ETA 2892-A2 Service Walkthrough

[VWatchie]

It is my impression that ETA's calibre 2892-A2 is usually found in more expensive watches and in luxury watches where oftentimes the movement has been modified. Mechanically, I don't think the 2892-A2 is superior to ETA’s classic 2824-2. Both movements have the same diameter (11 ½´´´ Ø 25.60 mm), the same frequency (28’800 A/h), and the same date complication. The decisive difference is the thickness where the 2892-A2 is one-millimetre thinner (3.6mm). That, combined with being a reliable and well-functioning movement, has made it popular for additional complications and alterations such as moon phase, power reserve display, co-axial escapement, chronograph modules from Dubois Depraz, and so on.

The Swiss Sellita Calibre SW300-1 is, as far as I understand, an excellent clone of the 2892-A2. There is also a Chinese clone, the Seagull Calibre ST1812 (reviewed by @Markin the video “Chinese eta 2892-A2 Clone - Service and Review - Seagull ST1812”), and possibly others.

Mark has made a playlist of videos that excellently demonstrate how to service the ETA 2892-A2 movement. The playlist is named: "Omega 2500 Co-Axial Stripdown and Service (ETA 2892-A2)"

I recommend Mark’s playlist for several reasons. Among other things, he shows how to mount the barrel bridge safely and how to hold the minute train bridge with your tweezers to easily get it into place on the main plate (which I found a bit fiddly). In addition, he shows and compares the parts that are all too easy to mix up.

One thing that is not shown in Mark's service video is that the Incabloc setting (chaton and cap jewel) for the balance and the main plate have different diameters. The main plate Incabloc setting diameter is smaller than that of the balance. The reason this is not shown in the video is probably that Mark removes, cleans, and lubricates the Incabloc settings one at a time after he reassembles the balance, so he wouldn’t notice. Anyway, don't mix up the two sets!

Something that I appreciate about Mark's videos in general and that sets him apart from basically all other watch repairers on YouTube is that he doesn't continuously babble in his videos but mainly talks to make clarifications. I enjoy those segments of silence where I can just focus on the work being done.

When I started my service, I decided to follow Mark's disassembly which worked perfectly. But for the assembly, I made up my mind to follow ETA's technical documentation to the letter. It turned out to be a mistake.

In ETA's documentation, the assembly of the movement begins with the keyless works, then the train of wheels and then the barrel bridge. The crucial problem with this arrangement is that it is physically impossible to mount the barrel bridge if the train of wheels is already mounted. It is also very fiddly and difficult to baste the end of the winding stem into the winding pinion hole because the hole for the winding stem in the main plate is both open and tapered and therefore does not hold the winding stem.

Mark takes a considerably more hands-on approach. He begins the assembly with the barrel bridge. He then mounts the keyless works whose constituent parts (the winding stem, the winding pinion, and the sliding pinion) are supported by the underside of the barrel bridge, making it considerably easier to get the keyless works in place. After I revised my strategy, this service walkthrough now follows Mark’s approach.

It surprises me, but it seems like no watchmaker has proofread ETA's technical documentation. Alternatively, ETA follows an established practice and expects those using the documentation to understand that the assembly order in the document is not significant.

I am also somewhat sceptical of ETA's recommendations regarding lubrication. Where we traditionally use grease, for example in the keyless works, ETA chooses mainly oil (HP-1300). I guess that ETA treats all parts of the movement with epilame (Fixodrop) and that oil may then be a better alternative. For better or for worse, my service walkthrough follows ETA's lubrication recommendations.

As usual, I would like to remind those of you with no previous experience in watch servicing that this service walkthrough should not be seen as a tutorial on how to service a watch movement. A lot of tools, consumables, training and know-how are required to succeed. Fortunately, there are several excellent resources and watchmaking schools online.

When looking through the pictures you’ll see that a few screws and plates are either marred or have pits and grooves in them. None of this is my doing but is either the result of rust (that I removed) or the doings of a less scrupulous repairer than myself.

Finally, someone may ask, “Why to bother to do a service walkthrough with pictures when there is such an excellent video?" The main answer to the question is that I find it interesting and fun, and I see it as a complement to Mark's service video. Using this walkthrough, you can quickly scroll through the pictures to read what the different parts are called and where and in what order they should go, what the screws to be used look like, and to read ETA's lubrication recommendations.

So, I hope you’ll find this ETA 2892-A2 service walkthrough useful, now or in the future.

*** ETA Calibre 2892-A2 Disassembly ***

'

*** ETA Calibre 2892-A2 Assembly ***

 

[Neverenoughwatches]

29 minutes ago, VWatchie said:

is my impression that ETA's calibre 2892-A2 is usually found in more expensive watches and in luxury watches where oftentimes the movement has been modified. Mechanically, I don't think the 2892-A2 is superior to ETA’s classic 2824-2.

