Seiko 5626B – Technical Guide

Introduction

The Seiko 5626B is a high-grade automatic movement with day-date complication, produced by Suwa Seikosha in the early 1970s. It is part of Seiko’s revered 56xx series, which powered many of the King Seiko and Lord Matic models. The 5626B is an update to the earlier 5626A, featuring technical refinements for better durability and precision.

As a hand-windable and hacking automatic movement with a high beat rate, the 5626B is considered one of Seiko’s best vintage calibers — balancing accuracy, robust construction, and mechanical elegance.

Technical Specifications

Features and Functionality

Automatic and Manual Winding

• The movement is wound by a bi-directional rotor using Seiko’s magic lever system, known for its efficiency.

• The crown can also be turned to wind the mainspring manually — a key feature in vintage Seiko automatics.

Quickset Day-Date Mechanism

• Date quickset: Pull the crown to the first click and turn clockwise.

• Day quickset: Turn counterclockwise at the same crown position.

• The day display is often bilingual (English + Kanji or Spanish).

⚠️ Do not use the quickset between 9:00 PM and 3:00 AM, as the calendar gears are engaged and damage may occur.

Hacking Seconds

Pulling the crown to time-setting position stops the seconds hand, allowing for precise synchronization — a rare and valued feature in vintage movements.

Movement Evolution: 5626A vs. 5626B

The 5626B is an improved version of the 5626A, with:

• Revised quickset mechanism for better durability

• Improved day/date jumper springs

• Minor enhancements in the calendar cam gear and setting lever

• Smoother hand-winding feel and more reliable crown assembly

Servicing and Maintenance

Lubrication Points

• Standard lubrication applies at the escape wheel, pallet fork, center wheel, and mainspring barrel.

• Be cautious when lubricating the magic lever — over-lubrication may cause inefficient winding.

Common Wear Areas

Identifying 5626B Watches

The 5626B movement was commonly used in:

• King Seiko 5626-7000, 5626-7040, 5626-7110

• Seiko Lord Matic Special and LM Deluxe models

• Chronometer-grade King Seiko models (signed “Chronometer Officially Certified” on the dial)

• Caseback engraving typically reads:

  • “5626-xxxx”

  • “JAPAN 5626B” near the balance cock

Summary Table

Conclusion

The Seiko 5626B movement represents the pinnacle of 1970s Japanese watchmaking — combining smooth high-beat performance, a practical calendar system, manual winding, and hacking seconds into one reliable movement. Collectors prize it not only for its durability but also for its placement in some of Seiko’s most elegant and historically significant models. A well-maintained 5626B remains a joy to wear and a worthy candidate for restoration.