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Movement comparison

4R35 vs 6R35

same diameter; same height. Can 6R35 replace 4R35? 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 Some fit figures are still unpublished, so this verdict is not confirmed.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 4R35, Seiko 6R35Dial side and side section at one scale, hand holes enlarged 8:1. A Seiko 4R35: Ø 27.4, H 5.32, date 3H, crown —. B Seiko 6R35: Ø 27.4, H 5.25, date 3H, crown — (vs A: Ø 0 H −0.07 mm).A Ø 27.4B Ø 27.4B 5.25A 5.32SIDE · HEIGHTS ON ONE BASELINEA Seiko 4R35Ø 27.4 · H 5.32 · date 3H · crown —B Seiko 6R35Ø 27.4 · H 5.25 · date 3H · crown —vs A: Ø 0 H −0.07 mm
4R35 vs 6R35 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.

4R35 vs 6R35 specification comparison
FigureASeiko 4R35BSeiko 6R35
Diameter27.4 mm1secondary source27.4 mm2secondary source
Heightdiffers5.32 mm1secondary source5.25 mm2secondary source
Jewelsdiffers234
2 sources disagree; show every value
  • manufacturer 234
  • secondary source 23, 241
246
Beat rate21,600 bph421,600 bph6
Power reservediffers41 h4
2 sources disagree; show every value
  • manufacturer 41 h4
  • secondary source 40, 41 h1
70 h6
Accuracy (maker)differs−35 to +45 s/day5−15 to +25 s/day6
Hands and functionshours, minutes, centre seconds, date4hours, minutes, centre seconds, date8
Hacking secondsYes4Yes6
Hand windingYes4Yes6
Date window3H1secondary source3H3secondary source
Do not set the date21:00–01:00421:00–01:006

Can 6R35 replace 4R35?

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
  • =diameterSame movement diameter: 27.4 mm.
  • =heightSame height: 5.32 mm and 5.25 mm.
  • =dateDate window at 3H on both.

Not published, so not checked: hand holes for 4R35; hand holes for 6R35; crown position for 4R35; crown position for 6R35; dial feet for 4R35; dial feet for 6R35.

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

Sources

Documents checked · Report a wrong number

  1. 1Grail Watch — Grail Watch Reference: Seiko Cal. 4R35 · html · read
  2. 2CaliberCorner — Seiko Caliber 6R35 watch movement page · html · read
  3. 3Grail Watch — Grail Watch Reference: Seiko 6R35 · html · read
  4. 4Seiko Watch Corporation — Instructions: Seiko Automatic Diver's Watch Cal. 4R15/4R16/4R35/4R36/7S26/7S35/7S36 (English) · pdf · read
  5. 5Seiko Watch Corporation — Instructions: Diver's Watch for Air Diving, Cal. 4R35 / 4R36 (English) · pdf · read
  6. 6Seiko Watch Corporation — Diver's watch for air diving instructions, Cal. 6R35 (EN) · pdf · read
  7. 7Seiko Watch Corporation — Instructions: Mechanical watch, Cal. 4R35 / 4R36 / 4R37 / 4R38 / 4R71 / 4R72 / 4R39 (English) · pdf · read
  8. 8Seiko Watch Corporation — Mechanical watch instructions, Cal. 6R31/6R35/6R38 (EN) · pdf · read