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Thread: Clutch master cylinder

  1. #1
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    Clutch master cylinder

    Just purchased a '89 535i with 230K miles. Nice car but needs some TLC. The clutch pedal makes a pop just after depressing. Spent today pulling apart the pedal assemble thinking it was a broken bolt inside the return spring. No luck, the spring is fine. Put back together w/o the spring which BTW, causes the cruise control to stay disengaged because the pedal does retract fully w/o the spring and activate the cruise switch. Anyhow, the pop is still there occurring the the top of the throw. I noticed with the pedal disconnected from the master cylinder rod, the rod flops around like it isn't connected to anything inside the cylinder. Is this normal? Seems like it should stay secure in parallel with the cylinder itself.

    Let me know if anyone has similar experience. Replacement cylinder is ~$200 so I'd really appreciate some inputs before pulling the trigger.

    Thanks all.

  2. #2
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    The rod does pivot because it is only attached to the cylinder with a circlip. But I would pull the boot and inspect it to make sure the circlip is in place. I buy the Febi masters for about $45 and they hold up nicely.
    demet

  3. #3
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    Quote Originally Posted by demetk View Post
    The rod does pivot because it is only attached to the cylinder with a circlip. But I would pull the boot and inspect it to make sure the circlip is in place. I buy the Febi masters for about $45 and they hold up nicely.
    Thanks for feedback. I’ll check it tomorrow. Looks like PO replaced slave and master not too long ago. Was hoping it wasn’t recommended to necessarily purchase the OEM master. Big price difference. Replacement job doesn’t look difficult.


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  4. #4
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    Decided the clutch master cylinder is defective so I'm replacing with an FTE brand. Supply line to the brake fluid reservoir was leaking so needed to also replace that (not so easy). Now I'm having a terrible time getting the nipple inserted into the rubber seal in the master cylinder. Is it necessary to first remove the rubber seal, connect it to the supply hose nipple, then reinsert into the master cylinder? That thing is so tight I can't get it.

    Thanks all.

  5. #5
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    Quote Originally Posted by jwhyland View Post
    Decided the clutch master cylinder is defective so I'm replacing with an FTE brand. Supply line to the brake fluid reservoir was leaking so needed to also replace that (not so easy). Now I'm having a terrible time getting the nipple inserted into the rubber seal in the master cylinder. Is it necessary to first remove the rubber seal, connect it to the supply hose nipple, then reinsert into the master cylinder? That thing is so tight I can't get it.

    Thanks all.
    There's no trick for the hose connector, just brute force, and the hose side is almost as bad... Those things are tough, I remember my fingers were sore for a couple of days after that

  6. #6
    moroza's Avatar
    moroza is offline MORΩN ΛABIA BMW CCA Member
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    Dish soap is a great rubber lubricant.

    My rule of thumb is that if a BMW part performs a relatively generic function - such as tierods or clutch hydraulics - it's ok to use aftermarket. If instead it's finely tuned to the application - such as suspension rubber or engine internals - OE is the only way to go. Cost and difficulty of replacement factor in as well. Note that sometimes, certain aftermarket manufacturers (Lemförder in particular) *are* the OEM, and all you're getting with the BMW-branded part is 1. a lighter wallet, and 2. a cast BMW logo that wasn't ground down.

  7. #7
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    Finally got the sucker back in. Used a trick to back tread the mount bolts to line up the holes. Also found the bolt closest to the firewall should be connect first for easier alignment. The 11mm flare nut is a bitch so I ended up disconnecting the other end that goes to a flex hose (on engine side of fire wall). Then, I could pull the M/C inside the get to the impossible to reach nut. Another thing I discovered is that before pressurizing the line & bleeding, the clutch goes right to the floor and the return spring works in the opposite direction (pinning the pedal to the floor). Interesting. Anyhow, bleed the system and took it for a spin. The "pop" is gone which was the main goal of this job. Noticed the pedal is not as responsive as my '90 535i5. Seems a little soft and doesn't return with the same responsiveness. Could this be caused by the slave cylinder? I plan to manually bleed the slave tomorrow to be sure there's no air in the line.

    Thanks!

  8. #8
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    One last question. The new M/C does not extend far enough (in the up position) to activate the clutch switch. Turning the eccentric bolt doesn't help because it's almost 1/4" too short. So, now the cruise doesn't work because it thinks the clutch pedal is always depressed. I noticed my '90 535i5 doesn't have this switch which I find odd. The electrical schematic shows no difference between '89 and '90. Thinking there might be a work around to bypassing the clutch switch.

    Is it possible the FTE M/C is shorter than the OEM by ~1/4 inch?

    Anyone else encounter this problem?

    Thanks.

  9. #9
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    You need to adjust the clutch switch by pulling out the plunger and then letting the clutch pushrod ratchet the plunger back into position.
    demet

  10. #10
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    Quote Originally Posted by demetk View Post
    You need to adjust the clutch switch by pulling out the plunger and then letting the clutch pushrod ratchet the plunger back into position.
    Solved - excellent!! Thanks a million.


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