Service + Repair: Omega Chronostop Driver’s watch calibre 865

IMG_9954Something very exciting today – an Omega Chronostop. This is the driver’s version, which means that the crown and pusher are on the left side of the case, and so is 12 o’clock. The watch is meant to be worn on the inside of the wrist, so it can be read when you have your hands on the steering wheel, so the 12 o’clock position makes sense. Neil, who is actually Philip’s father, sent this lovely watch in, as something slips when you try to wind the watch, and it needs a service.Looks like Omega wanted to be really trendy here, and was trying to capture a market outside the usual customer range. I have the vision of a TR6 driver with flies between his teeth, gripping the steering wheel madly whilst checking the time on his Chronostop 😉

It’s not a proper chronograph, and the single pusher just starts the central second hand. If you press the pusher again and keep it pressed, you can read the seconds elapsed. Once you release it, it goes back to 0. No indication of the minutes passed. I guess this rather enchanting uselessness makes the watch even more desirable! Nevertheless, a fairly complex movement lurks under the case back…IMG_9957

Quite complex, considering what the watch actually does!


This inverted pie-pan dial is simply gorgeous. Makes you hear a car revving up!IMG_9961

The calibre 865 came without a date dial, so the bottom plate is quite simple.IMG_9963

You can see that there is quite a bit of dirt, and now it’s time to take the top plate apart.IMG_9970

Making my way through the chronograph layer.IMG_9975

Almost done.IMG_9982

There is quite a bit of rust and dirt, and I will carefully remove as much of that as possible without taking too much material off.IMG_9985

The gear train, and more dirt and rust on the winding pinion and clutch wheel.IMG_9988

And here is the culprit. The barrel arbor is worn, and the mainspring slips around it.IMG_9993Everything goes into the cleaning machine.


The new parts have arrived – barrel arbor, crystal and mainspring.IMG_0054

I start off by putting the mainspring into the barrel.IMG_0056

I’ve cleaned the rust off the crown wheel, but it’s quite deep, and I don’t want to take off too much material.IMG_0057

The bottom plate components got a good clean as well.IMG_0058

The base movement is back together and ticking – now it’s time for the chronograph layer.IMG_0060

With a half-wound mainspring, this is looking good.IMG_0063

The chronograph layer is back together, and I can adjust the depthing.IMG_0064

The new crystal needs pressing into the case.IMG_0065

And the dial and hands go back on.IMG_0066

The movement cased.IMG_0067

The old gasket has solidified.IMG_0068


New gasket in place.


Pretty cool!IMG_0071


50 thoughts on “Service + Repair: Omega Chronostop Driver’s watch calibre 865

  1. Thank you so much for that in depth look into this watch..
    I have one to service at the moment, it has a broken escapement and the crystal is broken. I am just a little concerned what other damage I may find. And of corse the availability of some of the replacement parts. Thankyou again for the images and I site into this movement. Kind regards Jon.

  2. Hi. I have one of these watches that I bought from the NAAFI shop on RAF Gan in 1968 with the Mexico Olympics box. I have been after a replacement perforated strap for it as the original which I still have suffered from salt water damage. Do you know where I can obtain such a strap?

    • Hi
      I also have a Chronostop date bought back in 1972.
      It originally had a black perforated “Corfam” artificial leather strap with twist lock metal ends which located in the clasp and then twisted a tiny cam to lock in place.
      I still had the original strap which had gone hard and pretty much disintegrated.
      I contacted a Chinese company who agreed to make one to the same pattern but it was OK – ish but not as original as I wanted.
      I then contacted an Italian watch strap maker and sent the original to him as a pattern.
      As Corfam is no longer available he made one from selected black leather which he matched identically with the Corfam artificial “leather “
      The end result is stunning and identical to the original in size, shape, color, and fit.
      I reckon I have the only Chronostop in the world with a strap that even an expert could not tell from an original without microscopic examination / material testing.

  3. Pingback: [1966] 145.007 – Omega Seamaster Chronostop – OmeGANG, le Cercle Omega

      • Thanks, Christian.

        The thumb does not do the trick (cannot be lifted from the side). Thought the movement of this watch is pressed out through the front, or am I wrong? If it was, it could not use the case tool?!

        Best, Thomas

  4. I have a Chronostop Driver w/ date dial. It hasn’t been serviced in 30 years. It is in quite a good shape but it has a crack in the crystal so sometimes it shows some humidity inside. It also has an ugly bracelet. How can I get the parts for replacing the crystal and the bracelet?
    Thank you very much
    P/S I´m in Colombia

  5. I have a chronostop mesh bracelet. It doesn’t fit my 6.2″ wrist and needs to be shortened. Is this something you can do?

  6. hi,

    I have one of these and when you look through the crystal it has a chrome ring around the outside of the face on the inside where it meets the crystal. Is this a one piece continuous ring or should it have a join it it?
    Mine has a join a 6 marker…

    Any advice would be appreciated.

  7. Hi Christian,

    Fascinating write up. Could you advise please if the red seconds hand should always remaining at the 12 unless the timer is pressed? I.e. After timing is finished would it then return to show the current time in seconds?

    Thank you, Jonathan

  8. Pingback: Omega Seamaster Chronostop, injustement méconnue – copeaurnwatches

  9. Hi, I recently acquired the drivers chronostop 920, need a new strap but struggling to find one. Have also noticed the chronostop isn’t functioning.

    Where is best for a watch strap and would a general service sort out the chronostop as the watch is keeping excellent time.

  10. Hey, great tutorial.
    I just picked up the 920 movement version of this watch, however I noticed the movement is loose in the case.
    After removing the back I noticed it seems to be missing something I’m seeing in your pics.
    The two largest screws on the sides of the movement on yours seem to be attached to something thats holding the movement to the case.
    Whats this part called?


  11. i purchased a chronostop new in Germany in 1968 . have had eversence while winding the watch cw only the pusher came off . is this part available?

  12. G’day from Australia. I have a Chronostop Driver given to me as a gift by my favourite aunt in 1967. It still works like – well – clockwork. The stopwatch button actually has 2 stages. If you depress and hold fully, the second hand will stop. If you release it fully it will return to 12. If you half release (takes a bit of practice) the second hand will continue. Some years ago I presented it to a jewellers for a new crystal. Sadly, a non-original was fitted. I would like this rectified but have yet to present it to a genuine Omega Service Centre as I live on a farm ‘out bush’. Thanks for the overview.

  13. I once saw a watch of a similar layout which I believe was made for Bugatti drivers (I think, I saw it a long time ago) in the 20’s or 30’s. As you say to read the time without moving their hand.

  14. Hi – thank you for the write-up on this interesting movement.

    Do you think that there is any problem with leaving the seconds hand running all the time?

  15. Hi i have a Omega chronostop 865 it was working perfectly until the orange second hand fell off and lies within the watch face. i know it is a bit of work taking the watch apart but was hoping you could give me a rough price as to the cost of a basic repair without cleaning and probably a new gasket and second hand? regards

  16. Hi Christian, I desperately need my Chromostop cleaned and a new strap fitted.
    can you give me any help or advice please.
    Thnk you John Schofield

  17. Lovely pics Christian. I have the doctors version with pulsometer is also worn under the wrist with an id bracelet on the strap. Its very easy to use for taking a pulse but as you say maybe less useful in a diver.

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