Using a flathead screwdriver to remove vintage-style mounting screws.

Because a higher gear ratio lets the post rotate in smaller increments, you have more control over the tuning process. In other words, an 18:1 ratio offers a finer degree of control than an 11:1 ratio. Lower ratio keys make it harder to reach a precise string tension, and this can cause you to jump past the desired note as you tune up.

Modern replacement keys have a much higher gear ratio than vintage keys. For example, modern Grovers have ratios from 14:1 to 18:1. New Klusons are as high as 19:1. Gotohs range from 14:1 to 28:1, and Graph Tech’s new Ratio sets have variable ratios, from 39:1 on the low E to 12:1 on the high E.

Look beyond the ratio. If you’re planning to upgrade your tuners, there’s more to consider than just the gear ratio.

For starters, if you have a vintage guitar (or an expensive modern instrument) and the keys are deteriorating or not working properly, I recommend installing direct replacement keys that do not require any modifications. Whenever you drill new holes or enlarge the existing holes in the headstock—or anywhere, for that matter—it devalues the instrument.

For a vintage axe, always store the original keys in a safe place to preserve them. Gotoh, Kluson, and Grover make excellent direct replacement keys that typically offer higher ratios than vintage tuners, but are otherwise a drop-in retrofit for Strats, Teles, Les Pauls, and other popular models. If you do the research and find the right tuner, you can make a clean installation with simple hand tools. We’ll cover this in a moment.

If you have a modern instrument and decide to install tuners that aren’t direct replacements, be aware that this usually affects the guitar’s tone. When you change mass on the headstock—by adding heavier or lighter hardware—it changes how the neck responds to string vibration. It’s hard to predict exactly how the tone will change—and guitarists debate this endlessly—but if you like how your guitar currently sounds, think twice before you install non-direct replacement tuners.

Because a higher gear ratio lets the post rotate in smaller increments, you have more control over the tuning process.

Locking keys. If your guitar has a vibrato arm or tremolo bridge, locking tuners can really help you keep in tune. Locking tuners clamp the string in place either by using a rod inside the post or a collar that wraps around the post. Both methods are effective and eliminate the need to wind the string around the post more than once. When you eliminate multiple windings, the string doesn’t have to reseat itself on the post when it returns to pitch after being slackened. Companies that make direct locking replacements for existing keys include Planet Waves, Schaller, Sperzel, and Gotoh.

Staggered-height posts. If you have a flat headstock with six tuners in a single row—like those on a Fender—think about upgrading to tuners that have staggered-height posts. On most guitars, staggered-height tuners eliminate the need for string trees, and this too can improve tuning stability—especially on guitars with whammy bars. Staggered tuners typically have posts in three sizes: strings 1 and 2 take the shortest posts, strings 3 and 4 take the medium ones, and strings 5 and 6 use the tallest.

If the staggered height tuners aren’t direct replacements for your existing tuners, remember that changing the mass on your headstock has sonic consequences. You might actually like this, but you can’t really predict the outcome in advance.

Changing your keys. If you select direct replacements for your existing keys, installing the new ones is a simple process. Typically, you need a small screwdriver (flathead or Phillips) and sometimes a 10 mm nut driver or a deep-well socket.

Most modern keys use Phillips-head screws.