Our Guide to GS Movements

One of my primary goals in the watch industry has been to continually introduce new people to one of my absolute favorite brands, Grand Seiko. Today, GS is more popular than ever, but with the brand’s growth comes complexity. Two weeks ago I attempted to organize the entire brand lineup into a single guide to help simplify the process of finding the right Grand Seiko for you, but today I’m creating a simple, straightforward guide to every current-generation GS movement. This isn’t intended to cover every single detail of each movement, but rather be a quick reference for people to make sense of the increasingly diverse lineup.

I think it’s fair to say that there are very few brands, in Japan or otherwise, with the incredible diversity of movements of Grand Seiko. Like most highly respected watchmakers, Grand Seiko has a nice portfolio of mechanical movements, but unlike most of them, it also has some of the best quartz movements in the world and even a genre of movement unique to Seiko, the spring drive. As a result, GS has a bit of an embarrassment of riches, and this can be a bit daunting to someone who is new to the brand who wants to understand how they work and what makes them special. This guide is intended to briefly introduce you to the three families of Grand Seiko movements and also each individual member of the family, which can vary quite significantly. Many movements have been excluded from this guide, such as the 9S55, because they are long-discontinued and have virtually no chance of ever appearing in a Grand Seiko again, although I did try to include more recently discontinued GS movements that you might encounter on the pre-owned market.

9S Mechanical

We’ll begin with the family of movements that people new to Grand Seiko will be most familiar with, the 9S. The “S” movements in GS refer to purely mechanical movements, so you’ll find no quartz crystals here. While the 9S family might not be as technologically cutting-edge as its younger spring drive or quartz brothers, it is nonetheless very sophisticated, with features that have influenced some of the biggest names in the industry. The 9S has three unique scions, one of which was only released earlier this year. The first of these is the 9S6X, the mainstay of the mechanical lineup. The 9S6X beats at an ordinary 28,800 BPH, but it does boast an impressive 72 hour power reserve. A step up takes you to the 9S8X, formerly the high-end of mechanical Grand Seiko. This movement’s calling card is its unusually frequency, 10 beats per second (or 36,000 BPH). Finally, we get to the all-new 9SA5, which is by far the most advanced mechanical movement GS has ever put in a watch.

  • Purely Mechanical
    • All 9S movements are completely mechanical, bottom to top.
  • MEMS Technology
    • The 9S uses Micro Mechanical Systems technology to create unbelievably precise escapements, accurate to tolerances measured in thousandths of a millimeter.
  • Extended Power Reserve
    • All 9S movements have long power reserves. The 9S6X has a 72 hour power reserve while the 9S8X has a 55 hour power reserve, compared to the industry average of just 40.
  • Hand-Polished Gears
    • As incredible as it may sound, the individual teeth of each gear are hand-polished to reduce friction.
  • Skeletonized Escapement
    • To reduce weight, and therefore power consumption and wear, Grand Seiko removed unnecessary material from the pallet fork and escape wheel.
  • Six-Position Adjustment
    • Unlike nearly all other brands, Grand Seiko adjusts the 9S for all six positions, resulting in a movement that’s extremely stable regardless of its orientation.
  • 17-Day Trial
    • All 9S movements are tested for 17 days, ensuring accuracy, stability, and reliability.

9S6X

The 9S6X is the beating heart of Grand Seiko’s mechanical lineup, powering the majority of mechanical GSes, and also offering the greatest diversity of mechanical movements, compared to either of its siblings, the 9S8X or 9SA5. Each 9S6X has a superb 72 hour power reserve and beats at 28,800 BPH.

9S6X Family Variants

  • 9S65
    • By far the most common 9S6X movement, this automatic has three hands and a date complication making for a great everyday choice.
  • 9S68
    • An extra-large version of the 9S65.
  • 9S67 (Probably extinct)
    • An early version of the 9S6X, this movement once added a power reserve complication. You might find it in pre-owned JDM models.
  • 9S66
    • Similar to the 9S65, but with a true GMT complication. That means that it gains a fourth hand, which can either be set to your home time or to another time zone, and it has an independent hour hand.
  • 9S61
    • The most common hand wound Grand Seiko movement, this caliber is both thinner and dressier than the 9S65, omitting the date complication.
  • 9S63
    • A new hand wound movement for Grand Seiko, the 9S63 remains thin but adds small seconds and a power reserve complication.

