Miyota Caliber 8315

Miyota caliber 8315

Miyota Caliber 8315 Wide

ManufacturerMiyota (Citizen)
Caliber Number8315
Movement TypeAutomatic, self-winding mechanical
Lignes
11.5”’
Diameter26mm
Height5.67mm
Jewels21
Beat Rate
21,600 bph, 3 Hz
Lift Angle
49 degrees
Accuracy
See below…
Power Reserve
60 hours
Rotor Winding DirectionCounterclockwise
Hand Windable?
Yes
Stem065-212 (tap 10)
Dial Screws929-610
Case Clamps
082-060
Case Clamp Screws
924-460
Anti-Shock SystemParashock
Hand Sizes
1.50mm / 1.0mm / 0.17mm
FunctionsCentral hours; central minutes; central sweeping seconds; date calendar at 3:00
Hacking Seconds?
Yes
Quickset Date?
Yes
Finishing
“Fine finishing” decoration on the barrel bridge; blued screws on the oscillating weight, barrel bridge, and balance cock
Country of ManufactureJapan
Known Models(Add your watch in the comments below…)

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:

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:


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HoustonReal
HoustonReal
10 months ago

The Miyota 8315 replaces the 821A. It is a hacking and decorated version or the Miyota 8215, that has now been upgraded with a new mainspring. The power reserve is now a minimum of 60 hours, and the movement is offered in silver and gilt versions.

Diameter: 11.5 Ligne/25.6mm
Height: 5.67mm
Jewels: 21
Complications: Date
Power Reserve: 60+ hours
Lift Angle: 51
Antishock: Parashock
Hand Sizes: 100/152/17
Dial Feet: 25/50

miyota_8315_movementback.jpg
Miyota_8315.jpg
John le Carré
John le Carré
2 months ago
Reply to  HoustonReal

Very good and accurate text, @HoustonReal, lift angle is 51° – 53° though. Just helping here.

William Shatner
William Shatner
19 days ago
Reply to  John le Carré

@CC, I’ve measured my 8315’s lift-angle too. My Witschi-apparatus ensures me of the correct lift-angle of 52° (degrees).

John le Carré is thus fairly right though. Witschi is the correct Swiss measuring device, since a very long time, since I can remember anyways. No hard feelings, @CC.

Don B
Don B
2 months ago
Reply to  HoustonReal

It appears to be a descent movement. I just installed one in my Bulova Devel Diver 666, replacing to 8215 that they use from the factory. I really prefer the hacking function and the stock movement was just not doing it for me. The 8315 is a direct drop in movement and no mods were required. My unit is currently at +2 seconds with no beat error. I will run it for a couple weeks… Read more »

William Shatner
William Shatner
19 days ago
Reply to  HoustonReal

HoustonReal, you’re spot-on ( what’s a 1° deviation in your and my measurements (?) – it’s close enough, ey ?! 😉 )

I too find it a feisty little 8315-caliber. Another big win for Citizen ánd Miyota alike.

;
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