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Seiko 6139 - Anybody bought a new mainspring?

B3stia

By B3stia
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B3stia Member

B3stia

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Has anybody ordered a new generic mainspring for the 6139 movement?

I'm not looking to get the mainspring of a donor movement. I want to buy a brand new.

I found the mainspring dimensions at thespringbar.com. They should be as follows.

Screenshot_2016-06-03-07-59-13-01_zpssd106nrj.jpeg

I have tried cousinsuk since I live in Europe. But they didn't have anything with these dimensions.

Appreciate any help! Thank you

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B3stia Member

B3stia

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oldhippy > I saw some used complete barrels being sold on eBay. I guess that's my best option if I can't find a new spring. I have searched around but it's a mess finding a site with good information.

Ro63rto > I had seen that one earlier but I had hoped to not having to dish out a premium for NOS. $40 is a lot.

Thanks for the effort guys.

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jdm Distinguished Member

jdm

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Posted (edited)

You try can source a Seiko  401615 

From Cousins I think this one would work


Mainspring, 1.00 x .11 x 420 x 10 Automatic - GR24571X    

 

Edited by jdm
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  • 3 years later...
jdm Distinguished Member

jdm

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On 6/3/2016 at 2:11 PM, jdm said:

You try can source a Seiko  401615 
From Cousins I think this one would work
Mainspring, 1.00 x .11 x 420 x 10 Automatic - GR24571X    

I've found this old posting of mine and in hindsight I would say that 1.05 x .115 x 420 x 10.5 mm  - GR2534X would be better.

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Tipsy Member

Tipsy

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4 hours ago, jdm said:

I've found this old posting of mine and in hindsight I would say that 1.05 x .115 x 420 x 10.5 mm  - GR2534X would be better.

Whats your thinking behind this?

As a novice, looking at the dimensions, I would have gone for your original suggestion. 

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jdm Distinguished Member

jdm

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37 minutes ago, Tipsy said:

Whats your thinking behind this?

As a novice, looking at the dimensions, I would have gone for your original suggestion. 

I don't have one with me but the original should be 1.05 high for a 10.5 barrel.

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Tipsy Member

Tipsy

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2 hours ago, jdm said:

I don't have one with me but the original should be 1.05 high for a 10.5 barrel.

I thought these where the dimensions:

L 43.5 mm, H 1.01mm, Thickness .10mm 

1.01mm high makes me wonder if a 1.05 would work (note that I have no experience with the 6139 or 6138).

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saswatch88 WRT Addict

saswatch88

Posted
Posted (edited)
11 hours ago, Tipsy said:

I thought these where the dimensions:

L 43.5 mm, H 1.01mm, Thickness .10mm 

1.01mm high makes me wonder if a 1.05 would work (note that I have no experience with the 6139 or 6138).

You never want to go higher in height. Seiko sells the barrel complete with spring this is your best bet plus saves you the trouble of ruining a MS while trying to install it since you are a novice and would assume you dont have a MS winder. But If you dont want to spend the money then you can get aftermarket but not one that is any higher unless you want it rub on the barrel lids and cause a major problem in amp and power reserve.

Edited by saswatch88
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jdm Distinguished Member

jdm

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1 hour ago, saswatch88 said:

Seiko sells the barrel complete with spring this is your best bet plus saves you the trouble of ruining a MS while trying to install it since you are a novice and would assume you dont have a MS winder.

Seiko listed a barrell complete available for the 613 (206.613), but it has been unavailable since decades probably. Both 401.615 and 401.616 are listed compatible, and know to work well. https://www.thewatchsite.com/21-japanese-watch-discussion-forum/104345-seiko-6139b-mainspring.html
Attached the technical sheet.

The issue with getting a new original mainspring is now  availability cost. For someone, $50 for something of dubious authenticity is objectable https://www.ebay.com/itm/401615-Main-Spring-For-Seiko-Movt-6105-6117-6118-6119-6138-6139-6309-6306-/303388168815

Another source could be the well know Adrian of VTA Australia https://www.vintagetimeaustralia.com

So it's normal that people looks for alternatives. Now, the height of 1.01mm (which seems strange as normally sizes are every .05mm) has been given by the OP from a website. But someone else measured (with calipers - ideally you want a micrometer) at 1.05: https://adventuresinamateurwatchfettling.com/2019/04/05/seiko-6139-6012/ and that is pretty much a GR2534X 
Eventually he fitted a shorter MS, but he got a shorter power reserve. It could be that my initial suggestion of a  GR24571X  works well also, but I never tried either one.

Finally, when using a new MS no winder is needed, as its transferred straight from washer to barrel.

 

6139b.pdf

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thor447 WRT Addict

thor447

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I know this thread is a bit dated, but I recently ran into some issues with 6138 and 6139 mainsprings from eBay being slightly undersized and underpowering the watch.  I was finally able to find the exact correct replacement mainspring and thought I'd share it here for future reference.

The correct dimensions for the spring are:   1.05 x 0.115 x 420 x 10.5

A search online references GR2534X, which can be found from Cousins.  While the spring has the correct dimensions, the inner curve for the arbor is a bit wide and fits somewhat loose.  This can be adjusted, but there is another (and cheaper) option.  Cousins also has part # GR25341X, which has the exact same dimensions, but costs about 30% less.  This part number is not referenced (anywhere that I could find) for the 6138, but the inner curve is smaller and fits the barrel arbor perfectly. 

If anyone is trying to source a mainspring for their Seiko 6138 chronograph, the GR25341X is what you'll want to get!  I ordered a couple of them and just installed them in two of my watches.  It brought the amplitude up from 190/200 (with the eBay spring) to 230/240.

Here's a photo showing the difference in the inner curve between the two Cousins springs.  The correct spring is on the left.

613821791_Screenshot2023-02-11084400.thumb.jpg.eea54b30ddc802a190fca400a839361e.jpg

1591279988_Screenshot2023-02-11084421.thumb.jpg.7f841efb2f886909d981d2ffaf898b63.jpg

FYI, the washers are the correct size and the spring drops right in. 

I hope this is helpful for someone in the future trying to find the correct aftermarket mainspring for their old Seiko.

 

Edited by thor447
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