Vintage 1970 JAPAN SEIKO PRESMATIC WEEKDATER 5146-7040 27Jewels Automatic.

Vintage 1970 JAPAN SEIKO PRESMATIC WEEKDATER 5146-7040 27Jewels Automatic.

Welcome to my auction!
I am Japanese who live in Tokyo.

Item description

Movement :

• Pet name : 51 SEIKO PRESMATIC WEEKDATER .
• Caliber number : 5146A.
• Movement : Automatic.
• Beat rate : 28800bph.
• Year of manufacture start : 1969's.
• Factory : Kameido.

Externals :

• Serial number : 055119.
• Dial number : JAPAN 5146-7070R.
• Glass : Crystal.
• Case size : About 36.37mm.
• Lug width : 18mm.
• Band : New Leather Strap of SEIKO original.

Condition :

• Used, it runs well.
• Quick set(Day/Date) : Okay.
  Set the day of the week : English only.
  Set of the days of the week : Iteration the hour hand at 8:00 to 12:00.
  Set of the date: Press the crown.
• The day difference time of an used watch is about +-1 minute / day.
• For practical, everyday use, it would be advisable to have the movement cleaned and oiled.

Key Features

The Sovereign Peak of 1970 Kameido Executive Luxury (1970): Manufactured in **1970**—a milestone historical year defined by the Osaka Expo '70 and Japan's peak post-war industrial supremacy—the **Seiko 51 Presmatic Weekdater** represented Daini Seikosha's flagship high-tech alternative to traditional luxury dress watches. Sourced under reference **5146-7040**, this high-grade executive model sat directly below the King Seiko line, combining cutting-edge mechanical quick-set technology with bold, geometric Showa-era styling.

The High-Beat 27-Jewel Caliber 5146 Automatic Heart: Powering this historic instrument is the magnificent **27-jewel Caliber 5146A**, an in-house automatic engine operating at a swift high-beat frequency of **28,800 vibrations per hour (8 beats per second)**. Highly celebrated by vintage purists for its lavish **27-jewel specification**, this caliber minimized gear-train friction and incorporated advanced functionality including **hacking seconds**, hand-winding capability, and high chronometric stability.

Revolutionary ""Presmatic"" Hexagonal Crown Push-Date Mechanism: A defining technological triumph of the 51-series movement was its iconic **crown-center push button (Presmatic mechanism)**. By depressing the center button integrated inside the unique **hexagonal crown**, the wearer could instantly advance the date wheel with a crisp tactile feedback. This clever engineering eliminated the need for secondary case pushers while preserving sleek, water-resistant case lines.

Architectural ""7040"" Cushion Case and Faceted Dial Geometry: The reference **5146-7040** is globally distinguished among vintage collectors for its robust, **cushion-shaped case architecture** featuring sharp, angular facets and sweeping broad shoulders inspired by Taro Tanaka's **""Grammar of Design""** principles. The radiant silver sunburst dial features **hand-applied, multifaceted rectangular hour indices** paired with razor-sharp hands. Symmetrically framed at 3 o'clock, the dual-calendar window houses a **bilingual day disk** alongside the quick-set date configuration.

An Investment-Grade Masterpiece of Daini's Mechanical Legacy: Manufactured in the milestone mechanical year of **1970**, the 5146-7040 27-jewel Presmatic remains one of the most historically significant, highly sought-after Daini references worldwide. It captures the exact historical moment where Kameido perfected high-beat automatic utility right before the industry shifted into quartz technology. Built to an uncompromising heirloom standard, it stands as an eternal testament to late-1960s and early-1970s Japanese horological design.

For more information, please look at the pictures.

Notes

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