Quick clutch plate wear -- replace slave?

[Spidey]

I've been battling with my clutch for a while and was hoping for some feedback.  It's a (formerly) '03 M1000 with a dry clutch and an aftermarket slave (evoluzione, perhaps?).  The clutch basket looks ok.

I first noticed some clutch issues when it felt like it there was a problem disengaging the clutch.  Then it started when it was difficult to get into neutral.  Then, at lights, it wouldn't go into neutral and even with the clutch all the way in, it would engage slightly, forcing me to hold the break brake (damn, and I always get on people for making that mistake).  I bled the clutch a couple of time and it helped a wee bit each time.  But then it came back.  Symptoms grew increasingly worse until I couldn't get into neutral at all unless I was coasting to a stop, and the clutch wouldn't disengage completely and the bike would stall or try to force me into traffic.  It was getting dangerous.  I took out the clutch pack and one of the frictions plates had no friction material on it whatsoever.  It was metal on metal.  I replaced the clutch pack, bled the clutch and it was ok again.  Not perfect, but better.

Now it's come back again -- after less than 2k miles with mostly clutchless upshifting and less city riding than usual.  I hammer on my clutch plates and baskets, but this wear is WAY too fast.  It's gotten gradually worse, but now it's hard to get into neutral at a stop, and clutch is not fully disengaging.  I have yet to open up the clutch pack, but it's going to be the same -- at least one friction plate totally worn down to metal.  I'll replace the worn plates again and measure stack height (what is it supposed to be again?), but this is just going to reoccur.  

I'm betting it's a problem with the slave cylinder.  Is there something specific I should be looking for or should I just replace the thing and be done with it?  Any other ideas?

[Ddan]

The pressure plate bearing is OK?  I would think if the slave were gone you'd be losing fluid.  If the pushrod were drilling into the slave piston that would  do what you are seeing.

[Spidey]

Last I checked, I'm not losing clutch fluid.  I didn't check the pressure plate bearing.  I think I've replaced it before just as a preventative measure, but haven't seen one that's gone.  Anything specific I should be looking for or will it be obviously fuxored?

[Ddan]

I've never seen one gone either, but I'd guess it would be obvious.  It should be easy enough to see if the rod has been drilling on the slave piston though.

[Speeddog]

How many miles on the basket, and how many on the hub?
Both OEM parts?

The basket can get grooved bad enough that it'll make the clutch act oddly and/or make noise.

Hub can wear (under the washer) and when combined with a worn basket can use up a lot of lever travel, as the hub moves in/out.

[Duck-Stew]

It's a Yoyodyne on your bike Spidey and last I had the bike...  It was an OEM clutch basket.  I didn't replace the push-rod bearing and seal, but IIRC I did replace the pressure plate bearing.

The items Speeddog is talking about could cause you some issues.  Disassemble the clutch and take some photos...

[Howie]

I'm thinking Speeddog is right because of the plate wear.  You may have multiple problems though.

[Buckethead]

You may have multiple problems though.

This is certainly the case.

As for the bike, I dunno. 

[Howie]

This is certainly the case.

As for the bike, I dunno. 

OOPS!

[Spidey]

Stu, I *think* the basket was replaced with the rebuild (so probably 10k on it?).  The hub is OEM.  

I took out the plates last night to get a look at 'em and tried to loosen the hub with a breaker bar.  BANG!!!  I *may* have broken my pinky.    I gave up for the evening and started icing the swelling.  I woke up this morning and it's nearly the size of my ______.   I hate working on clutches.    And I'm getting an impact wrench.  

This morning, I checked the basket again and while it's grooved, it doesn't look *that* bad.  I've always seen baskets with a bit of groovin'.  The edges of the plates don't look awesome though.  I'll try to get it completely disassembled tonight and get pics, assuming I can use my right hand.    

