Ducati Monster Forum

So my 07 S4rs is in for the 7500 mile service right now and the tech said to think about replacing the stock clutch slave cylinder. I don't seem to have any issues but have read that they can be a problem.
Should I replace it because it's just one of those "matter of time" issues or should I be ok?

I have searched and haven't seen a definitive answer. Any suggestions would be great.

My OEM slave lasted about 40K.  Usually they fail gradually. 

Wasn't there something with the dry clutch bikes throwout bearing? At least I thought it was the dry clutch bikes. Throw out bearing would start to go, and it would cause the rod to spin, causing wear in the cup on the slave cylinder.

Mine lasted 16-18000 mile range but that was from a bad seal leaking fluid. Had I kept that area cleaner, it probably would have lasted longer.

Yes.  The push rod would drill a hole through the slave piston. 

So if I keep things clean and maintain the fluid I should be ok for another 8-10k?

No guarantees...maybe more maybe less.

Good point. So if I were to switch to an after market, i.e. Oberon, Evo etc, would I have a better chance of avoiding part failure?

They're not really built differently than the stock one....  The main reason people change them out (besides the 'bling' factor) is the availability of larger piston diameters which result in smoother clutch action and lighter lever pull.

Change out the bearing in the pressure plate, re-bleed the system periodically and every once in a while check the 2x O-rings on the push rod shaft...  And just ride the bike.  [Dolph]

Ok cool, thanks Duck Stew!

And everyone else for their input, this place is always the best!

As stated, most are similar since they all rely on Pascal's laws. What could be different would be the materials used, the number of seals, and manufacturing tolerances. What is different between the brands are the warranties, if that matters to someone.

Yeah, I think Yoyodyne and Oberon have good warranties. Matters to me.
BTW, my old M900 is on her original slave cylinder. ;D

AFAIK, failure rates on Yoyodynes are extremely low.  Two seals and hard anodized bore.  http://www.yoyodyneti.com/ProductInfo.aspx?productid=D002 (http://www.yoyodyneti.com/ProductInfo.aspx?productid=D002)   Again, you may have a lot of life left in the old one.

Mine is too...but it's had many new seals.

Original seals too.
Im impressed that seal kit is available. I should buy a few. Luck cant hold out forever.

I think the vet mentioned mine wouldn't take many more.

I'll most likely get the Yoyo when it's time. They've served well in this area.

In past threads Oberon seemed to be the preferred choice. Is it switching to the Yoyodyne now? Or are they both fairly equal?

 I got a gold colored EVR slave and it added 10 horse power! (To the look of the bike)

Spike, excellent point!

Please include any horsepower graphs for said option...

I've read (pretty sure here) that the stock slaves are largely responsible for clutch fluid turning dark/dirty quickly. I experienced this on both my Monster and ST2.

I assumed this was due to inferior build quality as compared to the aftermarket pieces. If true, this would be another argument to replace with aftermarket.

Dunno. I think it's more my tech likes dealing with Fred.

Clutch fluid still turns dark with aftermarket (Oberon) slave.

An often quoted tale.

My opinion is that a clutch MC piston experiences more travel than one in a brake MC. More piston travel equals more seal wear leading to a conclusion that the clutch fluid should darken faster than the brake fluid.

Lots of theories why this happens.  Aluminum from the bore, rubber from the seals and heat.  Until recently I thought heat was the least likely since clutches don't produce much heat and brakes do.  Then I noticed black fluid in the reservoirs on water cooled Multistradas.  The resrvoir is very close to the cat equipped exhaust.

I've got over 32K miles on my stock slave. No issues so far...

Same rate as with stock? Just curious...

Went to a local hydraulics guy who made custom seals. I got a spare (rare custom made from Brad) and this guy could do the same as the people in Sydney (iirc) who made the ones Brad had.

The guy said that the various rubber compounds available were not always compatible with different brake fluid compositions from the various fluid mfrs. Some brake fluids ate some rubber compounds more than others and there was evidence of rubber degradation from certain chemicals in the some brand fluids. That's all he would say. ;)

My guess is it may depend on the fluid you use and the compound of rubber used in particular batches of seals from the oem supplier. You won't know according to this guy until the seals fail early and inexplicably. It may be hard to know if there was another less obvious cause besides a buggered thrust bearing or rotten fluid.

He said that he could have a seal made that would stand up to current known chemicals in brake fluid, but he would give no guarantee. Food for thought.

My concern would be that NOS of oem slave cylinders and NOS of rebuild kits may not be compatible with the stuff in the latest brake fluid, if this guy is to be believed. I 'spose you could be lucky or unlucky. My old model type slave cylinder is still going, touch wood, but I would gamble on the rebuild kits for the old type if they were cheap enough. ;D

The rebuild 'kit' consists of a single seal.

Last I remember it was about $8.

My red Ducabike slave works great ('98 M900) and lessened the lever effort. My hands have had a lot of -bike accident-trauma & breaks, so that helps. The original one was working great when removed at 32k, no leaks. Had to easy out one if its 3 bolts. I was updating everything else on the clutch anyway (except master) and I also love the Ducabike slipper clutch. The fluid gets black sooner than the brakes on all of them it seems. Maybe not quite as quick now as with the oem unit. Ducati life. It seems to really bother some people : )

Before the HEL Performance line went on-
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