# Omega - Chronometer V Non-Chronometer



## aroma (Dec 11, 2009)

A question for all you Omega experts:-

I have a 1964 Constellation with a chronometer rated cal 551 and a 1964 Seamaster with a non-chronometer cal 552. OK, I know that the 551 was tuned before being sent to the Laboratory for testing and that the chronometer rating was only valid then (i.e. 1964). BUT what is the physical difference between the two movements - does the 551 use better components than the 552 or is it just down to the tuning?

Thanks in advance


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## William_Wilson (May 21, 2007)

I don't know the physical differences between those movements. However, the 552, if properly serviced, will maintain chronometer specs during day in day out knock around wear. My SM300 does with out a problem. 

Later,

William


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## harryblakes7 (Oct 1, 2010)

Just to add to William's comments the 552 is just marked 24 jewels on the back, whereas the 551 is marked "Adjusted to 5 positions & Temperature" This is presumably to show it has been adjusted by a watch repairer.

This could have taken him a day or more, as every wheel would have been re-checked, meshing etc. Pallet interaction would have been double checked to see if it could be improved and balance checked and adjusted for true by removing metal or poising the arms etc

Also they changed the balance hairspring on the 551 to a Nivarox according to Omega to help achieve temperature compensation, It was made from an iron, nickel, beryllium, titanium and silicon alloy. Other gears and wheels were inspected and tested to a much higher tolerance than the standard movement, anything less than the strictest criteria and they would change the wheel for another. The escape wheel was also tweaked and polished to achieve the best locking angles and impulse.

It's a bit like the BMW E36 M3 GT2............ The same as a standard M3, but the GT2 had hand selected compoenents for the gearbox and engine, selected using finer tolerances, and everything put together with more TLC than usual, the result? A more finely honed car, similar performance, but a lot sweeter to drive


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## dickstar1977 (Feb 4, 2008)

harryblakes7 said:


> Just to add to William's comments the 552 is just marked 24 jewels on the back, whereas the 551 is marked "Adjusted to 5 positions & Temperature" This is presumably to show it has been adjusted by a watch repairer.
> 
> This could have taken him a day or more, as every wheel would have been re-checked, meshing etc. Pallet interaction would have been double checked to see if it could be improved and balance checked and adjusted for true by removing metal or poising the arms etc
> 
> ...


This is a good comparison! TBH most vintage chronometer, particuarly the Omega 500 family are night on indistinguishable in terms of time keeping to their chronometer brethren! If they are well serviced and regulated properly then cal 501/550 etc will easily run within chronometer specifications

Interestingly the Omega Speedmaster 125, hailed as the first automatic chronograph chronometer only shared one physical difference to the standard 1040 movement, it had 1041 stamped on the main-plate! There are no different components on a 1041, they were (at the time) simply set up slightly better to achieve chronometer status!

Tom


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## flame (Apr 2, 2009)

dickstar1977 said:


> Interestingly the Omega Speedmaster 125, hailed as the first automatic chronograph chronometer only shared one physical difference to the standard 1040 movement, it had 1041 stamped on the main-plate! There are no different components on a 1041, they were (at the time) simply set up slightly better to achieve chronometer status!
> 
> Tom


Hi Tom

I had completely forgotten this point that you had previously enlightened me to....amazing (& a bit cheeky by Omega) !

Thanks Neil


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## andyclient (Aug 1, 2009)

Was there much difference in the retail cost at the time between the 551 chronometer and the 552 non chronometer watch ? I realise the Constellation was more expensive than the Seamaster but was this down to the model or the movement or perhaps both ?

Cheers

Andy


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## William_Wilson (May 21, 2007)

dickstar1977 said:


> Interestingly the Omega Speedmaster 125, hailed as the first automatic chronograph chronometer only shared one physical difference to the standard 1040 movement, it had 1041 stamped on the main-plate! There are no different components on a 1041, they were (at the time) simply set up slightly better to achieve chronometer status!
> 
> Tom


Yes, my Seamaster cal.1040 has no problems operating within COSC specs. 

Later,

William


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## dickstar1977 (Feb 4, 2008)

William_Wilson said:


> dickstar1977 said:
> 
> 
> > Interestingly the Omega Speedmaster 125, hailed as the first automatic chronograph chronometer only shared one physical difference to the standard 1040 movement, it had 1041 stamped on the main-plate! There are no different components on a 1041, they were (at the time) simply set up slightly better to achieve chronometer status!
> ...


It was one of those naughty little stunts Omega pulled in the 1970's, much like the misconception that there is any real difference between an Omega Marine Chronometer and a standard Megaquartz F2.4 Mhz, the only difference being that one has a grey circuit cover the other has a white! Proof in that the spare parts list for both watches is one in the same!

The only difference in the parts list between 1040 and 1041 cal's is the main plate, which is as I said identical with the exception of the number stamping


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## dickstar1977 (Feb 4, 2008)

William_Wilson said:


> dickstar1977 said:
> 
> 
> > Interestingly the Omega Speedmaster 125, hailed as the first automatic chronograph chronometer only shared one physical difference to the standard 1040 movement, it had 1041 stamped on the main-plate! There are no different components on a 1041, they were (at the time) simply set up slightly better to achieve chronometer status!
> ...


It was one of those naughty little stunts Omega pulled in the 1970's, much like the misconception that there is any real difference between an Omega Marine Chronometer and a standard Megaquartz F2.4 Mhz, the only difference being that one has a grey circuit cover the other has a white! Proof in that the spare parts list for both watches is one in the same!

The only difference in the parts list between 1040 and 1041 cal's is the main plate, which is as I said identical with the exception of the number stamping


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## flame (Apr 2, 2009)

Thanks again Tom !

All the best - Neil


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