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

  2. 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.

  3. 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.

  4. 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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