The Seiko NH36 movement is an unbranded version of their 4R36 movement, identical in accuracy, build, and performance. Seiko sells the NH36 to third parties instead of using it in their watches.
The NH36 movement has 24 jewels, a 41-hour power reserve, 21,600 BPH, and an accuracy of -20 to +40 seconds per day. It has hacking and hand winding.
It is affordable and compatible with various watch cases, making it popular among watch microbrands and modders.
Seiko NH36 Specifications
| Manufacturer | Seiko |
| Caliber | NH36 |
| Accuracy | -20 / +40 seconds per day |
| Movement Type | Mechanical, Automatic |
| Movement Diameter | 27.4mm |
| Casing diameter | 29.36mm |
| Height | 5.32 |
| Jewels | 24 |
| Hacking | Yes |
| Hand Winding | Yes |
| Vibrations per hour | 21,600 bph |
| Shock system | Diashock |
| Regulator | Etachron |
| Power reserve | 41 hours |
| Magnetic resistance | 4800 A/m (60 Gauss) |
| Winding direction | Clockwise |
| Country of manufacture | Japan and Malaysia |
| Known watches | Aragon Divemaster, Aragon Enforcer, Aragon Hercules, Addiesdive Monster AD2103, Pagani Design PD-1696, AbaloneIslander Mitchell “Day-T”, Islander DPA |
Seiko NH36 Accuracy
The accuracy of the Seiko NH36 movement is rated between -20 to +40 seconds per day. However, all the watches I own with the NH36 are much more accurate, within +/- 10 seconds per day.
The NH36 can easily be regulated, significantly improving its accuracy, even up to +/- 0 seconds per day.
Seiko doesn’t regulate these entry-level movements out of the factory to help keep costs down.
If you have an NH36 movement running outside its specifications, it is best to have the movement serviced by a professional watchmaker or source a replacement. Read on to find out how.
Where Is The NH36 Made?
Seiko manufactures the NH36 in both Japan and Malaysia.
Each comes with a custom rotor, displaying the country of the manufacturer, which is how you can tell the two apart. Aside from this, the movements are identical in build and performance.
Many third-party watch brands, however, opt to have a custom rotor installed that may or may not engrave, or stamp the country of manufacture on the dial.
Setting the Time
To set the time:
- Pull out the crown two clicks away from the case. This should activate the watch’s “hacking”, meaning it will stop the second hand. This allows you to set the time more precisely.
- Rotate the crown either clockwise or counter-clockwise to set the desired time.
- Push the crown back into the case.
Setting the Day and Date
To change the day and date of the NH36 movement:
- Pull the crown one click away from the case. The second-hand sweep will continue as opposed to when changing the time
- Set the day and date to a day before the intended date. Winding clockwise changes the day and counterclockwise changes the date.
- Pull the crown one click outward and wind the time forward towards 12 midnight when the date will change to the correct date.
- At this point, the day will have also started to change, but not fully. Continue winding till the day also changes fully, which happens at about 12:50am.
- The day should now have changed but will be in the secondary language (e.g Spanish). Continue winding till it changes to your set primary language (e.g English). This will be just past the 3:00 am mark.
- The date and day are now set. Continue winding to set the time.
- Push the crown back into the case to finish setting the day and date.
Warning: When changing the day/date on an automatic watch like the NH36, you should not change so when the time on the watch is currently set between 9:00 pm to 3:00 am.
During this time the gears controlling the day/date disc are engaged and changing the day/date may damage the movement.
Always change the time to one outside of this danger zone to avoid damaging the movement. I suggest setting the time to 6:30 when changing the day or date. Whether it’s set to 6:30 a.m. or p.m., it will be out of the danger zone either way and is a safe, easy option to remember.
Winding the 4R36
Automatic winding
To wind the movement using the automatic mechanism, hold the watch with the dial facing either up or down and give it a side-to-side shake. A one-minute shake will be enough to start the second hand’s movement. A five-minute shake would be enough to fully wind the mainspring for a 41-hour power reserve.
Generally, it’s enough to shake the watch for about 30 seconds, then wear it on your wrist and go about your day.
The movement has an automatic rotor, a weight attached to the movement. As the wearer’s wrist moves, the weight swings back and forth. This energy is transferred to the mainspring via a series of gears.
The automatic winding system includes Seiko’s proprietary magic lever which is designed to ensure that the gear connected to the mainspring moves in only one direction, regardless of the movement of the weight. This reduces the time needed to fully wind the mainspring.
Manual hand-winding
Unlike the automatic only 7s26 which had to be given a good shake to revive them, the NH36 can be wound manually using the crown. Turning the crown clockwise winds up the mainspring.
When fully powered down (no second-hand sweep), it takes about 20 turns of the crown for the second hand to start sweeping. Turning it about 10 more times gives the mainspring enough charge to maximize the power reserve (41 hours).
The mainspring cannot be overwound as the movement has a clutch system that stops any more winding of the spring when it is fully charged.
Handwinding the NH36 produces a grainy sound (sounds like a series of fast clicks). With this feature, one can know whether the mainspring is being wound up as opposed to a smooth silent winding, which may mean it’s not being wound properly.
Servicing the NH36
Seiko recommends servicing the 4R36 movement every 3 years, therefore, we can imply the nearly identical NH36 should be serviced at least as often.
However, in reality, Seiko watches are known for their durability, and watches with the NH36 can last up to 10 years without needing service. People have reported the 4R36 equivalent lasting that long, even with heavy wear.
