Ok, upper two pistons- if both retracted and the brake lever operated then only the external piston moves. If you hold the external piston in with a tool then the inner piston moves. Once you start the inner piston from its bore then it continues to move, even when you stop holding the external piston.
Ok, upper two pistons- if both retracted and the brake lever operated then only the external piston moves. If you hold the external piston in with a tool then the inner piston moves. Once you start the inner piston from its bore then it continues to move, even when you stop holding the external piston.
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