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Thread: Clutch slave cylinder symptoms

  1. #1
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    Clutch slave cylinder symptoms

    If the Slave Cylinder rod does not seat properly in the clutch fork, what will the symptoms be? In other words how will the clutch peddle feel?

  2. #2
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    As far as I have seen, it will either seat properly, or it will miss totally. If it's proper, you will have to force the slave to the mounting studs against hydraulic and spring pressure. If you miss, it will go onto the studs with little effort. Proper, the clutch pedal will feel normal. If you miss, the pedal will go to the floor, you'll hear a faint "tink" as the pushrod falls into the bellhousing, and you will be pulling the transmission.


    /.randy

  3. #3
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    If it's not seated correctly, the piston blows out of the slave cylinder and into the bell housing, followed by brake fluid. There is nothing subtle about it.

    What exactly are you feeling?

  4. #4
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    Well it was seated ok because the touch of grease I put on the fork was in the end of the rod.

    I feel a pedal that seems to hit a rock solid wall. It goes down half way and it feels solid. I took the slave back out and it seems ok. I double or triple checked each step as I put it all together.

  5. #5
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    I also made sure everything else was functional but there is no way, that I know of, to test a clutch, without the trans in place. Maybe thats a tool to make.

  6. #6
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    Let's back up a bit. Why did you take the slave out in the first place? Was it for this problem, or is this something fresh?


    /.randy

  7. #7
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    New flywheel and clutch installed. Stock type LUC

  8. #8
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    That means something is mechanically stopping the clutch travel. Combining this with the question you asked yesterday... Was the throwing star removed before installing the pressure plate, or was the p/plate unbolted from the flywheel, even loosened, after removing the star?


    /.randy

  9. #9
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    No to both. Your question about unbolting the pressure plate from the fly wheel. This means that can not be done without making that type of P/plate useless? The guy from LUC stated that if those yellow springs are expended then the clutch is garbage, even if brand new. Seems strange that they can assemble it and sell it but if you make the error you can't undo it.

    Anyhow I put the flywheel on, then the p/plate as per instructions, all torqued up per spec. Star removed after. (Actually I did that months ago because I have too much going on and it was snowing or raining anyhow.)

    How much travel should one get from the clutch fork. I noted the slave (with it's built in pressure) pushed the fork up to the P/plate so it is already tight before you press the clutch peddle. (I noted this after removing the slave and that the fork had to be pulled back.) Realistically the clutch needs very little gap to spin free. A tenth of a mm should do it but how much the p/plate has to be moved before you get free play is a good question.

    I need to find a way to see inside at the yellow springs.
    Last edited by catimann; 05-11-2017 at 08:45 PM.

  10. #10
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    During assembly, they have a jig to hold all the parts in place while inserting the throwing star. Search the E46 forums and youtube, people have devised ways to reassemble/reset those adjusting wedges. I personally never had to do that. One time one of my guys screwed up an install by putting the disc in backwards. Doing this kept enough tension on the plate that the wedges never moved, and I reinstalled the throwing star without incident. I do not remember the symptoms of the disc being backwards beyond it would not release. The disc goes with the thick side to the flywheel; backwards from how most clutches go.

    The total movement is surprisingly small. The pedal ratio is what, about 4:1. Then master to slave is 1.2:1, then the release arm is 2:1. The system rides the t/o against the plate full time.


    /.randy

  11. #11
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    I've reset a self adjusting clutch. It's not "hard" but I did do it at a machine shop. Slapped pressure plate on a lathe, and used the tailstock to press it in. Then I spun the internal adjusting mechanism to the original position.
    -Abel

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  12. #12
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    Quote Originally Posted by catimann View Post
    No to both. Your question about unbolting the pressure plate from the fly wheel. This means that can not be done without making that type of P/plate useless? The guy from LUC stated that if those yellow springs are expended then the clutch is garbage, even if brand new. Seems strange that they can assemble it and sell it but if you make the error you can't undo it.

    Anyhow I put the flywheel on, then the p/plate as per instructions, all torqued up per spec. Star removed after. (Actually I did that months ago because I have too much going on and it was snowing or raining anyhow.)

    How much travel should one get from the clutch fork. I noted the slave (with it's built in pressure) pushed the fork up to the P/plate so it is already tight before you press the clutch peddle. (I noted this after removing the slave and that the fork had to be pulled back.) Realistically the clutch needs very little gap to spin free. A tenth of a mm should do it but how much the p/plate has to be moved before you get free play is a good question.

    I need to find a way to see inside at the yellow springs.
    The pressure plate can be reset/reinstalled; this E-46 clutch (and its from birth engine/flywheel and 6-sp xmsn) were all installed in an M Coupe last year. The car was then driven from Texas to Monterey, CA and back.




  13. #13
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    Quote Originally Posted by rf900rkw View Post
    One time one of my guys screwed up an install by putting the disc in backwards. Doing this kept enough tension on the plate that the wedges never moved, and I reinstalled the throwing star without incident. I do not remember the symptoms of the disc being backwards beyond it would not release. The disc goes with the thick side to the flywheel; backwards from how most clutches go.
    Well now you have me wondering if I made an error installing the disc. I doubt there is a way to check that without removing the P/plate. Still the trans will have to come back out. At least that part I had figured out and it was smooth and easy.