9S8X

Turning now to the 9S8X, which has, until 2020, represented the high-end of Grand Seiko’s mechanical movements. It’s very similar to the 9S6X, but it has a much higher frequency, namely 36,000 BPH. This means that the 9S8X is one of only a handful of movements in the world that beat 10 times per second, leading to an ultra-smooth seconds hand. This movement is beloved not just for its accuracy and reliability, but for being historically connected to the brand’s legendary Hi-Beats of the 1960s.

9S8X Family Variants

  • 9S85
    • The 9S85 is, like the 9S65, the mainstay of the Hi-Beat line of movements. It’s a three-hand + date combination, the most popular configuration for mechanical watches in general.
  • 9S86
    • The 9S86 is the newest member of the 9S8X family and, like the 9S66, it adds a true GMT complication. That means that it gains a fourth hand, which can either be set to your home time or to another time zone, and it has an independent hour hand.

9S2X

The 9S2X is a comparatively new family of movements aimed at much smaller watches. As a result, these movements are also much smaller, just 19.4mm in diameter and 4.49 deep despite being automatics. Don’t think that these are just miniaturized versions of the 9S6X, however, as these are truly a distinct group of movements with a totally different design. While it’s a serious Grand Seiko movement through and through, the smaller size does come with some compromises, like a 50 hour power reserve and slightly reduced accuracy. At one time there was a 9S25 variant, which no longer seems to be in production, ostensibly replaced by the current 9S27.

9S2X Variants

  • 9S27
    • Currently the only available (at least in North America) version of the 9S2X, the 9S27 is a simple three hand + date movement in a very compact size. The 9S27 is apparently the replacement for the earlier 9S25, but that is unofficial.

9SA5

The newest mechanical movement from Grand Seiko, and the most sophisticated the brand has ever put into a watch, the 9SA5 is currently less a family than an individual model. The 9SA5 is an enormous leap in movement design for GS, introducing several improvements for the first time to modern Japanese mechanical movement design, such as a free sprung balance. It stays true to its heritage, however, and like the 9S85, beats 10 times per second. It vastly improves on the 9S85’s power reserve at 80 hours (up from 55), the highest ever offered in a mechanical Grand Seiko. It’s the first movement to introduce GS’ new Dual Impulse Escapement as well.

Currently, the 9SA5 is available in just one watch, the SLGH002, but hopefully we’ll see more 9SA5s in 2021.

9R Spring Drive

If mechanical movements are the heritage of Grand Seiko, spring drives, identified by their model number 9R, may be the future. Today, no movement is more recognizably Grand Seiko than their special 9R spring drives. What exactly spring drives are is a matter of constant philosophical debate between enthusiasts, but I prefer to treat the spring drive as a different kind of movement altogether. What isn’t a matter of debate, on the other hand, is that the vast majority of the spring drive is mechanical, very similar to the Grand Seiko 9S. Instead of the escapement you’d expect to find in any given mechanical watch, however, Grand Seiko has placed the tri-synchro regulator. This modern piece of horological wizardry takes the energy from an ordinary mechanical mainspring, converts it to electricity to power a quartz oscillator for timekeeping, and then uses electromagnetism to slow the rotation of the movement via the glide wheel.

Now, if that sounds really complicated to you, it’s because it is, but there are two really important, and easy to understand, consequences of using a tri-synchro regulator instead of a mechanical escapement. The first is that the seconds hand is perfectly smooth in motion. I don’t mean that it beats so quickly that you can’t see the ticking, I mean that it literally doesn’t stop the way all other (both quartz and mechanical) watches do, making it one of a kind. The other is that spring drives are supremely accurate, far beyond even the best mechanical movements. Even entry-level spring drives are rated for just 15 seconds a month.

  • “Hybrid” Design
    • The 9R incorporates elements from both traditional watchmaking and quartz technology.
  • Perfectly Smooth Seconds Hand
    • Due to the way a spring drive works, the seconds hand never ticks, it only flows smoothly.
  • Silent Operation
    • Because the 9R doesn’t tick the way an ordinary movement does, it’s extraordinarily quiet.
  • High Accuracy
    • Even an entry-level spring drive is rated for +/- 1 second per day, compared to +6/-4 seconds per day in a mechanical chronometer.
  • Long Power Reserve
    • The 9R family ranges from an impressive 72 hour power reserve all the way to an amazing 8 days.
  • Beautiful Finishing
    • The 9R movements are arguably Grand Seiko’s most visually impressive.

