Black Stinky Clutch Fluid: How Much Work?

[spacewrench]

I posted over at BMWST too, but:

How much work does "no clutch + stinky black clutch fluid" indicate? I did a quick half-assed flush at lunch and managed to get enough clutch action to go back to work, but it didn't even last 10 miles, so I'm going to have a tough ride home too.

What will I probably be spending my next bike-wrenching hours doing? Just a thorough flush? Or master rebuild? Slave rebuild? Digging any further into the clutch?

I drilled a weep hole at the slave cylinder during my last big project, but I forgot to check it this afternoon. It's not leaking enough to leave drips under the bike. (I hope that doesn't mean all the fluid is migrating up the pushrod and fouling the new clutch disc!)

Is there any good way to flush crap out of the system besides just Mity-Vac'cing a bunch of fresh fluid through?

[spacewrench]

Per the guys over at BMWST: "black stinky clutch fluid means slave cylinder failure." So no more mystery, just a medium-level surgery to access and replace a part. (The clutch slave on my second-favorite bike, a Honda VTR1000F, is right out in the open, easy to replace any part of that system. Just sayin'...)

[Groceryrun]

Do you think changing out some of the clutch lever parts would be advisable ?
Parts 5,10, and 12.

[spacewrench]

They said the master is maybe/probably OK, depending on how much crap was sent up there. Unfortunately, I think there was some sort of patent problem that prevented the sale of Magura master-cylinder rebuild kits. But yeah, I might as well rebuild if I can somehow.

[Groceryrun]

Looks like MAX BMW will have the parts.

I'm not sure if you have to remove the clutch lever , but if you do,
the hand lever bearing screw, part number 14, might have that OEM blue Locktite on it - that stuff
will make it a bitc* to un- screw the clutch lever bolt.

[phlam]

Earlier this year installed an after market slave cylinder from Beemer Boneyard. It is holding up well. No complaints.

[spacewrench]

Did your old one fail, or just preventative maintenance? If it failed, do you know how to tell if it screwed up your clutch disc as well? I'm worried that clutch fluid might have migrated up the pushrod and gotten on the disc. Is that common? Can you do anything about it (other than opening things up and replacing the disc)?

[JimMoore]

Originally Posted by spacewrench

Did your old one fail, or just preventative maintenance? If it failed, do you know how to tell if it screwed up your clutch disc as well? I'm worried that clutch fluid might have migrated up the pushrod and gotten on the disc. Is that common? Can you do anything about it (other than opening things up and replacing the disc)?

I've heard of that happening, but it didn't happen either time when I lost a slave cylinder. Replace the slave and ride it. If the clutch starts to slip, replace the plates.

[brentw1]

yes this happnes often people drill a drain hole in the transmission housing so when
the slave fails and leaks it just leaks out the hole and doesnt run into the clutch

[brentw1]

fyi masters usually dont fail.

[phlam]

Spacewrench, no my slave cylinder didn't fail, neither did my clutch splines, but while swapping the clutch, I did the rear main seal, the slave cylinder, some ground connection correction, new spring and a bunch of other preventative nick nacks. I plan to rebuild my old slave cylinder eventually. However; if you need it, then let me know where you want it shipped.

[spacewrench]

Thanks, @phalm. I have a new replacement from BBoneyard down in the garage. I'm gearing up to pull the swingarm (need to re-seat the front boot, plus it makes it easier to do the clutch and swap in a new rear shock). Hopefully I'll be back on the road by next Monday.