NH35 movement swap into a JK Factory sub - Tutorial

[NCRich]

So I've always been dissatisfied with the DG2813 and even less satisfied with a more expensive asian clone of a 2836 in a vintage Rolex sub. They are both assembled by small Chinese children in a dirty factory and they have no lubrication in the movement. To add insult to injury the 2836 clone is the wrong beat rate, and is more expensive. Still crap. If you get a low beat Swiss pulled out of some old watch then it needs service to be decent. Swiss 2836 still have the wrong beat rate.


So enter the Seiko NH35. Its a tank of a movement, still built by asians but in a clean factory with oil and QC. Its got the right movement and is one of the most popular automatic movements in the world. Purported to run for years through abuse and neglect. Its got pretty much the right beat rate. Only real beef anyone has with it is that its not quite as accurate as the vastly more expensive Swiss ETA 2836. But it can be had for $35-40.

I searched the boards and found people talking about how it was a waste of time trying to swap these in. Wrong hand size, need gasket fabricated, datewheel, etc. I looked at the specs and found not much difference at all. Hand sizes:

NH35 150/90/21

DG2813 150/100/17

ETA 150/90/25

The case sizes, stem height, and movement height are very close as well. When you figure in the plastic gasket the NH35 comes with its damn near a perfect fit. So lets see how to do it. I'm going to use my trusty old test DRSD. Its had damn near everything smacked about on it. Even got a countersunk Athaya crown.





So here is the NH35 with the plastic gasket it comes with.

Here is the donor 2813 that came with the watch. I use a single edge razor blade to carefully pry off the date wheel overlay.

Here are both movements, I've moved the overlay onto the NH35.

I glued the DWO onto the NH35 date wheel with a 5 minute epoxy. I like to line up the 3 with the stem.

Lay the dial on to see how it fits. Got some time to move it.

Hands are going to be the wrong size. I'm just going to go to my BIG BOX O HANDS and pick the closest.

I ended up using the 22 for the sec hand, and had to broach minute hand to fit. Just a bit. Both the handsets and the movements probably have .5mm error margins so it was no big deal.

I put the dial on using double stick tape.

The tape actually serves a double purpose, it holds on the dial but also adheres to the back of the rehaut to keep the movement in place.

Hands on!

Movement seated, looks good but just a little loose in the case.

I'd measured all this stuff long before I started and ordered an appropriate gasket to snug it up. I put it in before the stem was inserted.

All in! Fits like a glove.

And, the finished product!

Thanks for watching!

UPDATE

OK, there are the differences in dealing with the 5512 thru 1680 cases rather than the sea dweller case. The plastic spacer on the NH35/36 is a bit too large for this case. The solution for this is to snap the plastic case off the movement and use a dremel with a drum sanding bit to take the outer edge of the spacer down to size. Take your time and for God's sake don't do this with the spacer still on the movement as you will get plastic dust inside the movement. You need to take maybe 1/16 or so off to get it to fit. Then snap it back on the movement. After that all the other directions are the same. 

 

[cpd2186]

Love your tutorials Rich..... Always learn something.

 

[p0pperini]

Another clear and helpful tutorial that is useful for so much more than just achieving its main objective. For instance, I went straight to eBay and ordered a set of exactly the same broaching files. Thanks Rich!

 

[Watchpocketguide42]

I am actually doing something similar: building an explorer with a NH36 movement. A little advice: you don't need to use generic hands or broach them if using seiko movement (unless you want!). There are quite few suppliers who make hands for Seiko movements (including Mercedes hands). Monsterwatches.eu for the best quality, dagaz will also have pencil hands. Even raffles sell eta and seiko compatible hands.

 

[kilowattore]

Another excellent and very useful tutorial, thank you NCrich!

 

[NCRich]

I am actually doing something similar: building an explorer with a NH36 movement. A little advice: you don't need to use generic hands or broach them if using seiko movement (unless you want!). There are quite few suppliers who make hands for Seiko movements (including Mercedes hands). Monsterwatches.eu for the best quality, dagaz will also have pencil hands. Even raffles sell eta and seiko compatible hands.

Yes, good point. There are lots of suppliers of Seiko compatible mercedes hands. But that big old box of watch hands was about $25. 80 sets of hands. Most people pay more than that for 1 set (which in many cases turns out to be identical to these). I've been doing this for about 8 years so I have built up a pretty good parts box.

I usually sand and distress the hands and try new tricks so I will occasionally destroy a hand. Learning to broach hands gives you amazing flexibility and saves a ton of money. Its a good skill and the tools are inexpensive. In many cases I can just move the hands from movement to movement without buying new ones.

 

[mclarendude]

THANK YOU!!!! I’ve been wanting to do this for years.


Sent from my iPhone using Tapatalk

 

[Raddave]

Thats hard core Rich !!!

Nice Job !

 

[Waspy]

Well that's just incredible.

I would buy a Submariner rep with a NH35 movement in a heartbeat.

You din't mention the stem and crown, did you have shorten the stem at all? Did you use the rep crown on the Seiko stem?

 

[NCRich]

Well that's just incredible.

I would buy a Submariner rep with a NH35 movement in a heartbeat.

You din't mention the stem and crown, did you have shorten the stem at all? Did you use the rep crown on the Seiko stem?

I did mention it was an Athaya crown. Rep crown would work fine. I trimmed the stem a little. NH35 comes with 2 stems, one short and one long. Was able to use the short one with a couple mm trimming.

 

[Amaiel]

Good job man. And thank you for the time spent in sharing it. Really appreciate

 

[Manray]

Thank you sir.

 

[DD60]

Very interesting. Easy simple to the point post with clear photos. Thanks NCRich .

 

[Specter1000]

I've been using those NH35's in mods (Seiko builds...not reps) for a few years...and they are bullet proof. Last mod I did used a NE15 (6Rxx equivalent) from Startime...but not sure it's worth the extra $60 over the NH35. Love the work you did on this!

 

[Manray]

How is it that the movement doesn't move vertically inside the case?

 

[NCRich]

How is it that the movement doesn't move vertically inside the case?

Its tight with the gasket. Every NH35 in all those Invictas and others is a friction fit. Cases are machined to fit that plastic spacer.

 

[KJ2020]

Nice work Rich, as always!

 

[krizzy]

Thanks for the inspiration!
A friend had a cheapo Explorer rep, and I used the same technique to convert the broken DG to a nice smooth NH35. Used a movement I had lying around which a matching set of NH35 mercedes hands

 

[bigtiddygothgf]

I'm planning on dropping an NH35 in to a DG case but I cant quite find the same exact gasket you've used. Do you happen to have a link or SKU? thanks in advance.

 

[Spoons]

I'm planning on dropping an NH35 in to a DG case but I cant quite find the same exact gasket you've used. Do you happen to have a link or SKU? thanks in advance.

Hello. I'm not sure where NCRich got the gasket that he used (pictured above), but I have used this one from Star Time Supply: LINK

However, registering an account on Star Time can be difficult, so I think these gaskets would also work (choose the option with an outer diameter of 30.5mm and an inner diameter of 29.35mm or 29.5mm):

OFREI - Red I Style Gasket #3090.25

EBAY - 0.9mm Height Red Plastic Watch Back Case Gasket Waterproof O Ring 20-40mm