Signs you need a new clutch slave cylinder 1150GS

Discussion in 'GS Boxers' started by Sniperx, Nov 12, 2013.

  1. JimVonBaden

    JimVonBaden "Cool" Aid!

    Joined:
    Feb 11, 2005
    Oddometer:
    64,844
    Location:
    Alexandria, VA
    This is a decent example of how it is done:

    <iframe width="420" height="315" src="//www.youtube.com/embed/fDSLWYHuj4g" frameborder="0" allowfullscreen></iframe>

    Jim :brow
    #61
  2. Sniperx

    Sniperx Been here awhile

    Joined:
    Jul 1, 2013
    Oddometer:
    773
    Location:
    Socal
    Stay with me on this.....

    Maybe that cavity is SUPPOSED to fill with fluid. Thats what lubes the throwout bearing. That would also explain the need for an actual gasket there.

    Just a thought...

    Pretty sure its wrong though since there wasn't much of a sign of 90wt in there or on the push rod....actually that would encourage oil flowing down the the pushrod tub and into the clutch....disregard this ramble completely.
    #62
  3. vintagerider

    vintagerider Long timer

    Joined:
    Nov 20, 2005
    Oddometer:
    1,976
    Location:
    the west
    Sniperx: I am assuming that there is enough clearance between the pushrod and i.d. of the hollow input shaft so that the limited vacuum simply draws from the clutch side. No vacuum is applied to the interior of the gear box. There is certainly enough gap for leaked gear oil in the cavity to make it to the clutch disc. Anyway it was just a thought not a recommendation.

    You still have not made a case, at least to me, for not seating input shaft seal all the way in to the cavity. Steptoe ought to know and that is what he says that he does. Easy enough to make the pvc seating tool if you want to.

    I'm fairly certain that I say an uncovered bearing from the cavity in my 2000 build date. That does not mean that yours is not covered. I don't see what difference that makes anyhow. I do not recall an groove cut in the cavity to oil the bearing such that driving the oil seal in too far would block it.
    #63
  4. Sniperx

    Sniperx Been here awhile

    Joined:
    Jul 1, 2013
    Oddometer:
    773
    Location:
    Socal
    I'll get some pics this time while I'm in there. I'll even use the snake cam and get in there close if it looks like something.
    #64
  5. AntonLargiader

    AntonLargiader Long timer

    Joined:
    Aug 28, 2003
    Oddometer:
    4,736
    Location:
    Charlottesville, VA
    My BMW install tool has a lip roughly 1.5mm (where the 0.170" is in the drawing). It also has a pilot to guide the seal lip over the input shaft.

    Between the slave and the input seal should be dry. Not only do I omit the gasket completely, but I drill a drain hole. I actually have a bad slave bike on a lift now; the brake fluid ran down the pushrod and soaked the friction disk. With a drain hole he'd have noticed it before it got to the point that I had to disassemble the transmission to fix it right.
    #65
  6. GS Addict

    GS Addict Pepperfool

    Joined:
    Sep 24, 2006
    Oddometer:
    4,937
    Location:
    Sunshine Coast B.C.
    Yes, its done on a lathe. It's a shop tool that I can't live without.
    It gets daily use.

    Although I am a licensed Industrial Electrician I spent many years working in Process Control and Automation and had full access to machine shops. I was very fortunate to have had training from the old European masters who were more than willing to share what they knew if anyone showed interest.
    We were also allowed to work on personal projects after hours, not common today.
    I went into business 16 years ago for myself and own an electrical manufacturing company.
    At 56 I now look around me and there are few young men who are interested in anything but keyboard jobs. I wonder where it will all end up. The trades in NA are shrinking.

    If you get the chance to work at a machine shop, go for it. It's a pretty cool trade.
    #66
  7. Sniperx

    Sniperx Been here awhile

    Joined:
    Jul 1, 2013
    Oddometer:
    773
    Location:
    Socal
    Well I got in there again.

    Removing the seal was much easier this time. It was definately leaking from that seal. It was sealed all the way back there. When you remove the seal you expose a channel on top about 1/8 inch across. I inspected the shaft with my cam and it looked pretty good, didn't cause any damage. Must be hardened. I pushed the new seal in with my tool until it was flush with the case. The second lip barely clears the end of the shaft, but it's there. I ran the bike for 15 minutes plus 1 minute at 4000rpm....drY as a bone.


    Th bearing behind the seal definately is sealed or shielded. It's made by nsk. This could be why my seal wasn't working...the oil can't clear fast enough due to the sealed bearing. It still doesn't change that the seal could contact he balls or cage.


    So there's a few points here. Flush, 1.5mm, .170", 4.5mm, and to the bearing. So far, to the bearing doesn't seem to be universal advice. 4.5 comes from the dealer and confirmed by measuring Photos. .170 is close to 4.5mm. Flush was recommended on another forum and is obviously he hear minimum.


    So now I'm stuck how deep to go now.....
    #67
  8. AntonLargiader

    AntonLargiader Long timer

    Joined:
    Aug 28, 2003
    Oddometer:
    4,736
    Location:
    Charlottesville, VA
    I'll try to double-check tomorrow and make sure I was looking at the right install tool.

