Just can’t bring yourself to put a Floyd on that vintage Strat? Here’s a tip for keeping a non locking-trem in tune, be it Fender or Bigsby style.
Guitars go out of tune when using a whammy bar, because strings get caught at the nut or bridge when pressing the arm down, and are thus stretched tighter when the bar comes back up, so the sound sharp. The string windings can loosen, as well, and not tighten all the way when the bar returns to position, creating the same problem. While locking tuners fix this latter issue, and lubrication helps with the former, there is another trick that can help you stay in tune—even if your strings still stick a bit.
First ask yourself, “Am I primarily a wiggler or a bender?”
If you primarily rock the arm for vibrato, start by rocking the arm as you normally would, and then tune up without stretching the strings. This allows the strings to catch, and, once caught, they should stay there as you use the whammy bar. Should you bend a string, it may go flat, but all you have to do is hit your bar, and the guitar will magically return to tune for your next chord.
If you are a mostly a bender, you are better off stretching the strings before bending the bar. Then, bend the bar to determine which strings go sharp, and stretch them back into tune. Don’t retune them with the tuners until you pull them from their “caught position.” Should you use the bar during a solo, you will have to gently yank the offending strings with your fingers before your next chord. With a well-cut and lubed nut, you should only have to pull one or two strings.