Seth Thomas Clock Movement

Seth Thomas Clock Movement - Post 1950 ST clock movements are still available. Please cross referance the movement number to the new number. - Clockworks
Seth Thomas Clock MovementST IdentificationHow to Order STWhy Order STMovement IssuesHistorical Timeline
Please view these information tabs for assistance, there is important information needed for a new Seth Thomas Clock Movement.

Seth Thomas movement identification

Seth Thomas movement identification is a fairly easy process. ST clock movements have specific markings that identify them. Their fame began in the Antique days. They were known for making their own movements and clock cases. Of course, the craftsmanship was astounding. After the war era, they did not make anymore clock movements. Instead the use of Hermle clock movements began.

In the end

For the most part, the name Seth Thomas did not stay with one company very long after the war. The outcome of these takeovers are three types of Seth Thomas clock movements. The Antique Seth Thomas were in production during and long before WW2. The use of German units such as Hermle, as well as movements that operate by battery, also began post WW2 by Seth Thomas. Hermle clock movements are German made and of the highest quality. Clockworks offers these types of movements.

Is the clock an antique Seth Thomas?

There are a few ways to tell if the ST is an antique. The easiest way is if there are no pits in the movement plates. Please see the picture below. Notice the pattern on the outer plates. The antique Seth Thomas clock movements never had this design pattern on them. It will have ST with a circle around it for a logo. Additionally, the movement will say made in USA. They may also have a few numbers on it such as 89 or 124. It also means that it is not available new, and made before 1950. A repair would be the only option.

Seth Thomas Movement Identification

Modern Seth Thomas Movement Identification

The picture displays the small bumps, or pits, in the movement plates. This design on the Seth Thomas movement indicates some interesting things. In short, the date of the movement is between 1950 and 1979, and it was made in Germany. This also means have a good chance of getting a new movement from Clockworks. To get a new movement means the cost is a fraction of the price of an overhaul. It will also ship out right away. The clock will be running right away instead of months later. It is not possible to restore a clock movement so it is better than new. To order a new movement, match up the numbers on the Seth Thomas page. If questions please email us.

The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2022

German Seth-Thomas Clock Movements

German Seth-Thomas clock movements are still available. Finding a new movement starts with the identification numbers off the back plate. After 1950, ST did not make movements. So, the old unit now has a conversion numbers in order to get a new movement. Currently, Hermle of Germany makes these with the ST number system and ST name. So it is really a Hermle in disguise and put on the market by Seth Thomas. The Seth Thomas name was put on the Hermle movements and then married to the clock case.

How to order

The first step to replace a Seth Thomas clock movement is to get the numbers off of the back plate. If it starts with the letter A, such as A401-003 then it is a ST number and has to get the new conversion number. Find the ST number in the list and write down the conversion number. Then click on that version number. This will direct to where the movement is on the Clockworks website. Reference this number when selecting the options for the movement.

Do not completely trust the chart

The above instructions work as a guide only for Seth-Thomas Clock Movements. Unfortunately, this chart is often wrong. It is meant as basic guide only. This will help determine the series of the movement. It is best to double check the rest of the attributes for accuracy. Things such as CM lengths and hand shaft lengths, for example. Before ordering, email the Seth Thomas number to us. We will verify the information so ensure the correct conversion.

Conclusion for German Seth-Thomas Clock Movements

A new movement is better than even the best repair. These are 25 year movements and Seth Thomas was gone over 40 years ago.

The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2022

New Seth Thomas Movement

A new Seth Thomas Movement can ship the same day as ordered. So the turnover time to get the clock running is minimal. The new movement (if available) will cost less than a cleaning and overhaul of the old unit. It will also last much longer. This means the clock will be up and running within a week instead of months. Of course, we are always here to help with the installation. If have a questions, send us an email. We are happy to help.

The new movement

When deciding to purchase a new Seth Thomas movement, remember that Clockworks offers the same movement as the current. The only difference is that it will be brand new. It is exactly the same and not a knock off replacement. Receive a new German movement and not one made by someone else. Usually other companies will make a similar product and sell them for less money, however there will be plastic parts in it. The units we sell are completely brass.

The modern Seth Thomas clocks are made by manufacturers other than Seth Thomas. Their name may be on it as the designer of the clock and the case, but it will not be a Seth Thomas movement that runs the clock. This is true for all clocks made after 1950. It also causes some confusion when replacing the movement. Often enough, a customer will insist that they are replacing a Seth Thomas movement when in fact it is a Hermle.

Replace versus Repair

A new Seth Thomas movement is obviously a better choice. It does not make sense to chase the old movement. Once one thing breaks, another problem will occur. This situation is inevitable. A new movement is more cost effective and has a triple life expectancy. These facts alone should make a new Seth Thomas movement an easy choice. In contrast, a Seth Thomas clock made prior to the end of WW2 is a different story. Those are no longer made. However, send us the movement and we will provide the best restoration.

