I'm still not sure how air gets into sealed system if there aren't leaks or some other form of introduction hey, at least it's fixed now.

[Degsy]

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The only way air can get in there other than a leak is if the reservoir is low and you suck air in like that or if the brake fluid boils and water vapor forms.

[Marc R]

No apologies needed Bergs. I learned quite a few things from everyone on this thread. Thanks again!

My apologies for leading you in the wrong direction. While I'm still not sure how air gets into sealed system if there aren't leaks or some other form of introduction hey, at least it's fixed now.

[butcher bergs]

...or if the brake fluid boils and water vapor forms.

The way I have always understood it was, during brake or clutch fade (at the temps where such scenarios are created) air bubbles form when the moisture turns to gas and momentarily separates from the fluid but air bubbles do not remain within the system once the gas returns to liquid form and is actually re-absorbed by the brake fluid.

The moisture will not evaporate because it has nowhere to go since it is contained within a sealed system. It will expand when the temps are at that point to allow such a thing but the moisture stays within the system and does not introduce air (or create air pockets).

Again, this is how I've come to understand moisture in a sealed system that uses brake fluid.