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
Standard	4R38A NH38A 4R71A (skeleton) NH70A (skeleton) NH71A (skeleton, gilt)
Date	4R35A 4R35B NH35A	4R15A 4R15B NH15A
Day and Date	4R36A NH36A	4R16A 4R16B NH16A
Date, 24 Hour Subdial	4R37A NH37A
24 Hour Subdial	4R39A NH39A
Date by Pointer Power Reserve	4R57A

Calibre	Start Year	End Year	Diameter (mm)	Diameter (ligne)	Height (mm)	Complications
Seiko 4R15	2008	Current	27.40	12	5.25	Date, Quick Date Correction
Seiko 4R16	2008	Current	27.40	12	5.25	Date, Day, Quick Date Correction, Quick Day Correction
Seiko 4R35	2010	Current	27.40	12	5.32	Date, Hacking Seconds, Hand Winding, Quick Date Correction
Seiko 4R36	2010	Current	27.40	12	5.32	Bilingual Day Wheel, Date, Day, Hacking Seconds, Hand Winding, Quick Date Correction, Quick Day Correction
Seiko 4R37		Current	27.40	12	5.32	24 Hour Hand, Date, Hacking Seconds, Hand Winding, Quick Date Correction
Seiko 4R38	2012	Current	27.40	12	5.32	Hacking Seconds, Hand Winding
Seiko 4R39	2011	Current	27.40	12	5.32	24 Hour Hand, Hacking Seconds, Hand Winding
Seiko 4R57	2017	Current	29.36	12	6.63	Date, Date by Pointer, Hacking Seconds, Hand Winding, Power Reserve Indicator, Quick Date Correction
Seiko 4R71	2018	Current	27.40	12	5.32	Hacking Seconds, Hand Winding