main seal depth

[Lucky_Ted]

Well i thought i put the rear seal on right, but I should have payed attention to everyone else's stories about having to install a second seal. What I've done was place the seal on the engine shaft and allow the clutch housing to push the seal towards the engine. The result is that the seal is about 1.5 inches deep. Have I gone too far or not far enough?


I understand that the new seal is supposed to be 25mm with a "protrusion of .5mm towards the engine housing", does this mean that the seal is supposed to be driven 24.5mm deep or 25.5mm deep? Also, I remember reading a thread on here (can't find it now) stating that the inside of the seal should be "flipped out" to create a seal. I've only seen mention of this once, so is this what should be done, or should I leave the seal as is when I drive it in?


Lastly, should I rebuy any of the usual nuts and bolts that are always replaced on clutch inspection (i.e. clutch bolts, housing nut)? I built the bike up and tore it back down to redo the seal but haven't started it up (I don't know much but I know that you want to plug an oil leak before starting an engine), is it acceptable to reuse the "new" nuts, bolts, etc. even if they've already been torqued down once?

[rbm]

The seal should sit 0.5mm proud of the face of the casting.  Refer to this BMW notice:

http://www.motobrick.com/index.php/topic,4993.0.html

So, to use your parlance, the seal needs to be driven into the opening 24.5mm.

BMW's recommendation is to replace all washers, bolts and nuts when doing clutch service and/or seal replacement.  In practice, many guys reuse the parts.  I'd recommend replacing the main clutch nut but check the condition of the other fasteners to determine if they can be reused.  With new parts being more and more scarce, complete replacement of fasteners as a matter of course is an expensive proposition.