230SL Clutch Slave Cylinder

[Tomnistuff]

Sometime in the last two years, I bought a rebuild clutch slave cylinder for my 230SL restoration.  Now that I'm ready to install it, I find:
  1.)  inside the accordion boot which was installed with non-reuseable clamps, the piston had pulled out of the cylinder
        and was cocked and jammed,
  2.)  the assembly lubricant has all dried up and there is slight surface rust in non-critical areas,
  3.)  I've lost the original slave cylinder that I removed from the car, so I cannot compare the two,
  4.)  there is no spring under the piston in the new rebuilt slave cylinder,
  5.)  the BBB does not show a cross-section of the slave cylinder, however the Haynes Manual shows a tapered spring
        in the 230SL slave cylinder, and the EPC does not show a spring but does list an unspecified spring
        (A1119931110) following the part number listing for the slave cylinder.
 
I will clean and reassemble the rebuilt slave cylinder if someone here can help me answer the following questions.
  a.)  Is there supposed to be a spring under the piston of the slave cylinder?
  b.)  What grease is supposed to be used to assemble the piston into the slave cylinder, considering that there will
        be brake fluid used in the cylinder?

OOPS:  I just found a posting by Benz Dr. that says there is supposed to be a spring inside the clutch slave cylinder.  One down and one to go!

OOPS:  Another mistake.  I found that the spring part number above in item 5 is the "external" return spring, which I have, so the EPC does not show or list an internal spring for the clutch slave cylinder.  Where am I going wrong?

Tom Kizer

[wjsvb ✝︎]

Most manuals recommend using brake fluid in assembling the cylinder.  Jon

[Benz Dr.]

I think that it's the 280SL that has an internal spring. Since the 230 has an external return spring, it doesn't need a spring inside.

[Tomnistuff]

Hi Jon and Dan,

Jon, thanks for the tip on the brake fluid as an assembly lube.  I’ve been an engine guy all my life but my “chassis and body” experience and knowledge leave something to be desired.

Dan, what you said about the spring makes perfect sense to me.  The internal spring could only push the piston out to take up any clearance that occurs between the piston pin and the throw out bearing lever.  Since that hypothetical clearance is eliminated every time the clutch pedal is pressed, and all the other forces are trying to return the piston deeper into the cylinder (the clutch diaphragm spring acting through the throw out bearing lever and the throw out bearing lever external spring pulling the lever toward the cylinder), there is no reason for that hypothetical clearance to become real.  My inspection of the cylinder and fluid inlet convince me that there is no way the piston can be pushed deep enough to cut off the fluid flow. preventing bleeding.  I wonder where the Haynes Manual got the drawing since it does not show up in the BBB (at least not any more).

Thanks again to both of you.  I’ll now go back to work on it.

Tom Kizer