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Seiko Caliber 7s26a Movement

Seiko Caliber 7S26

Seiko Caliber 7s26a Movement

Manufacturer Seiko
Caliber Number 7S26
Movement Type Automatic
Diameter
27.4mm
Casing Diameter
27mm
Height
4.8mm thick
Jewels 21
Vibrations Per Hour
21,600 bph
Shock System Seiko Diashock
Regulator
Etachron
Lift Angle
53 degrees
Power Reserve
~41 hours
Magnetic Resistance 4,800 A/m (60 gauss)
Winding Direction
Bi-directional (Magic Lever)
Hand-Windable? No
Hacking? No
Functions Hours, minutes, central seconds, day/date calendar at 3:00
Country of Manufacture Japan/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.

Please allow us to interrupt your gear turning and caliber learning to say thank you. Thank you for being here! Now, back to the movement..

“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:

Is the Seiko Caliber 7S26 any good? Share your opinions, experiences and watches below... Keep comments respectful and follow our community guidelines.

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Carlos Velazquez
Carlos Velazquez

I need parts or the movement for Seiko 7S26
Thanks

Carlos Velazquez
Carlos Velazquez

Thank you for the information
Carlos

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Seiko Military/Pilot Style Watches SNK80x series

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Fred

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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Alan
Alan

Do you still need pictures of this calibre?

Ntseh Lovet
Ntseh Lovet

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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Jorge Lara Gonzalez
Jorge Lara Gonzalez

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

Dario Rodas
Dario Rodas

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

MA CHE COSA STAI FACENDO?

nizam
nizam

How much Dh ?

Carrie
Carrie

What is Dh?

Septian Blog
Septian Blog

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

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

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

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Buck

Also known as cal V676. 🙂

Carrie
Carrie

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

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

Buck
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Apologies for the typo Y676!!

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

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

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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
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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 you.

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You should not adjust the date of your watch while the hands are between the hours of 8:00 PM and 2:00 AM.

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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 will jump the date ahead.

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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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