Service & Repair: Breitling TransOcean / Valjoux 7740

IMG_5395Sometimes, we are very tempted to send a watch back, rather than attempt to repair it. The risk for us is pretty high, as we don’t charge for unsuccessful repairs, so we can get stuck with hours and hours spent on a watch without getting any money for our work.

This Breitling looked a bit challenging of first sight …The next challenge was to open the case back. Ray told me that the watch had been with Breitling for an estimate, but I couldn’t get the case back open… I have the normal Breitling dies with an odd number of corners, but this one had an even number. £50 later, I had the right die.IMG_5399

You can see that I’m not the first one trying to open the case!IMG_5853

This does not bode well. There is a lot of rust on the chronograph bridge, and you can see some below the start/stop lever as well.IMG_5857

I take the lever out, and there is even still some water in there. If I hadn’t invested £50 in the case opener die, I would probably send the watch back, but also, I do like a challenge, and this is a nice watch with a nice movement.IMG_5860

The dial looks nice for its age.IMG_5861

The 7740 has a date, and a quite peculiar sub-second construction.IMG_5862

The rusty chronograph bridge.IMG_5863

Below, it’s looking better.IMG_5870

I remove the chronograph parts.IMG_5873

Down to the base movement. No more rust here.IMG_5877

The gear train comes out.IMG_5878

The intermediate wheel has some rust at the bottom, but as it’s easily available, I order a new one.IMG_5879

The movement will also get a new mainspring.IMG_5882

The hour wheel has some corrosion as well. To the right of the hour wheel sits the little wheel that drives the centre second pinion (removed in this photo), which sits just above the wheel in the little hole that you can see.IMG_5883

The bottom plate comes apart, and I’m ready for cleaning.IMG_5997

All the parts ready to be put back together.IMG_5999

The new intermediate wheelIMG_6000

The gear train in place.IMG_6001

And the base movement is beating. Note the hollow screw of the crown wheel – the minute recorder goes through it.IMG_6003

Very nice performance, and what you would expect from a Valjoux.IMG_6005

Now I can put the chronograph back together.IMG_6006

I couldn’t find new original screws for the chronograph bridge, so the old ones go back in. They have been cleaned and won’t cause any harm. If new screws can be obtained, they can be changed later without any problems.IMG_6007

The bottom plate back together.IMG_6008

The orange hands all need some new paint.IMG_6023

The dial goes onto the movement.IMG_6024

All the hands back in place.IMG_6025

I’ve cleaned the case thoroughly in the ultrasonic cleaner, and removed the pushers and cleaned them separately.IMG_6026

The movement goes back into the case.IMG_6027

Final check and adjustment of the chronograph.IMG_6028

Now the new crystal goes back on.IMG_6029Great looking watch.IMG_6030

On it’s bracelet, a real stunner.


Now for some testing. For the chronograph, it’s best to run it against a stop watch, as any problems with the minute and hour recorders will show up that you otherwise wouldn’t detect. And I wanted to show off my lovely Junghans stop watch with 1/10s function 😉


13 thoughts on “Service & Repair: Breitling TransOcean / Valjoux 7740

  1. It went to Breitling for an estimate… and still came back with water in it? Seems strange any watchmaker wouldn’t let it dry out before returning it – even if the client didn’t want to proceed with the quoted work?

  2. I am working on the exact same chronograph. Is it correct that you can only turn the crown CW? The click as it is does not allow the crown/ratchet wheel to be turned CCW. Is this correct? Thanks, Craig
    PS – this one also had water damage so the cannon pinion and hour wheel had to be replaced.

  3. Not normally a fan of Breitling watches but this is one I would love to own!

    Is the bracelet after market? I don’t think Breitling would have left the bracelet proud of the watch case like that!??

  4. These sort of sub-dials always remind me of the old gallon petrol pumps when I was a kid. So had someone attempted to use it as a dive watch? The water seems to have got in around the pusher?

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