Brake problem

[Dave <dfox@blarg.net>]

Hello All,
 I'm at my wits end trying to solve this one. Please help !
In my '67 Midget ...
My brake pedal goes to the floor and requires a pump or two
after every right hand turn and sometimes after long staights. 
After a few pumps it's great and holds without fade.
I've bled the system a few times now and the problem stays the same.
The rear shoes are adjusted properly. 
Sticky caliper piston maybe ?

Thanks in advance,
 Dave Fox
'67 Midget