I was wondering if anybody knows if there is a rebuild kit for the rear brake master cylinder since a new one is just under 200 bones. Mine has a pretty good leak and the rubber boot is well past the age of innocence.

I'll replace the whole thing if I have to but it'd be easy to rebuild....if the parts were available.

Slowride

REPAIR KIT BRAKE MASTER CYLINDER D=13MM MAGURA Up To 10/1988 34311454438 $87.89USD

http://www.realoem.com/bmw/showparts.do?model=0514&mospid=47868&btnr=34_0620&hg=34&fg=10

try this. I got one from Motorworks but these people sell it for about the same money:
http://www.motobins.co.uk/displayfinal.php?s=0&function=show&subs=106d&title=%28BREMBO+%26+MAGURA%29+REAR+MASTER+CYLINDER+OVERHAUL+KITS&model=K100

Thanks guys. I appreciate it...