The Spring Drive technology has offered a third option to watch enthusiasts looking for superior timing precision along with mechanical refinement; it is perhaps the strongest answer to those who equally value quartz-timekeeping accuracy and a mechanical movement’s beauty. It was 1999 when Seiko first introduced the Spring Drive technology (you may read our exclusive article here), and since then, Spring Drive movements have powered many Seiko, Grand Seiko, and Credor timepieces.

Twenty-one years later, Grand Seiko reveals the Spring Drive‘s new-generation caliber, which marks massive improvements over the current one in terms of thickness, timing precision, maximum power reserve. As well as the new 9AS5 has paved the way to a new Hi–Beat movements’ generation, the same did Grand Seiko with the 9RA5 caliber among Spring Drive movements. Also, the Japanese high-end watchmaker has opened an additional workshop in the Shizukuishi area to possibly bring the Grand Seiko production volume to its full potential.

The brand has selected its professional diver’s watch as a flagship model to welcome the new caliber and launched a 60^th-Anniversary limited edition timepiece known as the Grand Seiko SLGA001 60^th Anniversary. We couldn’t be more surprised since we would expect Grand Seiko to equip the Grand Seiko SBGA229 with this new caliber first, instead of choosing an Hi–Beat SBGH257 or SBGH255‘s case.

It is a Spring Drive movement, disguised as an Hi-Beat.

Before commenting on the new movement, let’s briefly try and describe what sets the SLGA001 apart from its Hi–Beat siblings, aesthetically.

The case is 46,9mm across and is 16mm thick, shaving 1mm off an SBGH255‘s; yet the choice of adopting Seiko‘s patented and scratch-proof High–Intensity Titanium, cuts down its weight by approximately 40%, making the biggest sports watch in Grand Seiko‘s offering, more comfortable.

The rotating bezel has a black inlay (what a pity Grand Seiko didn’t opt for a Cermet-crafted ring, as Seiko did on a recently released limited edition Seiko LX), the font is squared, and the dial is pale blue, a color that not solely reminds the sea-depth, but is the signature Grand Seiko‘s brand color. Finally, the power reserve indicator is divided into five parts (will explain to you why later), showcases a red/orange hand, and is placed at 10 o’clock. No mention is made in the Specs sheet about the case polishing, though I believe Grand Seiko has adopted the zaratsu polishing technique.

A wholly re-engineered caliber.

The new Grand Seiko 9RA5 caliber is the game-changer. Thinner than the outgoing one, it measures 5,0mm instead of 9R6 caliber’s 5,8mm; the new Spring Drive caliber boasts, according to the brand, superior impact resistance and enhanced structural stiffness thanks to new gear-train design and layout, plus a one-piece central bridge placed on top.

Seiko‘s “Magic Lever,” a patented device introduced in 1959, geared towards efficiently recovering the energy provided by the bidirectional winding rotor, has been positioned afar from the caliber’s center, and in an area where it can maximize thickness’s reduction without conversely affecting the re-charging energy provided by the winding mass.

A 120-hour power reserve.

The new caliber totals a stunning five days (else said, 120h) power reserve, hence a 60% increase over the Spring Drive‘s current generation. This performance sets the Grand Seiko SLGA001 60^th Anniversary SLGA001 back to back with a Blancpain Fifty Fathoms, with the addition of the “Glide motion” seconds’ hand’s movement that no other competitor can boast.

Grand Seiko‘s engineers achieved this performance by adopting differently sized barrels (two) to provide the right torque from maximum to minimum power reserve while optimizing parts spacing.

Accuracy increases dramatically.

The outgoing Grand Seiko Spring Drive was already a top performer, but the new caliber significantly outperforms anything else. The new Grand Seiko 9RA5 caliber guarantees a ±10 seconds per month accuracy thanks to a new integrated circuit too, which includes, for the first time, a temperature sensor to compensate any deviation of a quartz crystal’s oscillation, given quartz crystals are affected by temperature.

By introducing this commemorative high-end diving watch, Grand Seiko sets new standards among professional divers and confirms once again itself as a leading brand in luxury watchmaking. The Grand Seiko SLGA001 60^th Anniversary SLGA001 will be available from August 2020 as a limited edition of 700 pieces, and each retailed at €11,500.

It will be sold inside a commemorative box that includes a blue replacement silicone strap. The retail price is high; this is by no means a flagship model, offering exceptional and unique technical prowess, but confirms how Grand Seiko is playing hard to position itself as a premium brand. 

(Photo credit: courtesy of Grand Seiko)

Francesco Falcone @Horbiter®