2005 S2R 800 - clutch issues, dragging - PROBLEM SOLVED

[pmazdan9]

Ducati uses a dished plate on the dry clutches to aid in disengagement...works like a spring. It's identified by a punch mark on the teeth.

It may not be included in the wet clutch packs. I don't own any wet clutch Ducs.

Don't think it's included in wet clutches... phew

If you don't have any thinner discs, you could sand some down on a surface plate using some 180/220 paper.

Thanks for the advice!

Don't dismiss the sensitivity to oil of a Ducati wet clutch. It's been a cause too many times with oil that worked fine in other bikes...

Fair enough, which oil works best with wet clutches, any suggestion?

and I know you say you have all the air out of the system, but you'd be surprised how many times a bleed fixes a clutch that's dragging.

I'm 100% sure there's no air, it's bled properly with speed bleeder. I also took it once to the mechanic who bled it for mee free of charge (when changing tyres) with a proper pump and it was still the same, no air bubbles.

[Howie]

Might be worth it to bleed the clutch again.  One trapped air bubble is all it takes.  In theory bleeding is easy.  Real life?  Not always.  

Some helpful hints:
   Try to position the bike so the master is as level as possible.
   Pump slowly.  
   When done zip tie the clutch lever to the grip.  Let sit overnight.
   Google back bleeding, pick a method and try it.

Hmmm...dished plate on a wet clutch...Speeddog to the red phone!

[ducpainter]

Don't think it's included in wet clutches... phew

Thanks for the advice!

Fair enough, which oil works best with wet clutches, any suggestion?

I'm 100% sure there's no air, it's bled properly with speed bleeder. I also took it once to the mechanic who bled it for mee free of charge (when changing tyres) with a proper pump and it was still the same, no air bubbles.

Castrol 4T...Klotz. In theory the Motul should be fine, but lots of things are theoretically fine, but don't work.

I've seen too many times where clutches are 100% air free, and there's a bubble trapped at the master. It might be worth getting a third hand and cracking the banjo bolt at the master. You might be surprised. Ever notice some masters include a bleeder?

[pmazdan9]

Fair enough guys. I'll order banjo bleed nipple for my master, it seems to be the cheapest option and it won't hurt so I'll start with that Anyone knows what size/lenght/pitch is it? nevermind, found it - M10x1

Thanks for all your help, I'll keep you updated with the progress. That's in ~2 weeks time.

[ducpainter]

Pretty sure they're 10 x 1.0.

[Speeddog]

Don't start it up in gear, just don't.
It's unsafe, puts extra load on the starter motor and it's gearing, and extra wear on the clutch.
There's just no reason to do it in normal starting.
The *only* time you should is if you've just stalled it and you're in a dangerous situation.

When the engine is still cold, it will jump a bit on first shifting into gear, and will drag a little.
When warm, it should be fine.

Larger bore slave cylinder can cause dragging as it doesn't move as far for the same pull at the lever.
APTC clutch is not a hard pull, so OEM bore size is best IMO.

Check to make sure all of the steels and friction plates are flat.
Dry them off first.
Make a sandwich of the steels, pinch one side and look for gaps on the other side.
Do the same with the frictions.

I don't remember seeing a cone steel on the APTCs.

Orient all steels the same way, they're punched from flat stock, and the edges on one side will be slightly rounded, other side sharp.
I don't remember if the steels have any feature that will define the clocking/rotational orientation, if they do, match that as well.

Stack height won't effect dragging.

Occasionally, APTC clutches will slip, that can be fixed with shims.
Do not over-shim, as that can coil bind the springs.
There's sufficient hydraulic advantage in the master/slave to bend/break/overstress parts if they coil bind.

[ducpainter]

Stack height won't effect draggging.

Raises hand.

I disagree.

But my logic is likely flawed.

[Speeddog]

I'm here all the time, so by definition I'm OK reading flawed logic, and I've certainly posted some of it myself. 

I'll restate:
Unless the stack height is so large that the springs can be coil-bound by pulling the lever, thus restricting travel, stack height does not effect dragging.

[ducpainter]

Don't forget reduced movement of the push rod due to a larger bore slave.

[pmazdan9]

Don't start it up in gear, just don't.

I couldn't agree more, I never do it unless I stall in the middle of the road with cars moving. In this case neutral is impossible to find unless i move bike back and forth etc so it's just safer ti fire it up in gear and go. My idle is set very low (another thing I'll need to sort out...) and because clutch drags, It's hard not to stall it in stop and go traffic (yeah, excuses).

When the engine is still cold, it will jump a bit on first shifting into gear, and will drag a little.
When warm, it should be fine.

I know (not trying to be cheeky!). Mine drags when it's warm as well.

Larger bore slave cylinder can cause dragging as it doesn't move as far for the same pull at the lever.
APTC clutch is not a hard pull, so OEM bore size is best IMO.

My OEM is leaking, and aftermarket is 30.5mm. I guess this is where the problem is then? I read a post on this forum and one said in his experience, anything larger than 28mm will cause a drag. OEM is either 25mm or 26mm IIRC.

Check to make sure all of the steels and friction plates are flat [...]

That I'll do

Stack height won't effect dragging.

Hmhh that's one thing I disagree with, surely if stack height is 2mm or so lower, it should be easier to separate plates? Especially with slave that doen't move the pushrod as far.

Anyway, to summarize, if cleaning/checking the clutch pack and reducing it's height, and bleeding the system through master doesn't help, then I guess it's my aftermarket slave. I bought it as I desperately needed one and it was 'local'. Looking back I wish I bought one with smaller bore... but it said 'fits s2r' (well, it does) and I like having a longer friction zone. Not bothered about pull, OEM is light enough for me.

[pmazdan9]

Right, I bought OEM slave in the end. Found a used one taken off s2r with 5400 miles on it apparently for decent price. I'll see if that solves the problem before pulling the clutch again. Fingers crossed!

[Speeddog]

I had written a bunch of stuff in reply, but honestly it was a waste of effort.

The bone stock configuration in proper operating condition will not drag and will not slip.
It's perfectly functional.

So changing stack height and swapping in a larger bore slave and longer springs etc etc is a waste of time.

Y'all have fun.

[pmazdan9]

I had written a bunch of stuff in reply, but honestly it was a waste of effort.

The bone stock configuration in proper operating condition will not drag and will not slip.
It's perfectly functional.

So changing stack height and swapping in a larger bore slave and longer springs etc etc is a waste of time.

Y'all have fun.

I don't think it was a waste of effort at all!

It might be bone stock configuration but remember I pulled the clutch a few times already, and the basket is from another bike. Maybe there is a problem in there, who knows. And even if not, it's good to know these things for the future.

I hope the OEM slave will fix the problem, otherwise I'll know what to look at. I'll keep you updated.

Thank you all!

[pmazdan9]

UPDATE:

It works! Clutch doesn't drag at all. My OEM slave was leaking, aftermarket has too big bore (30.5mm) so it was dragging. I installed new OEM slave and everything works fine.