Seiko Caliber 6L35

Manufacturer	Seiko
Caliber Number	6L35, 6L35A
Movement Type	Automatic, self-winding mechanical
In-House?	Yes
Diameter	25.6mm
Height	3.7mm
Jewels	26
Beat Rate	28,800 vph, 4 Hz
Beats Per Second	8
Lift Angle	Unconfirmed
Power Reserve	45 hours
Magnetic Resistance	4,800 A/m
Rotor Style	Ball-bearing
Rotor Winding Direction	Bi-directional (Magic Lever)
Hand-Windable?	Yes
Manual-Wind Direction	Clockwise
Anti-Shock Device	Diashock
Regulator	ETACHRON with fine tuning device
Hand Count	3
Functions	Central hours; central minutes; central sweeping seconds; date at 3:00
Hacking Seconds?	Yes
Country of Manufacture	Japan
Service Intervals	2-3 years
Known Models	Seiko Presage 2018 Limited Edition (Ref: SJE073), King Seiko KSK Reissue (Ref: SJE089, SJE091) (Add your watch to the comments below…)

The Seiko caliber 6L35 is an automatic 3-hander watch movement with a date complication. The 6L35 is part of the 6L family of slimline movements with a thickness profile of about 3.7mm thin. This movement was introduced at Baselworld 2018.

In Seiko’s own words:

“Caliber 6L35 is completely new and distinguishes itself from the trusted and much admired 6R15 caliber by its slimness and its accuracy. At 3.7mm deep, it is 1.3mm thinner than 6R, and it is accurate to within +15 to -10 seconds per day. To emphasize the slimness of the caliber, the new limited edition has a new case structure that gives the watch a slim and graceful profile. Together, the movement and the case are a mere 9.8mm in depth.” –Source

6L35 vs 6L35A:

6L35 is the number of the caliber, with the trailing letter designating the version or evolution of the movement. You may see the movement referenced as 6L35 but upon opening your watch, the rotor may say 6L35A. Don’t be alarmed, 6L35 and 6L35A are the same thing since A is the first version. At this time, there is only a 6L35A and not 6L35B, 6L35C, etc.

Accuracy:

Seiko claims that the cal. 6L35 is factory adjusted for an average accuracy in the range of -10 to +15 seconds per day, when worn in normal conditions and temperatures between 5 to 35 degrees C (about 41 – 95 F).

A note from Seiko on accuracy expectations:

“Due to the characteristics of mechanical watches, any actual daily rate may not fall within the range of time accuracy specified above dependent on the conditions of use, such as the length of time during which the watch is worn on the wrist, temperature, arm movement, and whether the mainspring is wound up fully or not, etc.” -6L35 Instruction Manual, last page, fine print

Recommended Service Intervals:

Seiko officially recommends for 6L35 powered watches to be overhauled every 2-3 years.

“Periodic inspection and adjustment by disassembly and cleaning (overhaul) is recommended approximately once every 2 to 3 years in order to maintain optimal performance of the watch for a long time.” -6L35 Instruction Manual, Inspection and adjustment by disassembly and cleaning (Overhaul), page 30

Replacement Prices:

At the time of this post, the calibre 6L35 is not sold individually, so the only way to get one is to buy the whole watch. Also at this time, there is not a non-Seiko branded version of this movement (such as from Seiko’s other divisions, TMI, etc).

TL;DR / FAQs:

Is there an SII/TMI version for microbrands?
No.

Is it manual winding and hacking?
Yes.

Can the mechanism be over-wound?
No.

When should I not set the date?
Do not change the date when the hands are between 8PM-2AM.

How many turns of the crown for the mainspring to be fully wound?
This is still unconfirmed, although Seiko does recommend winding the crown (slowing) for 20 turns when starting the watch from a stopped state.

Additional Resources:

• Official 6L35 instruction manual (pdf)
• List of Seiko movements