I was told that the best water temp for cranks was 75 to 80 when you should start pulling cranks. It works for me.
Your right 75 - 80 degree water temperature is the "best" but you can get bit at 60+ degrees. We where catching them constantly in October at 62 at Grenada.
PROUD MEMBER OF TEAM TWEENER! Member of Tri-State Crappie Anglers