This very early Seiko 6138-0010 “UFO” came in recently for some attention. The owner had bought it in 1971 when he was working as a race mechanic for the Tyrell formula one team when they were in Japan that season. He saw it on the wrist of a Japanese mechanic working for one of the other teams and fell in love with it so a deal was struck. It was worn continuously throughout his career and he eventually ended up running his own engineering firm that produced parts for race teams. The watch was regularly serviced until a number of years ago when he was told it wasn’t possible to get the parts anymore. He took it to a couple of watchmakers in the intervening years to try and get it resurrected but ultimately all that happened was it was returned not working with some parts missing! Having sold his company and taking life a little easier his thoughts came back to getting the watch repaired and this is where I come in.

The watch itself is a Japanese domestic market version of a model that has since been given the nickname “UFO”, the 0010 designation shows it was the Japanese “Speedtimer Sports” version. An early example like this is powered by the calibre 6138a, a hand windable automatic, 21 jewels, 21,600bph, twin register, column wheel with vertical clutch chronograph movement. The later models were powered by the calibre 6138b movement and there are a few subtle differences that I’ll point out later in the article.

On the caseback the production date of June 1970 can be seen.

With the caseback removed the movement can be seen….

….and with the oscillating weight removed you can see the column wheel at the top of the shot with the autowind bridge below it and the balance bridge below that. Incidentally the pushers fitted are incorrect for this model, I wonder where the originals dissapeared to? It does make you wonder!

Also the minute registers hand is incorrect, it should be a tapered black one.

With the dial removed you can see the kanji day wheel, a feature of all Seiko JDM models. I’ve covered the strip down of these previously so I’ll just comment where needed 🙂

Because it’s an early model the date driving wheel is metal not plastic, as is the intermediate date driving wheel. The date change finger is still plastic though.

Here you can see the hour register recording wheel driven directly from the barrel arbor.

With the movement turned over one of the differences between this and the 6139b is visible. The a movement has the intermediate minute driving wheel permanently fixed to the underside of the centre wheel bridge instead of being a separate wheel.

And in this shot the reset hammer pivot isn’t eccentrically adjustable as they are on the b movements. The hammer return spring is also shaped differently on these earlier movements. One of the missing parts was the second coupling lever return spring.

The third and fourth wheel top bearing and jewel aren’t covered over on the a, on the b there’s a cover which incorporates the intermediate minute recording wheels bottom bearing.

Soon it was stripped ready for cleaning and inspection.

Whilst the cleaning was taking place a set of correct pushers were substituted for the ones that were fitted, you can see they are longer and have decorative grooves machined in the end.

The pusher o-rings are an important part to renew on these chronographs, it’s the usual entry point for moisture as the original o-rings are normally as hard as iron by the time they reach me.

During inspection the hairspring was found to be roached, it’s more cost effective for the customer for me to swap it for a good assembly as opposed to reworking it.

The missing second coupling lever spring was replaced.

The intermediate upper crown wheel had also been lost so this was also replaced.

Finally the centre wheels vertical clutch was useless, you can see part of the pressure spring poking out from the wheel on the left. As these aren’t serviceable it was replaced.

The clean shiny bits assembled for rebuilding….

….starting with the mainspring.

At this stage the movement has to be turned over to get the bottom barrel arbor jewel in place.

This means rebuilding the keyless work, the motion work and the hour recording wheels and levers.

Once this plate is on it can be turned over and the chronograph levers and reset mechanism can be assembled.

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The rough timing and beat adjustments are done at this stage.

The complete handset was replaced (with genuine Seiko ones) as the old ones were tired and incorrect.

The movement recased….

….the autowind mechanism and oscillating weight refitted….

….the caseback on and it’s done! A beatiful sympathetic restoration of a very early ( and very hard to find) JDM UFO. I love it and more importantly the owner was over the moon, he thought he’d never see it running again!

Another nice touch was that it still had its original “Sports” bracelet, albeit a bit tight on the owners wrist now (funny how things shrink as we get older 🙂 ).

I didn’t have any original JDM links but a Pogue bracelet has very similar links so I tightened all the coupling links back up and installed one of those so the watch fitted his wrist comfortably again.

Another bonus for me was the owner turned up to collect the watch driving his freshly restored 1967 powder blue Lotus Elan, believe me when I say it was absolutely gorgeous!