Anniversary clock repair – a replacement suspension spring

Kundo standard size 400 day clock
Kundo Standard size 400-day clock wound once per year

Let me begin by saying that some people have good luck with torsion clocks and while others loathe them. For such a simple device they provide misery for some and it is no wonder that clock repairers steer away from them. I seem to be one of the lucky ones.

I gifted this clock to my daughter three years ago and during their relocation, to another part of the country, the clock “broke”.  “Can you fix it, dad?’. Leave it with me I said.

400-day clocks have been with us for over 100 years. Torsion clocks (as they are otherwise called) were produced from the mid-1890s in limited numbers but the real push was after 1900. Between then and about 1980, thousands were produced. They were a favorite as wedding and retirement gifts, hence the name “anniversary clock”.

The Kundo model we have here was made in the late 1950s to the 1960s, at the peak of production. Once quartz clocks were introduced, mechanical versions quickly faded away.

Kundo is a popular name in anniversary clocks and the name is a combined form of Kieninger and Obergfell, a well-respected German company. The company exists to this day as Kieninger, a subsidiary of Howard Miller USA.

Dial face Kundo Clock
Dial face Kundo Clock

Servicing a 400-day clock

To service a 400-day clock you must have the Horolovar 400 day Repair Guide as a reference. Can you repair a 400-day clock without one? Yes, but the Horolovar guide takes away almost all the guesswork.

This 400-clock is a Kundo Standard 53 that uses a .0032″ or .081mm Horolovar spring. If you do not have the time to assemble the suspension units, Horolovar (or most clock suppliers) will sell you a completely assembled unit but the cost is significantly higher.

Section 10 of the Horolovar guide shows templates for a number of clocks. A template allows one to follow a pattern when attaching the fork and upper and lower blocks to the suspension wire.

suspension spring installed on a Kern
The suspension spring assembly includes the top and bottom block plus the fork

The screws on the suspension assembly are very small and a good quality precision screwdriver will prevent serious damage to the tiny screws. The suspension spring is longer than necessary and must be trimmed to fit. Once the spring is securely screwed to the fork and the blocks, it is time to install it back onto the movement.

Kundo anniversary clock movement
Kundo anniversary clock movement

The suspension spring assembly hooks onto the top cock and bottom weights or balls. A threaded thumbscrew on the top base slips into the top block. The bottom block has two pins to which the pendulum hangs. Next are the back spring cover and the locking guard.

Torsion clocks have pendulum locking systems that must be engaged even when the clock is moved just a few feet. Often, the result of an unlocked clock is a broken suspension spring. The locking guard on this clock is an earlier design and looks pretty flimsy in my view but it should work.

Once the spring assembly is installed on the movement it is time to test the beat. The beat should be 8 beats per minute and there should be ample overswing in both directions. A 270-degree rotation is healthy enough.

What’s makes the 400-day anniversary clock a great clock to have in one’s collection?

They are:

  • Relatively inexpensive to buy, though some Schatz and Gustav Beckers are more desirable, thus, more expensive,
  • Very quiet in operation,
  • Easy to dis-assemble/clean and re-assemble as they have few parts,
  • Slow runners, there is seldom any wear issues,
  • A great conversation piece,
  • Long runners, some go for 400 days or more on a single wind.

Not so great because they are:

  • Notoriously poor timekeepers,
  • Frustrating to fine-tune at times.

Because I had serviced this clock previously I was able to release the tiny screws on the blocks and fork with little effort. Sometimes they can be tight and a hassle to remove. On this occasion, all went well and the clock has been running well for several weeks as of this writing.

While it is running slightly fast at the moment, incremental changes to the regulating dial will slow it down but you can only go so far, it is not a clock I would ever rely on for the correct time.

2 thoughts on “Anniversary clock repair – a replacement suspension spring

  1. I am a collector rather like yourself. Retired (electronics engineer) and coming lately to a lifelong interest that dates from early childhood, in things mechanical and things time. However I do not have all the facilities seen in your workshop. My collection of fairly ordinary examples is far from exotic but allows me to gain confidence over the last 4 more intensive years. I have enjoyed your BLOG and will return to it I’m sure. I came trying to remember the outcome of a previous search for the meaning of “Marque Possee” on a third French drumhead movement to come my way. I was hoping the serial (6331 48) would more accurately date it. I am puzzled how it can be that the same design was made by different makers. Who owned it, and granted the licence to make it?
    I also have a collection of 400 day clocks. Much as I have learned about them, still there are some awkward questions and conclusions. I was thinking of offering up some of these but as its your BLOG, it would seem like a take-over. Save to say that they are “challenging.” :<))
    Sincerely, BerryG in UK


    1. Thanks and welcome to my blog. Let me think about the offer. Regarding the drumhead movement, have you considered posting on the American clock forum site NAWCC. Registration is free. Although the emphasis is on American clocks there are members from all over the world who might have the answer you are looking for.


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