Confusion About Mainspring for 1912 Elgin Grade 303

[Techy101]

Hello, 

 

My dad will be bringing his 1912 Elgin Grade 303 pocket watch (Serial number: 16558327) over the holidays and I wanted to have a mainspring on hand. The pocket watch database says it's a Class 114 and my research shows that there are two mainspring options, 1720 or 2339, depending on whether it has the thin or thick going barrel. I am unable to figure out which of these would be correct from the serial number and was hoping someone could point me in the right direction. I have this sneaking suspicion that I won't able to know until I get it in hand but am hoping that's not the case. 

 

Thanks!

[gpraceman]

Maybe Dave from https://fixmypocketwatch.com/ can help you with that.  He helped me with some troubleshooting on my FIL's 1937 Elgin Grade 315 and I got a replacement mainspring from him.

[JohnR725]

17 hours ago, Techy101 said:

1720 or 2339,

technically there's probably three mainsprings the steel ones and then the newer Elgin alloy one. With the newer style more common. Of course there's the minor issue of thickness unless you get original spring the modern Springs are probably only going to be in one thickness?

 

 

so for instance here's a modern listing it narrows it down to basically the newer style so they can flip a coin as to which one you want by it's probably the newer style there is probably a serial number division if we had the right Elgin book that might tell us may be perhaps

then if you have an older list you can see both of them are listed in real life with watches like that the best way to figure it out is you have to take the spring out or purchase one of each and have a spare on hand

typically I like the link below for finding Elgin parts because they have the notes but I don't see the note for mainspring listed? This means we need to find a different material book like maybe a 1950 book?

http://www.elginwatchparts.com/Script_Find_Grade.php

but here is the problem with the 1950 book we get to the mainsprings well you have a choice and that doesn't seem to be any notes related to those choices?

this is why by the way unfortunate way with a lot of American pocket watches you have to measure whatever's there. It's not just mainsprings there's variations of balance staffs to lots of variations in the watches American watches in particular to get the right part you almost always have to measure

you will notice with the other grades for the mainspring they have funny little symbols and they give you the serial numbers but for some reason unknown on 303 I'm not seeing a funny symbol but maybe it's in the notes here maybe you can look at your serial number and make a guess as to what it might be otherwise you have to get both of them were probably air on the newer style especially if your serial numbers later in the serial number batch