Hydraulic Clutch-Loss Of Power

[torvil]

Hello I had a problem with the hydaulics on my "001 R1150RT Clutch over Christmas. The problem was easily remedies with fluid change as the old fluid was a dirty chocolate colour, giving impressive results with new DOT 4 in the system.
The clutch has recently lost some of it's power again, gear change clunky, biting point reduced etc.
I checked the resevior and found that the level has reduced and the colour has turned into a dirty graphite grey black colour.
It's now pointing towards the master or slave cylinder. I can see no apparent leaks form the master cyclinder without moving the body of the lift grip mechanism, neither is there any fluid on the floor from the slave cylinder.
Is there a way of inspecting/replacing the slave cylinder, without removing the rear wheel, shoch absorber, exhaust and collector box? Is there a walk thorough on here for the operation, as the Haynes manual, shoes little illustation.
I have three weeks to fix the bike before my tour of Scotland.

[iowabeakster]

It's almost certainly the slave.

I don't know how much different the RT is from my R. So, I can't help with directions for checking/replacing it on the RT.

You might want to check out: http://bmwsporttouring.com/ubbthreads/ubbthreads.php

Lots of RT riders hang out there.

[Sunbeemer]

Does the fluid smell like transmission gear oil (foul smelling stuff) or like brake fluid?
If it smells bad, your transmission seal could have failed allowing gear oil to collect in the slave cylinder and deteriorate the piston. Worse than that is the possibility that this oil is making its way past a felt seal around the push-rod actuator to the clutch plate if it is not repaired in time...

[boxermania]

Due to it's location and the proximity to the heat emanating from the cat converter, the slave cylinder on older bikes has a tendency to leak past the seal.

The leakage is usually minor, unfortunately, it is also internal to the system and usually travels via the pushrod that operates the clutch throwout bearing, ultimately getting onto the clutch disc and affecting the opertion of such.

As sugested by Sunbeemer it is in your best interest to take care of the problem as soon as possible. The correction requires the rebuiding or replacement of the slave cylinder along with a good flushing of the master cylinder and the interconecting lines.

Do search on the subject, CycleRob has some good pictures along with a mod to insure that the slave cylinder will leak outside the enclosure.

Good luck.

[CycleRob]

I checked the reservoir and found that the level has reduced and the color has turned into a dirty graphite gray black color.

The dirty graphite gray color is what I saw on my OilHead many months before the failed slave bearing was found during the clutch shaft spline clean-n-greasing. The graphite gray color is caused by frictional wear of the Aluminum slave piston spinning in it's Aluminum bore. That happens when the pushrod's throwout bearing that's built into the slave piston fails, the resulting friction causes the spinning clutch release pushrod to turn the slave piston. Just a "heads-up" for you to have the replacement slave assembly on hand before you take things apart.

It is possible to remove/replace the slave without taking too much apart, like lifting the frame or removing the swing arm, but the really tight, very difficult access will have you wishing you took the whole thing apart at the start! Here are my related pics:


Click on Thumbnails, then click on the pic that appears to get it full scale.

[Ol' Jeffers]

Excellent photo guide, Rob, great stuff!

[torvil]

Thanks CycleRob. I am going to run a mile after seeing the pics as I don't feel confident removing the shaft mech. My limit would be wheel, shock and exhaust. I'm taking it to a local bike mech who has done a slave on his 1150gs before.

[keithbw]

Agreed, Thanks CycleRob

I read his report many times before (and during) tearing mine apart. Invaluable info for the casual mechanic. While I was able tear my RR down and and get it back together, I needed many times more than the one weekend required by the more experienced mechanics on this board.

Once you've removed enough parts to easily access the slave, might as well pull the tranny and check out those pesky spines. Again, see CycleRob's posts for making cheap and effective guide pins for safe removal of transmission and other helpful hints.

Brian