Master Watchmaker, Clockmaker and Jeweller (since 1981)
omega panerai iwc patek and other fine watches by Nicholas Hacko Sydney
Suite 403, Level 4, Culwulla Chambers
67 Castlereagh St. Sydney 2000 NSW Australia
Phone: (02) 9232 0500     Fax: 02 9233 2273

Do It Yourself Project: Seiko 7S26 for Novice Horologists

Chapter 10: The Mainspring

This chapters deals with disassembly of the mainspring barrel and mainspring cleaning and lubrication. Before you undertake disassembly of the mainspring barrel note the following:

    - If you are working on a brand new watch then your mainspring is FINE and it does not need re-lubrication. Therefore information provided here is for educational purposes only and you are NOT required to do any disassembly.

    - If you are working on a 5-10 year old watch then you have two options: to replace the barrel completely (recommended by Seiko) or to clean and lubricate the existing mainspring. Should you opt for the latter, follow the instructions in this chapter.

    - If you are working on a 20+ years old watch then it is strongly recommended to replace both barrel and mainspring. Unfortunately, for some Seiko calibres, spare parts are no longer available so you should at least clean and re-lubricate the existing mainspring. Information provided here will enable you to do the job properly.

Clean and properly lubricated main spring is the key to a movement's overall performance. Gummed-up and dry spring, worn barrel and barrel cover are main reasons for lack of power reserve, poor auto-winding and poor amplitude of balance wheel. Therefore it is absolutely essential to clean and lubricate the mainspring as part of a general overhaul.

In the case of a Seiko Cal 7S26, new mainsprings are lubricated with a mix of grease and graphite powder. As watch repairers have found, such mixture allows adequate lubrication for many years. Unfortunately, original Seiko S4 lubricants are not easy to source and it is very messy to apply. A good alternative is Swiss-made lubricant Moebius 8200 (or 8141).

However, at the end of the day, the point is not necessarily in the type of lubricant but how it is applied. Too much lubrication is not only unnecessary, but will cause unwanted effects to the overall performance. The trick is to apply lubrication in a very fine film on both sides of the mainspring, over it's entire length and to lubricate inside the barrel wall as well.

Unlike wheels and bridges, a mainspring should NOT be cleaned with benzene or alcohol based cleaning solution. Proper cleaning consists of removal of old grease and dirt and it is best done with paper tissue or fine cloth.

IMPORTANT: do not bend or kink the mainspring. Bent mainspring will not perform as designed! Also avoid putting too much pressure on the beginning of the spring (coiled area in the centre of the barrel). The shape of the curved end is designed to allow the spring to "hook" onto the barrel tightly.

Use 'the gum' to clean fingerprints and excess lubricant.

Seiko 7S26 movement barrel complete top view

Automatic Seiko barrel complete bottom view

Seiko DIY 7S26 Repair

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Seiko Automatic Watch DIY Assembly

Seiko DIY Repair Automatic Movement

Seiko Repair Tutorial Automatic 7S26

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Automatic Seiko Watch 7S26

DIY Tutorial Seiko 7S26

DIY Tutorial Seiko 7S26 Movement

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Assembly and disassembly of Seiko Automatic

Assembly and disassembly DIY of Seiko Automatic Watch

Seiko Watch 7S26 movement

Seiko automatic movement 7S26

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Repair tutorial of Seiko Automatic Watch

Seiko Automatic Watch Repair DIY

DIY Seiko 7S26 tutorial

tutorial - Seiko 7s26 disassembly DIY

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Automatic watch 7s26 Seiko

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Seiko Auto Movement 7s26

Seiko DIY Repair Automatic watch

Automatic Seiko watch repair DIY

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