Was reading a little about the 2824 s yesterday. Available in a few grades based on the material of the balance wheel and hairspring and the number of adjustments. Maybe some other aspects that weren't mentioned. 

[VWatchie]

5 minutes ago, Neverenoughwatches said:

Was reading a little about the 2824 s yesterday. Available in a few grades based on the material of the balance wheel and hairspring and the number of adjustments. Maybe some other aspects that weren't mentioned. 

I believe this is true for the 2892-A2 as well. Yes, Googling I found this: "The ETA 2892. A2 exhibits three grades: Elaborated, Top and Chronometer".

[Neverenoughwatches]

46 minutes ago, VWatchie said:

It is my impression that ETA's calibre 2892-A2 is usually found in more expensive watches and in luxury watches where oftentimes the movement has been modified. Mechanically, I don't think the 2892-A2 is superior to ETA’s classic 2824-2. Both movements have the same diameter (11 ½´´´ Ø 25.60 mm), the same frequency (28’800 A/h), and the same date complication. The decisive difference is the thickness where the 2892-A2 is one-millimetre thinner (3.6mm). That, combined with being a reliable and well-functioning movement, has made it popular for additional complications and alterations such as moon phase, power reserve display, co-axial escapement, chronograph modules from Dubois Depraz, and so on.

The Swiss Sellita Calibre SW300-1 is, as far as I understand, an excellent clone of the 2892-A2. There is also a Chinese clone, the Seagull Calibre ST1812 (reviewed by @Markin the video “Chinese eta 2892-A2 Clone - Service and Review - Seagull ST1812”), and possibly others.

Mark has made a playlist of videos that excellently demonstrate how to service the ETA 2892-A2 movement. The playlist is named: "Omega 2500 Co-Axial Stripdown and Service (ETA 2892-A2)"

I recommend Mark’s playlist for several reasons. Among other things, he shows how to mount the barrel bridge safely and how to hold the minute train bridge with your tweezers to easily get it into place on the main plate (which I found a bit fiddly). In addition, he shows and compares the parts that are all too easy to mix up.

One thing that is not shown in Mark's service video is that the Incabloc setting (chaton and cap jewel) for the balance and the main plate have different diameters. The main plate Incabloc setting diameter is smaller than that of the balance. The reason this is not shown in the video is probably that Mark removes, cleans, and lubricates the Incabloc settings one at a time after he reassembles the balance, so he wouldn’t notice. Anyway, don't mix up the two sets!

Something that I appreciate about Mark's videos in general and that sets him apart from basically all other watch repairers on YouTube is that he doesn't continuously babble in his videos but mainly talks to make clarifications. I enjoy those segments of silence where I can just focus on the work being done.

When I started my service, I decided to follow Mark's disassembly which worked perfectly. But for the assembly, I made up my mind to follow ETA's technical documentation to the letter. It turned out to be a mistake.

In ETA's documentation, the assembly of the movement begins with the keyless works, then the train of wheels and then the barrel bridge. The crucial problem with this arrangement is that it is physically impossible to mount the barrel bridge if the train of wheels is already mounted. It is also very fiddly and difficult to baste the end of the winding stem into the winding pinion hole because the hole for the winding stem in the main plate is both open and tapered and therefore does not hold the winding stem.

Mark takes a considerably more hands-on approach. He begins the assembly with the barrel bridge. He then mounts the keyless works whose constituent parts (the winding stem, the winding pinion, and the sliding pinion) are supported by the underside of the barrel bridge, making it considerably easier to get the keyless works in place. After I revised my strategy, this service walkthrough now follows Mark’s approach.

It surprises me, but it seems like no watchmaker has proofread ETA's technical documentation. Alternatively, ETA follows an established practice and expects those using the documentation to understand that the assembly order in the document is not significant.

I am also somewhat sceptical of ETA's recommendations regarding lubrication. Where we traditionally use grease, for example in the keyless works, ETA chooses mainly oil (HP-1300). I guess that ETA treats all parts of the movement with epilame (Fixodrop) and that oil may then be a better alternative. For better or for worse, my service walkthrough follows ETA's lubrication recommendations.

As usual, I would like to remind those of you with no previous experience in watch servicing that this service walkthrough should not be seen as a tutorial on how to service a watch movement. A lot of tools, consumables, training and know-how are required to succeed. Fortunately, there are several excellent resources and watchmaking schools online.

When looking through the pictures you’ll see that a few screws and plates are either marred or have pits and grooves in them. None of this is my doing but is either the result of rust (that I removed) or the doings of a less scrupulous repairer than myself.

