Miyota 8200 - The Ultimate Workhorse? (Part 1)

[TylerEOT]

Great stuff, Jun! I do like the Miyota in my Magrette. They avoided the problems with it, by leaving off the date, and the seconds hand entirely! It runs a tad fast, but it doesn't make much difference the way I wear it. The only annoyance is the winding sound is a kind of grinding rattle.
I see a lot of companies now going with the new 9015, including Magrette. Keen to try it.

[dinkerson]

Question for Jun (or anyone else in the know)...

You seem to have a great deal of knowledge of Miyota movements (great post btw). I recently acquired a Kemmner automatic that uses a Miyota 9015 movement. I love the watch, and the time-keeping is generally good compared to the published specs, but I'm noticing a couple of worrying issues:

1. The watch makes a pronounced rattling noise when you tap the case or otherwise jolt it. It's very noticeable (can be heard at arm's length), and the case or crystal doesn't need to be tapped very hard to produce the sound. I'm aware it's considered a fairly noisy movement relative to others, but this sound is different to the whirring noise of the rotor when it spins. It's a definite rattling sound caused by tapping the case. I've seen others complain of similar issues on other threads, without a clear answer. Do you know the likely cause/fix?
2. The watch started out keeping very accurate time (after 1 week the watch was +2 seconds overall). It would tend to lose 1-3 seconds on the wrist during the day, but then gain them back overnight in the face up position on the nightstand. More recently, the watch seems to be consistently losing 4-6 seconds per day. I'm not sure if (a) this could be related to the rattling; or (b) it could be the result of the movement having stopped and been restarted (I read somewhere that each time the movement stops through lack of wearing and needs to be restarted, it will keep different time). Any thoughts on this inconsistency of time keeping?

Any help much appreciated. I'm wondering if I need to get it looked at or whether I can try something myself first.

Thanks!

[JunMel]

Hi,

I am also puzzled about the rattling noise inside the watch as you've stated. The Miyota 9015 is an upgraded version of the Caliber 6105 and not in the line of the Caliber 8200 which is 'famous' for its rotor bearing's roaring sound. The Caliber 6105 is a bi-directional winding automatic while the Miyota 9015 is uni-ddirectional. The designs, as I've said are very similar except for the winding direction.

Unlike the 6105, the 9015 has a 3-screw rotor fastener which I believe is a more secure system than the 6105's. The reason for the upgrade is that the rotor of the 6105 tends to break loose and often causes malfunction. You will know it has come loose when the rattling sound comes in for sometime. IMO, this will never happen to the 9015 because of the revised fastening system. I suspect a mis-seated movement retainer screw/clip inside the case that holds the movement against the case. This screw or clip can restrain the rotor's swing or even binds it when it gets stuck under the rotor. No winding means stoppage. Have it checked.

In case the winding is sufficient and the rotor is free of any obstruction, the slowing down in daily rate is due to the settling of the lubrication on the pivots and inside the mainspring barrel. This is normal to any watch that has come out recently from servicing or has sat for quite some time in the showcase and just been recently purchased. It takes a while for the balance wheel to acheive the required amplitude and only then it can be regulated to the correct daily rate. This is the reason why most service shops retain your watch in their possession for at least two weeks to complete the 'settling period', to let the lubricants migrate and be distributed evenly in the critical points then finally regulated before it is released so that slowing/gaining does not happen when the owner is already using it. It is like breaking-in a new automotive engine.

Have the movement holder screw checked. Hope that helps

[b-a-r-t]

Hi, excellent post!

Question: can my 52-0110 Citizen diver's 8210a caliber be replaced by any brand new Miyota caliber? If so, which one is best?

Kind regards,
Bart

[Syncro16]

Thank you Jun ever so much for this post. It is most interesting !
I love my Citizen NY0040 even more now that I have seen it inside and read your knowledgable tour of this movement.
Yes your effort of writing this is timeless, it is now Aug 2016 and still a gem.
Thanks.

[tzetz]

This article is priceless. I already have 3 watches using 8203 and this tour was really interesting for me.
Just a small question.
I have a watch which runs very accurate +3-4 sec/day but when it runs out of power and stops it takes about 7-10 winds/turns/ of the crown before the second had starts moving. Is there a problem with the movement?
My other two watches start almost immediately after the beginning of the maual crown winding.
Thank you for your support and reply!

[Henry Krinkle]

How old is it? Does it run as long as the specs state? Do you know when it was last serviced? It may need a service. It may just be a bit slow to start. I have found that mechanical watches can be delightfully/annoyingly singular in their habits.