    Until then, just take a bunch of measurements and have a good think.
    #68
  9. Sniperx

    Sniperx Been here awhile

    Joined:
    Jul 1, 2013
    Oddometer:
    773
    Location:
    Socal
    Well, I went ahead and split the difference and made a spacer for the tool. I pushed he seal into about 2.5mm past flush. I ran a shorter test with the same results. I buttoned the whole hint back up and bled the system for a reservoirs worth of fluid to flush any contminants. Topped up the transmission with some highend 80-90 weight for racing with moly in it and took it out. Works perfectly. The tranny has lost that industrial tractor feel and everything's nice quiet. Also played in the dirt a little today....this thing is fun off road. Dumped it on an hillside during a u turn in soft dirt. Did it the worst way too...wheels going up hill. After some cursing all was good again.

    I took lots of pics including some details he instructions leave out.
    #69
  10. vintagerider

    vintagerider Long timer

    Joined:
    Nov 20, 2005
    Oddometer:
    1,976
    Location:
    the west
    Important and should be in the sticky. Hopefully Steptoe will update his advice on this. I must have overlooked that oil channel on mine. I don't know why my seal which was driven all the way to the bearing isn't leaking. Could mean that I'm starving that bearing but perhaps it's sufficiently oiled from the gear side.
    #70
  11. AntonLargiader

    AntonLargiader Long timer

    Joined:
    Aug 28, 2003
    Oddometer:
    4,736
    Location:
    Charlottesville, VA
    The notch is about 5.5mm deep whereas the seal is 8mm thick, so the seal will not go in far enough to leave a gap at the top.

    I was looking at the 721 driver which is for a different version of the 6-speed so ignore my 1.5mm measurement.
    #71
  12. GS Addict

    GS Addict Pepperfool

    Joined:
    Sep 24, 2006
    Oddometer:
    4,937
    Location:
    Sunshine Coast B.C.
    I got the .170 from the first transmission I did (mine).
    It was original.
    I always record measurements before disassembling.
    #72
  13. Sniperx

    Sniperx Been here awhile

    Joined:
    Jul 1, 2013
    Oddometer:
    773
    Location:
    Socal
    Well, went for a long ride this weekend, no further problems.

    It seems the thing is designed to accommodate different depths, possibly for rebuilding purposes...allowing a clean shaft seal area.

    I would say any depth between 1mm-4.5mm is safe. Flush puts the second seal lip JUST at the end of the shaft right at the little bevel at the end of the shaft. This is too close in my opinion. "All the way to the bearing" may work in some cases, but definitely NOT in my case. The official word from BMW is to use the tool which sets it in at 4.5mm.

    A theory: With the seal all the way to the bearing, there may not be enough space for the oil to accumulate and flow back into the case. By setting the depth, the oil pools below the seal level. This is just a theory though.
    #73
  14. JimVonBaden

    JimVonBaden "Cool" Aid!

    Joined:
    Feb 11, 2005
    Oddometer:
    64,844
    Location:
    Alexandria, VA
    Lots of good information in this thread. Thanks for sharing with us your experiences. :thumb

    Jim :brow
    #74
  15. UT R1150R

    UT R1150R Long timer

    Joined:
    Feb 28, 2006
    Oddometer:
    9,316
    Location:
    Utah
    Would you please show where you drill a drain hole?
    #75
  16. Poe

    Poe Been here awhile

    Joined:
    Oct 23, 2006
    Oddometer:
    192
    Location:
    SC
    My clutch slave failed this past weekend (at about 36K miles on my '03 GS)... just pulled it last night to verify and it was indeed full of brown mud. What am I risking if I DON'T replace the clutch line or that seal in the back of the slave cavity? I'm thinking clean out the master cylinder and flush it and the line real well and clean out the slave cavity and just stick a new slave in there. I just don't feel real confident about being able to pull that seal out of there (where exactly do you drill a hole in it to insert a sheet metal screw?) - and get a new one back in there correctly (especially given all the confusion about what the correct depth is!).

    Thanks!
    #76
  17. GS Addict

    GS Addict Pepperfool

    Joined:
    Sep 24, 2006
    Oddometer:
    4,937
    Location:
    Sunshine Coast B.C.
    Disassemble and inspect the bore of the cylinder. Look evidence of the piston spinning (typically there is if the bearing is gone)
    The bore is hard anodized and if that surface is compromised a new seal won't help.
    The little bearing is only available to Magura so consumer replacement is not an option.

    Buy a new slave from BBoneyard and be sure to add extra grease to the little bearing (typically undergreased for the manufacturer)

    Flush all the old fluid thru (fresh DOT4) and don't worry about the lines, they are not rubber like the brake ones.
    #77
  18. Poe

    Poe Been here awhile

    Joined:
    Oct 23, 2006
    Oddometer:
    192
    Location:
    SC
    Thanks Addict. Sorry, I wasn't clear about which seal I was referring to. I was talking about the seal in the rear of the transmission case... inside the cavity that the slave assembly fits into - through which the clutch pushrod goes. How critical is it that I replace THAT?
    #78
  19. GS Addict

    GS Addict Pepperfool

    Joined:
    Sep 24, 2006
    Oddometer:
    4,937
    Location:
    Sunshine Coast B.C.
    Not, actually I cut a slit in the bottom so if the slave leaks the fluid runs out that way instead of along the rod and contaminating the clutch.
    Also noticeable then as well.

    Edit: Sorry I did not read thru. - if that seal is not leaking leave it be. If you do change it, be sure to put it back exactly at the same depth, do not bottom it as some have suggested on other threads.
    (The gunk is water soluble (brake fluid based), if you find gear oil then change the seal)
    #79
  20. 100RT

    100RT Long timer

    Joined:
    Nov 4, 2009
    Oddometer:
    1,192
    Location:
    N. E. OHIO
    Is he referring to the gasket or the seal?
    #80