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Seiko Caliber 7s26a Movement

Seiko Caliber 7S26

Seiko Caliber 7s26a Movement

ManufacturerSeiko
Caliber Number7S26
Movement TypeAutomatic
Diameter
27.4mm
Casing Diameter
27mm
Height
4.8mm thick
Jewels21
Vibrations Per Hour
21,600 bph
Shock SystemSeiko Diashock
Regulator
Etachron
Lift Angle
53 degrees
Power Reserve
~41 hours
Magnetic Resistance4,800 A/m (60 gauss)
Winding Direction
Bi-directional (Magic Lever)
Hand-Windable?No
Hacking?No
FunctionsHours, minutes, central seconds, day/date calendar at 3:00
Country of ManufactureJapan/Malaysia/Singapore
Known Brands
Seiko Scuba Diver’s (add more in the comments below)

The Seiko caliber 7S26 is an automatic movement used in many popular Seiko divers and the entry level Seiko 5 watches. This movement was first released to the market in 1996. The most recent tech sheets found were dated 2011.

Discontinued

Modern Seiko watches, such as the Next Gen Orange Monster, have since been upgraded to the caliber 4R36, making Seiko collectors happy because the 7S26 seen here does not hack and is not hand-windable – two functions that have become more and more popular.

7S26A VS 7S26B VS 7S26C

The letter indicates the evolution of the caliber 7S26. 7S26 and 7S26A is the first generation of this caliber and are the same. 7S26B is the second generation. 7S26C is the third and final version.

The difference between A/B in Seiko’s own words:

“Cal. 7S watches are changed from caliber “A” to caliber “B” in October 2006 production. According to the change, we would like you to pay attention to the design of the balance staff when repairing those watches.” -Source: Seiko Parts Catalogue/Technical Guide Cal. 7S26B, 7S36B. Published 2007.

The difference between B/C in Seiko’s own words:

“SEIKO Automatic Mechanical Cal. 7S26C / 7S36C are replacement caliber of Cal. 7S26B / 7S36B. Construction of the C series is same as B series, but using new parts. Since the size of movement is same as B series, the complete movement can be assembled into the watches which originally have the B series move-ment; however, as the parts are not convertible, please use the appropriate parts for each caliber.” -Source: Seiko Parts List/Technical Guide Cal. 7S26C, 7S36C. Published 20011.

7S26 VS 7S36

The main difference between the 7S26 and the 7S36 is that the caliber 7S36 has 2 extra jewels. The 7S26 has 21 jewels and the 7S36 has 23 jewels. Many enthusiasts refer to this as 2 non working jewels. There is speculation that the 7S36 was supposed to eventually replace the 7S26, but that never actually happened.

WUS user Biased&Critical explains the comparison in detail:

The extra 2 jewels are on the “lower bridge for 3rd wheel and pinion”. They are lower cap jewels for the 3rd and escape wheels. But that’s a bit of a fancy answer – here’s an easy one: they are basically useless jewels and do nothing to alter performance… To answer your question, as far as complete swapouts go, they are interchangeable. But that would be a practice in futility – you wouldn’t gain or lose anything but (your own) time. I have both of these movements, have for years, and there is no practical difference. But to repair, there are some things to consider. Some of the parts are different in size – you can find the details around here somewhere, but the 3rd and escape wheels have different axle lengths due to the jeweled capping. Not to mention this bridge that simply does not exist in the 7s26. Maybe something else equally minor.

7S26C/7236C Part Differences:

  • Screw for lower bridge for 3rd wheel and pinion
  • Lower bridge for 3rd wheel and pinion
  • Oscillating weight

Setting Time Backwards/Counterclockwise

A Caliber Corner community member started a discussion in the comments below about the ability to adjust the time in reverse rather than by advancing the hands forward. As with many topic on watches and movements, answers on different sites vary and opinions are all over the place. We contacted Seiko directly to get an official answer straight from the source.

“Dear Seiko,

The instruction manual on page 13, step 5 says: “Keep advancing the hands to set the correct time.” Can you please clarify if this means that the hands should not be turned counterclockwise when setting the time? For example, if traveling to a different time zone or daylight savings time, is it ok to move the hands backwards several hours to set the current time?”

“Dear Seiko Customer,

When traveling between different time zones, you can adjust the time backwards. We recommend you do NOT adjust the time when the watch is in the middle of changing the date.”

Therefore, it is confirmed that you can set your time forwards or backwards as long the date changing mechanism is not activated to switch over the calendar.

