Seiko Caliber 4R71

Manufacturer	Seiko
Caliber Number	4R71, 4R71A
In-House?	Yes
Movement Type	Automatic, self-winding mechanical, skeletonized
Diameter	27.4mm
Casing Diameter	27mm
Thickness	5.32mm
Jewels	24
Beat Rate / Frequency	21,600 bph / 3 Hz
Lift Angle	53 degrees
Accuracy Rating	-35~+45 seconds/day
Power Reserve	~41 hours
Rotor Type	Ball-bearing system, 1 screw
Hand Windable?	Yes
Hand-Winding Direction	Clockwise
Rotor Winding Direction	Bi-Directional (Magic Lever)
Anti-Shock System	Seiko Diashock
Regulator System	ETACHRON
Functions	Central hours; central minutes; central sweeping seconds
Hacking Seconds?	Yes
Country of Manufacture	Made in Japan
Known Models	Seiko Premier (Ref: SSA399), Seiko Premier Novak Djokovic Limited Edition (Ref: SSA374, SSA375) (Add your watch in the comments below…)

The Seiko caliber 4R71 (4R71A) is a skeletonized/open balance automatic movement used by Seiko Watch Corp. in their own branded watches.

This calibre is found in Seiko Premier Novak Djokovic limited edition watches introduced in March 2018.

Caliber 4R71 VS 4R72:

There is also a similar caliber 4R72. The difference between the two is color: The 4R71 is silver tone, whereas the 4R72 is gold tone. Everything else is the same, including dimensions, jewels, accuracy, etc.

Caliber 4R71 VS SII NH70:

The caliber 4R71 is basically a Seiko-only version of the NH70 (the NH70 is silver tone, the NH71 is gold tone). Seiko Instruments (aka SII) sells NHXX movements to other watch brands for use in non-Seiko watches.

Differences Between 4R71 and 4R71A?

The A indicates that it is the first generation of this caliber. 4R71 and 4R71A are the same, until Seiko releases a 4R71B which will be a second generation (if ever).

Accuracy Rating:

Seiko claims that the accuracy of caliber 4R71 is between +45 / -35 seconds per day.

This rating is based on normal daily wear on the wrist in temperatures between 5º C and 35º C. When testing your watch for timekeeping, make sure it is fully wound.

Crown Position Functions:

• 0 (against the case): Clockwise = Manual Winding / Counterclockwise = Nothing
• 1 (pulled out one click): Clockwise = Day setting / Counterclockwise = Date setting
• 2 (pulled out two clicks): Time setting clockwise and counterclockwise

Stem Removal:

To remove the stem, make sure the crown is in position 0 or normal position (not date or time setting position). There is a lever with a small indentation for your tool. Gently press down while pulling the stem out. See official instructions below for more guidance:

Examples of watches with this caliber:

 

Additional Resources:

• Official 4R71 user manual (pdf)