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Slave Cylinder Weep Hole


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Anyone have a photo of a 2004 1150RT or similar which shows where a weep hole might be drilled? I can't seem to find anything here after a bit of a search.

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12 hours ago, Andre1150 said:

Anyone have a photo of a 2004 1150RT or similar which shows where a weep hole might be drilled? I can't seem to find anything here after a bit of a search.


Morning Andre1150


Personally I don't dill the trans as I just slot the slave to trans gasket for the slave cavity drain. (the BMW 1200RT doesn't  even use a slave cyl gasket)


It is a pain  to drill a drain hole with trans still in the bike as the hole is slightly angled, access is difficult, & you need a long drill bit.


It is also advisable to pull the slave cylinder out before drilling to avoid damage.


If you really want to drill then just remove the slave cylinder as you can then see (sort of) where the drain hole needs to END UP in the slave cavity. Then angle (as needed)  the  long drill bit to try to end up there. The hole placement doesn't have to be real precise, just make sure that it is at bottom of slave cyl cavity & rearward enough to not hit or damage the rear input shaft seal. 


If you put    "slave cylinder"   into the search box at top of page (use quotes as shown) then there might be some drilling info in an old thread.



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I've read several times that my '99 R1100S engine is very similar to the R1150 engine, so maybe this will be of some help to you IF you haven't already completed it.


There are several ways to vent the hyd fluid from a failed slave cyl, the easiest might be as Dirt Rider described above.  There is a 1/32" or so annular space all around the slave all the way back to the three screw flange that holds the slave cyl (SC) on the trans.  The gasket that came with my new BBY SC was very thin and leaving a 1/4" gap at the 6 o'clock might be enough "hole" to handle the flow of DOT4 from a failed SC.  It seems to me that mine failed very quickly, dunno. 


Alother option is to cut a notch at 7 o'clock in the face of the boss that the SC mounts on. See pics A and B.


Remember this about the SC: the throwout bearing for the clutch is in the SC piston and is a tiny little sealed ball bearing.  ALSO, it is under a load from the push rod and is turning at crankshaft speed whenever the engine is turning.  It's under more load (and turning) with the clutch engaged.

I would strongly recommend replacing the SC if you so much as loosen the three screws that hold it in while you are doing a weep hole.  The clutch is easy to bleed, too.


In the pic below is the weep hole in the circle (1/16" dia).  This pic is looking up from under the toe shifter, #2.  #3 is the bottom left corner of the tranny.  #1 is the rear of the starter motor.


In the pic A, the arrow points to the drain hole from the inside,  the two parallel lines show the location of an alternative notch.


In B, it is a closeup of the hole from the outside and the alternative notch.


More pics here:https://goo.gl/photos/QEN3xyQVWXW1jraT6  and  https://goo.gl/photos/WB9DZXksFyRq5mPm8  and  https://goo.gl/photos/Aqdx8nEN6rjbZvw17

Weep hole for Slave Cyl.JPG

Weep hole for SC 2.JPG

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Having seen this tranny and SC out of the bike and "up close and personal", plus having to replace the clutch once because of the SC fail, I would feel very comfortable in drilling the weep hole "in situ" on a bike.  Loosen the three Phillister head screws and slide the SC back maybe 1/4" to be safe as Dirt Rider recommends (there is already a 1/4" space between the SC and tranny).  Don't even need to disconnect the 2 hydraulic lines. A weep hole is MUCH easier than a clutch job.  AMHIK.  


You would need a 1/4" hex drive drill bit (1/8" dia) and a 12" hex extension/bit holder to reach it.  You would need to use a punch to start the drill bit as the angle is not verticle to the surface. 


If I did it again, I would install a short brass tube (nipple) and a 6" long clear plastic tube (like the old float bowl drain on a carb).  You could then easily check it for any leaks.  A new clutch will cost you upwards of $1,400 plus parts.  Again, AMHIK.

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