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Discussion Starter #1
I've just finished the 36k mile service and was going to start the weep hole project. I'm looking at the Clymer manual and the BMW manual and I can't figure out how a slave cylinder leak can make it through the transmission to the clutch? Can someone please explain this to me.
 

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Wrencher Extraordinaire
2005 K1200LT
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The transmission input shaft is hollow and the clutch release rod resides inside it. One end in the throwout bearing at the end of the slave and the other end inside the clutch housing. I guess I should add that once the leak starts there is no where for the fluid to go except down the rod and into the clutch. The weep hole may or may not let all the fluid out but at least you will KNOW you have a leak if you check it periodically.
 

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Discussion Starter #3
Thanks John,
I thought there was a reason. Do you know how much clearance there is between the slave cylinder and the transmission wall when the cylinder is installed?
 

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Wrencher Extraordinaire
2005 K1200LT
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From the face of the slave to the boss with the rear shaft seal is about 3/16 of an inch.
 

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If you're referring to the front of the slave cylinder itself and the mating hole in the tranny, the fit is fairly close, perhaps a few thousanths. The problem is between the close fit and the gasket between the slave and transmission there is no place for any leaking fluid to go but along the shaft where it ends up dripping on the clutch. The void John refers to fills quickly.
 

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mjordans2000 said:
If you're referring to the front of the slave cylinder itself and the mating hole in the tranny, the fit is fairly close, perhaps a few thousanths. The problem is between the close fit and the gasket between the slave and transmission there is no place for any leaking fluid to go but along the shaft where it ends up dripping on the clutch. The void John refers to fills quickly.
Actually, the clearance around the nose of the cylinder is pretty decent, as there is a bit of a taper to the cylinder nose, and there is more than a few thousandths even at the rear of it. When the drain hole is drilled I always tried to get it to come out as close to the bearing as I could. That way the fluid has a very easy path out.

I still say the hole should be called a "drain" hole, not a "weep" hole. Weeping denotes a very slow leak, but when the slave seal fails (probably often caused by the throwout bearing tightening up and spinning the piston in the cylinder as at least one of mine did) the fluid is forced out under pressure at a pretty high rate, and you need it to "drain" out fast enough to keep it from rising to the center of the bearing where the actuator rod is.
 

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Wrencher Extraordinaire
2005 K1200LT
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David,


Maybe we should call it the anti-weep hole. If you don't have it and the leak develops you will be weeping when your clutch slips. :p
 

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jzeiler said:
David,


Maybe we should call it the anti-weep hole. If you don't have it and the leak develops you will be weeping when your clutch slips. :p
Makes sense. ;)
 

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Yeah, it's been a while. David's right. Not sure why the clearance is relevant, with the gasket the fluid can't go anywhere without the weep hole.
 
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