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Thread: Grover 409 Tuners OK on Loar 600?

  1. #1

    Default Grover 409 Tuners OK on Loar 600?

    Hello All,

    Does anyone happen to know whether any mods are required to replace Loar 600 tuners with Grover F style 409 tuners?

    If not then are there other tuners that will drop in?


  2. #2
    Registered User
    Join Date
    Oct 2015
    Howell, NJ

    Default Re: Grover 409 Tuners OK on Loar 600?

    I am not an expert on the subject but my understanding is that the post spacing on modern tuners is standard. The issues would be the location of the worm gear (over or under) and the post diameter if you use the same gromets. There was a rather detailed discussion on the forum recently on this subject and a good teutorial by Paul Hosteler. Here is a link that explains the worm gear issue.

    On this forum try searching for this thread

    "Source for f style worm over tuners"
    Bob Schmidt

  3. #3
    Registered User Mandobart's Avatar
    Join Date
    Apr 2009
    Washington State

    Default Re: Grover 409 Tuners OK on Loar 600?

    I've replaced the tuning machines on several mandolin family instruments. As Bob said above the roller (post) spacing has been standardized since before most of us were born. This is the least of your concerns.

    However, roller diameter and bushing size vary enough that I've had to modify the instrument or bushings every time I've done it.

    If you're lucky the new bushing outside diameter will be larger than your existing ones, in which case you just gently hand ream the headstock holes for a snug fit. If the new bushing OD is less than the existing ones you can build up the OD with coats of superglue or nail polish (let it dry completely before installing). Some people use wraps of Teflon tape. If the size difference is too much for that you could plug the headstock holes and re-drill, but if it were me I'd select a different set of tuning machines be for doing that. I have no idea if this will be an issue with the machines you are asking about.

    In some cases the bushing sizes might be the same (i.e., from the same mfr as the originals). Removing old bushings can be tricky. Removing the old bushings can be the toughest part of the job. I'd expect The Loar instruments may have the finish sticking to the bushings - sometimes you'll chip out some finish with the old bushings. I use a wood dowel that I sharpen in a pencil sharpener to try to gently press out old bushings from the back of the headstock. IF you have a very sharp exacto blade and a steady hand you could attempt to slip under the bushing collar and score the finish all around (without damaging the visible finish - pretty tricky). What works better is a hardwood scrap piece that has a hole that is drilled to be just a tiny bit bigger than the OD of the old bushing collar so you press out the old bushing with this wood tight against the front of the headstock. That should help prevent chipping the finish.

    And once you put the new tuning machines in you'll almost certainly need to drill new mounting holes for the plate screws. I plug the old unused holes with toothpicks glued in with Titebond liquid hide glue and trim flush with a sharp knife. If they're going to be visible with the new tuning machines in place I try to stain them to match the headstock.

    As Bob shared the worm position on the new tuning machines has to match the existing ones or the shafts and buttons will end up wrong and may interfere with the headstock curve (on an F like the Load 600). Also the tuner plates may hang over the bottom which you just don't want. Another issue I've seen is if the shafts are too short on the new tuning machines its very hard (sometimes impossible) to turn them as the buttons hit the headstock sides.

    My recommendation is buy good tuning machines from a known brand with a solid return policy if they won't work on your Loar.

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