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Re: Fully restored all-Swiss watch with 24-hour dial [message #6362 is a reply to message #6355] Fri, 18 December 2015 19:43 Go to previous messageGo to previous message
Thojil is currently offline  Thojil
Messages: 625
Registered: May 2013
Location: Arzier, Switzerland
Gruen Master
JackW wrote on Mon, 14 December 2015 03:26
These watches were likely what was later just simply marked with the 'Pan American' stamp on the case back. Otherwise there is not a discernible difference between these plain backs and Pan Ams.

My experience is that there is a critical difference between the Gruen only and Pan American signed ones. I found this when trying to replace a bad case of a Pan America signed watch. These cases are usually strongly corroded and I bought a good non Pan American case as a replacement. Unfortunately my joy was short lived when it arrived and found there is a 3.5mm difference in the threat diameter of the case back.

Initially I thought that I was just unlucky, but over time I have measured 3 Gruen only signed case backs and 4 Gruen Pan American case backs and found the same results. Why this difference I dunno. Maybe Gruen wanted to avoid exactly what I tried to do... Embarrassed Laughing

So be careful, you can't swap the case backs!!

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