Oberon Clutch slave leaking

[jerry]

the Oberon clutch slave on my S4 is leaking its been on the bike for 7 years and 23k miles

I have a refurbed old Ducati original to keep the bike running for my last week here , but will need new seals for the Oberon one ,,same thing happened on my M750 in Uk had to get new seals for the Oberon unit , at 9k miles use ,,,, so are they as bomb proof as claimed ,

[Mr Gazza]

I use an Oberon. Funnily enough I was studying pictures of the slaves only yesterday with a view to converting one for another project.

I noticed what they describe as "anti-rotation" grooves in the engine side of the unit.
There's no way that these grooves will stop rotation in our Monsters, with a standard pushrod.
But if the pushrod had a small pin through at 90deg, that engaged in the grooves then it would work.
I changed my thrust bearing as I worried that the pushrod was spinning the slave piston every time it touched it, thus chewing out the seals prematurely, but the pushrod was still just as tight a fit in the bearing as before.
This relies on there being more resistance in the pushrod's tube, than in the bearing, to prevent, or reduce rotation.

Thinking of trying a pin.. (Could be tricky?)

[Mr Gazza]

Like so...

[Capo]

The push rod is not supposed to spin, there is a bearing on the clutch end and only an O ring on the other. In fact it is the compression tension of this O ring that is supposed to prevent rotation.

[Mr Gazza]

Ah yes the little O-ring!
It has to be grippy enough to stop the rod spinning and slippy enough to allow it to move in and out.!?

I might change that when I change the clutch.

I console myself with the thought that I use a spacer piece at the end of the rod in the slave. If the rod is spinning then it would be reasonably difficult for the rod to spin the spacer and then the piston.

I still think that the fluid blacking, common on Monsters, is down to the piston spinning?

I guess there is no way to tell if the rod spins though... Maybe running it up with the slave off?

[Luddite]

Originally Posted by Mr Gazza

I noticed what they describe as "anti-rotation" grooves in the engine side of the unit.
There's no way that these grooves will stop rotation in our Monsters, with a standard pushrod.
But if the pushrod had a small pin through at 90deg, that engaged in the grooves then it would work.

I think the design changed with the introduction of the 696. I remember because the DP slave from my S2R wouldn't fit on the 1100 Evo.

On the exploded view, the pin (18) mentioned by Mr Gazza engages with the anti-rotation insert (22).



As there wasn't a Ducati Performance cylinder available initially, I fitted an Oberon six years ago and have had no problems with it.

[jerry]

i will change the Koyo throw out bearing anyway they are cheap

[jerry]

put the refurbished ducati on on and it blew its seals after 1 hour .... doh ???

found a local seal and o ring shop that had some nitrilebutile ones of correct size so rebuilt the oberon and refitted it ,,inside it was a horrible black sludgy mess ....... clutch is not leaking now but its a bitch to bleed ,even reverse bleeding , its working but still a bit soft ,, will leave it over night with lever tied back,, i think that the bleed screws allow air in ???

when im back in Uk will go to oberon and get the proper ones

oh yeah the push rod o rings and throw out bearing was in perfect order ...

[Darren69]

Can the later push rods with the pins be retro fitted to earlier models? Anyone know?

[Dukedesmo]

As an aside, I have an Evoluzione slave cylinder on my 916, been on it 19 years with no problems. It has a bearing in the piston that, they claim prevent the push rod from drilling the piston if it should start to spin due to pressure plate bearing seizure.

Got an Oberon on the Monster, had no problems with it but, unlike the Evoluzione the clutch fluid has darkened (like the OEM units do) whilst the 916 clutch fluid is always clutch fluid colour.

I would have bought a new Evo unit but the company ceased trading a few years back.

[Dukedesmo]

Originally Posted by Darren69

Can the later push rods with the pins be retro fitted to earlier models? Anyone know?

I would imagine they can, as long as the length is the same?

[Luddite]

Originally Posted by Darren69

Can the later push rods with the pins be retro fitted to earlier models? Anyone know?

As I understand it, Darren, the new-style slave cylinders have a deeper piston than the old ones so the associated pushrod is longer to suit.

The fact that many of the aftermarket cylinders, (including Oberon), come with a spacer to allow you to use them with old-style pushrods, suggests that the revised cylinders should be a straight swap.

Of course, you wouldn't have the benefit of anti-rotation unless you also fitted a new-style pushrod or, as Mr Gazza suggested, modified your old rod by drilling and pinning it, (and using a spacer).

Note that a new-style pushrod on it's own won't fit into the original slave; you need a new-style cylinder too.

Old...

New...

[Darren69]

Originally Posted by Dukedesmo

As an aside, I have an Evoluzione slave cylinder on my 916, been on it 19 years with no problems. It has a bearing in the piston that, they claim prevent the push rod from drilling the piston if it should start to spin due to pressure plate bearing seizure.

Got an Oberon on the Monster, had no problems with it but, unlike the Evoluzione the clutch fluid has darkened (like the OEM units do) whilst the 916 clutch fluid is always clutch fluid colour.

I would have bought a new Evo unit but the company ceased trading a few years back.

Is that the STM Evolutione one? There are some on ebay. It sounds like a good idea to have a bearing in the pistion to me. My Factory Racing slave has only lasted a few hundred miles on the S4 and is now leaking, not a lot but I would have expected better. I think the slipper clutch hammers them too much. And the seals are £25!

[Darren69]

Originally Posted by Luddite

As I understand it, Darren, the new-style slave cylinders have a deeper piston than the old ones so the associated pushrod is longer to suit.

The fact that many of the aftermarket cylinders, (including Oberon), come with a spacer to allow you to use them with old-style pushrods, suggests that the revised cylinders should be a straight swap.

Of course, you wouldn't have the benefit of anti-rotation unless you also fitted a new-style pushrod or, as Mr Gazza suggested, modified your old rod by drilling and pinning it, (and using a spacer).

Note that a new-style pushrod on it's own won't fit into the original slave; you need a new-style cylinder too.

Old...

New...

Thanks Luddite for clarifying. I guess I need something like a standard 1098 pushrod and slave then for that to work?

[Mr Gazza]

Thank you to Dukedesmo and Luddite for the info. It seems to confirm my hunch that piston rotation is responsible for fluid blacking and that Ducati were there long before me with the pin idea.

It just remains to be proven whether or not the later pinned rod would be a straight swap for my early one. I am assuming that I would need an anti rotation insert (#22) which I am also assuming would fit straight into my Oberon cylinder.

It stands to reason that I would omit the spacer if fitting a later rod.

Interesting stuff... Might be on the blower to Moto Rapido in the morning. Unless someone already knows the relative lengths of the two versions of rod?