Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > HELP!!! Clutch Slip

[Clippy]

It's an old problem, but this time there's a new twist...

I have a 998S with a Ducati Performance Bucci Slipper Clutch.

When I accelerate from 4,000ish revs the revs rise, but there's no increase in speed, then it grabs, then slips, then grabs and so on...

This points to knackered plates (even though they were only 600 miles old) so they were changed - with a set of SP/SPS plates that have 8 friction plates rather than 7 - hoping this would make the difference...

75 miles later and the slip is back!!!

- I've checked that the fluid level isn't too high or too low.
- I've checked that the clutch lever screw that activates on the master cylinder is letting the m/c all the way out.
- I've whipped off the slave cylinder and push-rod and there is no movement in the clutch to indicate that it's more fully engaged with these removed.

HELP!!! I'm fast running out of ideas other than "Are the springs not up to the job?". The whole clutch assembly is less than 800 miles old, but as it's an alloy clutch are the springs weaker, therefore can this clutch not handle the output from my 136bhp Testastretta engine???

Can some smart types help me out with any suggestions please?

Cheers

Giles

[keefer]

are you saying it used to do this before you changed the plates also ?
with regard to the springs are they standard ? and bear in mind that the superbikes have allot more power than your bike and there clutches only have four springs.
when you took it apart was the spider spring ok

[Clippy]

It did it on the 600 mile old standard plate pack and on the new SP pack.

The springs came with the slipper clutch kit.

Everything in the clutch is as it came out of the box.

I'm baffled...

Giles

[keefer]

with the pressure plate of what is the depth from the last plain plate to the top of the outer basket ?

[JPM]

Is the clutch pack depth correct? When I first got a slipper clutch I built the clutch pack and it work beautifully for a few hundred miles then started slipping, turns out the clutch needed another plate as when the clutch material started to wear a bit it was too shallow to bite.

Alternatively is the spider spring OK? is the clutch drum tight? the large diameter nut torqued up correctly? have the bearings slipped off the ramps?

[Clippy]

Cheers Guys,

The biting point is very near the full extent of lever travel, so maybe that also points to the pack being too shallow - if it was deeper the pressure plate would be further away from the slave cylinder and therefore the biting point would be further into the lever travel???

Will give this a go (sticking another friction plate in there somewhere) and let you know the outcome...
Thanks again.

Giles

[nelly]

Check the spider spring mentioned by JPM. They can and do break, or simply lose their tension.
I swapped mine last year after it gave up. If the pack is pretty new, then i'd guess that's your problem.

[Clippy]

Well...

My local dealer has got to the bottom of this at last - after stack measuring and friction plate replacement, playing with master cylinder actuating screws, bleeding the system etc etc it turned out to be a faulty (warped) plain steel plate that was causing the problem.

As it was not flat it was reducing the friction surface and slipping under power. Now replaced and....

...the clutch no longer slips....in either direction!!!

Back to the tool kit to take it apart again to get it slipping on the down-change where it's supposed to - but at least I now have reliable forward motion!!!

Thanks for all the advice.
Cheers

Giles

[rockhopper]

Isnt it supposed to have one dished plate?

[Clippy]

It's supposed to have dished ones front and back, but not warped ones in the middle that mean that the friction plates are only touching in certain places...