pedal drop

The problem happens After talking a fast hard turn without any pressure on the brake pedal. Then I go to apply the brake's and the pedal is low and needs to be pumped up to go back to normal. I think what is happening is the pistons in the calipers are pushing back from the G force. Dose this sound logical? Whats the solution? Check valve? Or am I off coarse? I am using o ring calipers. Thanks John

Excessive wheel bearing play, the pads get kicked back by the rotor (due to wheel bearing play)

Didn't think of that I will check the the rotor's this weekend.