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  1. theadmiral976

    theadmiral976 May 9, 2020

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    Hi all! Has anyone tried to upgrade the mainspring in their watch, specifically for an ETA 7750 / Calibre 16 movement? I have read that some of the 7750s from other manufacturers have been modified to attain longer power reserves - perhaps up to 72 hours in some cases...
     
  2. absolutemustard

    absolutemustard May 10, 2020

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    I would assume it would severely change the power delivery delta from the top to the bottom of the reserve if you just put in a larger spring, severely affecting the accuracy.

    Other companies probably replace a lot more items in the movement, and/or they reduce the beat rate
     
  3. ExpiredWatchdog

    ExpiredWatchdog May 27, 2020

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    I looked at a couple suppliers and both only list a single mainspring P/N and Barrel Assembly P/N. Honestly, the only thing I could see is what ETA did with the C07 movements where they lengthened the spring and reduced the arbor diameter. But then none of the C07 parts show up in the commercial suppliers websites; you have to have a Swatch account and order them directly from Swatch.

    A more likely mod would be to reduce the rate to 21600 with a heavier balance wheel and a 15 tooth escape wheel. That's a 25% improvement which would get you to 60 hours. Still, those parts wouldn't show up on the commercial suppliers websites either.

    Just bite the bullet and get a Speedmaster '57.
     
    theadmiral976 likes this.
  4. theadmiral976

    theadmiral976 May 27, 2020

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    Yet another Omega to add to my list lol

    Thank you both for your replies - very informative!