1970's Seiko 6309 Movement

The Seiko 6309 is a robust automatic mechanical movement, first manufactured in 1976, featuring 17 jewels, a 47-hour power reserve, and a beat rate of 21,600 vibrations per hour (vph). Known for its reliability and durability, it powers various models including Seiko 5 and dive watches and utilizes a unidirectional winding system. The movement also includes a day/date calendar function with a quickset mechanism.

Key Specifications:
Type: Mechanical Automatic
Jewels: 17
Power Reserve: Approximately 47 hours
Frequency (Beat Rate): 21,600 vph (6 beats per second)
Winding: Unidirectional automatic winding system
Calendar: Day and Date with quickset
Feature: Hackable

Reliability:
Considered a "workhorse" movement, it is highly regarded for its robust and dependable performance, even in harsh conditions.
Shock Resistance:
Its design incorporates a shock-resistant mechanism, contributing to its durability.
Serviceability:
Despite its age, the 6309 remains a highly serviceable movement, with parts and expertise available for maintenance. Distinction: SUA vs. Non-SUA The 6309 movement has two generations: early SUA (Suwa Factory) and later Non-SUA. SUA: movements were produced from 1976, while production of Non-SUA movements moved to a new factory outside Japan around 1981. Non-SUA movements are generally considered to exhibit better performance and build quality.