Finally, someone may ask, “Why to bother to do a service walkthrough with pictures when there is such an excellent video?" The main answer to the question is that I find it interesting and fun, and I see it as a complement to Mark's service video. Using this walkthrough, you can quickly scroll through the pictures to read what the different parts are called and where and in what order they should go, what the screws to be used look like, and to read ETA's lubrication recommendations.

So, I hope you’ll find this ETA 2892-A2 service walkthrough useful, now or in the future.

*** ETA Calibre 2892-A2 Disassembly ***

'

*** ETA Calibre 2892-A2 Assembly ***

 

Thanks watchie, you put such a lot of time and effort into creating these well informed walkthroughs. .  One little question though, what is this ?

[VWatchie]

3 minutes ago, Neverenoughwatches said:

Thanks watchie, you put such a lot of time and effort into creating these well informed walkthroughs. .  One little question though, what is this ?

[gbyleveldt]

Very nice @VWatchie, thank you for documenting this.

I'm in agreement with many of your points on the latest 2016 assembly sheet from ETA. First time I did one I also tried to follow it to the letter.

I agree it's just dumb to fit the train before the barrel bridge. ETA even went so far to chamfer the end of the barrel bridge that you're supposed to finagle under the previously fitted train wheel. It's retarded.

Also, using HP 1300 on the keyless works also leaves me baffled. I've serviced a lot of recent ETA movements (2005-2010) and there's heaps of oil around the keyless works (and I can confirm I've been the first in there). I understand that they want the winding action to be light and smooth but at the expense of flinging oil all over the show. And no, Epilame won't magically prevent oil from flinging off the clutch with enthusiastic winding. So I'm sticking to using grease in the keyless works.

Another little gotcha is the orientation of the intermediate reduction wheel on the automatic bridge. It's pretty easy to put it upside down and for the keyless works to lock up once the automatic bridge is fastened. And then some idiot goes and forces the winding works, breaking the ratchet wheel. Not my finest moment.

I also note that both ETA and Sellita insist on replacing reverser wheels during service (correction, if you were to wash them, you should replace them). These are still perfectly functioning parts and at 16GBP each they start adding up. So I do wash them but leave them in Lubeta V105 for a bit and re-use them. If they're physically worn then I'll replace them, but this is only an issue on older movements from the 90's that have really worked hard. What I do end up replacing frequently are the rotor bearings as these work pretty hard trying to keep a heavy rotor in place - that slight bit of 9010 you lubricate the balls with evaporates between services (we all know how thin 9010 is)

[Neverenoughwatches]

5 hours ago, VWatchie said:

Ah ok. Thanks watchie. I hadnt realised that was part of it.

[Endeavor]

Another phenomenal walk-through from you 

The clarity of the pictures, the "take-you-by-the-hand" approach & sequence, the additional descriptions (think of the amount of work involved!); everything is "second-to-none" !!!

I would say, currently the best walk-through kid in town

Excellent stuff   

A stiff competitor with Mark's video's

[Mark]

Fantastic post. Thanks for the work you put into this. 

[Kalanag]

A very well made walkthrough!

When I serviced an 25 years old ETA 2892-A2 recently I had to replace the reverser wheel and the rotor bearing. Both were shot.

[VWatchie]

21 hours ago, gbyleveldt said:

ETA even went so far to chamfer the end of the barrel bridge that you're supposed to finagle under the previously fitted train wheel.

So instead of updating the technical document, ETA decided to adjust the barrel bridge. It seems drastic, to say the least. On the other hand, it is common to start with the train of wheels on many movements, so perhaps they reasoned that it was a more long-term solution in line with what is customary. Who knows!

21 hours ago, gbyleveldt said:

And no, Epilame won't magically prevent oil from flinging off the clutch with enthusiastic winding. So I'm sticking to using grease in the keyless works.

I think it is a very wise decision that I will also follow in the future. After all, why deviate from a proven method that we know works!?

23 hours ago, gbyleveldt said:

Another little gotcha is the orientation of the intermediate reduction wheel on the automatic bridge. It's pretty easy to put it upside down and for the keyless works to lock up once the automatic bridge is fastened.

I looked through all my pictures to see if I could find a picture of the intermediate reduction wheel from the other side but couldn't find one. I'm guessing that the other side looks at least somewhat different, otherwise, I would have taken a picture of it. Anyway, good to know and be aware of!

23 hours ago, gbyleveldt said:

I also note that both ETA and Sellita insist on replacing reverser wheels during service (correction, if you were to wash them, you should replace them). These are still perfectly functioning parts and at 16GBP each they start adding up. So I do wash them but leave them in Lubeta V105 for a bit and re-use them.

