Grand Seiko Announces a Constant Force Tourbillon

Grand Seiko made enormous waves today when they announced that they had designed the brand’s very first tourbillon (setting aside Credor’s Fugaku, but although a Seiko, it wasn’t a GS), but it’s not “just” any tourbillon, it’s a constant force tourbillon. Unlike for Credor, this is a radical departure for the brand, because GS, while beloved for its accuracy and refinement, has never been known for wild design, aesthetically or horologically. Most important of all, it’s apparently rated for an astonishing plus or minus 0.5 seconds per day. There’s a lot to talk about here, so I’m going to break it down piece by piece, both how the movement works and the role this plays in the broader picture of Grand Seiko.

I want to start with that “historical context” part. Many great watch brands have humble beginnings. Grand Seiko is not one of these. GS went from birth to chronometer competition-dominating force of nature in less than a decade, taking on the very best movements that Switzerland could offer with strange movements like these, pushing horology to its absolute limit. Unfortunately for Grand Seiko, and really, really unfortunately for everyone else, Seiko’s own quartz Astron was about to shake the foundations of the industry in ’69, and Grand Seiko’s legendary mechanical movements faded into the background as a new generation of movements took over the quest for high-accuracy.

That’s the way it continued until the late ’90s, when Grand Seiko re-entered the high-accuracy mechanical watch arena. These early 9S5X movements were very respectable, both in terms of accuracy and robustness, and did the early job of re-establishing GS as a player in the area normally occupied by household names like Rolex and Omega, at least in Japan as GS wouldn’t be sold in the West until much later. But the days of intense competition in which Grand Seiko was forged were long gone. Modern chronometer testing wasn’t a competition where every brand was publicly ranked, competing against the world for the #1 spot. Worse yet, contemporary chronometer testing expressly banned non-Swiss movements from being certified, precluding even the possibility of competition with GS.

Nonetheless, competition merely shifted from direct to indirect, as companies like Rolex and Omega continuously improved their movements, accuracy, and features. Grand Seiko did the same, of course, releasing the current mainstay of mechanical GSes, the 9S6X, and its big brother, the 9S8X line. Very recently, Grand Seiko released a another radical departure from traditional GS movement design, the 9SA5, a truly high-end, if nonetheless quite practical, movement. The accuracy figures never changed, however, at least until today’s announcement. By releasing a movement that is boldly rated at just +/-0.5 seconds per day, Grand Seiko intends to send a message to its chief rivals overseas that they’re ready to fight it out again, for the first time since the ’60s. It’s not just my wild-eyed speculation here, this was literally in an article included with their press release:

In the 1960s, Seiko’s mechanical movements dominated top spots at the Neuchatel and Geneva Observatory Competitions, regarded as the most authoritative watch competitions then. With this new movement, Grand Seiko returned to the top in the world. – Masayuki Hirota, editor-in-chief of Chronos Japan

Before we get to what makes the movement so special, let’s take a moment to appreciate the haute horology beauty that is the T0. It’s truly a stunning design, one that looks as bold as it actually is.

Let’s first touch on the (impressive) basics. As this movement was, apparently, co-developed alongside the also impressive (but downright utilitarian compared to the T0) 9SA5, it’s not surprising to find a free sprung balance here, which is otherwise very unusual for GS. That said, it appears to be a relatively ordinary perfectly round balance wheel, as opposed to the Breguet-esque balance wheel of the 9SA5 with sunk areas for the screws to hide. Also unlike the 9SA5, there is no overcoil to the hairspring, likely due to the inherent thickness of an overcoil since GS is already stacking a remontoire onto a tourbillon (more on that later) and space was probably at a premium here. You can also see that dual mainsprings were used in this watch, in this instance not to increase the length of the power reserve but rather to increase the torque as they run in parallel, a necessity to operate the remontoire. Still, it manages an above-average 50 hours of power reserve, so it’s not as if this is an obstacle.

Alright, with that out of the way, we’ve got a few important elements to discuss. The first is the tourbillon. If you’re familiar with Grand Seiko, you probably already know what a tourbillon is, and that it was originally designed to rotate the components responsible for timekeeping with the goal of reducing the impact of position on stability. For instance, if you leave your watch crown up or crown down at night, it will probably run a little slower in one position and a little faster in another. The tourbillon aims to basically even that out by, in essence, unfixing the position of the balance wheel and escapement relative to the rest of the movement (and therefore the watch), rotating continuously throughout the day regardless of where the watch rests or whether your arm is by your side or across your desk. As impressive as a tourbillon is, however, there is something far more amazing in the T0.

