Service: Grand Seiko GS45 / calibre 4520A

IMG_2541This is my last post before going on holidays for the week, and Mitka has started on his first customer watch as well, which he will finish for me to check over when I get back. After 4 1/2 months, and dozens of his own watches serviced, he is ready to roll!

The first Grand Seiko in this workshop, and it belongs to Chris.

The dial has odd spots on it, but apart from that, the watch is looking good…IMG_2542

Lovely case back with the GS logo in the middle.IMG_2544

Certainly not your usual Seiko movement!IMG_2545

Not too bad, bad the movement is dry and dirty.IMG_2546

The bottom plate looks nice, too, and very un-Seiko.IMG_2547

A lovely movement.IMG_2548

The dial has odd red spots on it, and I try to dissolve them by putting a minimal amount of vinegar on one of the spots outside the minute markers, but I hove no luck – it isn’t impressed by the vinegar at all.IMG_2589

Time to take the movement apart. You can see the little hacking lever.IMG_2592

The gear train, with the hacking lever construction going around it.IMG_2595

With the barrel bridge removed, you can see the full glory of the hacking lever contstruction, which consists of 3 parts!IMG_2602

Now I turn my attention to the bottom plate.IMG_2607

All clean and ready to be put back together.IMG_2608

There are of course no parts to be had, so I re-use the still very spritely mainspring.IMG_2609

The balance cap jewel is put back into place.IMG_2613

Gear train and hacking lever are in place.IMG_2614

I put back together the bottom plate.IMG_2616

Straight as an arrow, and a slightly low amplitude, as all Seikos have.IMG_2618

The movement is cased. Very nice regulator construction.IMG_2619

I re-finish the case to its brushed finish.IMG_2620

Side view with original crown.IMG_2621Nice brushed finish.


33 thoughts on “Service: Grand Seiko GS45 / calibre 4520A

  1. Do you know where I can get a transparent case back for the 4500s?
    Would the eBay “5M23 5M63 5M43” or “SKX007 SKX 7002 SKX 6105” would fit? Thx

  2. Hi,

    My 4520A developed an issue where the winding mechanism stopped working. The minute hand moves slightly in both directions when I try to wind it but the watch will not start. I think the mainspring is fully wound but the mechanism just will not disengage properly.

    My plan was to source a 45KS movement for parts. Do you have any idea what could be wrong and what is the chance the parts from a 4500A in the KS will wokr in the 4520A in the GS? Without parts the local watchmakers won’t really even try to service a vintage GS.

  3. Pingback: Vintage King Seiko 45 buying experience | musingsofawatchaddict

  4. Hi!
    Cool watches! I can see you are using 52deg lift angle on the timing machine. Do you have information if this is correct or not? I know that Seiko has been “all over the place” in terms of this. I only have one Seiko “HiBeat” vintage, and that is an automatic caliber 5626. They have 56deg lift angle.

    • Unfortunately, we couldn’t find any definitive information about the lift angle, either, so we stuck to the 52 degrees. You can of course adjust the timegrapher by making the balance swing exactly 180 degrees, and then adjusting the lift angle until you get the 180 degrees on the timegrapher as well…

      • I was just wondering if this could have anything to do with the typical mediocre amplitude performance of Seiko watches on the timegrapher? Must admit my King Seiko has only about 210-220 deg amplitude even with the setting at 56 deg, however that is not all freshly serviced.

  5. Hi Christian,

    Great job! You mentioned that there were no parts to be had. Is that because Seiko does not sell parts to “non authorised ” watch makers or because Seiko does not support older watches?

    Thank you again for you great blog.



    • I’m pretty sure that all authorised service centres send any Grand Seikos back to Japan for a full overhaul (which can be very expensive) so even local Seiko service facilities don’t keep GS parts on hand. They do service older watches (just had a 70s hi-beat ladies’ decently serviced by them) but don’t always have parts for some older and scarcer movements.

      Fine and sensitive work, Christian: the 4520A movement is derived from the ‘Astronomical Observatory Chronometer’ calibre, so not to be sniffed at. Any indication of previous services?

  6. Hi Christian,
    I notice that you use a tool that looks a bit like a low tack sticky cotton bud for handling the smallest parts like cap jewels etc. It looks to be so much safer than tweezers; I reckon one of those would save me a lifetime of searching for the parts that went ping when I least expected.
    What is that tool and where can I get one?

  7. Hello!
    Very nice movement! Could you please describe the way you dealt with the duo-fix system on the escape wheel? Did you oil it like you do the Incabloc (oil only on the cap jewel) or did you use another way.
    Thank you,

    • Hi Bogdan,

      I oil it in exactly the same way as a shock setting. You put a tiny amount of oil on the endstone, and then turn it and put it on the jewel hole. You then fit the spring back.

  8. You mentioned that Seikos traditionally show a low amplitude … is there a reason for that?

    Nice refinish of the case, by the way!

      • Maybe the low amplitude is to save teeth, and I was wondering about the Hi-Beat Diver (6159 movement) you overhauled some time ago…I guess that was the highest amplitude you’ve ever seen on a Seiko (300-ish degrees)?

  9. Hi all. This is my watch and again Christian has done a great job. This watch was manufactured in April 1970

    Thanks again Christian. Have a great holiday.


  10. Out, damned spot, out! What is the dial made of?

    Even with the marking it looks very nice… but I cant date it – 70s?

  11. Hey Christian, I just wanted to ask ther are five wheels in the gear train in this watch but I thought there are usually four wheels in the train. So why one extra wheel?

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