So do I as explained in the assembly section of the walkthrough.

 

23 hours ago, gbyleveldt said:

What I do end up replacing frequently are the rotor bearings as these work pretty hard trying to keep a heavy rotor in place

I anticipated that I would have done that on this movement as it was in pretty rough shape. I even got the specialist tool for unlocking the bolt on the rotor that Mark demonstrates in the video "How to replace rotor bearing on an automatic watch. Valjoux 7750 + 2892-A2. Watch repair tutorials." However, the play was just fine so I didn't get any use for the tool this time.

[gbyleveldt]

20 hours ago, VWatchie said:

I looked through all my pictures to see if I could find a picture of the intermediate reduction wheel from the other side but couldn't find one. I'm guessing that the other side looks at least somewhat different, otherwise, I would have taken a picture of it. Anyway, good to know and be aware of!

@VWatchie observe the offensive little turd of a wheel. First pic is the top of it, as you have it on your pictures

And the bottom. Note that it's not flat but has a concave opening

And the area where it sits - you'll notice the raised edge where the wheel sits. You'll see the problem if you were to install it upside down like a certain someone...

Edited December 7, 2022 by gbyleveldt

[VWatchie]

6 hours ago, gbyleveldt said:

@VWatchie observe the offensive little turd of a wheel. First pic is the top of it, as you have it on your pictures

Thanks! And now that I see your pictures I remember well what the backside looked like.

6 hours ago, gbyleveldt said:

You'll see the problem if you were to install it upside down like a certain someone...

Indeed, and a truly great thing about making mistakes is that we can learn so much from them!

Edited December 7, 2022 by VWatchie

[Nucejoe]

On 12/6/2022 at 2:41 PM, Kalanag said:

When I serviced an 25 years old ETA 2892-A2 recently I had to replace the reverser wheel and the rotor bearing. Both were shot.

How do you tell if a reverser is shot ? 

Thanks in advance

[Jon]

19 hours ago, Nucejoe said:

How do you tell if a reverser is shot ? 

Thanks in advance

One way, would be to wind the watch in dial down position and see if the rotor spins, then see if the rotor spins when the watch is turned towards a vertical position. If the rotor does 'helicopter' this might indicate the reverser(s) being shot or just gunked up, so you would do the same test when clean. If I receive a watch that hasn't been serviced in over 10 years, then the rotor bearing and reverser(s) will get replaced as standard, as they can't put up with working with no lubrication. If they are not completely shot after wearing for 10 years, then they will be in the near future.

Another way would be to turn the auto module upside down and with the rotor attached, turn the ratchet driving wheel with a thin brass wire and see if the reverser(s) slip easily without much pressure being put on the driving wheel or the wire bending, indicating too much pressure is needed to make the reverser(s) slip. This emulates the movement being hand wound, thus the reverser(s) slipping.

I know the service manual says to replace the reverser wheels, but they will wash and Lubeta V105 just fine, as long as there is not too much wear.

[Kalanag]

On 12/8/2022 at 4:31 AM, Nucejoe said:

How do you tell if a reverser is shot ? 

Thanks in advance

After movement assembly using the old (cleaned) reverser the manual winding felt extremely stiff. I tried using a PTFE dry lube. Might have been a bad idea.

After installing the new reverser all was perfect.

Edited December 9, 2022 by Kalanag

[Nucejoe]

Let me try to  clarify my question. 

          Is there a test for determining the extent of reversers tiredness or loss of efficiency?         other than clean & lube and see how it winds on wrist ? 

Regds

 

 

 

 

 

 

 

 

Just now, Nucejoe said:

Let me try to  clarify my question. 

          Is there a test for determining the extent of reversers tiredness or loss of efficiency?         other than clean & lube and see how it winds on wrist ? 

Regds

 

 

 

 

 

 

 

 

Jon's tests heavily depend on the feel ,which takes time to develope. I dont know of a standard wire for the test.

[gbyleveldt]

2 hours ago, Nucejoe said:

Let me try to  clarify my question. 

          Is there a test for determining the extent of reversers tiredness or loss of efficiency?         other than clean & lube and see how it winds on wrist ? 

Jon's tests heavily depend on the feel ,which takes time to develope. I dont know of a standard wire for the test.

For me, there’s no binary yes/no answer to this. It really is a matter of feel, experience, inspection under magnification, the age of the movement and what a replacement costs vs invested effort to “revive” it that all play a role determining the answer above.

For an Omega 56x series reverser wheel you’ll spend more time trying to revive a reverser (which, by the way is also much more serviceable, but also harder and more expensive to find a replacement for) than you would an a Sellita SW200 where replacements are cheap and easy to find.

Edited December 10, 2022 by gbyleveldt