The ETA caliber 2892A2 is a thin 21 jewels Swiss made automatic watch movement with a frequency of 28,800bph. It is often considered to be the top of the line with regards to offerings from ETA.
Updated tech sheets for this caliber were found dated as recently as August 2016. Although official documentation indicates that this movement was in production as far back as 2004, it was actually introduced around 2000 when it replaced the 2892-2.
Some of the topics covered in this caliber listing:
You may see this caliber written as 2892-A2 or 2892/A2, but the official designation from ETA is 2892A2. Although Caliber Corner uses all 3 spelling variations for SEO purposes, I wanted to clarify that not only does the official documentation spell it as 2892A2, but on actual movements the number is also engraved without a space, hyphen or slash.
Typically, ETA adds a “-2” to an evolution caliber, but they had already evolved the 2892 to the 2892-2. Most of us could agree that the common sense thing to do would be to write the next evolution as 2892-3, but ETA opted for an A2 instead – sometimes causing caliber confusion. Just keep in mind that while most parts are interchangeable between the 2892/2892-2/2892A2, they are still different movements with different parts lists.
2892 VS 2892-2 VS 2892A:
The 2892-A2 is based the 2892-2 which is based on the original ETA caliber 2892. The calibre 2892 was a larger 28mm diameter movement with a beat rate of 18,000 bph – the smaller and more modern 25.6mm diameter caliber 2892-2 (and 2892A2) has a higher frequency of 28,800bph. To compensate for the increased rate, an improved mainspring and automatic winding system was needed on the 2892-2 (and 2892A2). Also, because of the reduction in overall diameter while retaining the same 3.6mm height, the rotor was also smaller with less mass – causing issues with automatic winding efficiency.
Here is an excerpt from The Little Engine that Could – An indepth look at the ETA 2892, explaining the evolution from 2892-2 to 2892A2 and how they compensated for the issues caused by shrinking the diameter:
“For the more technically minded, the final modifications to the automatic winding was to reduce the chamfer around the circumference of the oscillating weight – thereby increasing its mass. And to switch the stud and the jewel which supported the intermediate reduction wheel. This wheel, which drives the ratchet driving wheel, originally had a stud, but now has a jewel. The stud has now replaced the jewel in the upper part of the automatic winding bridge. This resulted in less winding friction due to this wheels much greater stability. Omega (and Girard Perregaux) have increased the winding efficiency further by reducing the diameter of the ball bearing support.” -Source: http://www.chronometrie.com/eta2892/eta2892.html
Off topic, but worth sharing, the aforementioned article goes on to say this about the 2892A2:
“So what exactly is it that makes this movement so special? Or to rephrase the question, how come this movement is so accurate and reliable? Beats me if I know!! To be perfectly honest, I think that it is just a great design with compromises that have been intelligently chosen and superbly executed in its best incarnation. It incorporates all the latest knowledge and advances in both materials and movement design. Its generous supply of available torque means that it will not be easily stopped, even when powering extra complications.”
ETA 2893A2 VS Sellita SW300-1:
The Sellita caliber SW300-1 is considered to be a clone of the 2893A2. Since the 2892A2 isn’t available anymore, the SW300-1 has taken its place. For that reason, you will find more SW300-1 in new non-Swatch Group watches.
As the Sw300-1 is based on the 2892A2, most of the base specs are exactly the same: diameter, height, lift angle, beat rate, rotor style, etc. However, there are some notable differences, including:
*The increased power reserve on some SW300-1 movements is thanks to Sellita’s “Optimization Barrel” option.
Accuracy of the ETA caliber 2892-A2 can range from as much as +/-20 seconds per day to just +/-5 seconds/day or COSC spec. The accuracy that your watch experiences depends on the grade that the watch manufacturer chose to power their watches. This could also depend on whether they regulated it beyond the factory specs.
Grades of 2892-A2:
Similar to other ETA movements, there are 3 grades of production quality.
Elaborated Grade – Adjusted to four positions / average accuracy of +/-5 sec/day to +/-20 sec/day.
Top Grade – Adjusted to five positions / average accuracy of +/-4 sec/day to +/-15 sec/day.
Chronometer (COSC) Grade – Adjusted to five positions / average accuracy of -4/+6 sec/day.
As Wikipedia puts it:
“The key components which differ at the line of demarcation between Elaborated and Top are the pallet stones, balance wheel & hairspring, and the regulator mechanism. The degree of decoration on the movement’s parts also increases with the grade.” –Source
2892A2 as a Base:
The 2892A2 is the base for a variety of ETA 289X-X configurations, including:
By now it’s old news that ETA movements are unavailable to brands outside of Swatch Group, however, there are still watch parts sellers with new old stock available. Raw movements can be found in the range of $300-500 USD, depending on the grade. The 2892-A2 always was, and continues to be, a pricey 3 hands + calendar movement, so much so that even the 2892-A2 clones from China cost between $100-$200 USD.