Seiko Caliber 7S26A Gallery:

Seiko Caliber 7s26a Etachron Regulator Seiko Caliber 7s26a Macro Gears

Example of a Seiko caliber 7S26C:

Seiko caliber 7S26C made in Malaysia

Seiko Caliber 7s26c Calvinwcyy

Seiko Caliber 7s26c Calvinwcyy 1

Additional Resources:

  • Official caliber 7S26A tech sheets here
  • Official caliber 7S26B tech sheets here
  • Official caliber 7S26C tech sheets here
What do you think about Seiko Caliber 7S26? Keep comments respectful and follow our community guidelines.
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[…] you might be able to read the tiny text at the bottom of the dial stating that the SNKK71 uses Seiko’s 7S26 automatic movement. With 21 jewels to damped vibration, this movement is renowned for its reliability and accuracy at […]

Carlos Velazquez
Carlos Velazquez
2 years ago

I need parts or the movement for Seiko 7S26
Thanks

Carlos Velazquez
Carlos Velazquez
2 years ago

Thank you for the information
Carlos

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Marco
Marco
2 years ago

Seiko Military/Pilot Style Watches SNK80x series

Richard Hufnagel
Richard Hufnagel
2 years ago
Reply to  Caliber Corner

Just picked up a Seiko recraft big 44mm cusion case style. Big and beautiful. Drives me nuts I can’t hand wind it though.

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Fred
Fred
2 years ago

Very good caliber, reliable and good accuracy and the shock system is very good. Mine felt from 1.5m on hard floor and no problems, really good and cheap workhorse caliber 7S26.

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[…] You might also want to consider the NH35. Further reading:Seiko Caliber 7S26 Watch Movement | CaliberCorner.com And it is also said, "go not to the Elves for counsel, for they will say no and yes." — […]

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[…] your frequent usage of the watch as it comes with a 40 hour battery reserve. The good side is that 7s26 is a decent automatic movement, beating at 21600 BHP and featuring 21 […]

Alan
Alan
2 years ago

Do you still need pictures of this calibre?

Ntseh Lovet
Ntseh Lovet
2 years ago

I have owned a Seiko 7S26A since 2007. It has sustained fall shocks and minor scratches but yet still works, albeit with constant time adjustments. I think it needs to be refurbished.

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[…] exactly what Seiko is all about. This superb Seiko 5 timepiece comes with 21 jewels and uses a 7S26 caliber self-winding mechanical movement that cannot be manually […]

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[…] I have harped on about a number of times, one of the most notable features of this range is the 7S26 Automatic movement with 40 hrs power reserve. It is quite a basic movement for Seiko, but let’s face it – […]

Jorge Lara Gonzalez
Jorge Lara Gonzalez
2 years ago

Tengo un seiko automatico 7s26c, necesito saber si es sumergible y a cuantos metros.

Dario Rodas
Dario Rodas
7 months ago

Jorge,

La característica de hermeticidad depende del reloj (conjunto, de caja, cristal, empaques y calibre) más que del movimiento en sí.
El 7S26 es usado en relojes como el SKX007 o SKX009 que tienen una hermeticidad garantizada de hasta 200m y cumplen con un conjunto muy exigente de requisitos (Standar ISO6425) de tal forma que puedes bucear con ellos.

Si el reloj que tienes es uno de los que menciono, la respuesta es 200m.

MARK WOLFSON
MARK WOLFSON
6 months ago
Reply to  Dario Rodas

MA CHE COSA STAI FACENDO?

nizam
nizam
2 years ago

How much Dh ?

Carrie
Carrie
2 years ago
Reply to  nizam

What is Dh?

Septian Blog
Septian Blog
1 year ago

This caliber overall is so good, i have nice experience with seiko 5 SNK805.

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Calvin
Calvin
1 year ago

Hi, i have very high quality photos of the movement for my Seiko 5. Would you like to have it?

Calvin
Calvin
1 year ago
Reply to  Caliber Corner

Cool, I have emailed and submitted 🙂

Chuck b134
Chuck b134
6 months ago
Reply to  Caliber Corner

I might be purchasing one what’s a fair value

Paulo Balsan
Paulo Balsan
1 year ago

Where can I find this caliber’s accuracy in seconds?

Buck
Buck
1 year ago

Also known as cal V676. 🙂

Carrie
Carrie
1 year ago
Reply to  Buck

In what watch? Never heard of V676 before. Are you sure this is correct?

Buck
Buck
1 year ago
Reply to  Carrie

Yes, I’m sure, it’s fitted to various Seiko sub-brands such as Alba.

