Omega 552 servicing notes

[jdm]

I'm always impressed just looking at these, and lucky enough to own a chronometer grade one, now finally had the chance to work on a repair, and all the positive opinions got confirmed.
The owner lamented water ingress and the watch stopping all the time. Seeing no major damage on a first inspection I undertook the work with good hopes.

Starting with the dial side the overall feeling of quality and maniacal height saving design becomes evident. The dial fits so precisely that a dial washer was not present or needed. This being a time only version I can't do any praising to the calendar works. 

As soon I lifted the hour wheel the watch started running strong in all positions with good amplitude, then I pulled the cannon pinion which was quite tight. Note to myself, MUST get a cannon pinion remover.

The black oxidation on the contact section was the root cause of the fault, but after 50 years it was time for a complete service, and I have the distinct impression that mine was the first one.
One incredible fact is that Omega still updates their technical documents about this long discontinued caliber, I can only think of the aeronautic industry doing something similar for certain "never old" airplanes and engines.

The way I did it may be called not fully professional, as I didn't do surface treatment, and used only 9010, HP-1300, and 9415 without an automatic oiler. However I'm happy with the results, and I hope that the owner will be too.
That being said I plan to upgrade on the above points in the immediate future. One tool detail that I really recommend is to use soft metal tweezers whenever possible, I have got cheap brass Indian ones which I then dressed to eliminate any sharp edge. These are OK to handle most of the screws and all the bridges and plates.

Keyless and motion works are rational, and easy to work with.

Some dirt and micro-spots corrosion, but nothing worrying.

The stem was the rustiest part, and the crumbles are all what was left of the crown gasket. It is defintely possible with some patience to open these and fit an o-ring, which luckily I had from an assortment box. Even the stem came out very decent after the due care.

Just give a tap or two to the washer to make it seat nicely again. I've even refitted the steel ring which matches well the O-ring profile.

Two screws hold the automatic bridge, and one can see that also the gib screw was removed. That allows the rotor to be removed even with the mov't in the case.

For regular service to the auto works it's enough to remove the larger bridge.

One of its screws is thinner due to more limited space. Note the use of a single reversing wheel, yet the winding in bi-directional and the overall manufacture is just amazing. I used HP-1300 on the pivots but probably that another synthetic type might have been better.

Note the space above the balance, which hosts the automatic work. At the time of its introduction this was the thinnest automatic movement with sweeps seconds and calendar, at just 4.5mm. And the Reed regulator is nothing less than amazingly beautiful.

The balance is then removed and inspected. Note the multiple tiny "drill kisses" on the rim for poising.

To save height, the train is different from the common design. Seconds pinion is driven by a pinion sitting above the the barrel bridge, and has a tension spring which controls its end-shake.

Releasing power is not easy as the space around the click is very limited, remember to use only something soft like a toothpick to do that. Only then we can remove the pallet bridge, another beautiful execution with two locating posts and screws. 

Then remove crown and ratchet wheels. We start to see the sophisticated design and the one-way automatic winding clutch. The machining of a cord on the crown wheel round holds precisely the hub of the crown wheel, with an off-center screw. Wow.

The auto winding wheel has special profile inner teeth which allows one-way power transmission from the ratchet wheel to the barrel arbor. The small pinion catches only one way to said wheel, otherwise it turns freely. That makes so that turning the crown in the opposite direction has no effect whatsoever, and also that a single reversing wheel is needed in the automatic work, because movement is transmitted only in one direction from the wheel on the arbor to the auto works.
I for one find difficult to understand what I wrote above and the principle of operation of that mechanism.

We can now remove the train bridge which only holds third, fourth and escape wheel. Al-tough, that does not make it particularly easy to fit back.

 

Finally the seconds pivot spring, pivot, barrel bridge can be removed, followed by the barrel and center wheel.

Speaking of the barrel, once opened it I found it quite dry, with the lid slightly corroded and heavily grooved.

As an experiment I hand polished this surface with a wide micro-fiber stick, and car polish compound. Grooves were gone, but it remained scratched.

I switched then to grade 20 or 30 of Chinese diamond paste until it got better.

And better with finer paste, to an acceptable smoothness

Now, I must say that I did not replace the mainspring, and not even removed it from the barrel as I don't have a winder, and wanted to avoid any distortion to it. In the end the watch performed well with plenty albeit not stellar amplitude.

The stripped main plate in its equally magnificent A and B sides.

 

Cleaning and reassembly was uneventful even if some screw are small enough to require full attention. I had some doubts about the seconds pivot being supported by jewel on the auto works when refitting hands, but in fact that worked OK. After lubricants settled the timegrapher response was completely positive,

One last note, you know you're holding a genuine vintage Omega dial when it has a fine clove  watermarking, a recess for the balance anti-shock device, and the feet are shaped for the screws to hold without damage.
 

After a long time spent hand polishing the acrylic crystal and other details the complete "Omega Geneve" watch came out stunning, sorry I didn't take a picture

Hope you have enjoyed this article.

Edited August 15, 2020 by jdm

[watchweasol]

Nice one jdm  a quality piece a quality job.

[JohnC]

So glad you posted this, as I am in the process of servicing one of these for a friend now. It’s a truly beautiful movement. I am still trying to understand how the bi-directional winding works. Perhaps it will be clearer on reassembly! If you could post a link to service docs, that would be great. Cheers. 

[Tudor]

I know Rolex gets all the glory, but I’ve known for a long time that Omega has been eating their lunch for decades. 
 

Rolex is a tractor to Omega’s formula one car  (though they are easy to work on)

Early Swatch Group offerings were far below this movement’s standard, but the Omega DNA slowly crept into ETA and they are doing amazing things now. 
 

I always love that warm rose gold glow when you open an older Omega. 

[Flubber]

On 8/15/2020 at 9:13 PM, jdm said:

One incredible fact is that Omega still updates their technical documents about this long discontinued caliber,

 

On 9/24/2020 at 5:38 AM, JohnC said:

If you could post a link to service docs, that would be great.

Thank you for the walkthru. It will help me too. It is an amazingly beautiful movement. I was fortunate to have a colleague entrust me with one for service. You can really see and feel the quality and thought that has gone into making this movement. 

I, like John I think, would be really grateful if you could post servicethe service docs should you have them.

Thanks.

[Knebo]

Amazing. 

I'm about to service one of these beauties as well and your post is very helpful. 

Thank you for taking the time to write it all down. 

PS: @jdm, you mentioned some doubts about using HP1300 on the automatic works pivots. I'd do the same. Or any new thoughts on this by you or anyone? Cheers 

Edited July 4, 2023 by Knebo

[jdm]

On 7/4/2023 at 8:48 AM, Knebo said:

PS: @jdm, you mentioned some doubts about using HP1300 on the automatic works pivots. I'd do the same. Or any new thoughts on this by you or anyone?

Yes, that almost three years have gone and the watch has not been returned for work. That means, if it's being worn, whatever not hyper-specialized oil is in there it's behaving well enough. And if it's not, said oil is slowly drying up like any other (synthetic) one and won't make a difference when somebody will want to use it again.

Edited July 8, 2023 by jdm