Seth Thomas Adamantine Mantel Clock with 89C Movement

Here’s a beautiful Seth Thomas Adamantine mantel clock I repaired. The case is black, with green, yellow and orange marbleized top and trim. The movement is the popular and long-lasting No. 89C (which appears to be the same as the movement marked 89 which is seen often). It strikes the hour on a heavy coil gong, and the half-hour on a bell. This example has a polished, nickel-plated bell. The bell may not be original, as almost all the others I’ve seen have an unpolished, brass bell. This movement uses an “American type” semi-deadbeat escapement.

IMG_9244 IMG_9239 IMG_9237

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Repair job 6409. I repivoted the rear time second wheel pivot (see the 2 pictures below).

IMG_9192 Repivoting process: The inserted pivot has been finished.

I polished the pivots and installed 15 bushings. I replaced the time click rivet, and the time mainspring arbor hook. This movement has the original mainsprings:

Time Mainspring: 3/4 inch wide by 0.0160 inch thick

Strike Mainspring: 3/4 inch wide by 0.0168 inch thick.

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  1. I have a two pillared on each side of dial Seth Thomas clock with lions heads that is similiar to this. The movement is marked 4 1/2.
    My uncle and aunt got it for a wedding present in 1907!
    Unfortunately most of the paper label is missing so Im not sure of the exact model.
    Clock does not run for an extended period of time. It was cleaned and serviced at least 40 years ago.

  2. Where would this 89c be stamped on the movement? I have 4 1/2 in lower right corner and American Made in upper left.

  3. I have the same original clock, 3 pillars. I was in storage for over 30 years. All original, not working. Looking to replace the non-working movement. This one has the same looking movement but is stamped with 4 1/2 and not 89C.

  4. That is a device to secure the pendulum rod during shipping. It is original to the clock. Some clocks have it and some don’t.

  5. Beautiful clock and work sir. Today I acquired a clock of an identical movement in a very similar casing – one column instead of 3, no lions. It appears one piece is missing – in your picture of the movement it’s the long hooked object extending from the lower left corner. Would you mind telling me what this is called please? Thanks very much,

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