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M50TU + zf trans clutch won't disengage

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    #1

    M50TU + zf trans clutch won't disengage

    As the title says I have a M50tu with a zf trans from a 95 m3. I'm using the s50 clutch with the e30 clutch master and m3 slave cylinder. Got the car running pushed the clutch ground the gears. Bled the clutch both with a power bleeder and with the slave out of the car and this time tried starting the car in gear with the clutch pushed and it rolled forward a bit. Clearly can't get the clutch to disengage.

    So I'm at a loss, pulled the slave and tried to manually push the clutch with a piece of bar stock and couldn't get anything to budge. Anyone have any idea what is going on? Thanks in advance.
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    #2
    Don't think you would be able to manually push the clutch like that. Sounds like too short of a slave cylinder rod or a not fully bled system to me.
    The best one-stop shopping for German car parts and lifestyle: http://www.gutenparts.com/

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      #3
      I did use a 24" pry bar on the bar stock so I was able to apply quite a bit of force. I had read something about the slave from a 325 working but I figured since I was using m3 trans and trans the m3 slave would work. Maybe the master doesn't move enough fluid for the m3 slave?

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        #4
        Did you try the two man method for bleeding it? Maybe there's still area somewhere the system?
        IG: deniso_nsi Leave me feedback here

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          #5
          I didn't try the 2 man because I figured bleeding the slave while it's off the trans is essentially the same thing, I'll put it on the list of things to try, thanks!

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            #6
            Originally posted by AlpineCoupe View Post
            I didn't try the 2 man because I figured bleeding the slave while it's off the trans is essentially the same thing, I'll put it on the list of things to try, thanks!
            are you sure the slave itself hasn't failed?
            IG: deniso_nsi Leave me feedback here

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              #7
              Brand new febi slave, replaced an AutoZone part figured it would be more stout.

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                #8
                A bit embarrassed to ask this but if the throwout bearing was installed on the fork incorrectly would we be experiencing the issues I've described?

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                  #9
                  system is not bled properly.

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                    #10
                    Did you happen to replace the pivot pin? Or at the very least inspect the one that came with the transmission?

                    Had this problem before.. pivot pin was completely smashed down so the throw out arm was too far inward so the TO bearing wasn't getting enough throw.

                    If the clutch slave was not able to move at all when bolted to the trans then your clutch pedal would be hard as a rock.

                    I've also seen this happen with the clutch disc is installed facing the wrong direction but usually on aftermarket performance setups.

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                      #11
                      Had a chance to look at the pivot and it was pretty well smashed in. Ordered the stainless steel pivot from rogue engineering, hopefully that will help get to the bottom of our issue.

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                        #12
                        Stainless won't squish but there is a reason it was made of plastic / delrin. High pressure and friction of two metals pivoting against each other will eventually wear a hole. This is why the other aftermarket metal ones are made of brass. Stainless is harder than the steel that the throw out plate is made of. Over time the stainless pin will drill through it.

                        Not a big deal if you will have the trans out for service every few years but a bad long term solution.

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                          #13
                          Good call with the metal differences, this is a track only car so service intervals will be pretty tight. And I think it would probably take a ton of miles before the pivot actually wore through the fork. But a good thing to keep in mind.

                          Kind of surprised BMW used a stainless pivot on the 8 series, maybe the fork was made to be a bit reinforced where the pivot hits on that model.
                          Last edited by AlpineCoupe; 03-12-2014, 01:26 PM.

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                            #14
                            Originally posted by AlpineCoupe View Post
                            Kind of surprised BMW used a stainless pivot on the 8 series, maybe the fork was made to be a bit reinforced where the pivot hits on that model.
                            All depends on the quality of the two metals but like you said it will see periodic service intervals so I wouldn't sweat it. If you still have issues with the pivot point you can also use some thick washers to space it out 5-10mm if even to just help adjust pedal feel.

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                              #15
                              Just wanted to post that the new pivot from Rogue seemed to do the trick. Car now drives under it's own power!

                              Clutch engagement is right off the floor (using no clutch stop) but it does work. Thanks for all of the replies.

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