Seiko 6309-7040

Not a lot more can be said about Seikos 6309-7040 to be honest! There’s a wealth of information out there but a quick history of the watch is that it was the replacement for the previous asymmetric 6105-8110 diver, and the key changes were the turtle type case design with a proper screw down crown, a fully printed dial that did away with the framed lume wells and a completely redesigned automatic, 17 jewel, 21,600bph non hacking movement. There’s a famous image of Mick Jagger wearing his in the seventies so he’s obviously a man of good taste ,not withstanding the fact he has supermodel Jerry Hall on his arm!


The watch featured came in for a service and a repair to the crown, and is an example from August 1980 that looks to be in very good original condition.


It’s even still on it’s original GL831 rubber strap!


Here you can see a common problem with these crown/stem assemblies. Because the stem has a shoulder where it meets the crown over tightening it can put undue strain on the threads with the result it eventually shears through metal fatigue.


The 6309-7040s stem is a spring loaded affair with a male and female end, this assembly takes up the play as the threaded crown is screwed home.


The dial and hands are in very good order.


The movement looks very good, just evidence of dried lubricant here and there.


The same on the bottom of the barrel arbor.


The watch was fully stripped ready for cleaning and inspection.



Once through the machine and inspected the re-assembly begins with the mainspring.


A spotlessly clean mainplate ready for the top balance jewel.


The going train coming together.


Pallet fork and bridge fitted along with the main bridge.


The autowind bridge fitted signifies the motion work is complete.


The keyless work installed on the calendar side.


A close up of the bevelled date window that was a feature on Suwa dialled models up until 1981. “Suwa dialled” refers to the Suwa factory symbol appearing below the 150m logo.


Handset now refitted.


And now recased so it’s time to sort out that broken crown/stem assembly.


The old crown and stem are essentially useless as the broken threads are stuck in the crown and the male part has no threads left! A NOS crown and stem were produced from the parts drawer.


The rebuilt assembly.


The case ready for closing.


It passes the pressure test with no issues.


And here she is ready for the next few years. It’s always nice to see these classic Seiko dive watches in good original condition.





  1. Love your work, telling from the pictures alone. I am a big enthousiast of the seiko diver. I have some of them, 30 odd pieces maybe I haven’t counted them lately. All first year productions and the ones with new “inventions” handwind, automatic, quarz and solar. Nevertheless I have an issue I can’t seem to solve and maybe you as very knowledgable can maybe help me out. Do you know the endyear of production for the 6309-7040? I bought one recently in almost mintcondition and the seriesnumber start with an 8 and a 3 after the 8.Kanjidial.
    Much appreciated.
    Keep up the good work there, love the things that you can do with watches…


  2. beste,
    Ik heb een seiko diver sinds jaar en dag en hij doet het nog als de besteMaar ik weet niet meer hoe oud hij is en volgens mij kun je dat aan het nummmer zien. het nummer is 8D1541 kun jij me vertellen hoe oud hij is? het type is 6309-7040
    met dank


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