Ducati Corse Slipper Clutch - Anyone else had experience?

[998Addict]

Dear All

I've recently changed my racing Mille for a 998S, just like my road bike. The last time I raced a Ducati, it was a 916BP (wouldn't pull the skin off a rice pudding) and I fitted a Casoli Slipper Clutch, which I believe is a copy of the Ducati Corse one. The unit fitted and worked perfectly from the off (with standard springs and plates) and slipped beautifully.

This time around, I managed to get my hands on a genuine DP Slipper, complete with ceramic plates and harder (red-painted) springs.

My problems started when I fitted it. After getting instructions directly from Ducati UK, I found that the clutch lever would only move about 1/3 of its full travel. I realised this was because the slave cylinder was reaching the full extent of it's travel (i.e. the pressure plate wasn't pushing back sufficiently against the actuation rod.

A call to the previous owner led him to sharing his theories:

1. My assertion regarding the actuation rod was true
2. He believed that the springs were getting coil bound (the spring materials were pushing against themselves).

His suggestions were (based on past experience):

1. Place a 1.5mm washer between the control pin and the bearing, in order to push-back against the push rod.
2. Place two 1mm washers between the posts on the drum and the spring collets, in order to reduce the preload on the springs.

I took these steps on at a time. With the former, the lever movement improved, but there was still about 1/3 of unused travel at the end of the stroke. On the latter, I decided to go with one 1mm washer for the latter, in order to reduce the prospect of clutch slip.

When I tried out this setup at Croft on Friday, I found the following symptoms:

1. There is a nasty "graunching" sound when first pulling away, that begins when the clutch starts to bite and stops when it fully engages
2. Whilst the clutch does slip on downchanges, it feels positively agricultural compared to the Casoli "replica" I used to have
3. The clutch lever is still stopping around 3mm away from the bar, suggesting that the slave cylinder is still reaching its full extent
4. The sound from the clutch changes between being off and on the power

All in all, I'm feeling a little bit uneasy about this lot. How come a genuine Ducati article seems to need so much more setup than a copy, and why is it necessary to do all this shimming with washers?

I'm aware that a key difference this time is ceramic plates and harder springs, but if anyone would be good enough to share their own experiences with this unit, or their thougts on the above symptoms, I'd be very grateful.

[stephens]

I have/had similar issues with my 999. My bike was only engaging at the very end of the clutch let out and rather than shim, the mechanics used a couple of my standard steels which are thicker than those in the carbon set to get the engagment right.
My carbon plates also make the same very sad sounds while engaging, but once on the move seem ok. I have done 1000km's so far with no problems outside of the noises.

[998Addict]

Thanks for getting back to me.

Wouldn't thicker steel plates push the pressure plate even further away from the pushrod?

[nelly]

Sounds like the clutch pack is too thick.
When all the plates are assembled in the basket, you should have 4mm - 5mm from the face of the outermost plate and the edge of the basket.
To reduce this you need to replace some of the the thicker 2mm plain plates with 1.5mm ones.
Another possible solution might be that if you've built the pack up using two plain plates innermost, before any friction plates are added, you could remove one of these and try it.

[998Addict]

Cheers, Nelly.

I agree with your viewpoint; my concern is why the hell does this happen when I follow the Ducati guidelines? Is it normal to have to shim these things/change the pack configuration?

One thing I've found in the past 9 years of riding Ducatis is that race stuff is usually spot-on and this just doesn't feel right to me.

[stephens]

Sorry
To clarify, I had the opposite problem to you. You should have a friction plate first, not a steel with the slipper clutch and finnish with a steel. I have ta soft copy of the 998RS parts guide which shows the order and types of plate, but it is 8mb compressed. let me know and I can email it to you.

[flyingbanana]

I had the same problem when bedding in the plates on my corse clutch. The sound still hasn't gone but only comes about when I engage the clutch in a hurry or badly. It takes a bit of getting used to and I found it better with the brembo master cylinder I had fitted which has made the feel alot better. Most peeps I've spoken to with corse clutches have had the same noise pollution and haven't managed to get rid of it. All your other issues must be down to set up I would hope. :roll:

[Felix]

Keep in mind, though, that the DP slipper clutch is NOT the same as the RS one. The proper RS slipper assembly will cost you around 1500 quid! I would not necessarily use the RS part book as a guide when setting up your DP slipper clutch on a street based bike. As I stated elsewhere, aside from a few nuts and bolts, almost no two parts are the same between an RS and a street based bike, or even an R bike.

[stephens]

The order and type of the plates are identical on all DP and Corse slipper clutches even though the plates may be different.
I have all of the RS and DP guides and they all say the same thing which is a different order to the standard clutch. BTW the Corse and DP part for the 999 are identical. On RS/Corse they are branded Ducati Corse, on DP they are labelled Bucci, the actual OEM.

[Whele]

How many dished plated have you installed in the clutch pack?

I suffered similar problems running a single plate, shuddering graunching noise and when letting the clutch out the lever would hit a notch at about 2/3 of its travel and the bike leap forward.

I stripped the clutch pack and installed two dished paltes one facing inwards in position two and the other facing inwards one plate from the end of the pack.

On the Bucci slipper the plates which are dished are identified with a dot just below the cut out. The dot signifies which side of the plate is concave. I'm not sure about the DP.

For heavy racing use up to four dished plates can be used provided they are evenly spread throughtout the clutch pack.

[998Addict]

my unit has a red pressure plate, with a Ducati Corse Logo on it. It also has what I assume is a part number (unless it is a really trick slipper with an IP address :-)): 194.1.012.1A-0. There is also the logo of what looks like a manufacturer on there (AL?), but it is definitely not Bucci.

There is also what looks like a date on there: 20-02-2002.

So - is it a DP or RS one?

Stephens - if you want to e-mail both guides to me, large file sizes don't pose a problem.

[Edited on 1-9-2003 by 998Addict]

[Felix]

The part number for the pressure plate is the same as used in the 998RS02 and RS03. Do you have part number of the internals, i.e. the clutch drum, basket, and flange (back plate)?

By the way the order shown in the exploded diagram in the RS manual is (from inside to outside):

6-8-6-7-6-8-6-7-6-8-6-7-6-8-6-7-6-7

where:
6 is friction plate
7 is 1.5 mm flat steel plate
8 is dished plate

Remember, though, that this is just a starting point and the make-up to the clutch pack ideal for your back may vary depending on tolerances, etc.

[998Addict]

I haven't yet had a chance to dismantle the clutch and check the part numbers on the flange, etc., but the part number on the box it came [to me] in, is 968244AAA.

HTH