How long do brake master cylindes last?

[Chris DeStaffany <destaff@yahoo.com>]

So, I was looking at E-bay and the description for a
new brake master cylinder said "your's will fail
sooner or later"  I'm wondering what an expected life
might be on these things.  I'm getting ready to
rebuild mine because I'm slowly changing out about
everything in the brake system and was just wondering
what others have found.

Chris DeStaffany
Friday Harbor, Wa 

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