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Seiko 6105 movement

Automatic, 17 jewels, 21,600 bph, made 1968–1977.

Download the caliber production-year table (CSV, CC BY 4.0)

Specs

Jewels
17[6][7]
Beat rate
21,600 bph[6][7][8]
Hacking
pending
Production years
1968–1977[1][2][3][4]

Watches that use the 6105

6105A vs 6105B

Both versions are 17-jewel automatics beating at 21,600 vibrations per hour, 27 mm across, with a date and no day. Neither can be hand-wound. The difference is the seconds stop: Seiko’s 6105B parts list adds a second-setting lever, part 391610, and Mizeni lists hacking for the B only.

The 6105-8110 diver of 1970 uses the B, and the earlier 6105-8000 usually the A. Seiko hasn’t published the changeover date, and The Watch Spot documented a 6105-8119 with an A inside, so a mismatch is a question for the seller, not proof of a swap.

6105 references

The 150 m divers are the best known:

  • 6105-8000 and 6105-8009 (1968 to 1970): the slim, symmetrical first case.
  • 6105-8110 and 6105-8119 (1970 to 1977): the asymmetric Captain Willard. See our 6105-8110 page.

The Seiko Guy lists 17 references with the 6105, including non-diver cases: 6105-6000, 6003, 6007 and 6009, and 6105-8060, 8063, 8067, 8069, 8080, 8089, 8090, 8093 and 8100. Seiko’s 1978 overseas casing parts list confirms the 6105-6003, 6007 and 8063. We’ll add more as each one is checked.

Parts shared with the 6106 and 6119

Seiko’s 6105A and 6105B parts lists name the 6106A as the basic calibre, so most base parts come from the 6106 family. Comparing Seiko’s 6105B, 6106C and 6119B parts lists:

  • Same part numbers: the barrel (205613), barrel arbor (213612), rotor (500620), transmission wheel (505611) and pawl lever (831611). The 6105B and 6119B also share the mainspring (401615).
  • Different: the automatic bridge (193552 on the 6105B, 193524 on the 6119B), the date dial, and the 6105B’s seconds-stop lever.

Watchmakers have gone further. Adventures in Amateur Watch Fettling rebuilt a 6105-8110 with the train bridge, balance and wheels from a 17-jewel hacking 6106C, and a Watch Repair Talk member moved a 6119 rotor bearing onto a 6105 bridge. Both are one-off repairs, not proof that every 6106 or 6119 part fits. A 6119 movement dropped into a 6105 case changes the watch: it adds a day and a push-to-set date.

Common faults

  • Hardened crown seals. On the 6105-811x divers the seals sit inside the crown, so the usual fix is a new crown, and even new-old-stock crowns can have hardened seals (The Watch Spot).
  • A rusted rotor bearing that has damaged the automatic winding, on a watch that still ran (The Watch Spot).
  • Gummed oil and damaged wheels from years without service; one restoration also found a hairspring damaged by an earlier repair (Adventures in Amateur Watch Fettling).

We haven’t found a Seiko document giving a time window when the 6105’s date shouldn’t be set, so we don’t give one.

Will Seiko service a 6105?

Seiko USA doesn’t list the 6105 among the calibers it no longer services, but it says other old calibers may be returned unrepaired when parts run out, and that it can’t guarantee water resistance on older divers. Its estimate for mechanical calibers like this one was $359 before tax and shipping in October 2026. Otherwise, look for an independent watchmaker who knows 6105s.

Before paying for a full service, check what the watch sells for in good running order. Our price guide will show sampled ranges per reference.

Sources

FAQ

What is the difference between the Seiko 6105A and 6105B?

The seconds stop. Both are 17-jewel automatics at 21,600 vibrations per hour with a date. Seiko's 6105B parts list adds a second-setting lever, so the B stops the seconds hand when you pull the crown; the A doesn't.

Can you hand-wind a Seiko 6105?

No. Neither the 6105A nor the 6105B can be wound by the crown. It winds from wrist motion only.

Which watches use the Seiko 6105?

Best known are the 150 m divers: the 6105-8000 and 8009 of 1968 and the 6105-8110 and 8119 Captain Willard of 1970. The Seiko Guy lists 17 references in all, including non-diver cases such as the 6105-6003 and 6105-8063.

Do Seiko 6119 parts fit a 6105?

Some do. Seiko's parts lists give the 6105B and 6119B the same mainspring, barrel, rotor and several automatic winding parts. The automatic bridge, date dial and calendar parts are different, because the 6119 has a day and date set by pushing the crown.

Will Seiko service a 6105?

Seiko USA doesn't list the 6105 among the calibers it no longer services, but it warns other old calibers may be returned unrepaired. Its estimate for mechanical calibers was $359 in October 2026. Otherwise, look for an independent watchmaker who knows the 6105.

Where to look

Watches with the 6105 on eBay(affiliate link)6105 movements on eBay(affiliate link)

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