Revision of a vintage Cartier Tank Onyx mechanical watch
Joshua GrilletThe world of dress watches has always been dominated by one major brand, and I am, of course, referring to Cartier.
Today, we are going to talk about a watch that I am particularly fond of, the Must de Cartier Tank watch with its onyx lacquered dial.

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The Must variation of the Cartier Tank was launched in 1977 to win over American customers and open up the Asian market. This model echoes the shape of the Tank L.C., featuring its sapphire cabochon crown.

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The first versions were mechanical and were replaced in 1980 by quartz versions. But let's take a closer look at the mechanical part in detail.
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I receive this watch in very good cosmetic condition, but the movement is stuck.
First step: remove the movement. The case is sealed with four screws on its sides. After removing the dial and hands, we are left with an ETA 2512-1 movement.

After complete disassembly, it can be seen that rust has affected two parts of the mechanism:
- A pivot on the intermediate wheel

- The entire barrel

After cleaning the parts, we find an intermediate wheel in good condition.

The barrel and its cover have been cleaned of rust. The barrel spring has been replaced with a new one.

Now that all the parts are in good condition, the caliber can be reassembled and oiled.






The movement is ready to be assembled. This ETA 2512-1 caliber measures 17.2 mm in diameter (7 3/4''). Here is an image that clearly illustrates its size:

The date of the overhaul is marked on the case back. The hands had a few stains and are now clean. The dial and crystal have a few minor marks.
Let's move on to the case.



This Tank has been damaged by moisture. There are two possible scenarios:
- The watch was simply exposed to water. Its design does not make it a water-resistant model.
- The barrel assembly suggests that an unscrupulous watchmaker “serviced” this watch without completely disassembling the movement. Liquid entered the barrel and was not dried because it was closed, causing all this damage.
To avoid the second scenario, it is essential to take your watch to a trusted watchmaker.
Today, our Tank is in great shape and letting us know it.



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To learn more about the history of the Cartier Tank, from 1917 to today, I recommend Franco Cologni's book “Cartier - la montre Tank,” which is a gem.
The first edition of the book was recommended to me by Roni Madhvani (@roni_m_29 on Instagram), a major collector of vintage dress watches and unusual timepieces, as he believes it is the most comprehensive work on vintage watches.

Some collectors dislike the Tank because they think it is too small or too feminine. I can only respond to them with this photograph, which shows the famous boxer Muhammad Ali on the right wearing a Louis Tank watch.

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This article is part of an ongoing exploration of vintage watches.
I offer independent analysis and private inspections for collectors.
Have a great time on the website!
Joshua Grillet