Re: "Crack" noise on either forward or backcast
Sorry I couldn't get back sooner... The answer is yes. The transition begins slightly before the line straightens and it begins slowly by moving the rod hand back toward the body from the extend position at the end of the backcast.
In practice, when the brain tells the arm "o.k. do it to it," by the time the arm begins to respond, the line will have fully straightened ... It's sort of like the lead you and I would give a fast moving dove when wing-shooting.
I need to emphasize that the rod hand plays no part in the transition until the arm has been withdrawn back into the side of the body -- the point where the rod hand begins the turnover into the forward cast. At the beginning of the transition, the rod hand should remain in the same position that ended the backcast.
The most frequent errors that I see is (1) the failure to pull the arm back toward the body and, instead, using the rod hand far to early in the forward casting stroke; and (2) powering into the forward cast with far too much speed.