Buck
Buck
1 year ago
Reply to  Buck

Apologies for the typo Y676!!

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Dave
Dave
11 months ago

Excellent movement for the basic Seiko 5 (excellent watches by the way, inexpensive but not ‘cheap’). However, the Orange Monster does need the NH35 movement, the 7S26 being too modest. Heck, I’ve got an Invicta Pro Diver (a great watch by the way, don’t be misled by watch snobs) with the NH35 movement!

Tim
Tim
10 months ago

What a beautiful Seiko! Do you know if they’re selling it in the US? I haven’t seen it around?

Toussaint
Toussaint
10 months ago
Reply to  Tim

Yes, you can find it on Amazon for $90.

David
David
8 months ago

Is it okay to adjust 7s26C backwards? like 6 hours counterclockwise? Due to traveling one timezone to another? Because i have seen lots of posts regarding adjusting backwards can cause damage to the movement. Thanks for the feedbacks! 🙂

G. Torres
G. Torres
8 months ago
Reply to  David

I never heard of such a thing. I always adjust the time on my watches clockwise or counterclockwise. The date it another thing though, I wouldn’t adjust that counterclockwise, and I don’t even think it’s possible. I also wouldn’t adjust the time one full day backwards for the same reason as the date. But 6 hours shouldn’t be an issue. If anyone else here says otherwise then I will be learning something new along with… Read more »

Wambly
Wambly
8 months ago
Reply to  David

You should not adjust the date of your watch while the hands are between the hours of 8:00 PM and 2:00 AM. It is fine to adjust the time of your watch forwards or backwards. On some watches without a quickset date, the way to adjust the date without going all the way around the dial twice, is to move the hands past 12:00 am and back to 8:00 PM then to 12:00 AM again… Read more »

David
David
8 months ago
Reply to  Caliber Corner

Thank you very much! I will wait for that “golden” answer regarding 7S26 if its okay to turn backwards 🙂

David
David
8 months ago
Reply to  Caliber Corner

Hello! Thank you very much for the response! Highly appreciated! I hope this also helps the people who has the same curiosity and also the ones who are too paranoid that they may break something 🙂

Timur
Timur
6 months ago
Reply to  Caliber Corner

Tell me please, what does the marking WP, KY, R on the back cover of a Seiko watch mean?

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Nikola Jankovic
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Seiko ReCraft Automatic have this movement.

roger kalter
roger kalter
6 months ago

i have a seiko snkp27 recraft, and although a stunning watch, the accuracy needs regulating. besides that, there is no lume. so i have ordered replacement hands for the 7s26 movement on ebay. hope i can get this done by my watchmaker, as well as regulating.
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Gio
Gio
5 months ago

How will I know if my 7s26 is good for shower or not? It says only water resistant but no specific bars. Thank you!

Krisotpher
Krisotpher
5 months ago
Reply to  Gio

7S26 is the movement. It’s hard to say without knowing which watch it is. Sounds like it’s not a divers watch if they don’t tell you how much water resistant is it.

Fred
Fred
4 months ago
Reply to  Gio

For shower, it should be at least 50m water resistent, most 7s26 are 100m WR, some are 50m. You can see on the back of the watch 100m W.R., or you can see it on the dial also.

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ck.chan
ck.chan
3 months ago

please advise where can I have a tech sheet of the movement 7S26A for making watch hands

ck.chan
ck.chan
3 months ago
Reply to  Caliber Corner

yes, I saw it but there is no data related to watch hands producing

Trevelyan Bloomfield
Trevelyan Bloomfield
2 months ago

I’m considering purchasing a Seiko 5 SNZG15 with this movement, however, the lack of hacking and handwinding leaves me cold. Is there another movement with hacking and handwinding that could be substituted in its place?

Tom
Tom
2 months ago

Hi! My seiko 5 stops (dropped by my kids couple of times) I need to get a new movement. I have the 7S26. Automatic with day&date not rewindable. Can I get a watchmaker to change it for another movement?

Deen kazamma
Deen kazamma
1 month ago

I love so much Seiko, spacialy seiko5,I use it at first time in 1984,vary good wath.i use it til 1996,then I loose it in motor bike acsident…maybe somebody stil it…after that I use other brand like rupina,orient,citizen but I like Seiko..don’t know why,Couse if I use other brand my hand feel itchy but with Seiko not itchy I don’t know what…good job Seiko make such lovely watch..until now I use Seiko new one model 7s26..

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Sajjad
Sajjad
3 days ago

Hi admin,
can you explain what is the power reserve in seiko watches. It means the movement time without wearing the watch right?

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