    Also if I understand this correctly these self adjusting clutches will totally become useless if you take off the P/plate for any reason? Unless you have the tools etc. to reset them.

    Just tested it with a friend. Clutch depressed, trans in gear is the same as no clutch at all. I guess I have a backwards disc. Just hope I can do the same as you did Randy and reinstall the throwing star. The thing is the disc is labeled in some way.
    Last edited by catimann; 05-12-2017 at 09:58 PM. Reason: Update

  14. #14
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    There are two ways to tell which way a clutch disk goes in:

    1) The clutch disk has the works engraved on it of "transmission" to tell you that this face looks towards the transmission.

    2) The clutch disk has a tab that interferes with the flywheel bolts if its the wrong way around. Before installing it, it is easy to hold the clutch disk up to the fly wheel and try and turn it. If it does not turn then the tab is up against the flywheel bolts and you have got it wrong.
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  15. #15
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    Quote Originally Posted by Muzz258 View Post
    There are two ways to tell which way a clutch disk goes in:

    1) The clutch disk has the works engraved on it of "transmission" to tell you that this face looks towards the transmission.

    2) The clutch disk has a tab that interferes with the flywheel bolts if its the wrong way around. Before installing it, it is easy to hold the clutch disk up to the fly wheel and try and turn it. If it does not turn then the tab is up against the flywheel bolts and you have got it wrong.
    Took out the trans again just now.

    Yes the LUC disc says "Getriebeseite" on it and that means Transmission side. I can see that between the spring fingers. I would say I did not install it backwards.

    The yellow springs on the p/plate are also still compressed.
    Last edited by catimann; 05-14-2017 at 10:22 AM.

  16. #16
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    I even checked the diameter of the throw out bearing but it is also ok. Really stuck.

    Thinking of taking off the p/plate and putting on the old one, just to test it.
    Last edited by catimann; 05-16-2017 at 12:24 PM.

  17. #17
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    Quote Originally Posted by catimann View Post
    I even checked the diameter of the throw out bearing but it is also ok. Really stuck.

    Thinking of taking off the p/plate and putting on the old one, just to test it.
    Might it be possible to just rent the SAC resetting tools locally, to verify that it didn't somehow get sprung either before or during the installation?

    Please note that since neither the M coupe nor Rdstr came with a SAC, I have very limited exposure to working with them__like maybe two (2) or three (3) times, tops, so I'm openly admitting that I don't know what I'm talking about

    For a visual comparison of what that clutch pictured above looked like before, during and after being reset, you can follow the sequence of pictures beginning mid-page here: http://spcarsplus.com/gallery3/index...S54_MR_?page=5 and continuing through page 7.

    Good luck; it's either going to be something really simple, or you were given the wrong parts.

  18. #18
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    Thank you for taking the time to read this and reply. Wrong parts, that is an idea I had not considered. The old clutch was not this type so perhaps it is possible. The pictures are interesting and I found this video on line. https://www.youtube.com/watch?v=xcAYG0h8Iaw It has no audio to speak of but seems to show the reseting of a pressure plate and how it adjusts under use. Knowing how it works always helps me. I do not think the p/plate is the same as mine but it is close enough.
    So I also talked with the LUK tech guy last Thursday. The wrong part no was the first thing he zeroed in on. He suggested that my hydraulic system could have air in it so I bleed my system to make sure I had all the travel needed and all new fluid. No difference, the clutch did not disengage. So I took the trans back out to remove the P/plate, after reinstalling the star (worked just fine). My plan was to try the old one. My original issue was a creaking noise that turned out to be the throw out bearing on the Guide tube (the grease had worn off over 80,000 mi, or was never there. (so the reason for changing the clutch was a noise and function was not. The difference in disc thickness was only 3/10mm. ). You can't have a BMW with a creaking sound each time you press the clutch!) Either way I put on the old p/plate and put it all back together. It works. Thus I now need a new new p/plate that matches my old one.
    Last time I use RM European.

  19. #19
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    You shouldn't put a grease on any of the components inside the bellhousing (not saying you did...) because the clutch material that gets worn off the disc will stick in it, creating an abrasive slurry.

    When deemed necessary, I've used a dry-graphite spray that hasn't seemed to produce any ill effects.

  20. #20
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    Thanks Randy I will look at that idea. When I removed the trans the guide tube was dry with only some clutch dust on it. There was also some polished surface area on the slave side. The side that the throwout bearing seems to rub along as it moves. My father was a machinist and I have his tools, so I used a micrometer to measure several diameter points on that guide tube. The wear was imperceptible.

    From what I can see my creaking noise (The reason for this whole inane re and re.) sounded like this:http://vid255.photobucket.com/albums...ps70upysds.mp4
    I replaced everything inside the bell housing with new parts except: The "throw out bering lever", the slave cyl and the Guide tube. (Also for the purpose of just testing the old p/plate was used as well. I am glad I had to do this for the simple reason of proving I had the wrong new p/plate and to prove that the old p/plate was not contributing to the sound)
    As i was saying the creaking noise was (I believe) caused by a dry contact, contaminated by clutch dust, of the throwout bearing to the guide tube. Thus I will look at some sort of lube for that sliding action.
    Perhaps this sounds like BS rambling but I just want to give as complete a picture to my issue as I can in case some other poor guy ends up with the same annoying sound.

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