That would be the remontoire. What appears at first to be a gorgeous blued six-arm tourbillon cage is actually two separate three arm cages. The outer carriage carries the rementoire while the inner carriage is for everything else, and they actually advance at different frequencies, so three of the arms rotate once per second while the other three rotate (very slightly) 8 times per second. Crazy.

So what does a remontoire do and why should we care about it? Well, it’s basically a solution for an old problem with mainspring design. Try as we might, we can’t quite get a perfectly “flat” power delivery from a conventional mainspring. Mainsprings, no matter how well made or with what materials, deliver more power fully wound and less when nearly unwound. This tiny difference affects the timekeeping, so a watch that is perfectly accurate when fully wound can be somewhat less accurate when nearly unwound, or vice versa. There have been a variety of fixes for this problem over the years, but the remontoire is by far the most logical choice for something as small as a wristwatch movement.

The solution is, in effect, a second mainspring (in the sense of a spring that stores energy) between the mainspring and the escapement that alleviates the differences in the power curve. The remontoire’s spring is re-wound by the mainspring, and from there the force is applied to the escapement. The remontoire mechanism can supply the crucial timekeeping mechanisms of the watch movement with nearly perfectly stable power, leading to accuracy that is almost entirely unaffected by the state of the mainspring. This gives this particular movement an interesting combination of high frequency “seconds hand” (represented by three of the blued arms), as 28,800 BPH is actually quite fast for a tourbillon, and a deadbeat seconds “seconds hand” (the other three arms) in the remontoire mechanism. Seeing it in motion, it almost looks like three of the arms are trying to catch up with the constantly advancing other three.

Most impressive of all is how the balance wheel and tourbillon mechanism is basically “stacked” on top of the remontoire in what Grand Seiko calls the world’s first fully integrated remontoire. I’m inclined to believe them. The energy from the remontoire not only drives the escape wheel, and but the tourbillon’s rotation itself. Setting aside the beautiful achievement that it is, placing the remontoire closer to the escapement (i.e. with less stuff between it and the escapement to interfere), the flatter and more stable the power delivery will be, and I can’t really imagine it being any closer than this, so mission accomplished.

There’s a lot more to the T0 to talk about, but for brevity I want to get to two final questions: what exactly is the T0 and what does it mean for GS.

As per what the T0 is, it’s a concept movement. You can’t buy one, much less buy a watch with one in it, and there’s no reason to think you’re going to be able to in the near future. It is, in other words, a magnificent proof of concept, created to show the world and GS fans what the brand is capable of.

The much more interesting question is what does the T0 mean for the brand’s future. I think there are a few answers to this question, all of which are pretty important. I think the first is to signal the intent to create more accurate watches, basically igniting an arms race with Switzerland, and I think that is strongly evidenced by their direct references to these competitions in their official literature. If they can bring down even part of this accuracy into their future mainstream movements, they could really take the fight to Switzerland like they did in the ’60s.

The second is aesthetic. Take a look at this watch and its hands. It’s pure haute horology, and all the impracticality that comes with it. Since 1960, GS has always aimed to be an extremely practical watch. Yes, it might have been very accurate and refined, but it was ultimately a tool to get Japanese VIPs to their meetings on time back when people really relied on their wristwatches, and it therefore had to be restrained, disciplined, and legible. The T0 is anything but. It’s a wild, flamboyant design, more at home beside an FP Journe or Grönefeld than a Snowflake. The tiny, almost vestigial, highly-stylized hands lack the utilitarian practicality of the brand’s famous dauphine hands and signal to the (theoretical) owner that time is of secondary importance; this is about the beauty and complexity of the movement, not about functionality. And yet, despite its wild looks, it remains somehow distinct from Credor’s relatively “flowery” skeletonized MAS spring drive offerings. The T0 is, at least, Grand Seiko-esque in its more serious, industrial looking appearance.

Could this signal more adventurous designs for production Grand Seikos in the future? Who can say, but this at least makes a case that it’s possible in a way we wouldn’t have thought just a year ago.

Finally, the T0 suggests that Grand Seiko will finally venture out from the simple date and power reserve complications typically associated with the brand. Who can say what the future holds, but it is now entirely possible that it could include perpetual calendars, rattrapante chronographs, and other exotic complications.

But one thing Grand Seiko has made abundantly clear in 2020, which is that no one can ever again seriously accuse them of being boring.

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