BMW OEM - Clutch Slave Cylinder, OEM - E46 incl M3, X3, Z4, Z4M (21526766279)This is the OEM clutch slave cylinder for all E46 including the E46 M3 and all Z4, including the Z4 M Roadster Coupe. A failed clutch slave cylinder will cause the clutch pedal to fall to the floor with no pressure. There's no pressure inside the lines because the seals inside the slave cylinder have failed. Unfortunately, this happens with almost no warning although if there is a spongy feeling or excessive slop in the clutch pedal travel it could be