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Movement · Seiko · automatic

Seiko 8R48 movement

Seiko 8R48 is an automatic movement by Seiko: 7.5 mm1secondary source high, 342 jewels, beating at 28,800 bph2, 45 h2 of power reserve.

Sources checked · How we source numbers
Seiko 8R48: movement drawingSeiko 8R48, dial side, to scale: movement diameter — (unknown); date 4.5H window (size unknown); height 7.5 mm; hour, minute, second hand hole Ø — (unknown).movement Ø —date 4.5Hsize —, position only7.5SIDE · SECTION · height 7.5Ahour, minute, second hand hole Ø —DETAIL A · 10:1
Seiko 8R48, dial sideDrawing from data, not a photo · mm

8R48 at a glance

Height
7.5 mm1secondary source
Jewels
342
Beat rate
28,800 bph2
Power reserve
45 h2
Accuracy
−15 to +25 s/day2

New to the terms? Read quartz vs automatic or watch movement types.

Setting and servicing the 8R48

The figures a watchmaker or a timegrapher needs for the 8R48, as Seiko prints them.

Accuracy (maker)
−15 to +25 s/day2Only if worn on the wrist in a temperature range of 5 C to 35 C
Power reserve
45 h2
Hacking seconds
Yes2
Hand winding
Yes2

What fits the 8R48

The figures a dial, hands or case must match for the 8R48, as Seiko prints them.

Date window
4:30H1secondary source

All 8R48 figures

Every figure we hold for the 8R48, with its source. Where sources disagree, each value is shown.

Size

Height
7.5 mm1secondary source

Running

Jewels
342
Beat rate
28,800 bph2
Power reserve
45 h2
Hands and functions
hours, minutes, small seconds, chronograph, date2
Hacking seconds
Yes2
Hand winding
Yes2

Accuracy and care

Accuracy (maker)
−15 to +25 s/day2

Fitting: dial, hands, stem

Date window
4:30H1secondary source

Origin

Made from
20141secondary source

Not published yet

  • Diameter: not in the documents we read
  • Height: not published
  • Lift angle: not in the documents we read
  • Hand holes: only in Seiko’s drawing; not read yet
  • Dial feet: only in Seiko’s drawing; not read yet
  • Stem part number: not published by Seiko
  • Do not set the date: not in the documents we read

Versions

8R48A · 8R49A[1]

8R48 questions

How accurate is the 8R48?

Seiko rates the 8R48 at −15 to +25 s/day, measured under Seiko’s own test conditions; a worn 8R48 can run outside the −15 to +25 s/day range.

Source [2]

How long does the 8R48 run when fully wound?

About 45 h from a full wind, per Seiko.

Source [2][1]

Does the 8R48 hack and hand-wind?

Yes, it hacks: the seconds hand stops with the crown pulled out. It can be wound by the crown.

Source [2]

More on movements

Sources

Documents checked · Report a wrong number

  1. 1Grail Watch — Grail Watch Reference: Seiko 8R48 · html · read
  2. 2Seiko Watch Corporation — Mechanical chronograph instructions, Cal. 8R46/8R48 (EN) · pdf · read