The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2022

The Broken German Seth-Thomas Clock

Repair a broken German Seth-Thomas Clock by replacing the movement with a new one. Seth-Thomas went out of the clock business about 40 years ago. So having a movement with the Seth Thomas name on it means the lifespan is over for that movement. The average life expectancy of a clock movement is 25 years. The Seth Thomas from WW2 and prior had American movements. However, after 1950 they had German made units. So they did not make any movements themselves after the 1950's. Instead Hermle made them. The Hermle clock company is flourishing so the movements are still available to replace a broken German Seth-Thomas clock.

What happened to the old one

After 25 years, the oil becomes a solid instead of a liquid. This will cause too much resistance in the movement for it to run. Eventually the movement will stop working. Just having the name Seth Thomas on the clock means it is about 40 years old at best. There are two choices to save the broken German Seth-Thomas clock. Restore the old movement or get a new one if possible. Obviously, a new movement is the best choice. A new unit costs a fraction of the price of a movement restoration. It usually ships the same day instead of waiting up to 6 months for a restoration. A new one will last another 30 yrs without much complaint.

After 25-30 years this happens

Why does age affect the operation of the movement? A broken German Seth-Thomas clock has oil that solidifies with age. What was once a lubrication to the Seth Thomas movement has now become a sticky black abrasive. This creates both resistance and wear on the movement and it ends up broken. This wear and resistance will ultimately stop the clock from functioning properly. The pivots that ride in the holes of the brass plates will not be able to spin freely as they did in the past. The holes have become oblong instead of round, which causes the pivots to pinch inside of the hole. The pivot then cannot spin and therefore the oil is an abrasive rather than a lubricant.

Conclusion for the Broken German Seth-Thomas Clock

So now you see the choice is pretty clear. The new movement, when available from Clockworks, is the best choice by far for fixing a broken German Seth-Thomas Clock. The movement will be the same movement for a fraction of the price, brand new, oiled, tested, and last decades longer than even the best restoration.

The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2022

Seth Thomas Historical Timeline

Overall, the Seth Thomas Historical Timeline is a great way to familiarize yourself with background information that may pertain to your clock. The Seth Thomas factory made countless clock movements during and prior to the second world war. Of course, the high quality standard made the company a great success. Furthermore, after the war they did not make any movements. They subsequently chose to use alternate makers. Alternate movement makers were chosen to produce the movements for their Seth Thomas clock cases.

Start of German made movements

So, the clocks were Seth Thomas however, the clock movements were now made in Germany. They were now German instead of American. For the most part, the German movements that they chose to use for Seth Thomas were made by Hermle clock company or Kieninger. Of course, Seth Thomas would match the units to the clock case and sell them under their company name.

A long History

All in all, Seth Thomas had a long history of clock making. Although there was an exchange in the name from one company to another throughout the years, they are now extinct. The timeline shown below will take you for a walk through the changes Seth Thomas went through.

Seth Thomas Historical Timeline


Seth Thomas starts in Wolcott, Ct by James Thomas.


James Thomas begins working with Eli Terry as a clockmaker apprentice near Waterbury, CT. Because Terry got an order to make 4,000 clocks.


James Thomas opens his own Seth Thomas shop in Plymouth Hollow, CT.


Seth Thomas starts using brass clock movements which were put in Ogee Clocks.


Seth Thomas Clock Company becomes a corporation.


Death of Seth Thomas, now run by his three sons, Seth Thomas, Jr., Aaron, and Edward.


The town of Plymouth Hollow changes its name to Thomaston in honor of Seth Thomas


Establishment of Seth Thomas Watch Company


Seth Thomas Clock Company becomes part of The General Time Instrument Company by the great grandson of Seth Thomas


The Thomas family no longer controls The General Time Instrument Company


Seth Thomas Clock Company becomes part of General Time. This is the start of all those electro-mechanical clocks with the wooden cases.


General Time becomes part of Talley Industries. This is when they were using German movements made by Hermle, Kieninger, Urgos or sometimes Jauch.


General Time ends and Colibri buys the assets of Seth Thomas


Colibri Group discontinues all business with clocks

As a result of these facts, this is the end of Seth Thomas Historical Timeline.

End of Seth Thomas

Given these points, the Seth Thomas Clock Company had a long run and a wild ride. Hopefully this history was an interesting account of where, or how, your clock came into existence. Of course, The company name may now be found on silly things like lighters and some quartz clock dials. However, what we offer and sell are the Seth Thomas units made in Germany. These are the units General Time and Tally Industries sold under the Seth Thomas name but put Hermle clock movements in the clock cases. These German units are high quality and last 25-30 years without much complaint.

The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2022
Important Note on Seth Thomas Conversions

This basic guide for Seth Thomas conversions is often wrong. ST often used one number that used multiple variations of the movement under that number roof. To ensure the correct part is provided the Movement will need to be verified. Please provide a picture of the front and back plate of the Movement in order to verify the correct replacement for your clock and email it to us [email protected], we will respond in a timely manner to verify the conversion accuracy.

Seth Thomas Logo

Seth Thomas Clock Movement OLD Number / NEW Movement Number
Please note, this list is often WRONG and is only a basic guide.

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  • * Rear Pendulum Seth Thomas clock
  • ** Front or Rear Pendulum Seth Thomas clock
  • *** Needs new pendulum with it. Need to reverse direction of chimeblock.

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