Daini Seikosha 45 Stream

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BRANDS: Daini Seikosha, Grand Seiko, Seiko

Production: 1968 – 1974
1910s	1920s	1930s	1940s	1950s	1960s	1970s	1980s	1990s	2000s	2010s	2020s

The “45 stream” was a series of hand-winding Hi-Beat (36,000 A/h) movements produced by Daini Seikosha for Seiko watches (including King Seiko and Grand Seiko) between 1968 and 1974.

Seiko 45 Stream Overview

Throughout the 1960s, Seiko had two internal operations competing for watchmaking supremacy. Suwa Seikosha, formed in 1959, focused on high-end men’s watches and originated the Grand Seiko line. Daini Seikosha, the historic watchmaking operation for Hattori Seikosha, developed the alternate King Seiko line before creating the famous Grand Seiko Style with the 44GS of 1967.

In 1968, both Suwa and Daini produced a Hi-Beat movement fit for a Grand Seiko watch. The Suwa 6100 stream was an automatic while the Daini 4500 was hand-wound. Both were used in Grand Seiko models until the decline of mechanical watches in that line around 1975.

The Daini Seikosha 4500 stream replaced the respected but slow-beating 4400 stream in King Seiko and Grand Seiko models. The move from 5 Hz to 10 Hz had been a singular technical challenge for Daini, both from a design and metallurgical standpoint. But the movement featured other technical advances as well, including an “instant” date change mechanism.

Compared to the Suwa automatic movement, Daini’s 4500 stream was more elegant in design, with a classic hand-winding look and full balance bridge. It was also notably thinner, giving Daini’s watches a desirable design differentiator.

Calibre	Production	Application	Date	Notes
Cal. 4500	1968-1972	King Seiko	No
Cal. 4502	1968-1973	King Seiko	Yes
Cal. 4520A	1968-1974	Grand Seiko	No	Some tuned for Observatory Chronometer use
Cal. 4522A	1968-1972	Grand Seiko	Yes
Cal. 4580 VFA	1969-1973	Grand Seiko	No	Very Fine Adjustment, limited production

Calibre	Start Year	End Year	Height (mm)	Complications
Seiko 4500	1968	1972
Seiko 4502	1968	1973		Date, Instant Date Change
Seiko 4520	1968	1974	3.5
Seiko 4522	1968	1972		Date, Instant Date Change
Seiko 4580	1969	1973