Service: Audemars Piguet Royal Oak 14800ST calibre 2125

P1020056Steven sent in his Audemars Piguet for a service. The watch doesn’t have a lot of power reserve, and isn’t the most accurate, either. Time for a service!P1020058

This certainly needs addressing. The amplitude is a bit low, and the beat rate and beat error are way out.P1020060

The case construction of the Royal Oak is rather unusual. The bezel is held to the case with 8 screws, and the case is monocoque.P1020061

The bezel has a gasket between the crystal and the bezel ring, which is held in a groove in the crystal and the bezel.P1020062

In the case below the rubber ring holding the movement is another nylon ring. This is not a gasket, as the seal is established between the case and the inner rubber ring. Note the two screws lying in the case – these are the screws that should hold the movement in the case ring, and they have come loose. No wonder the watch wasn’t working reliably…P1020066

And here is the case ring with outer rubber ring. This outer ring is pressed against the case and on the other side against the crystal, which provides the waterproofing. Unfortunately, AP doesn’t sell parts to independent watchmakers, so I will have to reuse the ring, rather than replacing it.P1020067

Nice dial in very good condition.P1020068

And here is the calibre 2125. It beats at 6 beats/second, so nothing spectacular there, but it’s main merit is how thin it is. At 3.5mm including the rotor, quite an achievement.P1020069

A beautiful movement indeed, and nicely decorated. The rotor has a 21 carat gold weight attached to it. As gold is very dense, you get a lot of weight per volume, which is important when making a thin movement.P1020073

With the rotor removed, you can see parts of the auto winder gears. The rotor engages with an intermediate wheel that sits in a ball bearing, which in turn drives a wig-wag wheel providing bidirectional winding.P1020076

Time to take the movement apart and see what lurks inside.P1020080

With the barrel bridge removed, you can see the rest of the auto winder gears. The wheel with the 3 spoke “Isle of Man legs” construction on top provides a clutch that engages in one direction, and freewheels in the other. This allows manual winding without turning the oscillating weight.P1020082

The centre second pinion.P1020091

The top plate is taken apart, and I will turn my attention to the bottom plate.P1020092

The bottom plate with the date disc.P1020096

The setting and date mechanism.P1020097

Only the date wheel and the date setting lever left.P1020181

All the parts are cleaned, and ready for reassembly.P1020182

A new mainspring.P1020185

To make reassembly easier, I order all the screws on a piece of rodico.P1020188

The keyless works sit on the top plate, and not on the bottom plate as usual. This is done in order to make the movement thinner. The gear train and wheel bridge are in place.P1020189

Now the barrel bridge and the auto winder gears go in.P1020191

That looks so much better than before!P1020193

With the movement ticking as it should, I can start putting the bottom plate back together.P1020194

The date mechanism is visible here before putting on its cover. P1020196

Dial and hands are back on, and it’s time for casing.P1020197

The movement goes back into the case ring.P1020200

With a new strap, the watch looks very nice indeed.

There is only one gripe I have with the watch. In my book, a watch should be able to make it for 100 years, so that it can go through at least 3 generations. A bit more doesn’t hurt. A rubber case ring will have degraded within 50 years or so, and at that time in the future, it’s unlikely that a replacement will be available, which will mean the end of the watch. I’d rather have something made from metal, and standard rubber seals that can easily be replaced, even 100 years down the line. My Rolex will have more of a chance to be worn by my great-grandchildren 😉

34 thoughts on “Service: Audemars Piguet Royal Oak 14800ST calibre 2125

  1. This is the only AP i love about, very well explained about the rotor and caliber it uses, I usually love the ETA mechanism and its calibers, now i know how to service it too, I have been owning a lot of ETA machine watches

  2. Hi Christian,
    I need some advice. I have a JLC Cal. 900 movement that needs a new spring for the date mechanism arm at about 9 oclock. It is a press fitted spring just like in this 2123 (jlc 889 based which is almost identical to the 900). What should I do to replace it? I have not been able to source one. I would appreciate any help.
    Thank you so much for sharing,

