Splitting a pair of eights Part 2: A Seiko Business-A 8346-9000 from February 1967

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The 83 series watches seem curiously neglected from most accounts of Seiko’s achievements in the 1960’s.  Early on in the life-cycle of the base movement, it was celebrated mainly for its slim profile and it didn’t really hit its stride until 1966 with the release of the 8305C by which point it had acquired a hand-winding facility in addition to its quickset date complication.  At its zenith it would only have two more years to run before being snuffed out in favour of the 56 and 61 series movements that dominated Seiko’s automatic mechanical movement output from the late 60’s through to the mid-1970’s.  Copies of pre-’68 Seiko catalogues are absent from general circulation and it is infuriatingly difficult to find much in the way of official information on the marketing of these watches through this mid- to late-60’s period.

It doesn’t help that Seiko chose to market the same models as both Seikomatic-R’s and Business-A’s.  The only real handle I can get on the Business-A branding is that it was targeting the youth business market and, in the only marketing material I can find promoting the Business-A brand, the word ‘thin’ is used in the copy (the kanji character 薄 in the third line of text in the image below translates as ‘thin’ but as a noun translates as Japanese pampas grass which is rather nice).

Given the wildly protuberant high dome Hardlex crystals fitted to the two examples described here, it is difficult to really swallow shallow depth as a compelling feature of these watches.  I think the safest strategy is not to concern ourselves with the marketing puff and brand engineering but instead focus on the simple fact that these watches are really rather lovely.

Let’s turn our attention to the second of our two 8346-9000 examples, this one a Seiko Business-A made in February 1967.

The horseshoe case back design of this example, produced just four months after the other watch, looks distinctly modern by comparison, if somewhat less charming.  The view from the front really does emphasise the importance of the crystal to the impact that this watch makes as a design statement.

Face on, the watch makes a good impression, with not a great deal to complain about other than an evidently stained date wheel and the fact that a clumsy watchsmith has at some point in the past gouged the dial.

The hint of a tint glimpsed through the day/date aperture turns out to be way beyond gentle patina.

The culprit appears to be the plastic dial spacer, stuck to the rear of the dial with lashings of watch oil.

The date code stamped on the dial is one month later than that suggested by the case back serial number and so once again, temporally consistent.

Another testament to the skill set of the previous watchsmith is the presence of the dial washer on top of the hour wheel but beneath the day disk.  The washer is supposed to sit on top of the day disk with the rear of the dial exerting a gentle pressure on the washer which in turn keeps the day disk and hour wheel from lifting.

In spite of these grumbles, the movement actually looks pretty tidy, if very dirty.

In fact, looking at the Diashock and Diafix settings, I am starting to wonder if the previous ‘service’ was much more than a squirt of WD40 under the hood.  The Diafix spring looks immaculate suggesting that the cap jewel beneath has not been removed since the watch rolled off the production line.  Before moving onto the cleaning phase, I pause to observe that the balance hairspring has a distinct asymmetry to its coils.  I will need either to try to correct this later or source a replacement from one of my parts watches.

Other than concerns about the balance, the rest of the movement looks fine, just in need of a proper clean, and so with the parts percolating in ammoniated cleaning solution, let’s turn our attention to the case.

In common with the familiar design used in the 6105 and 6306/9 divers watches, the Hardlex crystal is pressed into place by the external bezel and so its removal is achieved simply by levering the bezel away from the mid-case and then pushing the crystal out from inside.

As we saw from the other watch, rather than the L-profile rubber gasket used in the diver’s watches that share this crystal, in this watch the base of the crystal sits against a flat rubber gasket sitting in a channel between the removable chapter ring and an inner machined edge of the case whilst the edge of the crystal is sealed by a separate o-ring gasket.  The gaskets in this watch still retain some suppleness but they are some way from being soft and so I think I’ll see if I can find suitable fresh substitutes when I reassemble the case.

It might be of interest to take a proper look at the profile of what is undoubtedly the highest profile variation of the 320W10GN crystal.

We can see that the impressive height of the crystal is enhanced by the pronounced curvature of the inner dome with the outer radii truncated by the completely flat upper surface.  Later variants would adopt a gentle curve to the exterior too and so while these crystals are routinely referred to as double-domed, it is clear from this photo that the original version used just a single inner dome.

The case cleaned up easily enough but I have to confront the issue of the crystal gasket(s) because the originals are no longer available.  I have two choices:  one is to source as close a match as I can to the original pairing of a flat plus o-ring gasket and the other is to try a crystal gasket from a 6105/6309 diver’s watch.  A trial fit of an EC3160B worked but I was able to see the gasket through the crystal when fitted which suggested that it was just a little bit too bulky to sit inconspicuously beneath the crystal.  And so I opted to stick to a pair of generic gaskets in the spirit of maintaining a degree more of the original approach and to minimise the view of the gasket surface through the crystal.

The ring on the right-hand side in the photo above is the chapter ring and that goes in first, followed by the flat gasket, the o-ring and finally the crystal (not shown).  The whole lot is then held in place by the bezel, pictured to the left in the photo above.

The crystal I chose for this case is a high-dome sapphire last seen I think in an article I wrote a while back on Seiko 6105 watch crystals.  It stands nearly as proud as the Type I mineral glass fitted to the other 8346 but this crystal features a gentle outer dome rather than a flat top.

Reassembly of the movement proceeded smoothly, aided by the muscle memory of having so recently completed the same task with the other watch.

Those grotty calendar wheels did not respond to my attempts to clean them up and so I sourced a replacement date ring from Cousins and a day disk from one of my spares 8306’s.

You’ll notice that I’ve chosen to refit the dial washer above the day disk rather than below!  Satisfied that the calendar operates correctly with no slippage from clutch or setting wheels, I am ready to refit the dial and hands.

With the movement fitted to the mid-case and a full wind of power under its belt, it is achieving pretty much identical figures to the other watch:  270 degrees amplitude on a full wind, dropping to about 250 degrees after a few hours.  I’d not mentioned this earlier, but I’ve fitted a new GR2378X mainspring rather than reusing the original.

A fresh caseback gasket fitted, close her up and we are pretty much there.

Where I chose to fit a leather strap to the other watch, I felt this one deserved a bracelet.  I don’t have an original bracelet in the correct style but I do have one harvested from my Seikomatic-P, documented here some time ago which also uses 19mm endlinks.  I’d not used it with that project because it was just a little too tight on my wrist but I’ve since sourced an additional link and it is now long enough to fit comfortably.

Before I’d worked through all of the possible permutations of crystal and strap choice for these two watches, I was struggling a little to connect with either, the black-dialed version in particular.  However, I am now completely won over.  I think the silver-dialed watch suits my taste better and on this bracelet it hits the bullseye.  I really like it a lot.  Although I still don’t quite like the Seikomatic-R version as much, I am really pleased to have worked on this pair together for the contrasts that they have provided, not just in how they look but in how their different outward appearances suit the branding that Seiko chose to bestow upon them.

The standard blackjack player’s gambit when presented with a pair of eights is to split them to minimise the odds of a bust.  That remains an option here but for the moment, I’ll continue to ride my luck and play for 21.  Twist please dealer.