How to replace a Mechanical Clock Suspension Spring - Clock repair tutorial

All clocks with pendulums have a suspension spring. In this article, we will explain what a suspension spring is, how to avoid damaging it, when and how you may need to replace one if damage does occur.

Let’s talk first about what a suspension spring is, and where you can find it in the clock. You may expect a typical coil spring when you hear the term suspension spring. That’s not quite what we’re working with. A suspension spring is more akin to a leaf spring, and it is used to hang the pendulum in a mechanical clock. You can find it by simply following the pendulum shaft up to where it connects to the movement. The suspension spring will look like two flat pieces of metal connected by two smaller pieces of flexible metal.

Why would you need to replace a suspension spring? There are a few reasons. It may be that your clock is missing one, or you could have a suspension spring that is cracked, bent or creased. It’s not that easy to damage a suspension spring, but if you aren’t careful when winding up the clock weights, they can hit the pendulum which would bend or break the suspension spring.

Replacing the suspension spring will vary slightly depending on whether you have a newer Hermle or Urgos movement, or an older one. The newer ones use a thumbscrew to hold the spring in place. Simply unscrew it and remove the spring from the post. Swap it out for a new one and hang the pendulum again. The older ones have a tapered pin, which is basically a pin with one side larger than the other for friction fit. We don’t provide replacement tapered pins, but a cheap fix we recommend is using a paper clip if your pin is worn out.

Suspension springs should not need to be replaced often, so once you have yours in place and the clock running, you should be good for quite awhile!