Seiko 5 very stiff crown/stem

[kd8tzc]

I have a Seiko 5 with the 7S26C movement that has a very stiff stem.  Very stiff to pull out and very stiff to rotate.   My first instinct is to open it up and inspect the stem winding pinion, etc, but I thought I also saw someone advise to not work on a Seiko watch for some reason.  So, I figured I better ask before I start down a path I shouldn't.

Also, I'm not familiar with how to get the stem out of a Seiko.  I would think it would be similar to other watches, but wanted to check.

 

 

[RichardHarris123]

Watch this. 

 

 

[kd8tzc]

Thanks @RichardHarris123, I was also searching around, and I see our benefactor Mark, has a wonderful video of the disassembly and reassembly of a Seiko 5 with the same 7s26 movement.  He also appears (I have not watched the whole thing yet) to show lubrication, but he is not saying what he is using.  I know on the Seiko Tech Sheets, they will always reference Seiko oils (AO-3, S6 and S4).  Is it best to stay with the Seiko oils, or can one use Moebius, or others here too and if so, what would correspond to the three that are listed in this post?

I might give this movement a go at cleaning after I watch Marks full video as I can still buy a 7s26 movement if I screw it up too much.  I've had the watch since 2017, and I do love the watch.  If the stem is stiff I wonder if that is due to the grease in the key-less works drying up/out, junk getting into it, or something else.  I wonder what else may need to be cleaned, and re-lubricated.  Seem like a good learning opportunity.

 

 

Edited March 30, 2023 by kd8tzc

[RichardHarris123]

I would of thought Moebius would be fine, definitely sounds like it needs a clean and relubing. You might find other issues once disassembled. 

Post pictures once the movement's out. 

[kd8tzc]

I would think Moebius would be fine too, but which goes to which of the Seiko Oil's.

What really scares me now are the end stones.  I already lost an end stone from my practice movement (ST36)... but I think I learned a great lesson in protecting the stones and making sure they can't go flying off.

I'm waiting for a new movement holder which should arrive today, so I may wait to take it out until that comes.

[kd8tzc]

Okay, so I have it out of the watch, and when I reinsert the crown and stem, it changes the day & date like it should... nice and loose.

So what could be the issue then?  Something with the watch case?  Something that corrected itself when I removed the stem?

Should I apply some lubrication to the stem and call it a day?  AT 19:23 in the video of @Markplacing the stem back in the movement, he applies some lubrication to the setting stem, but he does not say what he is using.  The Seiko watch Tech Sheet says to use Seiko Watch Oil S-6. but I don't know what that translates to with Moebius.  Would that be  similar to Moebius D5?

[RichardHarris123]

Send us photos. 

[kd8tzc]

@RichardHarris123What exactly do you want to see in the photos?  Obviously the movement. but what should I get be looking at for you as I have not stripped the movement.  Just removed it and reinserted the stem.

[RichardHarris123]

I want to see the keyless works.  You could try lubrication of the stem, the gasket might be dry. 

[kd8tzc]

You won't be able to see the keyless works as the dial and everything on top is still there.  Would D5 work okay on the stem since it is low speed?

 

 

 

[RichardHarris123]

O would think D5 would be fine.  Let us know how you get on.

[kd8tzc]

Since I have the movement out of the case, I am going to take the opportunity to clean the case and back in IPA.

Would Molycote DX be okay to use on the o-ring on the case back and the rubbed gasket on the stem?  I have Mink oil too, but I highly doubt that would be suitable, but I know my Dad used that for o rings in the sink. 

[RichardHarris123]

Not sure, I haven't used it.

[kd8tzc]

Well, I got it all back to gather and with the lubricated stem, it was still stiff to turn the crown.  I noticed that the gasket on the stem was engaged at that spot, so I removed the stem again, and applied a tiny amount of Molycote DX to the gasket (someone can yell at me if this is a huge NO-NO), but it is like a new watch now.  Very easy to turn the crown.  Much nicer to set the date/time... glad I didn't have to tear it all down, but maybe it would still be a good thing to do sometime soon to get it all re-lubricated.

Before I would do that though, I want to find out what I can use for those Seiko oils.

[RichardHarris123]

11 minutes ago, RichardHarris123 said:

Not sure, I haven't used it.

Any silicone grease should do but people tend to use something like this. 

[kd8tzc]

Okay, thanks for the info, and thanks for guiding me.

Just starting out, so I don't have a lot of things yet.  Waiting in an order from Cousins that seems to be stuck over in the UK.  Hopefully some year it might get here.

[bklake]

Molycote dx is petroleum based and may not be compatible with the gasket.  It is also known to dry out.  I would clean and wash it off the stem.  Usually a silicone grease is used for the gaskets. 

I find Seiko's silicone grease very sticky and thick.  The stems I have used it on were hard to turn and sticky. I now use silicone grease from the plumbing aisle at the hardware store.  It was a huge investment at $2 a tube. 

[kd8tzc]

Thanks for the info @bklake, I was not aware that there was petroleum in Molycote DX.  I will make sure to clean it off this weekend and use the better stuff.  I might even have some silicone grease in the garage for something already.

I think I'm going to strip the watch down, clean and lube it.  When I put it on my timegrapher last night (I had not done this for some time), I was getting some very odd readings on the timegrapher.  I actually had to put one of my other watches on to make sure that the timegrapher was not broken.  I don't know if the fact that the watch was not fully wound was the issue or something else (if the amount of wind can affect the readings, please let me know).  That was always one of my pet peeves 7S26C was that you could not manually wind the mainspring. 

