Movement review Seiko calibre 4500-4580

In 1968 Daini devision of Seiko introduced their first high beat movement. This movement calibre: 4500 has a beat rate of 36,000 A/H. This movement was made for the King Seiko series but was also used by Grand Seiko. The date version is designated 4502.  Grand Seiko used the movement under the name 4520 and 4522. The ultimate version VFA (Very Fine Adjustment) version had finer finishing and was adjusted to keep accuracy within 1 minute pr month. The 4500 series all featured hacking lever and the date versions all have a quick date setting. This modern design was close to being perfect with the exception of one major issue being the amount of power needed to achieve the high beat rate. The powerful mainspring puts a lot of strain on the gear train causing it to wear and it’s not unusual to find completely worn out movements. There are a lot of jewels used, but strangely none where used as barrel arbour bushings unlike other seiko movements at the time. A movement in good condition will have a remarkable smooth sweep second hand, but as the sweep second wheel is driven of the escape wheel it is very sensitive and prone to stuttering due to the smallest amount wear or dirt. 

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