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Seiko 7S26 & 7S36 movement differences


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I have been working on a Seiko SKX007 watch for a while. The original SKX007 movement was fairly damaged. Seems like the balance wheel was not tight enough and whoever owned this watch in the past continued to use the watch. This cause the rest of the movement to get scratched and damaged. It is a 7S36 movement.

I bought an inexpensive used Seiko watch, with a 7S26 with the plan of replacing the damaged movement. The major difference between these two watches is the location of the crown. The SKX007 has the crown at 4:00 while the Seiko 5 has it at 3. This causes the day to be misaligned when I install the SKX007 dial.

 As you can see from the first picture, the date is aligned with the crown. But when the crown is placed at the 4:00 position, the date and day at 3:00 is misaligned.

I removed the date wheel on both of the movements. The black one is the original movement. The white is the one from the Seiko 5. The only thing I notice that is different between the movements is the position of the date driving wheel (black wheel on the upper left corner of the movement on the second picture).

Is this what is causing the date to be misaligned?

 

 

SeikoMovement1.jpg

SeikoMovement2.jpg

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Same movement. You could take the black datedisc and daydisc from the 7S36 movement and transplant it to the 7S26 and hey presto you have a working movement with the date and day at the right place. That is the only difference. The other is that the 4 a clock watch has a dial where the dial feets are at a different place. 

 

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I think I’ve found the answer to my own question. I replaced the Seiko 5 date wheel with the date wheel from the SKX007 and now the day-date are aligned at the 3:00 position with the winding crown set at the 4:00 position. I am assuming the day-date wheels are assembled different for both models.

 

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8 minutes ago, rogart63 said:

Same movement. You could take the black datedisc and daydisc from the 7S36 movement and transplant it to the 7S26 and hey presto you have a working movement with the date and day at the right place. That is the only difference. The other is that the 4 a clock watch has a dial where the dial feets are at a different place. 

 

Yes, that's what I will do. I didn't expect the discs to be different. I hope to get this watch completed tonight. It has been sitting on my box for quite some time now.

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14 minutes ago, jdm said:

The day disc is different depending on the crown position, and also between A and B to C versions.printed on them. See below document and compare with P/N printed on the disc.

https://docs.google.com/spreadsheets/d/1sYt_mI9c4tAPiKN3IM8lQx3NEEOyz2DMjVHx5I1_Mqw/pubhtml

There are three different dayrings or maybe more . My head spins around now? Not been drinking no :) 

There is a version where the date is at 6H also and crown at 3H?

But in this case it will work to move black disc from the 7S36 to the 7s26 movement? 

That is btw a nice part list where did you find that? 

Have a few nice 6309 day and date disc that would be great to now in which watch they work?  3H or 4H crown 

Edited by rogart63
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43 minutes ago, rodralph said:

Yes, that's what I will do. I didn't expect the discs to be different. I hope to get this watch completed tonight. It has been sitting on my box for quite some time now.

The disc are different so are the dial? So you must use the dial from the original watch skx007.

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I will be using the disc and dials from the SKX007. There is a very slight difference with the alignment of the Seiko 5 which makes the day to be misaligned when the crown is set at the 4:00 instead of the 3:00.

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1 hour ago, rogart63 said:

There are three different dayrings or maybe more . My head spins around now? Not been drinking no :) 

There is a version where the date is at 6H also and crown at 3H?

But in this case it will work to move black disc from the 7S36 to the 7s26 movement? 

That is btw a nice part list where did you find that? 

Yes, there are cases with date and and day at 6H.
I did this list, and had mentioned here before.
To move a day disc from a 7S26 to a 7S36 or viceversa, both must be the same version, A and B, or C..

Edited by jdm
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JDM,

That is very interesting. I did notice different numbers on the disks. I decided to go with the original disk. Not too bad for a quick movement swap. I am not too happy with the strap, so I ordered a leather one just now. Should be delivered on Sunday/Monday.

I think at some point I will be modifying this watch, but for now it will stay as a diver.

 

SKX007-End.jpg

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11 hours ago, rodralph said:

JDM,

That is very interesting. I did notice different numbers on the disks. I decided to go with the original disk. Not too bad for a quick movement swap. I am not too happy with the strap, so I ordered a leather one just now. Should be delivered on Sunday/Monday.

I think at some point I will be modifying this watch, but for now it will stay as a diver.

 

SKX007-End.jpg

Nice work with the discs. But i don't really think you got the hands in the right position? It looks like it is in good condition? i Say keep it as is? 

Edited by rogart63
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5 hours ago, rogart63 said:

Nice work with the discs. But i don't really think you got the hands in the right position? It looks like it is in good condition? i Say keep it as is? 

You're right. The hour hand is slightly off. I will be resetting them today. It is in very good condition for such an old watch. I really like the look of the SKX007 dial and the black day-date sets it off nicely. I think it will stay this way for a while.

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I finally got around to reset the hands to a more aligned position. The leather strap I ordered was delivered today, along with some Silicone grease. Since the watch was open, I greased the caseback gasket and the stem O-ring. I am really liking these thick leather straps.

 

SKX007-OnLeather.jpg

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  • 1 year later...
On 6/25/2016 at 5:16 AM, rodralph said:

I will be using the disc and dials from the SKX007. There is a very slight difference with the alignment of the Seiko 5 which makes the day to be misaligned when the crown is set at the 4:00 instead of the 3:00.

Hi, 

I am facing an issue of day mis-aligned with the date on my 7s36. This watch crown is at 4 o'clock, and part number found on the watch for day wheel was 160287 meant for crown 4H. Am I suppose to use the day wheel meant for crown 3H due to the day /date window at 3H?

22549951_10155249379653335_6303573711373108374_n.jpg

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1 hour ago, nickpeh said:

I am facing an issue of day mis-aligned with the date on my 7s36. This watch crown is at 4 o'clock, and part number found on the watch for day wheel was 160287 meant for crown 4H. Am I suppose to use the day wheel meant for crown 3H due to the day /date window at 3H?

No, the P/N is correct for the day disc you must use. How it has happened that it became misaligned, what is that you replaced?

Edited by jdm
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41 minutes ago, jdm said:

No, the P/N is correct for the day disc you must use. How it has happened that it became misaligned, what is that you replaced?

I didn't do anything to it, it's been like this for a period until recently I wanted to get it right then removed for inspection. I found out overt the night, in the morning the wheel didn't manage to rotate all the way to align with date. I was guessing the day disc or the drive wheel that has worn, after looking at it seems no damaged. Will the day spring affect the full rotation?

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