Clutch issues

[fester]

I had noticed before winter and the last couple of early winter rides that my clutch started playing up a bit.

A couple of times it remained disengaged after releasing the lever so not sure if the master was sticking or the slave. Second pull and was normally right and onyl happened a handful of times. I suspected the slave on that occasion (but haven't touched) as the master is a reasonably new and buy all accounts good condition remote res version with the large pivot pin like early SBK's and I think later injected SS's and ST's.

Last couple of times I rode before pulling front end apart I noticed it was a bit notchier when engaging first but didn't really think anything of it. When front was apart I pulled the clutch cover removed all the plates and blew out all the dust. Looked at plates but didn't touch and put back in in same order ( apart from maybe turning back to front the odd friction and steel plate but not the outside thick one).

Now bike is back on road the clutch is worse. No leaks but harder to get into first and creeps a little. Sometimes stalls at lights when you miss neutral from second and get first at low revs. Used to find neutral fine but hard now overshooting from both first and second. Also hard to change down on the move sometimes. Up shifts still fine and no jumping out of gear or anythign else strange.

Initially thought it time to look at new plates but then realised that worn plates would create slip which is not happening.

So my suspects would appear to be either the master or the slave but neither appear to leak. Also given the slave will surely be much older than the master I thinking that. Would it likely be crud in there somewhere stopping the slave from extending to correct depth. This is my next path of investigation but any ideas to help speed the diagnosis.

Also on the subject given the differences between new and old clutches what the best option as far as getting updated/new clutch plates and say springs for the older clutches.

[Laddie]

the "sticky" could be either of the cylinders...but should not cause the part-engagement problems.

if the clutch is dragging the main possibilities are:
a) worn slave cylinder seals [and it should leak in this case]
or
b) warped clutch plates
it could be a combination of both - (a) will cause (b).

my guess would be the clutch plates - if the clutch has been over-heated the plates will warp & bow...if it is creeping at the lights YOU ARE OVERHEATING THE CLUTCH EVEN MORE. This just makes it worse.

the clutch spring pressure tends to hold the clutch plates in the pack flat - even if they are warped.

when the clutch is "free" the spring pressure is off the clutch pack - any warped plates will warp even more...bowed plates take up the free-play and drag on the adjacent plates - so there is still friction - even when the clutch is at full throw out.
depending on clutch spring pressure they can flatten out enough to perform OK under load.

an indicator of warped plates is if the clutch slips under load (accelerate hard in top gear to test)

the only positive way to examine the plates for this is:
place them ALL on a FLAT surface plate - if they are BAD the warp or twist will be obvious.

step 2: look to see of they are "dished" (concave)

step 3: try to insert a 0.2mm feeler gague all around.

it would be an idea to use a micrometer to see if EACH plate is the same thickness ALL the way around, too.

[fester]

Thanks Laddie, didn't think of warped plates. Also after reading some of the installation orders for new plates it's possible that whilst I was careful to put them all back in the way they came out that I could have maybe put the one that's supposed to be dished in the wrong way. But this may have exagerated the existing problem as it was definately starting to pay up before I pulled the plates to clean it out.

Given the mileage (48,000 klm's) and the fact I believe the last owner did nothing to the bike and the owner before raced it in BEARS events the clutch just might be getting to the end of its life.

Next question is where is and what are the best combo of plates to get. Are there any decent replacement baskets for these clutches also or is Ducati the only possible supplier for the old bikes.

Time to refurbish the whole clutch me thinks and dig out that CNC pattern for getting the cover milled out for ventilation. Similar pattern to the old factory 750 F1 racers I believe.

I take it no-one has found any real source for the pressure plate. Also is there a source for new springs.

[jomo]

It sounds like there is still air in the system.

jomo

[gasfireman]

I find these clutches are difficult to bleed but a trick I find works is........

If you pull the clutch lever in to the bars, tie it back to the bars and leave it overnight, the air will usually find its way up past the master cylinder and out of the system.

[kirk332]

If you pull the clutch lever in to the bars, tie it back to the bars and leave it overnight, the air will usually find its way up past the master cylinder and out of the system.

Does that work for front brakes too? Having a shit of a time with these. The bleed nipple is so close to the rim. U need another pair of hands!

[jomo]

It is painfull. Be patient....and don't give up. It is a test to see if you really love a Ducati :laugh:

[james]

As I recall, one time I unscrewed the bolts holding the brake rotor onto the wheel as well as the caliper mounting bolts, and bled the brakes that way. Is that true love or is that cheating?

James

[gail]

Heard a tip on bleeding brakes/ clutch once upon a time, apparently the story is to have an extra long bleed hose and loosen brake/clutch nipple and suck fluid through. Take care with this untried method as a mouthful of this good gear will get you on TV. I would recommend clear hose and a spotter. If anyone else has heard this method or tried it give us some feedback , Happy sucking and bleeding, hopefully your not warped. ...... Marty

[duckboy]

Hi Fester
I went through all this a few years ago, i described the symptoms as the clutch seems to have lost pressure, and i replaced the master cylinder (internals), that didn't fix the problem, so i replaced the slave cylinder components, that didn't solve the problem either. Next i replaced all the clutch plates, which also didn't help, i tried many combinations of dished and flat plates, some better than others, but the problem still persisted. Finally, while disassembling one day, i noticed some cracks in the pressure plate (that bears against the slave piston), the cracks are virtually invisible if the plate has friction dust on it, and due to the combination of hard and soft metals, cannot be re-welded. i had no problem finding a new item, and WALAH! problem solved.
BOL
duckboy

[Tamburinifan]

That`s a new problem w a solution. Thx f sharing!