Clutch slave cylinder observations

[Stan Walker]

Gee I hope everyone is enjoying my spline lube as much as I am.

 

What with visiting this site, reading posts, adding new ones, I think I'm actually working on the bike about 3 hours per day........

 

I have a few observations on the clutch slave cylinder I would like to share with you and get your opinions on.

 

-------------------

First, I found about a teaspoon of tranny oil in the cavity where the slave cylinder fits. At least it smells like tranny fluid. Looks like my rear input shaft seal leaked a little at some point. It's not very recent as the fluid isn't the same color as my current tranny fluid.

 

Perhaps I should replace the seal, but, that carries some risk too.

 

Since this isn't all that hard to get to I think I'm going to let it slide and assume it was seepage that has long since quit...... But see the next observation.

 

--------------------

 

Any leakage from the slave cylinder (dot 4) or from the input shaft seal (tranny oil) has only one escape route. Down the clutch actuation shaft and onto the clutch disc. They even put a gasket under the slave cylinder to insure this will happen.

 

Bad design?

 

I'm thinking of cutting out the bottom most section of this gasket to allow any build up of fluids to exit down the rear face of the tranny. If I were really brave I would cut a slot into the tranny itself!!!

 

Any comment?

 

-----------------------

 

The slave cylinder itself is where the throw-out bearing resides. If you look down into the hole where the actuation rod goes you can see the exposed balls and carrier. Way cool.

 

I'm thinking about taking my grease gun with a rubber tip and injecting some grease into this bearing.

 

After all, I am hoping this slave cylinder will go another 69,166 miles!!!!

 

Stan

[steve.foote]

Stan, if it were me, and I had a 70k bike torn down to that point, I think I'd replace the slave cylinder. The little thrust bearing inside it is awefully small for the job it does. Mine was toast at 36k.

 

Just curious, but are you doing this on your '96RT? And if so, doesn't it use a cable/lever actuated throwout bearing instead of a hydraulic slave cylinder?

 

[edit] Oops, I just went back and looked at your profile only to discover that you also have an 1150RT. Please disregard that last paragraph. Sorry. [/edit]

[Stan Walker]

Just curious, but are you doing this on your '96RT?

 

I did the '96 RT earlier this year at 70,921 miles. It got a new clutch kit as it was nearing the wear limit, new clutch cable, new neutral switch, and new final drive pivot bearings. Splines were fine, regreased with Honda moly 60. Hopefully good for another 70,000 miles.

 

Stan

[Stan Walker]

Stan, if it were me, and I had a 70k bike torn down to that point, I think I'd replace the slave cylinder. The little thrust bearing inside it is awefully small for the job it does.

 

I did think about it. And I do have a brand new slave on hand.

 

But....

 

The old one feels fine. Looks fine. No apparent leaks.

 

Perhaps if I had installed a new clutch disc I would have replaced the slave too. Since I reinstalled the old clutch disc it only seems fitting that I install the old slave cylinder.

 

Stan

[Cali Kid]

Stan, if you have the clutch slave cylinder off, it is easy to diassemble. This will allow you to properly clean and pack that bearing. A much better idea than shooting grease down the hole. I think I cleand mine with a toothbrush and solvent, then repacked it with clean grease. Just remove the C-clip on the bearing end and the thing comes apart. Just bleed it as normal when you reassemble it.

Also, this will give you the opportunity to replace the cupped seal inside the cylinder. Does BMW sell these seperate? I heard they don't.

Anyway, its easy to get apart, clean, inspect and lube.

 

P.S. I wouldn't cut holes in gaskets. I'd hate to have that DOT4 fluid blowing all over the bike, it stains and peels paint.

[Clive Liddell]

Stan,

I was wondering if there's enough space on the slave housing to drill a small hole and press fit a short pipe into it? Then a length of tubing can join the other drains.

[Stan Walker]

I'd hate to have that DOT4 fluid blowing all over the bike, it stains and peels paint.

 

Good point. I'll keep a close eye on it. I'm not sure routing it to the clutch is a good idea either, guess where it goes from there?

 

Stan

[Stan Walker]

I was wondering if there's enough space on the slave housing to drill a small hole and press fit a short pipe into it? Then a length of tubing can join the other drains.

 

That's a really good idea. Wish you had thought of it before I put it all back together...... I'll keep it in mind for next time, in another 70,000 miles I hope.

 

If you drill really carfully that should be possible. It would be easier to drill through the tranny case though.

 

Stan

[Stan Walker]

A much better idea than shooting grease down the hole

 

Hmmm, my approach only took 10 seconds.....

 

Stan

[Ken H.]

I was wondering if there's enough space on the slave housing to drill a small hole and press fit a short pipe into it? Then a length of tubing can join the other drains.

That's a really good idea. Wish you had thought of it before I put it all back together...... I'll keep it in mind for next time, in another 70,000 miles I hope.

 

If you drill really carefully that should be possible. It would be easier to drill through the tranny case though.

 

Stan

When I had our '02 apart I thought about the same thing, creating an 'escape path' for any fluid that might accumulate in the tranny's slave cylinder cavity. In the end I didn't do it because I decided it was just a 'band aid' solution. I.e. - Not solving any leaking issues properly. I was also worried about what might get back into the cavity via the route I would create for something to get out of. I figured BMW put a gasket there for a reason.