Retired Pipe Polisher C2H6O+
Why? And what is that black crud that settles in the bottom of the clutch fluid reservoir? The brakes don't do it and you would think that would suffer the worst duty. ???
Thanks. Sounds logical. Your right, it's never been a problem, just looks nasty.It's caused by aluminium particles dissolving into the clutch fluid, probably from the unfinished aluminium bore of the crap standard slave cylinder. Most aftermarket slave cylinders have anodised bores, or are made from a better grade of aluminium, so you'll notice that bikes with aftermarket slaves don't suffer from the problem.
BTW, it doesn't adversely affect the operation of the clutch, just looks bad.
+1 The clutch travels the full range very often. The brake masters and calipers displace very little. So, there is very little fluid movement in the brake systems.The crud is as previously stated aluminum and rubber. The fluid darkens as it ages because it is hydroscopic and the water it picks up contributes to the corrosion of the cyl. bore.The reason it turns color so quickly is the relative distance the seals travel is about 4 times greater than in a brake cylinder.And the loading on the seal increases as it slides down the bore unlike the brake which stops moving pretty much at peak pressure.Just change the fluid once or twice a year if it gets too dirty.
My money is with tricklidz, that is why Ducati has gone with the pined push rod on all the latest slaves. It stops the rod spinning the piston in its bore.I could also be that the fliuid is being heated because the throw bearing is worn or defective and the rod is spinning the piston in the slave!!!
+1 I concurMy money is with tricklidz, that is why Ducati has gone with the pined push rod on all the latest slaves. It stops the rod spinning the piston in its bore.
Have you ever noticed when you sand aluminium with wet and dry paper how the water turns black? This is what's happening inside your slave.