Specs and Measurements of Seiko (SII) Caliber NH34A / 4R34
The New GMT Movement from Seiko / TMI /SII
The NH34 or also known as NH34A is a new movement from Seiko / TMI / SII that is becoming increasingly popular, due to its budget friendly nature and its ability to tell time in a second time zone (also known as a GMT movement). Depending on the source, this movement can also be named as 4R34, which is an identical movement with a different naming. Here is the basic measurements and specification of NH34A:
Basic measurements
Number of jewel: 24 jewels
Outside diameter: 27.40 mm
Lignes: 12”’
Casing diameter: 29.36 mm (with dial holding spacer)
Total height: 5.32 mm
Specification
Time indication
3 Hands (hour, minute, second)
Date calendar
24 hour hand
Basic functions
Manual winding
Automatic winding (Bi-directional rotor winding via Magic Lever)
Stop-second / hacking second
Quick date change
Second time zone setting (aka GMT function)
Technical specification
Frequency: 21,600 vibrations per hour (vbh)
Factory rated accuracy: - 20 ~ + 40 seconds per day
Lift angle: 53 degrees
Power reserve: 41 hours
Similarities with NH35 Movement
As veteran modders might notice, the specs and measurements are largely the same as those of a NH35 movement, the only noted addition being the GMT function. Does that mean you can simply do an GMT upgrade to your existing Seiko watch? Well, yes and no. The addition of GMT function means alteration to the hand post. If you account for this difference, the upgrade can indeed be carried out. We have written a detailed breakdown of the differences between the two movements, and how they affect their mod compatibility. Be sure to check it out!
The story of the 4 most iconic dive watches, each a trailblazer in its own right. Together they shaped the landscape of dive watch as we know today.
Learn how to swap and adjust watch straps to easily give your watch a new look for any occasion. This guide covers installation of various types of straps, including quick release straps, metal bracelets, metal bands, and fabric straps like parachute straps. Follow step-by-step video guides to learn how to install each type of strap, and adjust the length of metal bracelets and mesh bands. Give your watch a stylish upgrade with a new strap today!
Can you upgrade a NH35A watch into a NH34A GMT watch? Short answer: yes, but you'll need to adjust for two changes to the measurements. Read on to find out how to replace a NH35 with a NH34 movement.
The Seiko NH34A is a new GMT movement. Here are the specification and basic measurements of this mechanical automatic movement
It is definitely not a good sight when you discover moisture inside of your favorite watch. But don’t worry, it’s a fixable problem if you know what to do. Read on to find out
A good watchmaking tool is hard to find. Here is how we designed the premium tools in our Pro Tool Kit
Learn how to use appropriate case back openers to take off different watch case backs here.
Leather needs regular care in forms of conditioning. Learn more about what types of leather conditioner to use, and the best practice in apply leather conditioner
Blued hands and screws are ubiquitous existences in the history of watchmaking. Behind that frequent appearance though is a history and science that go beyond the aesthetic value of flame bluing.