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keith888 27-Jan-2009 21:23

clutch fluid contamination
 
1 Attachment(s)
Hi Guys,

Can anyone can identify the source of this light coloured fine 'stuff' that has slowly been accumulating in bottom of the 888's clutch hydraulic reservoir over the last couple of years? Hopefully more obvious on the photo. I always thought that the clutch fluid on Ducatis went black but (after 3 years) mine was still only a dark straw colour. I'm running a standard clutch slave that I rebuilt 3 years ago. Now cleaned (no sign of any leakage from the slave), fluid changed and all is fine but I'm curious.....

Thanks,

Keith

gordonparker 28-Jan-2009 11:55

Could be that the fluid is breaking down, normally you should change your fluid every 2 years regardless of use as I belive it will absorb moisture which in turn will affect the performance ???

Gordon

Jools 28-Jan-2009 14:49

I agree with Gordon. Moisture laden air is bound to get into the system over the course of a couple of years. Hydraulic fluid is very hygroscopic and will absorb the water from the air (that's why you always have to use fresh fluid rather than stuff from a can that's half empty).

The 'stuff' could just be emulsified fluid, but it's a good idea to flush it out because when the fluid gets hot the water in it will vapourise, and because you can't compress liquid but you can compress gas, the lever will get very soggy.

Not so much of a problem with your clutch, but with your brakes :eek:

keith888 28-Jan-2009 15:02

I'm certain its not the (5.1) fluid breaking down. I've certainly never seen anything like that before on fluid that was much more than 3 years old. The brakes were done at the same time certainly nothing nasty flushed out of that system so it seems to be something unique to the clutch system.

Keith

Scooter916 28-Jan-2009 23:57

Just athought, When you rebuilt the Clutch slave, Did you smear the seal in Grease??? it could be the grease finding its way back up the line.
Is 5.1 Compatable with the plastic pot????
Glyn

keith888 29-Jan-2009 12:54

Hi Glyn,

I only used brake fluid on the slave bore and piston seal as per manual. I did, however, put a fair bit in the cavity between the top of the piston and the seal that the push rod passes through. I did get a bit of air out when I was flushing the system so maybe my slave seal is actually on the way out (even though not dripping) and some of that grease got sucked into the system at some point?

Keith

007 29-Jan-2009 13:24

Hello Keith,

dot 4 (glycol based, boils at 230C)
dot 5 (silicone based, boils at 260C)
dot 5.1 (glycol based, boils at 270C)

Dot 4 & 5.1 are both glycol based and therefore hygroscopic.

Dot 5 is a silicone blend, and is not hygroscopic, but can cause premature wear in seals, as moisture is forced into the rubber or plastic. They are also more compressible.

Mixing DOT 4 & 5.1 is fine, but if yor wish to consider a silicone blend, you will need to flush the system, or you will experience a chemical reaction causing solids to precipitate out of the mixture and clog up your braking system.

Best regards.


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