sometimes it's the trussrod. when you take all the tension off the strings by divebombing, the trussrod/neck shifts slightly causing a sound. very annoying. try to divebomb the trem while you have a finger on the back of the neck and see if you can feel it when it makes that crack sound.
other than that...is your
locking nut loose? check the 2 screws that hold it down.
if you're comfortable adjusting the trussrod, i would just give it a slight turn and see if it's loose, or if it finds a better spot and stops making that noise. but just like 1/4 turn.
1/2 turn max. you can always put it back to where it was if it doesn't do anything.
