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Seiko 7S26 / 7S36 mainspring

DrJoe

By DrJoe
in Watch Repairs Help & Advice

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DrJoe New Member

DrJoe

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The variety and types of mainsprings is pretty amazing. I'm looking for a mainspring for several Seiko 7S26 / 7S36 movements. Seiko used to sell a barrel / mainspring unit but that part has been discontinued. Can anyone point me to a replacement mainspring?

Thanks!

jdm Distinguished Member

jdm

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7 hours ago, DrJoe said:

I'm looking for a mainspring for several Seiko 7S26 / 7S36 movements.

Here again 9ne of the most recurrent Seiko questions

How do you know with certainty that movt' wont be acceptable without replacing the mainspring? Facts are, first these are quality mainspring and can easily last 50 or more years, and then a brand new NH36 with manual winding and hacking is like 5 or 10 euro more than a complete barrel, or an (imperfect) replacement GR mainspring.

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DrJoe New Member

DrJoe

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18 hours ago, jdm said:

Here again 9ne of the most recurrent Seiko questions

How do you know with certainty that movt' wont be acceptable without replacing the mainspring? Facts are, first these are quality mainspring and can easily last 50 or more years, and then a brand new NH36 with manual winding and hacking is like 5 or 10 euro more than a complete barrel, or an (imperfect) replacement GR mainspring.

While replacing the movement would be the most expedient and cost effective route, I am trying to learn watch repair, not swap out entire movements. So far, after opening 4 of a dozen junk watches, 1 had a broken mainspring and one was corroded. The challenge is to repair as many as possible of the lot through repairing, sourcing, substituting or fabricating the needed items.

jdm Distinguished Member

jdm

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2 hours ago, DrJoe said:

 So far, after opening 4 of a dozen junk watches, 1 had a broken mainspring and one was corroded. The challenge is to repair as many as possible of the lot through repairing, sourcing, substituting or fabricating the needed items.

I'm pretty sure that on this particular one the MS is not broken or corroded, thanks to its good quality and sealed barrel design mentioned above. Also, when working on junk or just economical mov'ts, it seems sensible to consider the cost of buying brand new parts, if that is 50 - 75% of  its value or price bought new then maybe is better to consider another way.

Anyway, the issue of opening or even replacing with new parts the Seiko barrels has been debated at lenght. If you use Google site search for these terms you will find them, including more part numbers, etc.

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