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Seiko 4R Family

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BRANDS: Seiko, Seiko Instruments Inc., Time Module Inc.

Production: 2008 – Current
1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s 2000s 2010s 2020s

Seiko 4R Family Overview

Introduced in 2008, the Seiko Instruments Inc. (SII) 4R family is a mainstream automatic watch movement used in many Seiko models and offered to third parties by Time Module Inc. (TMI). It is an evolution of the Seiko 7S family of movements, produced since 1996, and is related to the higher-end Seiko 6R family.

All movements in the 4R family operate at 21,600 A/h and measure 12 ligne (27.4 mm) in diameter by 5.32 mm in height. Cal. 4R15 and 4R16 have 22 jewels, Cal. 4R35A has 23 jewels, and all other 4R and NH movements have 24 jewels. The NH series movements sold by Time Module Inc. (TMI) are rated as slightly more accurate from the factory, at -20/+40 rather than -35/+45 for the Seiko branded movements, and some differ in the finish, number of jewels, and rated power reserve.

Seiko 4R Movements

There are two branches of the family: The 4R1x movements (4R15, 4R16) came first and have an advanced Spron 510 mainspring but lack hacking and hand-winding. The 4R3x movements (4R35, 4R36, 4R37, 4R38, 4R39, 4R57, 4R71) appeared after 2010 and have a traditional mainspring but add hacking and hand-winding. The 6R family has both improvements.

There are only a few complicated members of the family, with a 24 hour subdial (4R37 and 4R39), or date by pointer subdial and power reserve indicator (4R57).

Traditional Mainspring
Hacking/Hand-Winding		Spron 510 Mainspring
Standard4R38A
NH38A
4R71A (skeleton)
NH70A (skeleton)
NH71A (skeleton, gilt)
Date4R35A
4R35B
NH35A		4R15A
4R15B
NH15A
Day and Date4R36A
NH36A		4R16A
4R16B
NH16A
Date, 24 Hour Subdial4R37A
NH37A
24 Hour Subdial4R39A
NH39A
Date by Pointer
Power Reserve		4R57A

Calibre Start Year End Year Jewels Diameter (mm) Height (mm) Complications
Seiko 4R15 2008 Current 22 27.40 5.25 Date, Quick Date Correction
Seiko 4R16 2008 Current 22 27.40 5.25 Date, Day, Quick Date Correction, Quick Day Correction
Seiko 4R35 2010 Current 23, 24 27.40 5.32 Date, Hacking Seconds, Hand Winding, Quick Date Correction
Seiko 4R36 2010 Current 24 27.40 5.32 Bilingual Day Wheel, Date, Day, Hacking Seconds, Hand Winding, Quick Date Correction, Quick Day Correction
Seiko 4R37 Current 24 27.40 5.32 24 Hour Hand, Date, Hacking Seconds, Hand Winding, Quick Date Correction
Seiko 4R38 2012 Current 24 27.40 5.32 Hacking Seconds, Hand Winding
Seiko 4R39 2011 Current 24 27.40 5.32 24 Hour Hand, Hacking Seconds, Hand Winding
Seiko 4R57 2017 Current 29 29.36 6.63 Date, Date by Pointer, Hacking Seconds, Hand Winding, Power Reserve Indicator, Quick Date Correction
Seiko 4R71 2018 Current 24 27.40 5.32 Hacking Seconds, Hand Winding