Miyota caliber 8315

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.

Accuracy:

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:

1. 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.
2. 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.
3. 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).

Replacement Prices:

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.

Compatibility:

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).

Additional Resources:

• Miyota 8315 tech drawings (pdf)
• 8315 instruction manual (pdf)
• Miyota 8315 parts list (pdf)
• Miyota movement list