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What is Seiko caliber 4R36?

October 23, 2019

What is Seiko caliber 4R36?

After reviewing calibers 6R15, 7S26, 8L35 and 4R35, we have decided to have a deeper look at 4R35’s close cousin - 4R36 movement. In 2019, Seiko launched new Seiko 5 Sports line with 4R36 in all 27 watches in the collection, so let’s see what makes it tick.

Seiko calibers 6R15, 7S26, 8L35 and 4R35

Seiko caliber 4R36 is another automatic caliber used by Seiko Watch Corp. for their in-house watches. As its predecessor, caliber 4R35, it is a 2011 upgrade of a popular 7S36 movement as it offers the hacking and hand-winding functionality, with addition of day/date display, which is its only difference from 4R35. The caliber 4R36 has a day/date calendar upgrade displayed at 3:00, while caliber 4R35 only displays the date. Everything else is the same, including dimensions, jewels, accuracy, etc.

Manufacturer Seiko
Caliber Number 7S36, 7S36C
Movement Type Automatic
Jewels 23
Vibrations Per Hour 21,600 bph
Shock System Seiko Diashock
Power Reserve 41+ hours
Magnetic Resistance 4,800 A/m (60 gauss)
Winding Direction Not hand-windable
Hacking? No
Diameter 12”’ / 27mm
Height 4.8mm
Functions Hours, minutes, central seconds, day/date calendar
Country of Manufacture Japan/Malaysia
Known Brands Seiko 5 Sport SNZG15J1 (add more in the comments below)
Original information from calibercorner.com

Now let’s get down to the specifics.

Caliber 4R36 is an automatic movement with 24 jewels and beats at 21,600 beats per hour (6 times per second) which ensures over 40 hours of power reserve. It has a clockwise winding direction and includes Seiko Diashock anti-shock system and an ETACHRON regulator.

w_4r36-movement-recraft

The caliber 4R36 is basically a Seiko-only version of the caliber NH36. Seiko Instruments (aka SII) sells the NH36 to other watch manufacturers (so called micro-brand watches).

As its predecessor 4R35, 4R36 comes in two variants: A and B. The A version indicates the first generation so 4R36 and 4R36A are basically the same thing. Caliber 4R36B is expected second generation, yet to be released.

4R36 Accuracy

The expected fallout of caliber 4R36 is between +45 / -35 seconds per day. This estimate is based on normal daily wear of the fully wound watch in temperatures from 5 ºC to 35 ºC.

Seiko New Turtle Prospex Special Edition PADI SRPA21 200m

Seiko New Turtle Prospex Special Edition PADI SRPA21 on curved lug Endmill Bracelet

Which watches are run by 4R36?

Caliber 4R36 is mostly found in lower and middle priced Seiko pieces, as well as Seiko Prospex timepieces.

w_4r36-movement-new-turtle

When it comes to Prospex New Turtle series, there are wonderful pieces such as :

  • Seiko New Turtle Prospex Special Edition PADI SRPA21 200m
  • Seiko New Turtle Prospex SRP777K1 Diver Black. Then there are watches like
  • Seiko New Green Turtle Prospex SRPB01K1 Limited Edition 3500 pcs.
  • Seiko New Turtle Prospex SRPB11 Blue Lagoon
  • Seiko Watch Prospex Black Series Limited Edition New Turtle SRPC49K1
  • Seiko Watch Prospex Deep Blue Batman New Turtle SRPC25K1
  • Seiko New Turtle Prospex SRPC44 Diver Goldtone Case
  • Seiko Watch Prospex Save the Ocean Special Edition New Turtle SRPC91K1
  • Seiko Prospex SRPC95K1 Divers Watch Limited Edition Orange New Turtle 200m
  • Seiko Japan Edition SBDY004 Prospex Black Turtle Automatic Gold Ring
  • Seiko Prospex Gold Fin Baby Tuna Limited Edition 200M Rose Gold Watch SRPD14K1
  • Seiko Watch Prospex Black Gold Turtle Special Edition SRPD46K1.

