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Discussion Starter #1
I just put an STM 28mm slave cylinder on my bike to replace an Evoluzione 30mm unit, now the clutch won't re-engage. I can put the bike in 1st gear, let the clutch out, and instead of getting the bike moving forward you feel a slight push but mostly the clutch just spins/slips. Visually it looks like it's returning to about the correct spot (relative to the top of the spring retainer caps at least).

With the Evoluzione slave, it re-engaged just fine, but since it was a 30mm cylinder size it didn't have enough travel so finding neutral was difficult. I wouldn't have thought that replacing the slave cylinder would cause that... but here I am :eek:.

Clutch pack is pretty new, has about 600 miles on it maybe, and I've never had problems with it slipping before.

Ideas?
 

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2001 900SSie
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This is a link to Oberon instructions with a reference to an extension piece for pre 2000 models.

http://www.oberon-performance.com/acatalog/Ducati Clutch Slave Cylinder InstructionsVIII.pdf

I had a similar problem when reinstalling the stock slave. The piston was not located/pushed back and was still connected to the hydraulic line. I must have used the clutch lever thus pushing the piston out a little.

I removed the slave, cracked open the bleed nipple and pushed the piston back.
Then reinstalled (there should be no resistance to putting it on the rod/engine) then bled the clutch.

Richard
 

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Discussion Starter #3
I had gotten a decent bleed on the system, from both the master and slave cylinders. Odd thing about the STM slave is it has a built-in spring that pushes the piston out... and its pretty strong. You can push the piston back into the bore, but the spring shoves it right back out before you can get it mounted on the bike. Never used a slave cyl that had a spring before, so not 100% sure if I'm missing a step or something like that.
 

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Did the STM come with the spacer? Just wondering if perhaps you are using the spacer but don't need it (i.e. your push-rod is already the new longer style).
 

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Are you installing without the hydraulics so there is no pressure on the piston.

+ 1 on the spacer.

Is the pushrod correctly located in the pressure plate on the clutch side?
 

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Discussion Starter #6
You may be right on the pushrod size. I did have the spacer installed in the slave, may not need that. Can't remember if I replaced the pushrod when I installed the previous unit. I know I didn't need any additional spacers w/ the Evoluzione slave.

What is the overall length of the newer style pushrods?

When I originally installed the slave, it was with the entire hydraulic system empty. Did take it off after that though - might also have something to do with it.

I'll give some of those ideas a shot tomorrow and see what happens. Thanks guys!
 

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According to the Oberon link I posted, pushrod lengths changed in 2000 needing the spacer.

I get the impression from the link that the spacer is very short and sat inside the Oberon slave rather than attached to the pushrod.
 

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Discussion Starter #8
Took almost a week, but I finally got to fixing the problem this morring. Looks like there were a couple issues... first, I don't think the pushrod was properly seated in the pin that sits in the pressure plate bearing (which was keeping the pressure plate pushed out slightly and preventing it from re-engaging the clutch), and second, there was still some air in the system. I pulled the pushrod, re-seated it, reinstalled everything, re-bled the system from both the master and slave cylinders... and now everything works great. Took a quick test spin to test everything and it appears we're back to normal. :D. Gotta love it when stuff works!
 

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Discussion Starter #9
I get the impression from the link that the spacer is very short and sat inside the Oberon slave rather than attached to the pushrod.
Yup, that's exactly how the spacer works. I actually ended up not using it, I had a later-model pushrod sitting around that I threw in.

The other difference between the new & old pushrods is that the older one has a rounded end that goes in the slave cylinder, whereas the newer one is machined flat.
 
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