Citizen 8280a mainspring reference

[Tino]

Hi,

I'm in the process of a full clean/service of an old citizen watch I got that uses a 8280a movement. I would like to take the opportunity to replace the mainspring since it doesn't look in very good shape but unfortunatly I can't find its reference to buy a new one. I tried here: https://oldswisswatches.com/watch-parts-branded/watch-mainspring-new-old-stock/citizen-watch-mainspring-nos/ but the 8280 isn't listed. Diving a bit deeper I found that I could try to determine an equivalent by measuring the current barrel, but having never done that I'm not too confident to try it on a working movement. Would appreciate if anyone could give me some leads to find the good ref. to buy :).

Thanks!

Edited September 23, 2022 by Tino
typo

[mikepilk]

Nothing listed on Ranfft, Cousins or the GR Mainspring database.

Is it automatic or manual wind? Do you know the "base" movement ?

Can't you measure the existing spring?

[Tino]

Hi mikepilk, thank you for you answer. 

It's an automatic wind movement, the only reference that appears on the movement is on the rotor as seen in the first attached picture. I wonder if I could find an "equivalent" Miyota movement but couldn't confirm it neither.

I didn't take out the spring still I'm unsure if I can find a replacement. I've also attached the inside and outside readings I got from measuring the barrel.

 

Edited September 24, 2022 by Tino

[mikepilk]

53 minutes ago, Tino said:

I didn't take out the spring still I'm unsure if I can find a replacement. I've also attached the inside and outside readings I got from measuring the barrel.

It needs to come out for cleaning !

Do you have spring winders ?

[Tino]

16 minutes ago, mikepilk said:

Do you have spring winders ?

Unfortunately I don't. This is why I was looking for a replacement. I saw that I might be able to clean it and re-wind it without a tool but I've never tried it. Guess I'll have to do it if I can't find a new one..

[mikepilk]

You can wind them in by hand. It's a bit fiddly, especially with automatic springs with the bridle at the end.

e.g https://www.youtube.com/watch?v=IoUil-td8DQ

I have seen that for other 82## calibres, the "complete barrel" is sold, hence no reference to spring size.

[Tino]

Thanks for the video, will definitly try it ! 

52 minutes ago, mikepilk said:

I have seen that for other 82## calibres, the "complete barrel" is sold, hence no reference to spring size

Just to confirm does it mean that I can use any 82## barrel like this one? I tried to look for a complete  barrel for the 8280 but couln't find it.

[mikepilk]

One very useful website is JulesBorel : http://www.julesborel.com/

Select "JBC Watch Parts Database"  then " Search for parts for manufacturers from A to F", Citizen.

Find " CIT 8280A" , then any part you select, it will show which other movements use the same part.

Unfortunately it doesn't list mainspring or complete barrel. 

So, I'm not sure 

[clockboy]

5 hours ago, Tino said:

Hi mikepilk, thank you for you answer. 

It's an automatic wind movement, the only reference that appears on the movement is on the rotor as seen in the first attached picture. I wonder if I could find an "equivalent" Miyota movement but couldn't confirm it neither.

I didn't take out the spring still I'm unsure if I can find a replacement. I've also attached the inside and outside readings I got from measuring the barrel.

 

Looking at the pic it certainly needs cleaning. If careful this can be done without a winder and providing the spring is not damaged lubricate and re fit by hand.. Before this take measurements height and strength just in case you need a replacement. 

Edited September 24, 2022 by clockboy

[Tino]

So, I took of the mainspring, cleaned it and the moment I tried to fit it back starting with the tail it broke in 3 parts. My lack of experience surely did not help but I think that the spring itself was not in such a good shape anymore. I'm back to my first plan to buy a replacement, but am still confused to how do I find one.

17 hours ago, clockboy said:

Before this take measurements height and strength just in case you need a replacement

Measurements I have is:

• spring Height: 1.00mm
• spring Thickness: 0.10mm
• spring Length ~350mm
• barrel internal diameter: 10.1mm

I found this site where you can use a calculator to reverse engineer the mainspring based on your measurments: https://www.vintagewatchstraps.com/mainsprings.php#calculators.  

I got the followin estimate with my barrel internal diameter and spring thickness: Results: spring length = 356, turns = 7.9, barrel/arbor = 3, barrel/spring = 101, arbor/spring = 34.

But again can't find and online site where I could actually use this information to buy and equivalent.

Thanks for your help!

[clockboy]

Cousins offer search by size. The nearest they have is GR2436X which is a touch under strength and length. 

[mikepilk]

21 minutes ago, clockboy said:

Cousins offer search by size. The nearest they have is GR2436X which is a touch under strength and length. 

That would do the job :