Pressure plate difference? S4RS vs. others

[CDawg]

I just received Rizoma's star shaped pressure plate.  Included in the packaging were 6 small washers (~2mm).
Their instructions suggested that for the S4RS and a couple of other models, than the washers be installed between the spring cap and the clucth stacks.  The caps I bought from SpeedyMoto didn't have additoinal washers.  Does anyone know what is the difference in the dry clutched between the S4RS and other models?

Thansk!

[johnster]

Hmmmmm......

I always thought that ALL dry-clutch Ducs were identical, in that there are no differences from model to model in terms of installation....I'm actually expecting my Motowheels pressure plate to arrive today, so I'll be interested to see if they come w/these washers....

It really would only affect lever-pull ease I would imagine, as the only thing the washers would do is increase the spring preload....

Maybe the Rizoma fits different because of the way it's machined?? 

[CDawg]

It really would only affect lever-pull ease I would imagine, as the only thing the washers would do is increase the spring preload....

The washer are smaller than the diameter of the spring.  I was concerned that they would just rattle around which is why I posted.  I haven't removed the OEM so I don't know if the washer would be pressing against anything.

[ducpainter]

Only differences I'm aware of is in some slipper clutches.

Thought all dry clutches were basically the same.

[hiero]

actually, I believe the clutch actuation rod is of a slightly different length on some models?  or was that the piston in the slave cylinder... i forget

[Bill in OKC]

The clutch on my S4Rs slipped quite a bit stock.  I replaced the springs with SS and the slipping stopped.  Maybe the difference is the S4Rs puts out more torque and the extra preload (assuming stock springs) gives the clutch more bite.

[CDawg]

The clutch on my S4Rs slipped quite a bit stock.  I replaced the springs with SS and the slipping stopped.  Maybe the difference is the S4Rs puts out more torque and the extra preload (assuming stock springs) gives the clutch more bite.

Yes, except the washer is smaller than the springs...I called PJ Parts (Rizoma importer) and they said to ignore it unless I'm getting a lot of slippage.  I called and email Rizoma's tech dept today as well.  I'll do some work in the garage tonight and report back tomorrow.

[Speeddog]

If the spacer will fit between the spring and the cap, it will increase the preload, and the clutch will be less likely to slip.
Downside is harder pull at the lever.

If the spacer fits between the cap and the post on the hub, it will decrease the preload, and the clutch will be more likely to slip.
Upside is easier pull at the lever.

[CDawg]

If the spacer fits between the cap and the post on the hub, it will decrease the preload, and the clutch will be more likely to slip.
Upside is easier pull at the lever.

Speeddog nailed it.  I installed everything las tnight and the washers does indeed sit between the cap and the post (but inside the spring).  I didn't feel any noticeable change in clutch pull.  I will keep an eye on clutch slippage when I take it out for a shake down ride this weekend.  So far the clutch engages fine with when I pushed it around the garage.  For what it's worth, Rizoma just recently started shipping pressure plates with the washers.  My rationale for using them as oppose to excluding them was that Rizoma went throught the trouble of including separate installation diagrams and cost of including them...  If the clutch slips a lot/more I will remove the washers and report back.

[CDawg]

BTW, here's the reply from Rizoma after the sales person checked with their tech department:

I've checked with our Technical Dept.
 
They gave me these instructions (which I guess you received together with the item) and explained to me that it's recommended to use these washers for DUCATI S4 and S4R. 
 
So, just mount them and the result should be fine.

[c_rex]

BTW, here's the reply from Rizoma after the sales person checked with their tech department:

I've checked with our Technical Dept.
 
They gave me these instructions (which I guess you received together with the item) and explained to me that it's recommended to use these washers for DUCATI S4 and S4R. 
 
So, just mount them and the result should be fine.

I still don't see why they'd be any different  for the S4 and S4R but I'd go without the washers and see what happens.

[Speeddog]

There may be a difference in clutch stack height, but IMO that's not so likely.

[CDawg]

For what's its worth, the pressure plate for the S2R1K and the S4RS have different part numbers (194.2.001.1B versus 194.2.015.1A).  The part number for caps, springs, nut and clutch drum are all the same.

My guess is that the OEM pressure plate for the S4RS is a hair thicker (by the thickness of the washer to better withstand the increased HP) so Rizoma started to include washers to decrease the pre-load since all their pressure plates are "omni-models"