Mainspring Size?

[rogart63]

Need to find a new mainspring for the Citizen 5420 i think? Wonder a little how they measure the barrel? Outside or inside diameter? 

[Geo]

Inside!

[clockboy]

Need to find a new mainspring for the Citizen 5420 i think? Wonder a little how they measure the barrel? Outside or inside diameter? 

I think the 5420 is a Quartz so you have the wrong caliber Id

[rogart63]

I think the 5420 is a Quartz so you have the wrong caliber Id

It's also an old Citizen automatic movement . Can't find so much about it besides http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&Citizen_5420

[clockboy]

It's also an old Citizen automatic movement . Can't find so much about it besides http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&Citizen_5420

Ok  my "General Resorts"  catalog shows Cal 5201-27 Auto GR No. 2637

Height 1.10 strength 0.11 length 380  dia.10 

If this size matches the old spring or fits into the barrel It will not be far away from your requirements.

[rogart63]

Ok  my "General Resorts"  catalog shows Cal 5201-27 Auto GR No. 2637

Height 1.10 strength 0.11 length 380  dia.10 

If this size matches the old spring or fits into the barrel It will not be far away from your requirements.

That could work . But unfortunaly i have already orded a spring . So 1.10 check . 0.11 i took 0.115 .360 length because there was no 380 . And i measured the diameter to 10.5 inside the barrel . Could this mess up the movement? 

Edited September 29, 2015 by rogart63

[rogart63]

Could a 360 length work ?  Can't find any 380 on Cousinsuk . 

[Geo]

It would be worth trying as long as the thickness (gauge) is correct. Being slightly shorter it will fit into the barrel, but it won't last quite as long as the 380 would when fully wound.

[clockboy]

The key element is height & strength if it is to high it can bind on the barrel cover & if too strong it can cause the issue of over banking. Best to go under rather than over.

[rogart63]

I calibrated my micrometer and measured the old mainspring again .Two times . Got it to 1.10 and  0,115 . 0.11 or 0.115 is very hard to measure .  5 thousands of a millimeter isn't much?

[clockboy]

The spring you have ordered will be Ok because the watch is an auto so the spring stays fully wound while wearing.

It,s just the stand by time that changes with the length. IE my Rolex does not have an original Rolex mainspring fitted, the only difference is the one fitted is a bit shorter but it works perfect.