Crown Differences – SKX & 5KX

Crowns Mods SKX & 5KX – The crown, or winder, is one of the parts which differ from the SKX to the 5KX. The SKX has a thread which creates a screw to seal or lock/unlock the crown. The 5KX has a push/pull crown to seal or lock the crown into the watertight position. On most watches, certainly on these two models, the crown is used to operate the movement of the watch. This can be setting the time or date as well as the day on your Seiko. For operation instructions, please see the instructions for the NH36.

One of the OEM crown mods that was made before the advent of the aftermarket mod parts, for the SKX, came from using a Seiko SARB033 crown. This crown has an engraved S. The crown and stem are the same size and length, so it was an easy mod to make. Both the SARB and the SKX, being 200m rated cases, have a screw-down crown. For 5KX users, this part is not compatible with your model.

The OEM crown for the SKX differs from the 5KX and aftermarket crowns. The SKX crown is one piece, crown and stem. The 5KX crown and stem are like the aftermarket products, two items joined together with a thread. This does not mean that you will not need to cut a new stem to mod the crown on a 5KX. The stock 5KX crown is different in that it doesn’t allow as much of the thread to enter the tapped hole on the crown. Therefore, generally, the stock stem is of no use. You will need to source a new stem as well for this mod.

Seiko SKX crown.
Aftermarket SKX crowns.

Fitting a New Stem – Crowns Mods SKX & 5KX

Tools and Consumables

  • Permanent Marker (Fineline)
  • Finger Cots
  • Pliers
  • Cutters
  • Verniers
  • File
  • Desk Vice
  • Dremel – Polishing/Grinding Wheel is a luxury
  • Silicone grease
  • A4 paper or a gauge
  • Oil (Moebius 9010) – Guide coming soon

Removing the Corwn

The stem you have been shipped will be far too long in its current state. You will need to trim this to fit. Your pliers will need to be clean. Before you start you may need to remove the original crown and stem from the case. This can be done on a watch cushion with the case face down to access the setting lever (release button). At the same time as pressing this the crown can be pulled out by hand.

Press the setting lever.
Remove the crown.

Joining the Crown and Stem

Start by taking the stem in the pliers and the crown in between your thumb and forefinger. The stem and crown will need to be square/parallel to one another so that the threads can engage with one another. The thread works like any other thread, right (clockwise) to tighten. The pliers will ensure you engage the thread to the final resting position. You may be inclined to use your fingers, but persevere with the pliers as you will not be able to achieve the required torque. You may also contaminate the stem. Be sure that the stem is fully locked in as tight as possible without breaking the stem.

Once you are satisfied that the crown and stem are nice and tight, locked into one another, the stem will need to be placed into the watch and locked into the movement. The movement will take hold of the stem when it is engaged correctly, it may require a a little twist, avoid applying excessive pressure. 5KX modders will want the crown in the winding position. SKX modders will want the crown in the non-operational position.

Measuring the Excess Stem

Next, take your verniers and measure the distance between the crown and the case. Make note of this measurement. You can also lock off your verniers so that they retain the length you have measured.

Tighten the stem with pliers.
Fit crown and stem.
Measure the distance.

Cut the Stem

Remove the crown and stem from the watch so you can cut the stem.

Detach the crown from the stem in the same fashion that you attached it. Using pliers to hold the stem and your thumb and forefingers to wind the stem anti-clockwise (left) until it comes free.

Placing your stem on the desk, you can use the verniers and your pen to mark where to cut the stem.

It is recommended you cut a little less from the stem than you require. This will allow you to use a dremel or file to give the stem a good leading edge to engage with the crown.

Create a leading Edge

If you are using a file, you will likely require a desk vice to hold the stem. The stem is rather weak, so doing this with a file is an arduous task. A dremel is faster, easier, and you can hold the stem in some pliers or your fingers, although the latter may hurt.

Crowns Mods SKX & 5KX - How to guides and reviews
Crowns Mods SKX & 5KX - How to guides and reviews

Once you have made the cut and cleaned up the rough edges that your cutters may leave, you can re-attach the crown in the same fashion as before and insert this into the watch.

5KX – Final Fitting

If you have cut this to the correct length, the stem of the 5KX will have locked into the movement. The crown will now be in the winding position. If there is a noticeable gap between the case and the crown in this position, you will need to remove more from the length of the stem using this same process. Depending on the length you have left to remove from the stem, you may choose to just Dremel or file the stem only, as cutting may take away too much of the length. If you have cut too much from the stem, you will find out when you insert the stem back into the movement, and it will not lock into the keyless works correctly. Manual operation may be erratic it the crown is too short. You will need another stem so you can begin the process again.

SKX – Final Fitting

If you have been successful in cutting the stem correctly for the SKX model, you will now need to confirm this by screwing the crown into its watertight (locked) position. Once in this position, you can confirm the length is correct by checking that the crown locks in tight to the case.

After the correct stem length is achieved it can be a good idea to join the crown and stem with loctite, or some other thread sealing adhesive.

Crowns Mods SKX & 5KX - How to guides and reviews
Crowns Mods SKX & 5KX - How to guides and reviews -
Crowns Mods SKX & 5KX - How to guides and reviews -

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Useful Information

OEM Replacement Parts:

  • One Piece SKX Crown& stem: 1E70A3SNWO
  • Crown Gaskets (3 pack): EZ0140B0A

Tap Size :

  • NHXX & 7S Stem – 0.9mm

Procuring a Seiko 5KX

Seiko have lots of options in the 5KX range a link to the collection can be found here.