9R6X

The 9R6X is the heart of the 9R family and equips the vast majority of spring drive models offered. It’s your all-purpose automatically-wound movement, and it also tends to be the most affordable way to get a spring drive Grand Seiko. That said, it’s still super accurate at +1/-1 second per day, and even has a model that cuts that in half. This movement is perhaps best known for powering the most popular Japanese luxury watch in the world, the SBGA211 Snowflake.

9R6X Family Variants

  • 9R65
    • The 9R65 is the most common 9R movement because it has everything you need: three hands and a date.
  • 9R15
    • The 9R15 is an upgraded version of the 9R65, identical in almost every way, but accurate to just +/- 0.5 seconds per day. It also gets a special rotor with a gold medallion.
  • 9R66
    • The 9R66 adds a true GMT complication to the 9R65, giving the wearer a GMT hand to track a second time zone and an independent hour hand.

9R8X & 9R9X

Confusingly, both the 9R8X and the uncommon 9R9X are part of the same family, but given how unlikely it is that you will encounter a 9R9X movement, I wouldn’t worry too much about it. The 9R8X family are Grand Seiko’s most complicated movements ever produced and, not coincidentally, also the only chronograph movements Grand Seiko offers. These tend to be used for large, sporty watches, so if you’ve ever found Grand Seiko’s design too plain, looking for a 9R8X-powered model may be just what you need.

9R8X Family Variants

  • 9R86
    • The 9R86 is the heart of this family and the most complicated movement Grand Seiko makes. It combines a date, chronograph, power reserve, and GMT complication into a single movement.
  • 9R96
    • The 9R96 is basically identical to the 9R86 but, like the 9R15 movement, improves accuracy to an amazing +/- 0.5 seconds per day. It also gets an upgraded rotor with a gold medallion. This movement is generally found in high-end Grand Seiko limited editions.
  • 9R84
    • The 9R84 is a relatively obscure version of the 9R8X that is basically identical to the 9R86 but lacking the GMT complication.

At this point we get to movements that, although they share similar names (like 9R01 and 9R02), their actual design is so divergent that I don’t think it’s useful to treat them as being in the same family. Thus, we’ll be discussing each of these in isolation.

9R01

The 9R01 is arguably the most high-end Grand Seiko movement to ever find its way into a production watch and it certainly has the longest power reserve of any Grand Seiko ever made at an astonishing 8 days. This beauty was created by the elite watchmakers at Seiko’s Micro Artist Studio (MAS) and is rated for just +/- 0.5 seconds per day. Thanks to being hand wound, there’s no rotor to obscure the gorgeous finishing. The 9R01 is extremely rare and found only in high-end models.

9R02

It might sound similar, but the 9R02 is a totally new movement. Also hand-made by the MAS, it features an arguably even better looking movement, thanks to its slightly more complex design. Although still a masterpiece, this is a somewhat more accessible movement than the 9R01, and consequently, it has an 84-hour power reserve instead of 8-days, and a more conventional +/- 1 second per day accuracy rating. Like the 9R01, very few Grand Seikos use this exotic movement right now.

9R31

The 9R31 is closely related to the 9R02, but was offered in much more accessible models. Although closely related, we should be careful to appreciate that this is still a distinct movement, not simply a version of the 9R02. The 9R31 uses the same basic layout and dual-mainspring design as the 9R02, but with finishing closer to that of a 9R6X movement. The power reserve is also similar to the 9R6X, at 72 hours. Still, this great movement allowed mainstream Grand Seiko fans to get a taste of a next-generation spring drive movement, and a manual-winding one at that. Sadly, although more affordable, it’s just as rare, inside very few Grand Seiko models.

