It may be ironic, but most people have no idea how one of the the most important features, fine tuners, were developed on the Floyd Rose. The whole experiment resulted in a tremolo that has essentially been forgotten in time, the FRT-4. The production FRT-4 started creation sometime in 1982 by Fernandes Japan and was the first Floyd Rose to feature fine tuners. It is said that 25 prototypes of the FRT-4 were made in the USA by Floyd Rose, many of them going to high profile artists. The production units (made in Japan) were only made for four months, which may make it the most rare production Floyd Rose unit along with the FRT-1 and USA “5150” FRT-5.
The FRT-4 was most notably played the Eddie Van Halen on his 1982 Frankenstrat with a sanded Kramer logoed neck. Eddie, however, played a prototype hand-made version (and not a production version).
The invention of fine tuners were the direct result of many musicians complaining that the non-fine tuning Floyds would go flat or sharp once the locking nut was clamped. This wasn’t an issue with Floyd’s early FRT-1 prototypes because he could make the locking nuts to small tolerances. When the FRT-1 and 3 were brought into production, however, the factories could not recreate the extremely detailed tooling tolerances Floyd used in his shop.