Watches & Wonders 2025: Grand Seiko Introduces The Spring Drive ‘UFA’ The Most Accurate Spring Drive Yet
The new watches also feature a new movement: the next-generation caliber 9RB2.
In 1972, Grand Seiko debuted the first of a new series of watches. These were the Grand Seiko VFA models – VFA stands for Very Fine Adjusted, and the VFA watches, which were produced in a number of different models from 1970 to 1975, including quartz models, and the mechanical VFA watches were the pinnacle of Grand Seiko mechanical precision; they were adjusted to a precision of ± 2 seconds per day, and moreover, they were guaranteed to maintain that precision for the first two years of ownership. The series was a major achievement for GS but VFA also debuted just one year after Seiko launched the world’s first commercially available quartz watch, the Astron, and by the mid-1970s, “Seiko Superior” quartz watches were achieving a precision of ±1 second per month, which led to the retirement of the entire Grand Seiko line. Grand Seiko would not reappear until 1988, and mechanical Grand Seiko watches didn’t show up until 1998. Just a year later, however, a new technology appeared: the first Spring Drive watches were introduced, with the first Grand Seiko Spring Drive watches debuting in 2004.
Since then, Spring Drive has continued to evolve; the latest generation of Spring Drive movements are the 9R series, with the 9RA5, launched in 2020, offering a precision of ± 10 seconds per month. For Watches & Wonders 2025, Grand Seiko is launching the Spring Drive UFA, or Ultra Fine Accuracy, which brings Spring Drive into the world of precision previously only available to high precision quartz watches – the new caliber 9RB2 is accurate to ± 20 seconds per year.
Spring Drive movements can be a little confusing when you encounter them for the first time; they are a unique electromechanical design which has features of both quartz and mechanical watches, as well as features found in neither quartz or mechanical, but only in Spring Drive. Spring Drive watches are as the name says, powered by a mainspring and are available in both hand-wound and automatic models. Automatic winding systems are based on the famous double pawl Magic Lever system, and the gear train of Spring Drive watches is more or less identical to the one you’d find in a conventional mechanical watch, right up to where the escape wheel would be.
Here’s where things get unusual. The last conventional gear in the going train drives what Grand Seiko calls a “glide wheel” which is a rotating disk which acts as the rotor of an electrical generator. Energy produced by the glide wheel is fed to a quartz timing package, which produces a reference signal used to regulate the speed at which the glide wheel rotates. The power produced by the glide wheel is also fed to a high-efficiency integrated circuit. This circuit continuously monitors the rate of rotation of the glide wheel and compares it to the reference rate from the quartz oscillator and applies an intermittent braking force to ensure that the glide wheel rotates exactly eight times per second. The glide wheel rotates smoothly, and therefore, so do the wheels upstream of the glide wheel in the going train.
This produces the signature feature of Spring Drive watches: a smoothly rotating seconds hand that moves forward in a continuous motion, rather than the incremental jumps seen in a mechanical watch. There is no battery and if the mainspring runs down the watch will stop, same as a mechanical watch. The whole glide wheel, IC and quartz timing package, and generator/brake system is called the Tri-synchro Regulator.
The new UFA watches, SLGB001, in platinum, and SLGB003, in Grand Seiko’s High Intensity Titanium, are at ± 20 seconds per year, the most accurate Spring Drive watches ever made and the most accurate mainspring powered wristwatches ever made.
The precision of caliber 9RB2 is not the result of any single technological breakthrough but it does represent what’s possible when there are incremental improvements across the entire regulating system. The quartz crystal used in the timing package is aged for three months to allow it to settle down on its rate, and as with the 9RA series, temperature compensation is built into the system as well. Quartz crystals actually vary on their rate with temperature change, albeit to a much lesser degree than balance springs, and each quartz oscillator used in the 9RB2 has its rate measured at several different temperatures. That information is then programmed into the integrated circuit. The oscillator and temperature sensor are vacuum sealed, to reduce temperature variations and also to seal the package against intrusion by moisture, the effects of static electricity, and to minimize temperature related rate variations. The caliber 9RB2 also has a rate trimmer, which allows fine regulation of the movement during service in order to compensate for long-term frequency drift.
The rate trimmer is visible above, just above the GS logo and the glide wheel is to the upper right, at about 2:00, with the power reserve indicator above the word “ultra.” The glide wheel and the last wheel of the going train both have antishock springs on their pivots.
As is usual for Grand Seiko, the dials of the new Spring Drive UFA watches are inspired by nature. In this case, the dial pattern’s inspired by the Kirigame Highlands, which are famous in Japan for their snow covered trees in winter.
The Spring Drive UFA watches are part of the Evolution 9 collection, with its characteristic sharp, geometrically clean transitions, emphasis on legibility, and large, faceted, mirror polished indexes and hands. Case sizes are a bit of an echo of the era of mechanical VFA watches – the case dimensions are 37mm x 11.4mm.
This is an exciting new development for Grand Seiko and a shout out to those years in the early 1970s when Grand Seiko was demonstrating its dedication to improving precision. Such watches were never the bulk of GS production, but for those Grand Seiko fans who are also interested in advances in horology in general, and in the pursuit of high precision, the Spring Drive UFA watches are a sign that the glorious past is also alive in the present.
Grand Seiko Spring Drive UFA Evolution 9 Collection: cases, platinum (SLGB001) or High Intensity Titanium (SLGB003); 37mm x 11.4mm, water resistance 10 bar/100 meters; magnetic resistance, 4,800 amperes per meter; box shaped sapphire crystal with AR coating on inner surface; sapphire display back. Movement, Ultra Fine Accuracy 9RB2, Spring Drive automatic, 72 hour power reserve adjusted to ±20 seconds per year. Prices, $39,000 (SLGB001, 80 piece limited edition) or $10,900 (SLGB003).
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