Seiko Mod SKX Sub Batman UK

Seiko Modding – take a Seiko watch such as the SKX009 Japanese edition and make it your own. Style it like a Sub or anything you can imagine. Seiko have developed their own movement in-house and built on this over the years, changing complication controls and adding new features such as hacking and winding.


It is important to trust your supply of parts as quality in the world of Seiko Mods can be varied. For this Mod we have chosen to use a number of trusted suppliers, DLW, Namoki and Seiko Mods. The Oyster bracelet with RLX style deployment claps, suitable for the Seiko SKX or SRPD, came from another supplier.

Always best to check all the products to seek out imperfections to which I doubt, using these trusted suppliers, there will be any. It is however important to do this because, with the large quantities of parts that suppliers process, sometimes things can slip through quality control.

If you are reading this and considering a Seiko Mod yourself it may be prudent to protect your case. That is if this watch is your pride and joy. Low tack, no residue paper tape to cover the lugs and edges of the case. This covered with as much gaffa tape (duck tape) as required. A first-mate on a yacht once said, “protection is better than the cure”. Being a sailor, I know he was talking from experience!

Movement Upgrade

For this particular mod the client has chosen to upgrade the movement to a Genuine Seiko 4R36. This was ordered from UK distribution. The 4R36 has come with a set up for the 3 o’clock crown position. The SKX has a four o’clock crown. The day wheel needs to be swapped, so this lines up in the display box on the dial. The movement holder is also required for this upgrade.

The hands are removed from the original 7S26. The dial can then be removed with a screwdriver. Using the indents in the movement holder, the dial comes away. It’s neat how this has been developed and the dial just sits there under pressure without the need for a locking system like the early 7000 series and many other movements on the market.

A little cir-clip is removed which retains the day wheel. There are lots of ways to remove this. I like to use a blade, Roddico, and lift the day wheel away.

There are a number of screws under the day wheel to remove. Once the screws are out, all the parts can be removed to gain access to the movement holder, which pops off with a twist.

Repeat the process on the replacement 4R36 movement and reassemble as required. Inspect the crown functions to ensure they perform as normal.

Now it’s time to place the dial and hands on the Seiko 4R36. The dial is just pushed on with a little pressure and the new hands can be placed into position.

Seiko Case Mods

Moving on to the case and the exterior mods. The case needs to broken down into its component parts. The original Seiko bezel needs to be removed from the watch case, so that the Seiko Hardlex crystal can be removed. I have taped up my dyes as I still see that first mate scratching and I wonder if he was ever cured!

The case is cleaned before reassembly. The chapter ring can then be put in place followed by the crystal gasket, with a little silicone lube. This helps install the crystal by reducing the friction and it adds extra protection against the water ingress.

Water Resistance Test

Once the crystal is in place, the crown and case back are replaced. The gaskets (seals) are given a touch of silicone grease for a pressure test. This is performed twice after the mods are made – once with and without the movement. I’m sure you can work out why!

Bezel Modifications

The bezel is cleaned of grease with acetone to get a good adhesion to the tape. The insert is cleaned with a solvent remover that is less harsh than the acetone.

Finally, cutting the stem for the new ‘S’ etched crown, screwed in with a little Locktite and cured for thirty minutes.

The movement can then be placed in the case, crown inserted and then regulated. On this occasion on the timegrapher the movement is adding 2-5 seconds per day, with an amps of 290, and a beat error of 0.2. The bench test performed at +3 second per day.

If you are considering your own Seiko mod and looking for inspiration please check out my socials, linked below, or the Seiko Mods Page.

Categories: Seiko Mod


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