I don't understand your complaints with the 8L, you would have to be far more specific. The obvious answer is the SD. I will add that the 6309 are so well-made they run 50 years with moisture issues and no servicing, just saying.

 

When I purchased my MM300 new the AD stated that the movement was equivalent to Rolex accuracy and quality. This set my expectations high. It just isn't near +2/-2 a day. More like -10/+12 depending on how it is worn. Also, the rotor on my 8L35B requires a special tool to remove in order to service it.

The finishing is rather plain and the quality is just not great. I am told I have to send it back to Japan for service at Seiko and can not service it myself. My Rolex movements are far more accurate and have much better finishing. It isn't that the 8L is a bad movement. It is just that it is in no way near a Rolex or Omega in terms of accuracy or finish. My 4R36s are more accurate than my 8L. Maybe my view would be different if I wasn't told it was "just as good as Rolex".

Is it true that the 6306 and 6309 have the same movements?

What is the SD?

 

It's hard to kill a 6139 or 6138, any of it's versions. All this in 1969-70. Vertical clutch, in house and one of the first automatic chronographs. Rolex didn't start using a vertical clutch till the late 90's. If the 6139 was a Swiss watch, it would have the equivalent cost today as any high end Rolex or Omega. Just a lot of elitism involved in Swiss watch prices.

 

I’m confused by your complaints. What is the price of your MM300, compared to a brand new Rolex or a new Omega with a coaxial movement? Your salesman may have exaggerated a bit, but so what! He’s a salesman. Is Your Seiko a certified chronometer? Is that even possible? A COSC certificate is only available for Swiss made movements. BTW, certified chronometers are guaranteed to be between -4 to plus 6 sec. per day. What does your Instruction manual say about the accuracy you can expect? If it’s less than what Seiko guarantees, send it for warranty service.

Kat


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Yeah...I expected someone to point this out. Understand that at the time I didn't have the information I have now. Hence why I am grateful for those in the know to educate me on the topic.

 

TigerUK has an MM300 that runs at something out of this world like 2 seconds or month or something unreal like that.

My 3 x 8L35s are all super solid on the timegrapher for positional variance and daily rate. They are not currently regulated to COSC but that is of little matter to me as they get worn in rotation.

My Rolex 3135 is essentially perfect on the timegrapher in all positions so surely for timekeeping that is better but again the 8L35s just were not set at the factory to positions as are the GS counterparts.

Remember, the 8L35 has MEMS technology and incredible isochronism on a par with Rolex. It is truly a top shelf movement, undecorated by design.

 

Wow, mine doesn't even come close to this. What did TigerUK do to get his to run this accurate?

 

6106 for vintage.
6R35 for modern.
both solid performers ....

 

I once had a lengthy, wonderful chat with a watchmaker in Louisville. A topic somewhat similar came up, and he made a strong case for the high-beat 4S15 movements in the mid-90s Alpinist and the like. I wish I could specifically recount why, but generally his case is that they were consistently high-performing, robust, and repairable.

 

Yes these are based on the 5200 series of King and Grand Seikos and are indeed considered one of Seiko's finest movements. 28,800 bph (8 per second) I, like you, don't really know the particulars.

Here is the back of my SAGN005:

 

I get great performance out of the 63XX movements. Probably have serviced these the most. Great workhorse, cheap, keeps great time. What more could you ask from movements that are around 35-45 years old.

 

It might just need a calibration and you'll be able to enjoy the piece. If I was in your position, I take it back and ask for this to be done. At times salesmen have been known to be too enthusiastic and use flowery language but in this case, the movement is a good pedigree and needing some microadjustment..