Seiko 4S Family

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BRANDS: Credor, Daini Seikosha, Seiko

Production: 1992 – 2015
1910s	1920s	1930s	1940s	1950s	1960s	1970s	1980s	1990s	2000s	2010s	2020s

The 4S series was a high-end automatic watch movements from Seiko introduced in 1992. It was used by a variety of Seiko brands, including Credor, until 2015. During that time it was used in high-end luxury, military, exploration, and dive watches and made notable appearances in historical reissues. The 4S series was largely replaced by the 8L and 9S movement family.

The first member of the family was perhaps the most important. Seiko’s revival as a maker of high-end watches began in 1992 with the release of Cal. 4S35, which powered a new high-end Seiko Automatic series. It was based on the 52 stream of movements, the last great design from Daini Seikosha in the classic period of Seiko mechanical watches. Much of the design and development work was performed by Daini workers who returned from retirement to contribute to the new movement series.

A more simply-decorated version, Cal. 4S15, was released in 1995 in the revived Alpinist and new Titanium Diver watches, and this would also be used the following year in the famous SUS Military watches. These would disappear for a few years until the 6R15 was released. 1996 also saw the complicated Cal. 4S77 Credor retrograde GMT, presaging the future of the line.

In the 2000s, the 4S series was limited to Brightz and Credor models. The last 4S movement was Cal. 4S79 in the Credor Node GCAY, which was removed from the catalog in 2015.

Unlike many other contemporary Seiko movements, the 4R series uses a conventional reverser gear for the automatic winding system rather than Seiko’s Magic Lever system. This is derived directly from the 52 stream, which also used this winding system.

Although there are a large number of 4S movement numbers, the list of variants is somewhat smaller:

Simple time and date movements: 4S15, 4S25, 4S35, 4S12 (with fixed 24 hour hand), 4S71 (no date)
Hand-winding time-only movements: 4S24 (center seconds), 4S28 (small seconds)
Hand-winding with power reserve at 9: 4S29, 4S79
Complicated automatic with retrograde day, date by pointer, independent GMT hand, and retrograde power reserve: 4S36, 4S76
Complicated automatic with retrograde day, date by pointer, and sub-dial GMT: 4S27, 4S77

Most movements in the series have a 40 hours of power reserve, though the 4S27/4S77 and 4S36/4S76 have 50 hours. Accuracy for all of the 4S1x and 4S2x movements is -15/+25 seconds per day, while the 4S3x and 4S7x movements are accurate to -10/+15 seconds.

There were quite a few complications available in this range:

Small seconds at 6:00 – 4S28, 4S29/4S79
Date pointer at 6:00 – 4S27/4S77, 4S36/4S76
Retrograde day pointer at 2:30 – 4S27/4S77, 4S36/4S76
Retrograde power reserve indicator at 9:30 – 4S29/4S79, 4S36/4S76

Additionally, there were three variations on a 24 hour “GMT” hand:

Central non-independent 24 hour hand – 4S12
Central independent 24 hour hand – 4S36/4S76
Subdial independent 24 hour hand – 4S27/4S77

Early Seiko 4S Movements

From the 1992 introduction of the Seiko 4S family through the early 2000s, Seiko used the 4S line as a high-end movement for diverse watches, including the SUS military, Alpinist, and Titanium diver. Most of these models were retired shortly after introduction, and the series of simple 4S movements was phased out by 2003.

	Production	Watch	Winding	Jewels	Notes
4S12	1997-1998	SCFF	Automatic	25	Date Fixed 24 hour hand
4S15	1995-2001 2006	LHAM SCFF SCVF SCVN	Automatic	25	Date
4S24	1990s	LJAL SCVG	Manual	21
4S25	1993-1998	SCVH SCVJ	Automatic	25	Date
4S28	1994-2000	LJAK SCVG SCVM	Manual	24	Small seconds at 6:00
4S35	1992-2000	SCVK	Automatic	25	Date
4S71	1995-2003	GCBB	Automatic	25

Complicated Seiko 4S Movements

After 2000, Seiko had more diverse mechanical movements to choose from. The 4S family was moved upmarket as a base for modules to use in complicated upscale watches. The last 4S movement was retired in 2015.

	Production	Watch	Winding	Jewels	Notes
4S27	2003-2007	SAGN	Automatic	28	Retrograde day at 2:00 Date pointer at 6:00 GMT subdial at 9:00
4S29	2003-2007	SAGN	Manual	29	Small seconds at 6:00 Retrograde power at 9:00
4S36	2007-2013	SAEN SARN	Automatic	31	Independent 24 hour hand Retrograde day at 2:00 Date pointer at 6:00 Retrograde power at 9:00
4S76	2004-2010	GBBT GCBT	Automatic	31	Independent 24 hour hand Retrograde day at 2:00 Date pointer at 6:00 Retrograde power at 9:00
4S77	1996? 2000-2005	GCBG	Automatic	28	Retrograde day at 2:00 Date pointer at 6:00 GMT subdial at 9:00
4S79	1998-2015	GBAY GCAY	Manual	31	Small seconds at 6:00 Retrograde power at 9:00

Calibre	Start Year	End Year	Diameter (mm)	Diameter (ligne)	Height (mm)	Complications
Seiko 4S12	1997	1998				24 Hour Hand, Date, GMT Hand, Hacking Seconds, Hand Winding, Quick Date Correction
Seiko 4S15	1995	2006	25.60	11.5	4.17	Date, Hacking Seconds, Hand Winding, Quick Date Correction
Seiko 4S24			25.60	11.5		Hacking Seconds
Seiko 4S25	1993	1998	25.60	11.5	4.17	Date, Hacking Seconds, Hand Winding, Quick Date Correction
Seiko 4S27	2003	2007	25.60	11.5	5.38	24 Hour Hand, Date, Date by Pointer, Day, GMT Hand, Hacking Seconds, Hand Winding, Independently-Adjustable 24 Hour Hand, Modular, Quick Date Correction, Quick Day Correction, Retrograde Day
Seiko 4S28	1994	2000	25.60	11.5		Hacking Seconds
Seiko 4S29	2003	2007	25.60	11.5		Hacking Seconds, Hand Winding, Power Reserve Indicator
Seiko 4S35	1992	2000	25.60	11.5	4.00	Date, Hacking Seconds, Hand Winding, Quick Date Correction
Seiko 4S36	2007	2013	25.60	11.5		24 Hour Hand, Date, Date by Pointer, Day, GMT Hand, Hacking Seconds, Hand Winding, Independently-Adjustable 24 Hour Hand, Power Reserve Indicator, Quick Date Correction, Quick Day Correction, Retrograde Day
Seiko 4S71	1995	2003	25.60	11.5		Hacking Seconds, Hand Winding
Seiko 4S76	2004	2010	26.50	11.5		24 Hour Hand, Date, Date by Pointer, Day, GMT Hand, Hacking Seconds, Hand Winding, Independently-Adjustable 24 Hour Hand, Power Reserve Indicator, Quick Date Correction, Quick Day Correction, Retrograde Day
Seiko 4S77	1996	2005				24 Hour Hand, Date, Date by Pointer, Day, GMT Hand, Hacking Seconds, Hand Winding, Independently-Adjustable 12 Hour Hand, Quick Date Correction, Quick Day Correction, Retrograde Day
Seiko 4S79	1998	2015				Hacking Seconds, Hand Winding, Power Reserve Indicator