Service: Excelsior Park Chronograph calibre 4-68

IMG_8077You don’t see these too often, and this is the first of its kind in this workshop. As it’s a nice chronograph, you will already have guessed that it belongs to Anders from Norway 😉

The watch doesn’t work, and it feels like the mainspring is broken.IMG_8078

The EP 4-68 movement in all its glory. It has Inca shock protection on the balance, which is nice to have, and has a very smooth reset mechanism.IMG_8080

The bottom plate. The winding/setting mechanism resembles that of some pocket watches, with the see-saw that either engages with the barrel wheel or with the intermediate setting wheel.IMG_8081

Last look before I take the movement apart.IMG_8092

Nice cote de Geneve decoration on the bridges. Note the construction of the fourth wheel with its driving wheel for the chronograph. On most movements, the driving wheel has to be pulled off. Here, the fourth wheel and driving wheel are held by a cock of its own, which means that they don’t have to be pulled apart.IMG_8098


And here it is with the cock removed and taken out of the movement. I like this construction very much!IMG_8103

With the barrel removed, you can see the winding mechanism.IMG_8104

As suspected, the mainspring is broken.IMG_8106

Looks like it was about time for a service 😉IMG_8111

Fresh out of the cleaning machine, and waiting for a new mainspring.IMG_8114

The pushers are rusted through, and will need replacing.IMG_8293

New pushers fitted.IMG_8294

I managed to find a mainspring that is close enough – a 1.25 x .115 x 360 x 10.5 T-End.IMG_8297

Time to put the movement back together.IMG_8299

The winding mechanism goes in, so that I can wind the movement for testing.IMG_8301

The base movement is back together – let’s see how it performs…IMG_8303

Looks like I got the mainspring right. I chose one that was quite a lot thinner than the one that was fitted.IMG_8304

Now I can start on the chronograph.IMG_8306

Almost back together.IMG_8307

Anders found two dials, and I chose the middle one, as the original hands will fit. The one on the left has smaller sub-dial, which means that I would have to shorten the sub-dial hands.IMG_8309

That looks rather nice! Look a the font of the numbers – you got to love the 4 and the 7!IMG_8310

The movement cased.IMG_8311

Ready to go back to Norway.


19 thoughts on “Service: Excelsior Park Chronograph calibre 4-68

  1. Hello
    I have the same Excelsior Park that you serviced above. I am looking for a dial, my dial is in poor condition. I saw you once found different dials, maybe you can help?
    thank you so much
    best regards

  2. I have a Zenith calibre 143, which is the EP calibre 4. It’s in 18kt gold, with a superb dial and unpolished case in excellent condition. The watch is ‘pre-star’ (and without Incabloc), which puts it before 1956, I believe. After servicing, it runs beautifully. Before, however, the return chrono pusher worked perfectly, but was soft (and with no click). Is this normal for the Z143/EP4, please?

    By chance, my watchmaker had another 143 for service at the same time, which had a coil spring for the return pusher that wasn’t in mine. So, he made one. I have read elsewhere, however, of other 143s that also have soft pushers (and no click) – indeed, so soft that the return pusher sits deeper in the case than the start/stop one – and that this is a feature of the movement, especially when older. Is this so, please?

      • Good! Thank you. 🙂
        On two Zenith 143/EP 4 I’ve seen, though, the now-60-year-old return pushers have so little support that they appear shorter than the start/stop pushers, because they have sunk into the case. A watchmaker has suggested that this is a basic design weakness. Certainly, the addition of a spring to the return pusher makes it stand properly and operate well.

  3. Where did you find the replacement main spring? With the lighter mainspring, did you have any issues with the chrono functions?

  4. I have one excelsior park 1950 cronograph in gold ,
    Its working perfect never stopt and keeps time perfectly,
    I been looking on internett bit dont find so much info . Is the watch worth something ,,?

  5. Pingback: Excelsior Park - Page 23

  6. Hi,

    By any chance, do you still have pictures of the movement main plate ?

    I am try to solve a problem on a EP4 caliber. When the stem is in time-set position, the gears slip and user must maintain upward pressure on the crown to prevent it.

    Stem is good and I am suspecting that the stem is loose in the movement mainplate. I would like to see how it is made before fully disassembling it to confirm

    Thanks !

  7. Indeed you dont see Expark chronos all too often, but t’s worth noting that Gallet and Girard Perregaux used those great movements…

  8. A stonker.

    I was a little worried about the dial change and it would have been nice to see it cleaned and a photo of it so we could have a discussion….

    But that new dial really does have a lot going for it…made me smile when I looked at that and as Christian says that font is top.

    Thanks for sharing this jewel with us Anders.

    • Really too much corrosion on and under it. When an original NOS dial came up at reasonable money I really did not have to think too long.

  9. I know nothing of Excelsior Park… is this an in-house movement or something re-branded by them?

    That replacement dial is a vast improvement – and very smart!

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