Originally Posted by dlbushey
My girlfriend has 2 K1100LT's...a '93 and a '95. She has over 100,000 combined miles on the two bikes and has used the same dealer (in fact, the same mechanic) the entire time she has owned the bikes with no issues in his performance. However, I have heard from others that this guy "couldn't fix a ham sandwich."
I bring this up because of my slave cylinder problem. I asked him if he would drill a drain hole while everything was apart during the repair. His reply was that the drain hole fix is a myth. When the slave cylinder leaks, the oil follows the piston right into the clutch drain hole or not.
I would not allow him to fix my ham sandwich then. The fluid leaks past the piston seal, and is then already past the piston, and falls into the cavity between the nose end of the slave cylinder and the transmission input shaft rear bearing. As BMW delivers the bike, it cannot escape.
Look at the attached picture. When the slave cylinder fails, the fluid has to build up to the level of the hole you see in the center of the transmission input shaft, then it is forced down the shaft around the actuating rod, which has been pulled out in this picture. Then and only then can it get into the clutch. You can see that brake fluid has alread wetted the bearing seal here, but the clutch had not yet been contaminated to any extent. This was on Ken's bike, done as a preventative maintenance procedure, and his slave was showing signs of leaking a little. We may have been a little late, because a few thousand miles later he is showing signs of clutch problems, but he thinks it is engine oil this time.
If the fluid is allowed to drain out, which the drain hole does, then it cannot get to the level of the hole through the tranny shaft, so cannot get to the clutch.
There are very few really knowledgeable BMW mechanics who can analyze something and come up with other than the BMW documented procedures (most do not even know a high percentage of those). To most, if it is not "in the book", it is automatically "wrong". They may be good mechanics for all normal procedures, but are not "thinking" mechanics. A smart mechanic will see the hole drilling as a positive thing for preventing undue clutch problems caused by a slave cylinder failure.
Unfortunately it is like that for mechanics for all motorcycles, automobiles, and everything else. Very few really good master mechanics who see beyond the "book".