Guide to Seiko Mod Compatibility of NH34A vs NH35A

Seiko watches have been around for over a century, and their reputation for quality and durability has made them a popular choice among watch enthusiasts. Seiko’s movements are no exception, with the NH34A and NH35A movements being two of the most popular choices for Seiko watch mods. But what exactly is the difference between these two movements, and how do they affect mod compatibility? In this article, we’ll explore everything you need to know about the Seiko mod compatibility of NH34A vs NH35A.

NH34A vs NH35A: What’s the Difference

At first glance, the NH34A and NH35A movements may seem nearly identical. They both feature a 3 o’clock crown position, a 41-hour power reserve, and a frequency of 21,600 beats per hour (BPH). However, there are some key differences between the two movements that can affect mod compatibility.

The most significant difference between the NH34A and NH35A is the position of the date wheel. The NH34A features a date wheel at the 4:30 position, while the NH35A has a date wheel at the 3 o’clock position. This may not seem like a major difference, but it can affect the placement of the dial and hands in a watch mod.

Another difference between the two movements is the height of the stem. The NH34A has a stem height of 7.50mm, while the NH35A has a stem height of 6.00mm. This can affect the compatibility of certain watch cases and crowns, as the stem height must match the case and crown specifications.

Mod Compatibility with NH34A

The NH34A movement is a popular choice for watch mods, as it offers a hacking and winding mechanism, as well as a date complication. However, due to the position of the date wheel at the 4:30 position, it may not be compatible with all watch dials and hands.

When using the NH34A movement for a mod, it’s important to choose a dial and hands that are specifically designed for the 4:30 date position. This can limit your options somewhat, but there are still plenty of aftermarket options available.

In terms of case and crown compatibility, the NH34A’s 7.50mm stem height is a relatively common specification, so it should fit most watch cases and crowns without issue.

Mod Compatibility with NH35A

The NH35A movement is another popular choice for watch mods, as it offers many of the same features as the NH34A but with the date wheel positioned at 3 o’clock. This makes it a more versatile option for modders, as it can be used with a wider range of dials and hands.

When using the NH35A movement for a mod, it’s important to choose a dial and hands that are specifically designed for the 3 o’clock date position. However, since this is the more common date position for Seiko watches, there are many more aftermarket options available.

The NH35A’s 6.00mm stem height can be a limiting factor when it comes to case and crown compatibility. Some watch cases and crowns may not be compatible with this stem height, so it’s important to check the specifications before making a purchase.

Conclusion

When choosing between the NH34A and NH35A for a mod, it’s important to consider your specific needs and preferences. If you want a wider range of dial and hand options, the NH35A may be the better choice. However, if you prefer the 4:30 date position or need a higher stem height for your case and crown, the NH34A may be the way to go.

Ultimately, both movements offer reliable performance and are popular choices among Seiko modders. With the right parts and a little bit of know-how, you can create a unique and personalized Seiko watch that perfectly suits your style and needs.

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