Clutch Slave Cylinder granules

[peltonjohn]

I removed the clutch slave cylinder as part if an engine removal on my 1984 GL1200A. When it came out there were all these yellow granules, like coarse sand. What is it?

[WingAdmin]

If it's white and powdery, it's corrosion of the aluminum slave (or master) cylinder (or caliper).

But the crusty stuff you're seeing is brake fluid that seeped out, mixed with moisture in the air, and gradually dried out, leaving behind that residue. You'll want to remove all traces of it during the rebuild.

[peltonjohn]

Brake fluid in the clutch slave cylinder? I thought that would have been transmission fluid or something that sounds related to the clutch...

[WingAdmin]

Brake fluid in the clutch slave cylinder? I thought that would have been transmission fluid or something that sounds related to the clutch...

No, it is brake fluid. The clutch slave cylinder is just an actuator - like a brake caliper. The clutch lever pushes a piston, which pushes brake fluid from its reservoir down the clutch line and into the slave cylinder. There the fluid pushes on the piston inside the slave cylinder, which slides in the cylinder and pushes a rod, and the rod pushes on the clutch, actuating the clutch.

Brake fluid is just hydraulic fluid, and that's what is happening here - changing force on the clutch lever into hydraulic pressure, and back into force at the slave cylinder.

There's no transmission fluid in a motorcycle!

[peltonjohn]

Thank you very much! I did know that the transmission system is often lubricated by the engine oil, but I had never dealt with the slave cylinder before.