I've often wondered if I could swap it for a different Seiko movement, but with the crown at the 4 o'clock position, I'm not sure how easy that would be.  I know the new watch of the same design comes with the 4R36 movement which has hacking and you can wind it, but I bet the thickness and dial diameter are different (if anyone knows let me know).

 

[tomh207]

54 minutes ago, kd8tzc said:

Thanks for the info @bklake, I was not aware that there was petroleum in Molycote DX.  I will make sure to clean it off this weekend and use the better stuff.  I might even have some silicone grease in the garage for something already.

I think I'm going to strip the watch down, clean and lube it.  When I put it on my timegrapher last night (I had not done this for some time), I was getting some very odd readings on the timegrapher.  I actually had to put one of my other watches on to make sure that the timegrapher was not broken.  I don't know if the fact that the watch was not fully wound was the issue or something else (if the amount of wind can affect the readings, please let me know).  That was always one of my pet peeves 7S26C was that you could not manually wind the mainspring. 

I've often wondered if I could swap it for a different Seiko movement, but with the crown at the 4 o'clock position, I'm not sure how easy that would be.  I know the new watch of the same design comes with the 4R36 movement which has hacking and you can wind it, but I bet the thickness and dial diameter are different (if anyone knows let me know).

 

I’m pretty sure you could use a seiko NH36 movement. The dial is likely to be the standard 28.5mm and I think the date/day wheels can be swapped as well. There is a huge Seiko modding community out there that would be worth searching to see what they say. The NH36 is the movement Seiko sell to 3rd parties and is basically the same as the 4R36.

 

Tom

[kd8tzc]

I thought I heard that the pinion for the second had was higher or something, so not 100% certain.  Possibly I would have to swap the crystal out too to accommodate that if it is higher.

Edited March 31, 2023 by kd8tzc

[tomh207]

Everything I have seen is the NH36 is a drop in replacement for the 7s26 range. Only things you will have to do is move the 7s26 day and date wheels over along with the crown as the stem is different I believe. Have a look at sites like namokimods, they are a pretty reputable modders site and I think they have articles on this type of upgrade. There are loads of Seiko modding suppliers out there, one of them will have something on this.

 

Tom

[kd8tzc]

Thanks Tom... looking at the spec sheets, I see the 7S26C has a height of 4.9mm while the NH36 has a height of 5.32mm.  That's a 0.42mm difference.... I'll have to check if that is significant enough to be an issue.

I also see that Cousins has this movement for 36.96 Pounds, but namokimods has it for significantly more at $95.  I'm not sure what the difference is other than with namokimods I can get the 4 o'clock crown position.  What am I missing here... does it HAVE to be a 4 o'clock crown position movement or couldn't I just rotate the 3 o'clock one to the 4 position?  or do things just not line up right then... I'm thinking that must be the case when I look at the image. 

Anyone also know where namokimods ships from?  I'm a little leery of Cousins right now since I can't even talk with anyone about my order from a few weeks back that has not left the UK yet.  I'm all for trying namokimods, but that is a big price difference.

[bklake]

The stem is a different part number for the 4R36 and 7S26.  You will need to swap the stem.  The 7S26 stem is very different.  In modern times, usually, but not always, Seiko uses a one piece stem. You cannot unscrew the stem from the crown.  If you see threads on your stem, it is an easy swap.  No threads, it is a one piece unit and cannot be separated. 

I guess you can find a generic crown that fits and use that.  IIRC, that model is not screw down.  A lot of matching of diameters and gasket sizes but it can be done. 

The NH36 will be significantly cheaper than a 4R36.  In theory, the same movement and interchangeable.  In practice, from different factories and distribution.  Be careful comparing heights listed.  Between generations, the height is measured from different places.  It will take a deep dive into the drawings to see if there is a real difference.  I believe the stem height is the same between the two if you measure from the same place.  I have swapped a couple of NH36 movements into 7S26 cases and have not encountered problems. 

It is actually a 3.8 o'clock stem position.  4 o'clock is close but not exact.  The date wheel will line up but the day wheel will be off.  Seiko figured out that 3 and 3.8 line up at the same place where true 4 o'clock does not.  They were able to reduce to one part for both configurations.  You can buy a 3.8 Day wheel and swap it but by the time you factor in the cost of the part and your time to swap it, it is easier to buy in the configuration you need.  A Day wheel change is pretty easy. 

[tomh207]

Maybe these will work for you @kd8tzc

https://usa.crystaltimes.net

https://watch-modz.com

i am sure I read something about moving the plastic ring over for some watches but can’t find a reference now. Avoid Aliexpress and eBay now for Seiko movements, there a a lot of expensive fakes hitting the market now out of China.
 

Tom

[kd8tzc]

Thanks @tomh207, I sent a message to namokimods asking them what I might need for this movement to go in that case, so hopefully I will hear back from them in a day or two.  I'm sure they have helped a few people through this.

Right now, I am taking the 7s26c apart and I plan to clean and lubricate it.  Nothing else, it will he a good movement to practice on.  It was running strange anyhow, so I guess it was time.  It was either this or an Orient that I have.  I want to do a few practice movements before I tackle my Grandfathers Hamilton Morton from the 1950s or the Sellita mechanical that was my wife's Grandma's watch (not a very expensive watch I don't think, but a HUGE sentimental thing for her).

One of the things I will need to start thinking of is a mainspring winder for this sucker.  I can't afford to buy a whole set of them, so how do I figure out which size I need?  I'm looking at a chart that Esslinger has and iit asks for a MM Diameter (is that the INSIDE diameter of the barrel housing (or is it the outside diameter).  Arbor diameter I think I understand.

 

OR should I just not take the mainspring apart?  The watch is about 6 years old, so I think the right thing to do would be to open it up and clean and lube it.