The Seiko 6139 and 6138 series - the all-original and fully serviced 1975 Seiko 6138-0030 Japanese Domestic Market "Kakume" SpeedTimer here counts itself among the latter - were the first fully integrated automatic chronograph in the world featuring column wheel and vertical coupling mechanism. A unique feature of these sporty 6138-0030’s were square hour and minute subdials, hence its nickname “kakume,” Japanese for “square eyes.” Unusual for the time, this 6138 is rather beefy in size, measuring in at 43mm in width.
With the 6138 movement, Seiko - as usual - set the standard followed by the Swiss watch industry 20 years later. The same movement configuration was adopted by Rolex when it made its own in-house movement for the Daytona in 2000, 30 years after Seiko released its 6139 and 6138 calibres. Oddly, the 6138 was the successor of the 6139 automatic chronograph movement, and produced in parallel with it until 1979.
The 6138 was technically at least equal to its Swiss counterparts, as it featured a fully integrated chronograph vice stacked modules. There were two versions of the 6138, with the first, the 6138A, introduced in 1970 with 21 jewels. The 6138B – like the one for sale here – was introduced subsequent, and featured 23 jewels. Both had a column wheel that regulated chrono functions, and a vertical clutch mechanism for engagement. The 6138A/B was a two register chronograph, counting up to 30 minutes on one subdial and another 12 hours on the second dial. All 6138 movements feature a quick-set day/date indicator and can be handwound (unlike the 6139 model), relatively unique for Seiko chronographs of this era.
This 6138 Kakume comes with a leather strap, nylon NATO strap, Pelican travel case, and springbar tool.
1975 Seiko 6138-0030 JDM "Kakume" SpeedTimer Automatic Chronograph
DIAL: Original SpeedTimer and Suwa-signed dial, with original hour, minute, and chronograph hands; that said, it appears possible someone painted the chronograph hands a nice red before this Kakume arrived to us. Day and date function at the 3 o'clock position work correctly as designed. Patina is evident on the upper subdial
CASE: Original hefty 43mm (w/o crown, 44.5mm with) x 45.5mm stainless-steel cushion case. Matching original caseback.
CRYSTAL: Hardlex crystal, scratch-free.
BAND: This Kakume comes with a light brown leather strap and a blue nylon NATO strap, with stainless steel hardware – a comfortable and stylish strap that compliments the colors on this vintage Seiko 6138 Kakume.
MOVEMENT: Original 6128B Seiko 23-jewel automatic movement, manufactured in August 1975, which beats at 21,600 beats per hour. This watch was fully serviced in early November 2019.
CROWN: Original unsigned stainless steel crown.