Service: Tissot Automatic calibre 285

This gorgeous Tissot from Norway is in great shape. The dial is near-perfect, the hands are great, but it only ticks for a couple of seconds and stops – something that a good service will probably sort out.

The owner has already put a new crystal in and cleaned the case, so it’s the movement now.

On first sight, this looks almost identical to the Omega Bumper movement.

With the bumper and its gears removed, I can take the movement out of its case.

I love that dial.

The bottom plate is quickly cleared.

Time for the top plate.

With the balance jewels removed and the balance back on the plate, I’m ready for cleaning.

The mainspring is old and tired, and I’m putting in a new stainless steel one.

With all the parts cleaned, rinsed and dried, it’s time for reassembly. I start off by putting some braking grease on the barrel wall and pressing in the new mainspring.

Barrel bridge, wheel bridge and pallet fork mounted – ready for the balance.

Balance in, and the movement ticks.

Bottom plate complete and ready for the dial.

The hands are pressed on.

Stunning watch. If you are thinking of getting one, do! They are great value for money, with a super little movement and superb looks!


8 thoughts on “Service: Tissot Automatic calibre 285

  1. Hi Christian,

    I am just restoring a Tissot 28,5 bumper and want to replace the old mainspring with the separate slipping spring. In the archive of watch movements (Ranfft) I found information about the mainspring: Tissot 28,5 (1,30 x 9,0 x 0,10 mm, no information about the lenght). Omega bumper movements, which are almost identical to the Tissot bumper movements: 1,10 x 8,5 x 0,10 x 250mm. The informations are differing.
    Which mainspring would you recommend for the tissot bumper movement?


    • The second spring you list is a lot weaker than the first … I would start by measuring the spring that was in there, and check how it fits the barrel (height, percentage of space taken up), and then decide what to fit. The proof is always in the pudding, e.g. in the amplitude you will achieve in the end.

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  3. Hi Cristian,

    Can you tell me what kind of crown the caliber 285 needs? I found this one on eBay but I don’t know if its the right one…

    Brand Tissot
    Crown diameter 3.5 mm
    Stem size/crown tap 0.9 mm
    Crown opening/ flex case tube diameter 2.4 mm
    Color Steel

    Yours, Ronin

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