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Movement comparison

6R35 vs 6R55

Can 6R55 replace 6R35? The known figures match. Some fit figures are still unpublished, so this verdict is not confirmed.

Sources checked · How we source numbers
Movements to scale: Seiko 6R35, Seiko 6R55Dial side and side section at one scale, hand holes enlarged 8:1. A Seiko 6R35: Ø 27.4, H 5.25, date 3H, crown —. B Seiko 6R55: Ø —, H —, date 3H, crown —.B Ø —A Ø 27.4B —A 5.25SIDE · HEIGHTS ON ONE BASELINEA Seiko 6R35Ø 27.4 · H 5.25 · date 3H · crown —B Seiko 6R55Ø — · H — · date 3H · crown —
6R35 vs 6R55 to one scaleDrawing from data, not a photo · mm

Published figures

Differences are highlighted. Each number links to its source; an empty field says what is missing.

6R35 vs 6R55 specification comparison
FigureASeiko 6R35BSeiko 6R55
Diameterone side only27.4 mm1secondary sourcenot in the documents we read
Heightone side only5.25 mm1secondary sourcenot in the documents we read
Jewels243244
Beat rate21,600 bph321,600 bph4
Power reservediffers70 h372 h4
Accuracy (maker)−15 to +25 s/day3−15 to +25 s/day4
Hands and functionshours, minutes, centre seconds, date6hours, minutes, centre seconds, date4
Hacking secondsYes3Yes4
Hand windingYes3Yes4
Date window3H2secondary source3H5secondary source
Do not set the date21:00–01:00321:00–01:004

Can 6R55 replace 6R35?

The direction matters: this checks a watch built for the first calibre with the second installed. Size alone does not prove that hands, dial, stem and case will fit.

Drop-in· not confirmed
  • ?diameterDiameter not published for both: the case seat cannot be checked.
  • =dateDate window at 3H on both.

Not published, so not checked: diameter for 6R55; height for 6R55; hand holes for 6R35; hand holes for 6R55; crown position for 6R35; crown position for 6R55; dial feet for 6R35; dial feet for 6R55.

Check the actual case, stem height and parts before ordering. Compare another pair.

Sources

Documents checked · Report a wrong number

  1. 1CaliberCorner — Seiko Caliber 6R35 watch movement page · html · read
  2. 2Grail Watch — Grail Watch Reference: Seiko 6R35 · html · read
  3. 3Seiko Watch Corporation — Diver's watch for air diving instructions, Cal. 6R35 (EN) · pdf · read
  4. 4Seiko Watch Corporation — Mechanical watch instructions, Cal. 6R55/6R5J (EN) · pdf · read
  5. 5CaliberCorner — Seiko Caliber 6R55 watch movement page · html · read
  6. 6Seiko Watch Corporation — Mechanical watch instructions, Cal. 6R31/6R35/6R38 (EN) · pdf · read