So I'm tracking down some funky clutch feel issues and decide to go ahead and spring for a new slave and master cylinder first to eliminate those two factors on a fairly high-mileage R53. It supposedly got a new clutch before I bought it, so I'm reluctant to jump straight into that job without doing the simple stuff first.

I bought a Sachs master cylinder and the fitment is just kind of sloppy for the 90 degree elbow that mounts into the rear of the master cylinder. The previous unit is snug-ish but was not leaking. Everything was bone dry before I fixed what might not have been broken. I put a little fluid into the reservoir and let it sit overnight and sure enough the joint is leaking with no pressure on the system.

I have had bad luck in the past just taking an o-ring to the local auto parts shop and trying to match it up. They don't have any metric o-rings on hand typically. I could order the line coupling for basically 50 bucks and wait a week and a half, but I would much rather just sort the o-ring if possible. Any idea if there is some sort of secret data-base of these o-ring sizes somewhere? Real OEM just gives me the line part number, no specs on any seals.

 

When you bleed the clutch, make sure you do it with the slave cylinder fully pressed in with a clamp system, otherwise you will have a hard time getting the air fully out, the bleed screw and inlet are too close together.


Even with a power bleeder, it didn’t work until I did this.

 

Has this been resolved? Did you find a matching O ring at the local store or online?