Service: Longines calibre 340

P1120062A good customer has sent in his vintage Longines calibre 340. It’s not running very well and the rotor is loose. I have been a little reluctant doing these as parts are few and far between, so I do it on time and material with no guarantee of success. If everything is straight forward I will of course only charge normal service fee:) 

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The Longines calibre 340 is designed around the autowinder device. The oscillating weight has teeth that engage with the reverser wheels allowing for very effective winding.

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Not preforming very well.

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You can see the scars from the oscillating weight being slack.

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I have removed the hands and dial and you can see the setting/winding mechanism.

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You can also access the reverser wheel and intermediate auto winder wheels from the dial side.

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The setting lever spring is actually accessible from the top side of the movement.

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Here you can see the gear train layout. The big toothed wheel is the intermediate autowinder wheel that engaged with the oscillating weight.

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One dirty mainspring! (ironically it says do not open on the lid)

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Getting a new oscillating weight ball bearing is out of the question. But it’s possible to tighten the bearing plates that hold the balls using the staking set. The bearing balls are made out of rubies on this one, but were not put up on the movement ruby count;)

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I clean the movement and it is ready to be put back together.

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I clean and fit the mainspring.

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I see that the balance moves freely after fitting the shock jewels. The Longines 340 has a nice micro regulator.

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Base movement back together and running.

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I fit the winding/setting mechanism.

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I fit the autowinder wheels.

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I have to say it’s a very cool movement and nice to work on when nothing is too worn out.

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Hmmm as you saw in my last blogpost I was not happy with the sad state of most of these Longines enamel case backs.

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A little cold enamelling magic and we are in business!;)

Another classic watch ready to be worn again.

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2 Responses to Service: Longines calibre 340

  1. I love looking at these photos of these incredible, delicate machines, and seeing the journey you take with them — although the intricacies are lost on me! I wonder, how long does it take you, typically, to work through all these steps?

    Liked by 1 person

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