Ducati Monster Forum

Happends after just 200 km’s refreshing it.
Reason why?
Enough to take hose off and flush it?

Speculation is heat causes the fluid to darken. I think once a year is enough.

Agreed.

Question...flushing with fluid from a brand new, unopened bottle, or something that has been hanging around?

Brake fluid seems to suck in moisture whenever it can.  Even the possible condensation from the reservoir and lines.  Combination of H2O and heat will darken it quickly. 

New bottle this May.
When dark, clutch works less good,
release closer to handlebar.
So, how to avoid heat, slave located where it is?

I don't think it's possible to avoid.

You could try DOT 5.1.  No guarantee.

Or try high heat racing brake fluid.

An example is Motul 600 or 660, there are other brands with equivalent reputations in the trackday/racing world.

My '99 ST2 fluid darkened fairly quickly, though no notable loss in performance. I switched to a slightly newer sealed unit and it stays much cleaner for a lot longer. Don't know if yours is the sealed kind, but if not, there are lots of take-offs on e-bay, etc. as folks always seem to replace the OE units with aftermarket bling.

When you say sealed unit, are you talking the reservoir? I thought they were all sealed?  ???

No, sorry. I meant the clutch slave. Left out that important detail.

The one on my '99 ST2 was the older rebuildable unit with the rubber bellows as a seal. I don't think it ever sealed very well in the first place, but of course with heat and age it gets brittle and torn. And of course is in one of the grimier areas of the bike being next to chain and sprocket.

That rubber bellows was just there to keep out the grime. The seal is inboard of that. I think it's just heat that does it.

Ridocolously expensive, but, maybe Castrol React works? 70$...

https://www.youtube.com/watch?v=RLgbsgNZ_Ss

Seeing a theme here. I'm using Dot 5.1 in the rear brakes of some bikes that cook their fluid. Some models have the brake lines too close to the exhaust and some have a caliper/disc combo that overwhelms the fluid with anything but light use.

So as suggested by others, this might be a fix for your clutch fluid as heat does appear to be an issue. The reservoir is small so a low volume and the fluid is not only subjected to a workload but also consistent engine heat.

5.1 needs changing each year however.

I don't know why, but the Dot 4 clutch fluid in both my Monsters keeps a good colour. I only change it every 2-3 years. I'm using Motul, Castrol or Penrite.

I think one it turns black the only way to reverse the situation is disassemble and clean everything.  Just change the fluid once a year and don't worry about the color. 

This.

A good quality DOT4 - I like to use Motul 660, I'm sure there's others equally good.

[thumbsup]

All my ducs (not that many, but anyway ....) have been like that. In the begining, I worried about it and changed the fluid, but with age-induced laziness setting in, fluid changes started happening only when made necessary by other causes. So far, I´ve never noticed a difference this way or that.

Infrequently, if not renewed as per above, I do pump thru some fluid and top up the reservoir, but that´s it.

May not be the correct way, but it has worked so far  [coffee]

The open unit allows for a lot more ingress, particularly if/when the bellows fails. Which would accelerate wear on the inboard seals. The slightly later units did away with the bellows and instead sealed up against the case. At least in my case, the closed unit cleared up my issues with dark fluid. Although, at 20+ years, I suppose all seals and OE rubber lines could be suspect for contributing to suspended particles.

Not worried about colour, it`s that the the function gets worse.
Season almost over, will try other fluid next year.
What makes DOT 5.1 a better candidate?

Higher wet and dry boiling points.