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7C43 Professional diver

1940 Views 15 Replies 5 Participants Last post by  diesel powered seiko
Hi all.

Does anyone have a cross section of 7C43-700A (or similar). I am just trying to work out in the crystal retainer has an undercut for the bezel retaining gasket, or if it is tapered downwards.

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From what I see on the crystal retaining ring it has neither a cut out or tapered, there is a ring that runs around the ring about 1mm from the bottom edge. Here's a photo, sorry about the quality, I grabbed the ring on the way out, I'm on the train to work :) . Hope it helps.

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You still have that mint 7C43?

Was that meant for me? Just to say, I bought the watch in that condition, someone didn't have a specific tool for the job, but definitely access to heavy tools.

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Thanks for that pic - (where would we be without this place).

I had wondered if mine was original - and now (thanks to your pic) it looks like it is . Am curious as to how the bezel stays on though - the lip on it seems too low to retain the o ring ( as the o ring groove in the bezel is higher up).

I do know the o ring on mine is below size - currently trying to get a 0.9mm cross section one . But even with that , its still not going to be physically retained.

Wondering now if the crystal is the correct one . If its too thin the retaining ring will sit too low .

But sure if was the correct thickness (2.46mm i think)

And if the other question was for myself - then yes i still have the NOS item. Lovely piece. But since acquiring it, it has spurred me onto buying others - so am at about 6 of them now (oh the voices in my head).
If your crystal was to thick, the bezel would sit proud of the case. Too thin and you'd not get a good seal on the "L" ring. Not been able to find a NOS or AM crystal, but use the one from a 6309/7584, different bevel edge but same thickness and all four of mine seal fine, and bezel works correctly, sits correctly.
Is there a lip on the bottom edge of the bezel itself? Never looked, just taken as given it clicks and works. I believe the gasket is just for "resistance" and prevent it from wobbling.
NOS 7C43, I don't believe you :) .

Regards, David

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Hi David,

It is teh gasket that actually holds the bezels in place . Whilst it does also offer some friction / resistance to teh bezel, it also holds it in place. When you press the bezel on, it is the gasket that deforms not the case or the retaining ring. Without the gaskets, the bezel simply falls off.

I was thinking that if my crystal was too thin (or the chamfer wasn't right angle), the retaining ring would sit lower than it should. And then the gasket would not be able to get over that lip as shown in the above pic. So the gasket would be sitting on the upper section - it would be unrestrained.

But - firstly - this glass was in a batch with another identical one- and that all works fine. And as far as i know, the retaining ring squashed the L seal sufficiently that the ring actually bottoms on the case. So metal touches metal. Hence the dimension will be the same.

So i am not sure why its not getting retained.

And yep - its true - a 100% NOS Pepsi 7C43, Acquired off the very a couple of years ago. Paid what i thought was a high price at the time - but looking at what they go for now it was a bargain :)
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Holy moley that's a good catch. My first one is my dads, now I have both Kanji and black bezel one. The prices are creeping up and up, think they are more rare than earlier models.
I've read it's the gasket that holds it in place, but I get an occasional snap, when I get the bezel on, on any of the watches I own. Wouldn't of thought rubber would of caused this. I'm intrigued, so I'll have a play around and see what I find.

Regards, David.

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Its the rubber David. That was is causing that resistance and then teh snap. Even though its less than a mm, it has no where to go. And it takes quite a bit of force to squeeze in it. And get them off !!! I am often amazed just how much force it takes to distort a tiny section rubber o ring. But if one was having to distort that amount of steel (or even less down to 0.1mm) - the bezels would never come off

But as i say - try an bezel without the gasket. They simply fall off without any effort - there is nothing holding them on.

The attraction of the 7C43 over say the 7548 is a strange one. To a normal person , they are pretty much identical. But the additional features of 7's case, the all white and black hands plus the word 'Professional' on the dial, to me , makes them so much more desirable .
Just removed bezel gasket from my dads all original, except gaskets, and on putting the bezel back on it still snaps on, and stays in place, but the side play is horrendous.

There is a lip on the bezel though, not the best photo, juggling a phone, loupe and bezel :)

Not saying your wrong, but that lip would happily fit under the ring on the crystal ring.
I like the unidirectional bezel system, not JDM one though :( , sets them apart I think, better and "easier" crystal ring (obviously). Found a H558 case back tool I bought ont 'bay fits perfectly.


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I don't want to get into disagreements with anyone as I am still a newbie on the whole but I spent a lot of time looking at bezels. My conclusion was that the small rim on the crystal retaining ring engages on the slightly reduced diameter of the bezels lower edge, locking over it and the gasket helps the seal and fit but not acting as the holding feature.
So am I, not a guru by any standard, and probably never will be. As the saying goes 'you learn something new everyday'. Had a nightmare putting the bezel back on, no surprise there.
Hope this get settled by one of the long standing members of this forum, and put us all to rights :) .

Regards, David

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And yep - its true - a 100% NOS Pepsi 7C43, Acquired off the very a couple of years ago. Paid what i thought was a high price at the time - but looking at what they go for now it was a bargain :)
Was it from Mike Mounce? If so, you beat me to it. What a great watch.

Best wishes,
mmm - you got me a thinking now. Have to do some digging.

David - do you use silicon grease before you try putting them on? It not only makes them easier to fit - but also makes then turn smoother.

I tend to apply some to the groove in the bezel first - then apply some dabs to teh o ring when its in the bezel. Then i just spin the bezel whilst its loose on teh case to distribute the grease.

Most go on by hand - but if they are a pain i use a press and dies to get them square. Quite often the o ring doesn't sit right and the ebzel is hard to turn - and then sometimes locks up. If so then its off with teh bezel again - i have a trick up my sleeve for doing that thou - which causes no damage.

Myles - i have had a couple from Mike but cant recall if the NOS one was from him. I will no doubt have it written down :grin:
If you look at Davids last photo, the notches seen at the slots for the click ball (looks like saw teeth in the pic) are the smallest diameter at the interference side of the bezel. It's this that snaps over the ridge of the crystal retaining ring in the earlier photo.
This locks it in place and the combination of click ball and good gasket do the rest.
Divers without the crystal retaining ring, where the crystal is held by press fit to the seal alone, tend to have the ridge in the case so that the bezel can lock on in the same way, 7002 for instance.
Barryw, I love silicone grease, not excessive amounts, but these watches are getting irreplaceable, so reducing friction, wear and water ingress/corrosion is paramount to me.
Hope the photos helped, and you find the "full stop" to your question. I've never paid much attention to the bezel until now. Looks like I need some new bezel gaskets as well.

Regards, David

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