At 8000 mi. you are well within the neighborhood of wearing out a clutch. If you were to take the clutch pack apart and measure each disc with a vernier caliper and if you knew what the original thickness of each plate was, you would probably find that each plate was something like .020"-025" thinner than they were new. Add up all those plates times .020" and you have reduced the "stack height" to a point where the spring pressure is insufficient to fully lock up the stack, resulting in slippage.

I have taken a clutch pack apart and done this and compared with new plates and thats what I found - new plates maybe .135" and the worn plates something like .110". That's one reason I keep old plates so when I start to get slippage I can replace worn plates with old, but almost full thickness plates and get no slippage - it's a short term fix.

Buy a new clutch pack. Takes about 30 min. to change out. The Barnett red plates are cheap (Ca-CycleWorks), but don't last as long as the OEM plates. And FWIW, the 14 tooth does help a little on getting off with less intentional slippage on your part, if you know what I'm getting at.

I'm very good to my clutches, always in neutral at stop lights and easy on take off etc., and that's about all I get out of em.

Of course YRMV.

LA

Idk about that, LA. I mean, I've been flogging the S4R for quite some time-it's got 27k on it and it's still on the original clutch. What are you doing to yours?

I've been having the same problem (slippage)  with my 999.. its like when i shift into first  with the clutch held in, the rear wheel starts to move. Also getting into neutral has been a pregnant dog lately... time for a plate kit??

To: Mr Bread

You are having the opposite problem of slipping, worn plates. You aren't getting full release which can be a leaking slave, air in the clutch hydraulics, the clutch stack height is slightly too high or the plates are sticking.

Mac,

So i do not have worn plates which are slipping.. I have a leaking slave, air in the hoses, or stack hight is too high or stickey plates.

I've had the bike for 3 months now, put around 5k on it and have had no problems until recently.

What would make the plates stick? and is there any trick to bleeding a clutch?


Thanks

Your fluid is probably getting old. I bleed them every 3,000 miles. It really depends on how much you abuse your clutch. my fluid goes pitch black in a matter of days, where someone elses goes black over the course of a 2 months. I ride the clutch alot because of traffic and over all urban abuse.

It takes maybe 30 min to dissemble the clutch and inspect it. If it is slipping as in engine build revs that don't get translated into MPH, it's probably a combination of lack of friction material left on the plates and stack height. I can't see it being hydraulics. Seems like hydraulics would affect disengagement rather preventing lockup. ?

??LA

engine keeps disconnecting to the wheel = slipping plate (plate cant transfer 100% power)
Engine wont disconnect from the wheel = air in clutch, STICKY plates that prevent full disconnect, (plates will not disconnect 100% power from engine)

I have the later problem. caused by learning how to do burnouts.  still good though.

I guess the clutch operation concept is kind of hard for some folks to grasp and harder for others to grasp completely. No sweat. I get to explain it all the time in my line of work.

Worn plates, which can cause slipping are the main cause of slipping. Slipping being where the engine revs up but the bike is either not moving enough with the engine or isn't moving at all with the engine.

Worn plates = a clutch that is near to disengagement. Symptoms show up as slipping when shifting gears or when accelerating, i.e. twist the throttle and the engine revs up but the bike barely accelerates. Since a slipping clutch is almost disengaged worn plates will never cause difficulty in finding neutral or shifting into gear. Worn plates will never prevent an engine from full disconnect but, rather, will never allow full connect. Slipping can also be caused by worn, weak springs in the pressure plate. Once in a great while, very rarely, is there a problem in the hydraulics where something is not allowing the complete release (engagement) of the clutch.

On the other side of the coin anything that would cause the friction plates to stick to the metal plates would cause problems selecting gears, finding neutral and possibly even stalling with the clutch lever pulled all the way in (clutch disengaged) but the bike still in gear, i.e. shifting into 1st at a stop and having the engine stall immediately. Clutches can stick due to rust (for dry clutches), dirt, expansion of the friction plate material or warping of either the friction plates or the metal plates. It's also possible for the clutch to not fully disengage because the entire clutch housing is coming loose from the input shaft. In that case the clutch housing is moving away from the clutch release rod so the rod can't push the pressure plate far enough out to allow the plates to separate.

The symptoms and causes of the two conditions are separate. You could, I suppose have worn plates and a leaking slave at the same time. That would be kind of messed up but still possible so that combination would make diagnosis a little harder. Woe be it to the tech who would have to explain that to the customer.

Mac,

Thanks for laying it out like that. Seems like i have some sticky friction plates, or perhaps the the housing is moving from the release rod.

When i pull the clutch in, its like nothing is happening, the revs go down a LITTLE, like 500rpm and you can hear the clutch doing is 'dry clutch sound' for a fraction of a second, then its like i dont even have the clutch pulled in anymore. I have adjusted the lever to allow the maximum travel from lever to bar to see if it would help and it seemed to for a little while then it didnt even matter. On my way home last night I had to shift w/o the clutch, except for 1st from a stop which was like dumping the clutch, (stalled a few times).

So for sticky plates.. do i just take them out and clean them off? Or is there a super secret ducati trick to it?


Thanks for the help guys, and sorry for totally jacking this thread.

Back on topic, did LA ever get his clutch issue sorted?

Quote from: Mr Bread on August 18, 2008, 06:16:34 AM
Mac,

Thanks for laying it out like that. Seems like i have some sticky friction plates, or perhaps the the housing is moving from the release rod.

When i pull the clutch in, its like nothing is happening, the revs go down a LITTLE, like 500rpm and you can hear the clutch doing is 'dry clutch sound' for a fraction of a second, then its like i dont even have the clutch pulled in anymore. I have adjusted the lever to allow the maximum travel from lever to bar to see if it would help and it seemed to for a little while then it didnt even matter. On my way home last night I had to shift w/o the clutch, except for 1st from a stop which was like dumping the clutch, (stalled a few times).

So for sticky plates.. do i just take them out and clean them off? Or is there a super secret ducati trick to it?


Thanks for the help guys, and sorry for totally jacking this thread.

In your case I would verify that the hydraulics are in good working order first of all. Make sure the line is bled properly and then test it. If it shifts OK at first and then gets worse it's likely that you have a bad slave. You could also remove the slave and inspect it for leaks. BTW, you should remove the slave anyway before taking apart the pressure plate & discs.

Update on the S4: I took it for a test ride last night, and it seemed fine around town, no slipping.  Took it across the bay bridge to work in SF this morning, and it's still fine (it's a nice cool day today).  Seems that the heat last week contributed to the situation.

Not gonna test my luck though, gonna take it into the shop later on this week.  Eventually I'd like to learn how to work on the clutch myself but unfortunately I'm not quite there yet... for now I'll let the professionals take care of it.

Quote from: mxwinky on August 16, 2008, 03:56:40 PM
Yeah, the clunk going into 1st gear is totally normal, but having a hard time getting into 1st is not normal. 

Interesting...   thanks for the info.  Just to clarify, I should have said that I have a hard time getting into first without a little clunking.  I always try to get the exact ratio of throttle to clutch that results in no clunk, and sometimes I think I'm gonna stall so then I give it a little too much throttle before the clutch is fully engaged and then comes the clunk.  Does that sound normal? 

Quote from: Bigbore4 on August 18, 2008, 06:39:11 AM
Back on topic, did LA ever get his clutch issue sorted?

What issue? You mean that I wear clutches so fast. I dunno. They're easy to install and I have em either all the way in or all the way out and always go to neutral at stops. I ride the bike pretty hard, but so does everybody. Don't know.

It's really only the Barnett's that I wear out, it that's what you mean.

LA