Teardown: Omega Seamaster Automatic DayDate calibre 1020

Another one of Constantine’s watches he sent from NY – an Omega Seamaster with the 1020 calibre. This is a great movement beating at 8 bps / 28,800 bph. He sent it in as it hardly has any power reserve when using the auto-winder, but it’s fine when hand-wound. Probably something a service will sort out.

To start off with, let’s put the watch on the timegrapher.

Nice and straight lines, a bit too fast, and the amplitude is a bit low. But this looks good.

The watch back snaps off.

Looks like it’s been a while since the last service. No service marks on the watch back, but there are other people than me that don’t like to scratch their customers’ watches 😉

I remove the winding stem, and take the movement out of the case. Now I remove the hands and the dial.

The day and date rings on the bottom plate. As usual, the days of the week appear twice, so that the wheel doesn’t have to be moved 1/7 of a turn every day, but only 1/14.

The date changer is actually made from plastic. Nothing wrong with that, it will make the day change sound less clanky.

The winding and setting mechanism is very dirty, and parts are oxidized. Looks to me like water got in past the crown and down the winding stem.

Definitely no waste of time to give this watch a service.

Now I turn the movement around to the top plate.

The auto-winder bridge and assembly.

Onwards and upwards ….

With the wheel bridge removed, you can see that the mainspring barrel drives the second wheel (there is no centre wheel), and the third wheel drives on one side the second hand arbor, and through the plate, on the bottom plate, the cannon pinion which drives the motion work.

Balance wheel assembly.

Just the pallet fork left.

The pallet fork needs some cleaning as well.

The worst damage is on the pull-out piece, but I’ll probably manage to clean it up.

The hairspring looks very good, and so does the balance wheel.

The mainspring doesn’t look too bad.

Ready for cleaning ….

The story continues here.

11 thoughts on “Teardown: Omega Seamaster Automatic DayDate calibre 1020

  1. Hi,
    Im interested to buy your balance wheel /bridge/cock. are they clean, good condition?
    What is your price please?

  2. Repeating the question – why doesn’t it have seamaster on the face? Was the back added later ? I have a 1970’s automatic and it looks very much like this one.

  3. I have a 1972 Omega SS Seamaster day/date that watchmakers can’t seem to regulate. What is the cost range to have you service and calibrate?


  4. Hiya Christian, lovely presentation! My 35 yr old Seamaster uses the same movement, but I’vve never seen it myself up close like how you shown it.

    What does the long number ‘45418074’ represent – it’s above the 1020?

    Is there an adjustment when a 1020 is a few seconds fast per day?


    • Hi Edward,

      That number is the serial number of the movement. If it’s constantly fast by a couple of seconds per day, you can adjust the speed at the regulator – no problem.

      If it’s not constantly fast, it might require a service.

      Best regards,


  5. You have my permission to scratch anything you want on my watches :). Seriously.

    Actually, I consider watchmakers’ scratchings useful and valuable, not to mention sort of an interesting form of modern day hieroglyphics.

    • I rather like to see service dates inscribed on watch-backs… shows it has been owned by someone who cared enough about it to actually get it serviced!

  6. Pingback: Teardown Omega Seamster Automatic Day/Date calibre 1020

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