# 4R36 vs 6R15 is there any significant difference on performance?



## cyndog (Feb 21, 2013)

Hi guys,

4R36 can hack and wind, so does 6R15.

And I heard that it's part is interchangeable.

Currently, I'm using 4R36 on my FFF mod,

And I'm thinking about swapping movement to 6R15, because it has more better quality,

Does it worth it?


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## Pawl_Buster (Mar 12, 2007)

The quality and finish are the same. Some parts are interchangeable. The whole movement can be swapped with the appropriate changes made to the crown and stem.

The big difference is that the 6r15 has a different balance spring which may contribute to better precision in time keeping.

I don't think it's worth swapping them unless you are looking for a little more consistency in time keeping.


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## Alpinist (Nov 3, 2010)

The 6R15 has a different mainspring, barrel and adjustment lever. 

this means -15/+25 accuracy and a 55h power reserve on the 6R15 compared to the -35/+45 and 40h power reserve on the 4R36, both can be tuned to cosc specs, but the question is how long do they stay there...


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## Pawl_Buster (Mar 12, 2007)

Alpinist said:


> The 6R15 has a different mainspring, barrel and adjustment lever.
> 
> this means -15/+25 accuracy and a 55h power reserve on the 6R15 compared to the -35/+45 and 40h power reserve on the 4R36, both can be tuned to cosc specs, but the question is how long do they stay there...


I highly doubt that either could be regulated to achieve COSC specs...that's five positions and temperature. The 6r15 maybe but the 4r36 definitely no more so than the 7s26 it really is.


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## sirgilbert357 (Mar 21, 2012)

Pawl_Buster said:


> I highly doubt that either could be regulated to achieve COSC specs...that's five positions and temperature. The 6r15 maybe but the 4r36 definitely no more so than the 7s26 it really is.


Agreed. It could be regulated to run fairly accurately on the wrist (say within 5 sec per day), but to pass all the COSC spec testing...not gonna happen.


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## yoshiki (Jan 1, 2009)

Alpinist said:


> The 6R15 has a different mainspring, barrel and adjustment lever.
> 
> this means -15/+25 accuracy and a 55h power reserve on the 6R15 compared to the -35/+45 and 40h power reserve on the 4R36, both can be tuned to cosc specs, but the question is how long do they stay there...


thanks for the information. I was templating between the newer dress watches with 4R movement or the older ones with 6R, but the 6R ones do not have 'open heart' designs. decisions decisions..


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## Topher1556 (Aug 22, 2007)

yoshiki said:


> thanks for the information. I was templating between the newer dress watches with 4R movement or the older ones with 6R, but the 6R ones do not have 'open heart' designs. decisions decisions..


They don't have 'open heart' looks because really...the movements aren't that pretty to look at. Both movements are workhorses designed to be somewhat accurate along with being durable and easily cleaned/repaired.


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## xzqt (Jan 26, 2013)

Just checking Pawl, thought both the 4R and 6R share the same stem ?


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## yoshiki (Jan 1, 2009)

Topher1556 said:


> They don't have 'open heart' looks because really...the movements aren't that pretty to look at. Both movements are workhorses designed to be somewhat accurate along with being durable and easily cleaned/repaired.


I do recall that there are seiko dress watches using the new 4r movements with openheart design..


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## ec633 (Jan 6, 2012)

Pawl_Buster said:


> I highly doubt that either could be regulated to achieve COSC specs...that's five positions and temperature. The 6r15 maybe but the 4r36 definitely no more so than the 7s26 it really is.


I thought the 6r15 is identical to 7S26 except that the former is the modified version of 7S26 with hack function.


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## Alpinist (Nov 3, 2010)

btw... how hard was it to fit a 4R36 in to the 7S36 case ?


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## cyndog (Feb 21, 2013)

My local watchmaker did it, 

said it has little difference in stem, but no problem at all.


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## Alpinist (Nov 3, 2010)

damn, wish i had a watchmaker like yours, had to buy the 4R36 yourself or he had them ?


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## Pawl_Buster (Mar 12, 2007)

xzqt said:


> Just checking Pawl, thought both the 4R and 6R share the same stem ?


Yes; they are the same part number.


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## xzqt (Jan 26, 2013)

Pawl_Buster said:


> Yes; they are the same part number.


Thanks Pawl !


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## xzqt (Jan 26, 2013)

cyndog said:


> My local watchmaker did it,
> 
> said it has little difference in stem, but no problem at all.


If you are referring to the 7S26 and 4R36 stem being the same.... the answer is NO..
I know because i have one sitting in the container waiting for a stem.


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## MandoBear (Apr 7, 2010)

yoshiki said:


> I do recall that there are seiko dress watches using the new 4r movements with openheart design..


That might be this one...
https://www.watchuseek.com/f21/new-...er-open-heart-automatic-pic-heavy-702809.html

Incidentally, the movement plate around the open heart is finished a bit better, it's angled and polished on the dial side.


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## DaBaeker (Jan 29, 2008)

Pawl_Buster said:


> I highly doubt that either could be regulated to achieve COSC specs...that's five positions and temperature. The 6r15 maybe but the 4r36 definitely no more so than the 7s26 it really is.


 i realize that my case may be unusual but my sumo/6r15 has been running within cosc specs since it was delivered new '12. it runs consistently +4sec which is admittedly near the limit but doesn't really surprise me as my experience with seiko has always been better then expectations. (i have another '72' panda chronograph that runs consistently at +2-4 and it hasn't been serviced in 9yrs.) other seiko's I have mostly run at the normal -40-+40 range with the monster, skx and other asst. vintage. unfortunately-i haven't been able to justify buying a GrandSeiko or vintage KS hi-beat or a rare Seiko vintage with 'chronograph' marked dial)


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## FongSayYuk (Jan 23, 2015)

I am wearing the SSA213j2 and have it only for 3 weeks... first it was running at +/- 25 seconds a day, but it has slowly gone to +16 seconds a day. I anticipate that it will go down gradually and hopefully. haha as it is my first watch I was at first bothered by it, but then agan.. when looking at the watch..

simply beauty


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## New_World (Nov 5, 2012)

FongSayYuk said:


> I am wearing the SSA213j2 and have it only for 3 weeks... first it was running at +/- 25 seconds a day, but it has slowly gone to +16 seconds a day. I anticipate that it will go down gradually and hopefully. haha as it is my first watch I was at first bothered by it, but then agan.. when looking at the watch..
> 
> simply beauty
> 
> View attachment 2854138


nice watch............beautiful actually but I'm a sucker for seikos. =)


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## firithmorgulion (Apr 12, 2011)

ec633 said:


> I thought the 6r15 is identical to 7S26 except that the former is the modified version of 7S26 with hack function.


that what ive found for those movements:



> Mid 1996 - 7S26A introduced
> Late 2005 - 6R15A introduced, based on the 7S with Etachron regulator and Spron 510 mainspring
> Late 2006 - 7S26B introduced with Etachron regulator
> Late 2006 - 6R15B introduced - new parts:
> ...


from here: Seiko 4R36 -The Family In Brief - Watch Reviews, Info and Musings


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