Crown for Lord Marvel 5740-8000

[JerSievers]

I have Lord Marvel 5740-8000 I am servicing I could use some advice/help:

It's stem was a little short and part of issue with watch. A new stem for the 5740C should be Seiko 351.572, and crown is 55W12NS1.

351.572 has stem treads at 1.0mm (TAP 9), I measured.

The short stem that was cut too short has 0.90 stem treads?! also measured. (Measured the crown too, it fit the more standard 0.90, like seiko 7s26, eta 2824-2)

I think the past owner (or service) took the 351.572 and taped it down from 1.00 to 0.90. They probably had same issue I have, can't find a crown that fits.

Well I can, but don't want to spend $80 on a vintage one...rather just get one that fits, Cousins doesn't have 55W12NS1. The dial is a little damaged so, not worth a huge investment for this specific watch.

Watch stem tap numbers seem to be crazy and inconsistent, some call TAP 9 (0.90 mm). TAP 9 is 1.0mm and TAP 10 is 0.9mm. Someone can probably point me to the correct measuring standards, but a side topic.

So, I think the last person who worked on this watch just tapped the stem down to a .9mm as the crown fits other standard crowns.

The spec should be a TAP 9 (1.0mm) Crown 5.5mm, no extension, swiss style waterproof, for 2.6mm tube.

So many questions/options,

1. Should I just tap the stem to fit the crown I have? (doesn't seem like a great idea)
2. Just cough up the money for 55W12NS, but a little concerned about it not fitting, maybe crown tube was replaced too, just not sure?!
3. 351.572 fit a lot of different seikos, so cross-referencing helped locate a lot of options, but a rabbit hole for sure.
4. Then there are other "NOS" seiko crowns that are easy to get that could make work without sourcing 55W12NS1, like crown for 6220, part 45W24NS, were these same size? 1.0mm (TAP 9)

 

Edited December 11, 2022 by JerSievers

[LittleWatchShop]

https://blog.esslinger.com/stem-tap-mm-size-cross-reference-chart/

 

[JohnR725]

On 12/11/2022 at 11:27 AM, JerSievers said:

5740C

 

On 12/11/2022 at 11:27 AM, JerSievers said:

They probably had same issue I have, can't find a crown that fits.

Even though Seiko watches are Easy to find anywhere on the planet their problems. Parts typically are only distributed into the regions where that watch is supposed to be. So if you  are in the US for instance and try to get parts for an overseas Seiko it's problematic. Sometimes a material house can try to figure out what will fit Possibly with something available in your region if they understand the part numbers but otherwise you might be out Of luck.

Then there is the other problem with any watch did Seiko anticipate that from when the time this watch was made until now that they would need to supply parts basically forever unfortunately not vintage Seiko is harder to get parts for

Then your watch is interesting watch I'm attaching the parts list.

Then I have a link this is a interesting watch it's just not an ordinary Seiko it's definitely an interesting watch

https://wornandwound.com/affordable-vintage-seiko-lord-marvel-5740-8000-lm5740-hi-beat/

 

 

5740C-Lord-Marvel-36000.pdf

[Nucejoe]

 Eighty dollar crown and an imperfect dial on 36000 bph watch. .

But you have time to keep hunting for a donor watch with good parts that you need ( ebay....) , you'd have a good watch plus bunch extra parts to sell. 

Like John says, its a good watch. 

Rgds