The Miyota caliber 8315 is a 21 jewels automatic movement, made in Japan. It is part of Miyota’s line of “Standard Automatic” watch movements, but what sets this calibre apart from the others is that is has a longer running time with more than 60 hours power reserve. Miyota states that this is their longest running mechanical movement.
Some of the topics covered in this caliber listing:
Miyota claims that the cal. 8315 has an average accuracy rating of -20 / +40 seconds per day in normal operating conditions.
Time and Date Setting:
As a basic 3-hander with a date, setting the 8315 is straightforward. There are 3 crown positions:
Crown against the case – Manual winding: full power serve is reached when the crown is turned at least 51 times. You cannot over-wind the movement.
Crown pulled out one click – Date setting mode: turning the crown counterclockwise will advance the calendar datewheel. Do not make this adjustment when the hands are between the hours of 9:00pm and 1:00am.
Crown pulled out two clicks – Time setting mode: rotate the crown to set the time of the hands. The seconds hand will be hacked in this mode (aka stopped for precise time-setting).
At the time of this post, replacement pricing for the Miyota 8315 was found online in the range of $85 to $89.95 USD. When ordering bulk from Miyota, the minimum order quantity is 100 pieces.
The 8315 is based on the 8200 series framework. Therefore, it is compatible with most caliber 82XX dials, hands, and cases (such as the popular Miyota 8215).