As you can see, there are many limited edition pieces with this 4R36 caliber inside.

w_4r36-movement-baby-tuna

Regarding Baby Tuna series :

  • Seiko Prospex PADI Tuna SRPA83 Ceramic 200m Automatic
  • Seiko Baby Tuna Prospex Divers Automatic Men’s Watch SRPA82K1
  • Seiko Prospex 200m Diver Tuna Limited Edition Automatic Watch SRPA99K1

Also have a 4R36 heart.

w_mc221805b002b_seiko-recraft-srpc13-blue

Seiko Recraft SRPC13K1 Blue Cushion Case 4R36-06G0 on Solid End Massy Mesh Band

Three watches from Recraft line fit into this group:

Seiko SRPC15K1 Black Cushion Case, SRPC16K1 Gold Cushion Case and SRPC13K1 Blue Cushion Case.

w_4r36-movement-monster

Two watches from Monster series also have this caliber in their cases:

Seiko Blue Monster SRP455 Limited Edition 500 pcs and Seiko Prospex Monster SRPD27 Black Dial Dive Watch.

w_ss221805bfg033s_seiko-stargate-srp510

Seiko Stargate II SRP510 on full IP Gold Tone Endmill Bracelet

As far as we know, only one Stargate watch is run by 4R36:

Seiko Superior Limited Edition Stargate II SRP510 Gold Tone Diver.

2019 Seiko 5 Sports - 5 "S"

When it comes to new Seiko 5 Sports collection, all 27 watches (19 different models) are run by caliber 4R36.

w_ss221820b020-s5_seiko-5-sports-srpd69k1-red

Seiko 5 Sports SRPD69K1 Red Suits Style on Endmill Bracelet

Historical overview of Seiko movement releases

Just for a reference, below is a brief timeline of Seiko caliber releases, just so you can see how 4R36 fits the story.

Mid 1996 saw the introduction of caliber 7S26. It was not until late 2005 that the introduction of caliber 6R15A happened. It was based on the 7S but included ETACHRON regulator and Spron 510. In late 2006, caliber 7S26B was released, as a version with ETACHRON regulator. The same year, 6R15B was released and included new parts (barrel and train wheel bridge, centre wheel and pinion, movement barrel, ratchet wheel and its screw and oscillating weight). Around the middle of the year 2008, calibers 4R15 and 4R16 are introduced. They were based on caliber 6R15 but without manual winding and hacking options. The caliber in question today, 4R36A was introduced in mid 2011, along with other 4R3x variants (35, 36, 37, 38, 39), which included upgrades in winding and hacking terms. The end of the same year saw another two releases. The first was that of 6R15C, with addition of one jewel (upgrade from 23 to 24), new barrel, modified ratchet sliding spring and date indicator maintenance plate and new balance wheel. The second was the release of 7S26C that included changes to date mechanism and pinion heights for better hand clearances, plates and balance cock. Early 2019 was marked with the introduction of caliber 6R35.

The 4R caliber family

As far as 4R series is concerned, including now relatively common caliber 4R36, all calibers in it beat at 21,600bph. Below is the overview of their main characteristics. All calibers in 4R3x series are using traditional mainspring, instead Spron 510 found in more expensive pieces.

  • 4R15 – 22 jewels, date only, no hacking or hand-winding option, Spron 510
  • 4R16 – 22 jewels, day date, no hacking or hand-winding option, Spron 510
  • 4R35 – 24 jewels, date only (4R35 is now relying on B series – A series has 23 jewels), hand-winding and hacking options
  • 4R36 – 24 jewels, day date, hand-winding and hacking options
  • 4R37 – 24 jewels, date only, 24 h sub dial, hand-winding and hacking options
  • 4R38 – 24 jewels, no date, open heart, hand-winding and hacking options
  • 4R39 – 24 jewels, no date, open heart, 24 h sub dial, hand-winding and hacking option

Conclusion

4R36 Caliber of Seiko 5-Sports close up

Caliber 4R36 is relatively new caliber that is a ticking heart of quite a few nice watches on the lower and middle end of the price range. But the real point here is that it has everything one needs from a watch movement. In the end, it’s Seiko’s caliber, so it’s surely well made.

Written by M.H. , Photo by Toni

 

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