9RA5

The 9RA5 is not the most high-end spring drive Grand Seiko offers, but it is the most advanced. This brand new movement is, unlike the last three, automatic winding, and it attempts to improve on almost every element of spring drive design. Most interestingly, although all spring drives are renowned for their reliability, it’s the first spring drive explicitly made for toughness with a more rigid and shock-resistant design. The power reserve is enormous, at five days, and is wound by a new version of the extremely effective Magic Lever bidirectional automatic winding system, offset to reduce thickness. But by far the most radical change made in the new 9RA5 is the use of thermocompensation, a trick that has been used to increase the accuracy of pure quartz movements for years but had never been applied to a spring drive before. At the time of this writing (late 2020), the 9RA5 is available in only a single watch, the limited-edition SLGA001.

9F Quartz

The 9F is one of the most respected quartz movements ever made, a legend not merely for its incredible accuracy, but also for its toughness, longevity, and, surprisingly, its good looks. While most brands in Grand Seiko’s price range treat quartz as some sort of second class citizen for people who can’t afford their mechanical watches, Grand Seiko offers unique, high-performance movements specifically designed for their watches. It should be no surprise that GS takes quartz so seriously, given that Seiko, and its Astron, revolutionized the watch industry by releasing the very first quartz wristwatch in ’69, so quartz is in its blood. With Grand Seiko, quartz is simply one of three great choices, not an alternative or substitute.

  • Extreme Accuracy
    • All 9Fs are rated for at least +/- 10 seconds per year and a select few for +/- 5 seconds per year.
  • Thermocompenssation
    • All 9Fs are thermocompensated to account for differences in rate owing to changes in temperature.
  • Twin Pulse Motor
    • Due to Grand Seiko’s large and thick dauphine hands, a unique twin pulse motor was designed that could not only move these hands reliably, but do so with a normal battery life.
  • Backlash Auto-Adjust Mechanism
    • A special anti-backlash system prevents the shuddering associated with the seconds hand at the end of each tick.
  • Hand-Assembly
    • Unusual for quartz movements, each 9F is assembled by hand, requiring two specialist watchmakers per movement.
  • Sealed Cabin
    • A special shield in the 9F prevents dust from entering the more sensitive interior of the movement, even during battery changes.
  • Aged Quartz Oscillators
    • Grand Seiko ages quartz oscillators for 3 months each, subjecting them to various voltages until they stabilize. After this period, they are tested, and only the very best of those are placed in 9F movements.

9F6X & 9F8X

9F Family Variants

While technically the 9F has two different sub-categories (9F6X and 9F8X), they’re so similar that I’ll be treating them as one.

  • 9F61
    • The 9F61 is one of the simplest 9Fs, lacking a date complication. Like the 9F62, it’s smaller than the 9F8X movements.
  • 9F62
    • Similar to the 9F61, the 9F62 is a simple three-hand movement but it adds a date complication.
  • 9F82
    • The 9F82 is essentially a larger version of the 9F62.
  • 9F83
    • Now unfortunately somewhat rare, the 9F83 is a day-date version of the 9F.
  • 9F85
    • A new and beloved member of the 9F family, this movement appears to be identical to the 9F82, but it adds an independent hour hand like a GMT watch (minus the GMT hand). This lets the wearer change the time on their watch while they cross time zones or adjust for daylight savings time without affecting the timekeeping.
  • 9F86
    • Like the 9F85, the 9F86 has an independent hour hand, but this one goes all the way and adds a GMT hand for world travelers.

T0 Concept

The T0 Concept is a family with just one member at this time, but I’m hopeful that we’ll be seeing more amazing concept movements down the road. If we do, it’s unknown if they’ll adopt this name scheme (i.e. will we see a T1, a T01, or perhaps U0), so this section is highly speculative. I can’t possibly cover all of the weird and beautiful aspects of the T0 here, so please read my article on it if you want to know more.

The T0 is not only Grand Seiko’s first tourbillon, it’s also the brand’s first remontoire (constant force) movement. Like the 9SA5 that it was co-developed alongside, it features one of the brand’s only free-sprung balances as well. It’s a radical new design for one of the most traditional brands around, and an exciting development for fans. Still, it’s worth emphasizing that, as the name implies, it’s a “concept” movement. It does exist in the real world, rather than just on a computer, but you won’t be seeing one in a watch–ever. Instead, you’ll have to visit the GS museum in Japan if you want to appreciate this one in person.

So that wraps up my primer on Grand Seiko movements that are either currently available or might plausibly become available again in the foreseeable future. Naturally, this is subject to change as Grand Seiko is expanding very rapidly, so I’ll be updating this each year.

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