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Replace Rotor Bearing

Mark
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Mark Distinguished Member

Mark

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How to replace a rotor bearing in two watch movements - the ETA 2892-A2 movement (on an Omega Dynamic watch). And a Valjoux 7750 movement (on an Ikepod watch).The rotor bearing on these watch movements and their variants often wear faster then the other parts in the watch due to constant movement and vibration.

When servicing these movements it is best practice to replace the bearings so that the automatic mechanism runs optimally.

Replacing them is a near impossible task without the correct tool. The bearing nut tool is made by Horotec and also Bergeon makes one.

There are two key sizes. The 7750 is smaller than the key for the 2892-A2.

Attempting to remove the bolt without the correct tool will likely cause damage to the weight. Refitting the bolt without the correct tool is almost impossible.

The tool is relatively easy to use. I recommend placing the weight on a small staking block so that you can apply pressure to the bolt without depressing the weight (causing damage).

I have created a quick video showing the removal and replacement of the bolt on both these watch calibres.

Feel free to comment below.

Click here to view the article

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    • Neverenoughwatches
      Stem removal after fitting hands

      By Neverenoughwatches · Posted

      So leave off the seconds. Stand the movement on its edge, its the dial edge that rests on the pad ( either rubber or cork , something that wont slip ). Use a finger of your left hand to hold the movement upright,  right hand presses the release and flicks out the stem. I do it this way so i can see what I'm under a microscope. But you could hold the movement between two fingers of your left hand, its the right that has to manipulate the stem out by pushing the release and flicking out the stem with  right ring finger nail. Sounds more complicated than it actually is. I guess you could fix a push pin to something solid, then all you need to do is push the release against the pin, leaving your right hand completely free to pull the stem out.
    • HectorLooi
      Battery

      By HectorLooi · Posted

      Try putting everything back together and closing the back cover. I think one of the two springs has to contact the metal casing to ground the casing. So when you press the button, it will touch the contact on circuit board and close the circuit.
    • PeterS
      Stem removal after fitting hands

      By PeterS · Posted

      Yes, the seconds hand is the longest and goes almost to the edge of the dial. I can’t quite picture it how you do it on the rubber pad
    • Murks
      Battery

      By Murks · Posted

      A don't think so it leaked or damaged it because the watch itself works it just the buttons ain't working not connecting with the circuit board have taken more pictures of where the buttons makes contact with the circuit board.
    • Neverenoughwatches
      Stem removal after fitting hands

      By Neverenoughwatches · Posted

      I think what peter means oh is once he has fitted the hands and  checked for  alignment if them and that they dont foul, how does he then hold the movement to remove the stem in order to case up. The dial cannot be laid on a cushion or in a movement holder as the hands will get damaged. This can be quite tricky for a beginner, what i do is  to stand the movement on edge on a rubber pad so it doesn't slip. Hold the top edge with one finger then my dominant hand uses 3 fingers to press the stem release and flick out the stem. See below peter, leave off the second hand as this is the longest and gets caught the most, then fit it once the stem is out. Alternatively place the movement in one of the cup style holders, i imagine this is what they are designed for. They only touch the very edge of the dial.  
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