[bigiain]

I first noticed some clutch issues when it felt like it there was a problem disengaging the clutch.  Then it started when it was difficult to get into neutral.  Then, at lights, it wouldn't go into neutral and even with the clutch all the way in, it would engage slightly, forcing me to hold the break brake (damn, and I always get on people for making that mistake).  I bled the clutch a couple of time and it helped a wee bit each time.  But then it came back.  Symptoms grew increasingly worse until I couldn't get into neutral at all unless I was coasting to a stop, and the clutch wouldn't disengage completely and the bike would stall or try to force me into traffic.

This is _screaming_ to me of a dud hydraulic seal. Especially if bleeding it helps briefly, and if "pumping up the clutch" sometimes works.

If you're 100% sure you're not losing any fluid, it'll be the seal inside the clutch (master) pump leaking fluid back into the reservoir when the line's under pressure. I can get replacement pistons (with new seals on them) for ~$26 here - they're a standard Brembo replacement part. Take care fitting them, it's easy to damage the seal lips when installing them into the cylinder.

If, like me you're 100% sure you're not losing fluid, but you're actually dripping a small amount from the slave, you'll need new seals in the slave (or a complete new slave). I've got a stock slave cylinder with the Evoluzione "upgrade piston" in it ( http://www.joepopp.net/ducati/2009/05/evoluzione-clutch-slave-piston-upgrade.html Evoluzione's site seems to be empty and parked), so I could just replace the 2 orings for a grand total of (I think) $0.32. Chris Kelly used to sell and recommend the Yoyodyne ones, so I'd guess he can tell if/how to get replacement seals (or sell you a replacement assembly).

(I _think_ the reason I was convinced I wasn't losing fluid was that I really wasn't losing _much_, but what _was_ happening was that when the clutch was disengaged (which is most of the time) there's a small light spring pushing the slave piston out against the clutch pushrod. My suspicion is that every time I parked it, as the motor cooled and the pushrod contracted, that spring was enough to suck a little air back into the slave past my workout seals.)

I've-done-all-the-dumb-things-Big ( )

[Spidey]

Thanks, gang.  Dunno if it's the seals as bleeding barely helped, but we'll see.  I'll try to post pics tonight, but I had Tigre come over last night for a second set of eyes.  And cuz I wanted to borrow his impact wrench so that I didn't have to jump up and down on a breaker bar for a second evening straight.  The plates, basket and hub look acceptable.  Not new, but ok.  The friction plates are not worn like the last set (i.e. none of them are down to metal) and look good.  The basket (OEM, it appears) shows a wee bit of wear, but it's not not badly notched.  The hub (OEM) has some notching, but it's not the end of the world.  I might snag a second hand hub from the local shop or tigre just in case.  I didn't see anything on the slave that stood out as a problem.      

I'm gonna see if I can swap out the slave for another and see if that helps.  Three immediate things:

1)  What's the torque spec for hub nut?  I think it's 180NM, but I can't remember.
2)  The convex washer on the outside of the hub, but beneath the nut.  It fell out and I didn't get it's original orientation.  Should it be concave facing outward or convex facing outward?  In other words, should it bulge toward the outside or curve toward the inside?
3)  Stack height is 38.7mm.  IIRC, that's w/in spec.  Can anyone confirm?  

[Spidey]

If you're 100% sure you're not losing any fluid, it'll be the seal inside the clutch (master) pump leaking fluid back into the reservoir when the line's under pressure. I can get replacement pistons (with new seals on them) for ~$26 here - they're a standard Brembo replacement part. Take care fitting them, it's easy to damage the seal lips when installing them into the cylinder.

Hmmm, this kinda makes me wonder if it's just a loose bleed valve on the 999 master cylinder.  It's got a bleeder screw inside the coffin reservoir.  Another thing to check.

[Ddan]

Hmmm, this kinda makes me wonder if it's just a loose bleed valve on the 999 master cylinder.  It's got a bleeder screw inside the coffin reservoir.  Another thing to check.

According to my tech, the 999/749 clutch masters are prone to this, I don't know exactly what the flaw is but I know of  a few that have done it.

[Desmo Demon]

I didn't replace the push-rod bearing and seal,

If your push rod looks like the one on the left, it could be a source for some of your issues.