  3. Great blog, really amazed by these stylish and elegant Audemars Piguet designs. Have been a huge fan of royal oak series , already own one of it, now after checking this article in detail, may be I will get one more of it. Thank You for the information on the mechanism

  4. Christian,
    Have a 17+/- year old Stainless Steel Royal Oak 14790ST (2225 calibre) that was purchased new.
    Have had no service on it since purchase. Noticed battery reserve depletion and loss of a minute every 5 days for 5 years.
    Now, watch just stopped dead.
    Since >15 years since manufacture, AP Repair states “no parts”. Estimate they gave me to repair was eye watering high $$$.
    First, should not this watch last much longer?
    Second, do I have any other options aside from letting them replace the movement, central fourth wheel, etc for an insane amount of money?

    • You mention the word “battery”… Surely the 2225 is a mechanical movement. A mechanical watch needs regular servicing, and your watch stopped because you didn’t do that. That said, AP should have the necessary parts to perform a service and repair, and I presume that is what they quoted for.
      The problem is that you bought a watch from a manufacturer that doesn’t sell spare parts to independent watchmakers. So they can do as they please, and that’s what they are doing.

  5. Thanks providing this guide on Audemars Piguet. Great blog, really amazed by these stylish and elegant Audemars Piguet designs. Great anatomy! Thanks to add such a useful knowledge to watch lovers like us.

  6. Hi, saw your writ about the Audemars cal. 2125 –
    Would you happen to have a datewheel for that calibre ?
    If so, how much would it cost ?

    Thanks for your time,

    Detlef Riecke,
    Vancouver, B.C.

  7. Hi! Thinking about getting one of these, pre-owned of course. Is it difficult when it comes to changing straps? Do you, for instance, have to use custom straps?

    Thank you in advance!

  8. Great tear down and always enoy readings your blogs. 1 thing I just do not understand is why you thow all the parts in 1 bin like that. It looks amateurish and you risc scratching bridges, mixing screws (yes they are in there) and bending dial washers. You should know better my friend!

  9. @Christian – love your blog.

    Question: when you receive a mainspring from Generale Ressorts, do you lubricate it and then pop it in the barrel, or is there enough oil on it directly from the factory? I’ve always put a blob of 8200 grease on the spring once it’s in the barrel but i wonder if it’s necessary?

    ~Mark (a BHI DLC student)

    • Hi Mark,

      All GR mainsprings come pre-lubricated. They use a waxy white lubricant, and it doesn’t like oil. So I just lubricate the barrel arbour top and bottom with HP1300, and close the barrel. You also apply braking grease to the barrel wall if it’s an automatic.

      Best regards,


  10. Hi,

    Lovely review.

    Regarding the rubber gasket it does not look so special to me. Not oversized or vey wide to me. I could imagine some properly stocked material houses have a close fitting size?


      • Christian – I’m sure a man of your talent and resourcefulness could machine a replacement. Rubber can be turned and drilled when frozen, but you will need liquid nitrogen to freeze it sufficiently and remember it becomes quite brittle.
        “Flashings” from the moulding process can also be machined off using a razor blade at room temperature.
        Not tried it personally, but info comes from conversations with a rubber parts supplier many years ago.

  11. Another superb job. Thanks for showing us how this watch is taken apart. I agree with your gripe about the rubber case ring and wanting a watch that will last a long time.

  12. Hi Christian
    A question which has bugged me for years about the Royal Oak, how do you turn the screws on the bezel? (as they are hexagonal in hexagonal holes)

  13. The caliber 2125 is based on a Jaeger leCoultre caliber (888).
    Let´s hope 3D “home design” has come to a high enough standard by the time they need to replace the gasket:-)
    All in all a very nicely executed piece I would say!

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