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Hi Ya'll

My question comes from replacing clutch discs and then realizing that I didn't need to remove my pressure plate which I did of course. My assumption was to tighten the pressure plate's six bolts all the way. Upon doing this I had no action on the pressure plate via the clutch lever. So I backed out all six roughly 4 turns each and had action on the pressure plate via the clutch lever but it would not completely release the gear with the clutch lever fully pulled in. Obviously I didn't observe the original position of the six pressure plate bolts before my initial dis-assembly so I have no idea if they where originally tightened all the way down.

So any input would be a help at this point (sun's down - dinners ready). I am prepared to back out the six pressure plate bolts to roughly 5 to 6 turns and use some thread locker on them. But I'm wondering if the sweet spot is somewhere between fully tightened and 4 turns out? Hmm . . .

Of note is the fact that my 750 is also suffering from wear on the contact point between the clutch's slave piston/puck/bearing and the pressure plate center point/pin, which, of course, has broken itself loose from the welds holding together with the pressure plate. WHEW!!!

Thanks

I'm assuming that these are the bolts you are referring to.

Someone correct me if I'm wrong but they should be done up tight,and torqued down
to 9.8 Nm.You should use some thread locker on them as well.
As for the clutch not releasing perhaps you have installed too many plates or it is not bled properly.

The welds on my pressure plate pin broke as well,I carefully ground off the old welds and then fully welded
it back together.It has been in service for nearly 10k km with no sign of cracking.

Hey Ken

Yup those are them. I didn't need to bleed as I just removed the cover and went straight to changing out the plates. Which brings me to you next point; plate thickness. So I'll go and measure the old plate set and the new plate set and get back here with the differences. I'm thinking this should be the issue as this is the only thing that has been changed.

Of note as well - once the 6 clutch pressure plates have been tightened all the way the springs are completely compressed. Shouldn't there be more travel left in the springs for the clutch slave piston to compress the pressure plate to dis-engage the clutch?

Hmm as I'm sitting here scribbling an some scrap paper I'm beginning to understand - plate thickness - Well at least I've got all day to d!ck around with this - back to the bike

Ethan

what`s the partnumber of the pack you bought ?

G.

I just removed two plates; 1 friction and 1 smooth and was successful.
I tightened the 6 pressure plate bolts all the way on this time as well.

On another note:
Here is my clutch piston's condition!
I'm wondering if the piston is too worn to replace the bearing

and the contact point on the pressure plate.

HI,

The pressure plate should not be dished. I have been told that the contact area should be slightly concave.
I think you need a new set (bearing and pressure plate) or have them refurbished.

Greetz Joep

Anyone else have an opinion on the shape of the pressure plate? I have only this one so if there are other ones shaped differently could someone post a photo for comparative purposes.

G'day Ethan
All the pressure plates on the 750's & 906's are the same.Unfortunately yours is severely worn
and needs to be replaced.You could try taking it to an engineering company,they may be able to repair it.

I agree as far as the pressure plate's contact surface. I'm taking it to my buddy's machine shop tomorrow. As far as the pressure plate itself, its not showing any fatigue cracks or heat distortions as you can see by the photos. Do you have a good slave piston and pressure plate to go with the plates you PM'ed me about Higgy?

ir_joep wrote:HI,

The pressure plate should not be dished. I have been told that the contact area should be slightly concave.
I think you need a new set (bearing and pressure plate) or have them refurbished.

Greetz Joep

So I'm unclear as to what part of the pressure plate your (ir_joep) referring to. Are you talking about the curved part I've pointed out in the photo below OR just the contact point in the middle of the pressure plate?



Thanks, Ethan

Hi Ethan,
I had the same issue with my clutch a couple of years ago.
The very center of the pressure plate should be flat, not have that ring machined into it. You can see that the little point in the center fits perfectly into the button that sits in the slave piston. That little point shows you the original thickness of the pressure plate.
Several years ago Ducati started supplying clutch slave pistons with STEEL buttons (the part that actually presses on the pressure plate).
The original buttons were bronze, so they would wear down instead of the pressure plate.
With the steel buttons, the pressure plate now becomes a consumable part! Good for the parts suppliers, not so good for owners. I don't know if the new bikes (which the steel button is obviously for) use a hardened pressure plate.
I found another (not so used) pressure plate and had a couple of buttons machined out of bronze.
My suggestion would be to ditch the steel button immediately and replace the pressure plate (if you can find one) or get the plate welded up (with a hard alloy).

Michael

Hi,

What I ment was the contact area between pressure plate and bearing/slave. Yours is indeed worn.

Sorry Joep

As a general rule of thumb,

Tighten until the bolt strips the thread, then back off half a turn.

(this is of course a joke and shouldnt in any way be applied to any securing devices on your motorcycle...or car...or bicycle...or saftey equipment....or house...childrens play equipment....toys....aircraft, whether passanger or cargo, trains...electrical equipment...etc etc etc)