Full service by Seiko for the 4R36 movement costs about $150. At this price, it’s cheaper to simply buy a replacement movement, and in some cases, an entirely new watch.
Watch the video below to see the 4R36/NH36 movement being disassembled and serviced.
Seiko NH36 vs 4R36
The NH36 and 4R36 are one and the same movements. Seiko produces the 4R36 movements and uses them in their own watches. When it sells the movement to other manufacturers, they sell them under the name NH36, with a different rotor. In a nutshell, the NH36 is a 4R36 used in watches that are not Seiko branded.
Seiko NH36 vs NH36A
The NH36A is the first generation of the NH36. As of now, they mean the same thing and are often used interchangeably as NH36A is the only generation in the series. When Seiko rolls out the 2nd generation, it will likely be named the NH36B.
Seiko NH36 vs 7S26
The 7S26 is Seiko’s former entry-level automatic movement. Although more affordable, it lacked features that the NH36 has, such as hacking and hand winding.
Seiko NH36 vs NH35
The NH36 is an upgraded version of the NH35 that has a day function. Both NH36 and NH35 have date functions. The NH36 movement is more versatile as its day disc can be removed. This modified movement can then be used in place of an NH35 movement.
the series, it would be called NH36B if Seiko maintains its previous trend.
Common NH36 Problems And How to Fix Them
Day/Date Quickset Not Working
If you are attempting to adjust the day/date on the NH36, and it is not working, there are a couple of possibilities:
- The crown stem is the wrong length or broken.
If the crown is too short, too long, or broken altogether, it will not be able to change the day or date. You can verify if the crown is the issue by attempting to change the time on the watch. If the hour and minute hands don’t move either, it’s more likely you have a damaged crown or stem than a damaged quickset.
Solution: Have the crown stem or the movement replaced.
- The day or date has been changed from 9:00 pm to 2:00 am, when the day and date naturally shift from PM to AM, thus, damaging the day and date wheels.
The NH36 shifts from PM to AM beginning at 9:00 pm and ending at 2:00 am. If a user attempts to change the day or date while the movement is set between these times, it will damage the movement, and likely make you unable to use the quickset feature in the future.
Solution: Replace the movement.
- The crown is not pulled out to the right position.
Solution: Pull the crown out to position 1, 1-click away from the case before attempting to set the day and date. More information on setting the day and date can be found earlier in this article.
Loose Automatic Rotor
The automatic rotor has also been reported to scratch the case back, causing scratching sounds. In some cases, this can cause the watch to suddenly stop. This is often the case if the watch case is too short for the height of the movement, or if the rotor is not screwed down all the way.
One way to know if a loose rotor may be the problem is to inspect the inside of the case back for a black ring caused by the rotor scratching against the case back.
Solution: A simple fix is tightening the rotor screw. If the problem persists, you will likely need a taller watch case or case back.
Check out the video below to learn how to tighten the watch rotor.
It’s also possible to replace the rotor altogether, which will not only solve this problem but also allow you to add some custom flair to your movement.
Cases For the NH36 Movement
If you like modding watches with custom cases, any case that supports the 4R36 will also support the NH36 movement. Some watch cases that fit the 4R36 (and thus the NH36) movement are:
- Seiko Turtle
- Seiko 5 Sports Divers
There are also a variety of third-party cases that support the movement.
Can The NH36 Fit In 7S26 Cases?
Although it’s possible to fit an NH36 in a case that supports the 7S26, it’s not a simple swap.
The stem of the 7S26 crown is not compatible with the 4R36 movement, requiring an entirely new crown and stem.
The height of the hands is also taller on the NH36 than on the 7S26, which means you’ll generally need a taller case to have enough clearance.
Where to Buy Replacement NH36 Movements
You can purchase replacement NH36 movements from Amazon or mod sites such as Namokimodz and Watch-Modz.
Make sure you buy the version of the movement with the correct crown position for your case. The crown is positioned at either 3:00 or 4:00 and will not be interchangeable with the wrong version.
Seiko NH36 Price
A new NH36 movement can often be found for around $40 – $65.
Note: All parts between the NH36 and 4R36 are completely interchangeable since they’re nearly identical movements in all but their name, who they are sold to, and their rotors (which are also interchangeable, just have different engravings).
Brands That Use The NH36
Many watch microbrands prefer this movement as it is cheap, reliable, durable, and inclusive of features that make its use easier, such as hand-winding. Some brands that use the movement include:
- Islander
- Rado
- Aragon
- Heimdallr
- Addiesdive
- Steeldive
- Proxima
- Switzerland carnival
- Tandorio
- Debert
- Nautilus
- Pagani
- Seestern
- Parnsrpe
- Kuluze
- Carnival I&W
- Shiyunme
- Sea knight
- Guanqin
- Lige
- Bliger
- Octopus kraken
- Reginald
- Cadisen
- Dwayne Campbell
Summary
The Seiko NH36/4R36 is a versatile movement that is preferred by many. It has lots of features that its predecessors lacked, such as hand-winding, hacking, and date-and-day functions. For its low price, its accuracy when well regulated is extremely impressive. The movement is typical of Seiko movements as it does not need frequent servicing and can go up to 10 years before it needs servicing.
Perhaps best of all, the movement is widely available, and there is a large variety of third-party manufactured cases to support this movement. This gives modders the ability to experiment with different dials and hands to create tons of modded variations, all using the NH36 workhorse.
