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I'm a big fan of Seiko dive watches, I have a SSC017 and recently bought this case off ebay. I've checked out a few vids on youtube about modding this watch and being a newb, wanted some input on the movement type to put into it. I've heard some people say NH35/36 and wanted to know if I bought this mvmt new if it would have the mvmt spacer and come complete with day/date rings or for that matter if any other mvmts would fit.  Thanks for any and all info.

IMG_20190529_171230.jpg

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The original movement is the 7s26 which can be found some places online, but is not that easily available. NH36, which is day-date (NH35 is date only), is available from CousinsUK or for a similar price on Ebay/AliExpress. You have to switch out the day wheel to one that is for a 4 o'clock movement, as 99% of the NH36 movements you find online come with a 3 o'clock day wheel. The supplied grey spacer ring which is already mounted on the movement does fit in most cases, but there's a tiny chance that it'll be a bit too snug as it's a bit bigger in diameter than the black spacer, which is found on the 7s26.

So, NH36 is a day/date movement that you can use, but you have to get some 4 o'clock day wheels.

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14 hours ago, Leitemods said:

The supplied grey spacer ring which is already mounted on the movement does fit in most cases, but there's a tiny chance that it'll be a bit too snug as it's a bit bigger in diameter than the black spacer, which is found on the 7s26.

So, NH36 is a day/date movement that you can use, but you have to get some 4 o'clock day wheels.

Actually the holder rings are of the same diameter, but the diver version is slightly taller and will make proper contact with the caseback. Refer to page 8 of the attached technical guide.
And, you have not mentioned the most important parts, that is one will need a new crown because the windable mov.s the stem is different.
Some people like to buy an original Seiko crown/stem combo typically from a SARB for around $50, others including myself do just fine with one from the known Ebay sellers.

7S26C_36C.pdf

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3 hours ago, jdm said:

Actually the holder rings are of the same diameter, but the diver version is slightly taller and will make proper contact with the caseback. Refer to page 8 of the attached technical guide.
 And, you have not mentioned the most important parts, that is one will need a new crown because the windable mov.s the stem is different.
 Some people like to buy an original Seiko crown/stem combo typically from a SARB for around $50, others including myself do just fine with one from the known Ebay sellers.

7S26C_36C.pdf 2.84 MB · 0 downloads

good info, thanks for the correction! I just saw the technical guide that I found on NH25 VS 35 and saw a .1mm difference in casing diameter while the height was identical. Do you know how much the difference in height is, between the diver/non-diver?

 

And yes, I forgot the crown and stem... The SARB059 crown is commonly used, but usually more expensive and harder to find than aftermarket options. That one works without any modifications on the SKX. Crystaltimes, DLW Watches, Watch&Style, SeikoCrown and probably some more supply aftermarket crowns which will fit the stem that is supplied with the NH36 movement. It's possible to use the stem that's threaded on the plastic crown without trimming it, as that one already has the right length that is required for the SKX. I've personally chosen the pre-cut stem/crown combo from Crystaltimes, when I've swapped to the NH36.

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4 hours ago, GregC said:

Would the 7s,26 from a Seiko 5 work in the skx case?

Yes with very same 3 specific parts needed as mentioned above. 

Seiko 5 generally have stem at 3, thinner holder ring, and push type crown. 

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I finally got around to getting the NH36 movement and changed out the day wheel. When I put on the dial and was turning the crown to establish the 12 o'clock position to install the hands, I noticed that no matter how much I turned the crown, it would not change over. Did I screw up something? I was turning clockwise like my other 7S26 Seiko. 

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On 5/31/2019 at 4:01 PM, GregC said:

The one I have here has the stem at 4 and date at 3. Any idea where I could get a ring to fit?

For what it's worth:  I replaced the movement in an SRP-775 (re-issue turtle) with one of the $36 NH36's from Ebay.  Put my day wheel and ring on it and it worked fine.  This watch has crown at 4.

The movement is impossible to regulate well.  I wonder if anyone else has had issues with the replacement movements.

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6 hours ago, nichod said:

The movement is impossible to regulate well.  I wonder if anyone else has had issues with the replacement movements.

NH36 are good mov'ts and should be accurate to the specifications or better. You can post pictures on the timegrapher (or equivalent application) take in 2 or 3 positions.

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9 hours ago, GregC said:

When I put on the dial and was turning the crown to establish the 12 o'clock position to install the hands, I noticed that no matter how much I turned the crown, it would not change over. Did I screw up something? I was turning clockwise like my other 7S26 Seiko. 

Do the day change? With the dial removed check that the day / date  driving wheel turns, that date ring is free and its finger spring is engaged. You will need to remove the calendar plate to correct any problem in this area. At the same time check quick-set. Attached service sheet.

 

7S26C_36C.pdf

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10 hours ago, jdm said:

NH36 are good mov'ts and should be accurate to the specifications or better. You can post pictures on the timegrapher (or equivalent application) take in 2 or 3 positions.

I just got a new Timegrapher 1900 out of the box a few minutes ago.  It looks to be about the same as the Watch-O-Scope I been using as far as the readings.   My beat error is way high at about 2.5 MS.   I can get it down to about 1.1 or so and then it goes the other way.  I'll try again on the new machine and report back.    Perhaps I should have opened a new thread.....

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11 minutes ago, nichod said:

I just got a new Timegrapher 1900 out of the box a few minutes ago.  It looks to be about the same as the Watch-O-Scope I been using as far as the readings.   My beat error is way high at about 2.5 MS.   I can get it down to about 1.1 or so and then it goes the other way.  I'll try again on the new machine and report back.    Perhaps I should have opened a new thread.....

You should be able to bring  Beat Error to under 0.5 ms with careful tiny motions. But what matters more that BE is amplitude and pattern regularity. You can also expect a position error of 30 sec/d day between some positions, which may (or may not) be reduced turning the Etachron regulator. All that is in the service manual and discussed many time on this forum 

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Yes.  Many many times before.  Thanks so much for the reminder.

Problem is my lash up was difficult to use.  With the Timegrapher got it down to .2 MS easily.

Onward and upward.

 

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Ok, I took off the day wheel and replaced it with another which does the same thing. It makes an attempt to change and goes plix and stays on the same day. I put the original wheel it came with and it does the same thing. What am I doing wrong? The only thing that moves is the black wheel between 10 and 11 o'clock. 

 

IMG_20190721_183023.jpg

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3 hours ago, GregC said:

I have a nice big concrete block outside. I feel like taking this POS, putting it on that block  and pounding the shit out of it until its a nice homogeneous, flat piece of metal.

Ha ha ha.

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9 hours ago, GregC said:

Ok, I took off the day wheel and replaced it with another which does the same thing. It makes an attempt to change and goes plix and stays on the same day. I put the original wheel it came with and it does the same thing. What am I doing wrong? The only thing that moves is the black wheel between 10 and 11 o'clock. 

Does that with both time advance and quick setting (white plastic wheel, dot up)? Check that the finger spring engages, normally it does as soon the wheel is turned. When it doesn't, the wheel remains raised above it.

The black (day/date) wheel should be turning all the time. Of course the fingers engage only every 24h.

For a refresh is always good to watch, subscribe, and why not take the course by our Host Mark Lovick. 

 

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2 hours ago, hpekala said:

Check datejumper position.

Jumper is indeed the correct term. I don't know why, it comes natural to me to call it finger, as above.

Edited by jdm

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