In partnership with Grand Seiko

A Look Inside Grand Seiko’s 9S Hi-Beat Mechanical Movement

High-beat movements, or calibers that run at 36,000 beats-per-hour/10 beats-per-second, are relatively uncommon in the industry today. The prevailing standard for quite some time now has been 28,800 beats-per-hour, or 8 beats-per-second, and it’s for good reason. These movements strike an excellent compromise as far as overall performance is concerned, with 28,800bph calibers being capable of excellent timekeeping without undue wear and tear on components.

Grand Seiko Ref. SBGJ219, one of the brand’s “Hi-Beat” GMTs.

Nevertheless, high-beat movements are exceptionally cool and come with two notable advantages. The first is aesthetic — higher-beat movements feature second hands with a smoother sweep. Advancing at 10 beats-per-second, a high-beat second hand glides elegantly across the dial, further masking the start-stop operation of the escapement which one can still make out in slower rate movements.


The second advantage is greater reliability. Ultimately, a balance operating at a faster beat rate will show greater resilience to external rotational forces, like sudden shocks, which in turn results in more reliable daily timekeeping.

But as I briefly mentioned into above, higher-beat movements are not without their downsides, chief among them a decreased power reserve and increased wear and tear on components. So when Grand Seiko approached their modern high-beat movements,, which they call “Hi-Beat,” these concerns were top of mind. Ultimately, by employing state of the art manufacturing processes to ingenious architecture, Grand Seiko’s engineers were able to devise modern Hi-Beat movements that are beautiful, hard wearing, and reliable.

Here you can really see the smoother sweep of a “Hi-Beat” movement.

Let us take a closer look at Grand Seiko’s Hi-Beat mechanicals, starting with the all-important mainspring.

Breaking down Spron 530.

Grand Seiko’s engineers needed a special type of mainspring with 1.5 times the torque of your standard mainspring. Grand Seiko works with a proprietary metallic alloy they call Spron, and for their purposes here they developed a special reinforced variant dubbed Spron 530. This mainspring has the right amount of torque needed to achieve the higher beat rate, and it also manages a higher-than-average power reserve of 55 hours, also notable because higher-beat movements naturally consume more energy.

“Ultimately, a balance operating at a faster beat rate will show greater resilience to external rotational forces, which in turn results in more reliable daily timekeeping.”

Speaking of energy consumption, this is where MEMS comes into play. Now, if you’re at all familiar with Grand Seiko, you may have heard of MEMS without truly understanding what it is and why it’s important. So without getting overly technical about it, MEMS stands for Micro-Electro-Mechanical Systems, and it’s essentially a highly advanced manufacturing process Grand Seiko brought over from the production of semi conductors. Grand Seiko uses MEMS to fabricate certain precision metal parts for their 9S movements, and through this process they’re able to achieve structures that would otherwise be difficult to produce through traditional machine cutting. Additionally, parts produced via MEMS feature smoother surfaces, which minimizes friction, a major source of energy loss inside a movement.

Pallet fork.
Escape wheel.
Note the L-shaped tips on the escape wheel.

Two components Grand Seiko produces with MEMS are the escape wheel and the pallet fork. Through MEMS, Grand Seiko makes skeletonized escape wheels that are 5% lighter and pallet forks that are 25% lighter than their conventional counterparts. Furthermore, to address the higher degree of wear and tear sustained by hi-beat calibers, these parts are engineered for the purposes of better oil retention. If you look closely at Grand Seiko’s escape wheel, you’ll notice that in addition to the unique skeletonized structure, the cogs feature L-shaped tips designed to better retain lubricant for a longer period of time.

As far as the architecture is concerned, Grand Seiko’s watchmakers also had to redesign the gear train, but they took a different and significantly better approach than what would be considered more common. What generally happens with higher-beat movements is watchmakers will add more teeth to the gear train’s fourth wheel, or the wheel that drives the second hand, to achieve a higher gear ratio. While this is a solution, it is not a great one, because in order to add more teeth, you have to decrease their size, and doing so can cause slippage between gears and results in less stable transmission of energy. Also, smaller teeth are more fragile, and therefore more prone to breaking.  So Grand Seiko’s engineers came up with an excellent solution — they added an extra wheel to the gear train, allowing them to achieve the appropriate gear ratio without sacrificing stability.

Note the extra wheel on the gear train.

Ultimately, what you get from Grand Seiko here is an incredibly accurate movement, with Grand Seiko rating their Hi-Beat calibers to +5/-3 seconds a day, a spec that is well beyond what the COSC specifies. Hi-Beat models marked “Special” have even greater tolerances of +4/-2 seconds a day, and VFA, or Very Fine Adjusted models, are calibrated to a whopping +3 -1 second a day.

To read other installments in this series, click here. To explore Grand Seiko’s 9S Hi-Beat, visit Grand Seiko.

Movements and watches featured are instructional samples. No Grand Seiko watches or movements were hurt in the making of this series.

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Ilya is Worn & Wound's Managing Editor and Video Producer. He believes that when it comes to watches, quality, simplicity and functionality are king. This may very well explain his love for German and military-inspired watches. In addition to watches, Ilya brings an encyclopedic knowledge of leather, denim and all things related to menswear.