Grand Seiko Caliber 9f85

Grand Seiko Caliber 9F85

Grand Seiko Caliber 9f85

Manufacturer Grand Seiko (Seiko Time Corp.)
Caliber Number 9F85, 9F85A
In-House?
Yes
Movement Type Quartz, battery-powered
Chronometer Spec? Yes
Thermocompensated?
Yes
Jewel Count
Nine (9)
Frequency
32,768 Hz
Accuracy Rating
+/- 10 secs/year
Battery Cell
SR920SW
Battery Life
~3 years
Regulator?
Yes
Hand Count 3
Functions Central hours; central minutes; central seconds; date at 3:00
Special Features
Time Difference Adjustment, Twin Pulse Control Motor, Backlash Auto-Adjust Mechanism
Hacking Seconds?
Yes
Quickset Date?
Yes
Country of Manufacture Made in Japan
Known Models
SBGP001, SBGP003, SBGP005, SBGP007, SBGP009, SBGP011, SBGP013, SBGP015 (Add your watch to the comments below…)

The Grand Seiko caliber 9F85 (9F85A) is a high accuracy quartz (HAQ) watch movement found in SBGP series watches. This movement is part of the 9F family of Grand Seiko quartz calibers with 9 jewels and various proprietary technologies discussed below.

Grand Seiko states that this in-house caliber is handcrafted and requires two watchmakers to complete the assembly of each movement: one specifically working on the calendar complication and another working on the remainder of the assembly.

High Accuracy Quartz:

Seiko states that the 9F85 is capable of an average accuracy rating between -10 to +10 seconds per year.

Thermocompensated:

While the term “thermocompensated” is typically used for certain Swiss made quartz calibers, a similar concept applies to the Japan-made cal. 9F85. Despite having an on-board temperature control system, the 9F85 still has a battery life of up to 3 years. This is thanks to the low-power integrated circuit that handles the temperate correction.

Regulator Switch:

While Grand Seiko makes it clear in their marketing materials that the typical owner will never need to regulate their 9F85 powered watch, the movement is equipped with a regulator – or “regulation switch” as Seiko officially refers to it.

“If, because of environmental conditions or other factors, a Caliber 9F watch ever becomes too fast or slow, the switch can be used to correct for such divergences. Owners who come to know intimately the individual characteristics of their watch over the years can easily adjust the accuracy and enjoy the high precision of their watch for many years even if it is worn in unusually high or low temperatures or other conditions.” –Source, Regulation switching for precision control in a quartz movement

The regulation switch is a tiny knob located below the battery (with the crown facing upwards), with a minus sign tot he left and a plus sign to the right. As with most fine-tuning devices on mechanical watches, the knob or switch can be gently turned right or left depending on the timing adjustments needed. It is not recommended to move this knob unless you’re sure your watch needs regulated. Chances are, your 9F85 watch is already regulated to the best of its ability directly from the Grand Seiko factory.

If you have experience moving the switch and regulating your own watch, please share the details below…

Setting the time:

The 9F85’s claim to fame (what sets it apart) from the other 9F family members is its ability to set the hour hand independently of the seconds and minutes. Similar to what many Omega quartz watch owners are familiar with (thinking of the Bond SMP quartz here), pulling the crown out to adjust the hour hand does not hack the seconds. This allows for the wearer to keep the time set exactly as it was, but change the hour hand accordingly as they “jump” across time zones.  Therefore, it is not a GMT in the traditional sense (with a 4th hand displaying a 2nd time zone), but it is a traveler’s companion.

Another unique feature of the 9F85 is that when setting the minutes hand, the hand rotates at a much slower rate than other quartz watches. For example, when turning the crown of a typical quartz watch, where a full turn of the crown may result in a full hour of advancing the hand, the 9F85 advances only 20 minutes. This means it could take 3 times as long to set the time, but it also gives the user extra precision when fine-tuning the hand to the exact minute desired.

Additionally, the 9F85 is equipped with Time Difference Adjustment. In Grand Seiko’s own words:

“Caliber 9F85 has a time difference adjustment function that allows the hour hand to be adjusted without stopping the seconds hand and thus preserving its high precision when the wearer changes time zones.” –Source

Twin Pulse Control Motor:

Grand Seiko’s Twin Pulse Control Motor gives the movement the ability to handle heavier sets of hands than can typically be used on quartz movements. In order to manage the extra weight while exerting enough force to maintain accurate time display, the movement actually impulses two times per second, rather than one impulse/second. This extra impulse allows for larger (broad) Grand Seiko hands.

Backlash Auto-Adjust Mechanism:

Perhaps the 9F85 should be added to the mecaquartz list (although some “mechaquartz purists” would disagree) as it borrows a mechanical element from mechanical watches not seen in other quartz movements: a hairspring. Grand Seiko uses a hairspring in the 9F85 movement as a method to stabilize and control any occurrences of shuddering or play when the seconds hand lands on its mark. In other words, thanks to the Backlash Auto-Adjust Mechanism, the seconds hand on 9F85 watches should line up with the marker with every “tick” of the seconds hand. Keep in mind that this also depends on optical illusions when looking at the watch from different angles, as well as the fact that watches are built by humans and there is always a slight margin for imperfection.

As GS describes it:

“The mechanism makes use of a hairspring, a core component of mechanical watches. By utilizing the slight spring power afforded by the hairspring, the faint shuddering of the second hand can be stabilized so that the seconds hand advances precisely and with no shudder.”

The 9F85 is engineered for precision and accuracy, but this Backlash Auto-Adjust Mechanism aides the human observation of the accuracy by eliminating any chance of the eyes catching the time being off by even a fraction of a second. Because, let’s be real, when getting to measuring accuracy of a watch within seconds, it really comes down to how the measurement of time is interpreted by the person holding the watch.

Instant Date Change:

Another mechanical feature found on the 9F85 quartz movement is a cam and lever date changing system for the Instant Date Change Mechanism. This ensure that the date flips as close to midnight as possible. But again, even though it is assisted by mechanical tech, it comes down to assembly by human hands. For this reason, the date is said to leave the factory set for changing within 5 minutes of midnight.

Replacement Price:

This movement is not available for individual sale so there is no retail price to list. At the time of this post, watches powered by the 9R85 were priced in the range of $2,600 to $3,900 USD.

Examples of watches with this caliber:

Additional Resources:

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