Ultra Chron service

[Anza]

Hello all,

I’m trying to prepare for my next service project, a Longines Ultra Chron with 431 movement, currently enroute from an eBay purchase.  I know these were rather finicky in their day, requiring special lubricants for proper function, and am hoping that modern Mobius lubricants will be sufficient.  Is this a correct assumption, or will I need more specialized lubricants?  Thanks for any advise, service info on this movement seems a bit difficult to find.

 

-Anza

[handwound]

Hey Anza,

I don't have experience with the caliber 431 in particular, but by looking at it, my guess would be that using modern high quality lubricants (moebius for example) will to the job just fine. 

May anyone correct me if i'm wrong

[JohnR725]

On 12/16/2021 at 1:05 PM, Anza said:

requiring special lubricants for proper function,

You left off an important detail of why would it require special lubricants? The problem is when you're running your escapement twice as fast there is a concern. You should Be able to use 9415 but I Would think about surface treating just to keep the lubrication where it's supposed to be.

Then there's the other weird problem found in the parts list. Also I saw a reference when I googled the movement is the mainspring barrel is sealed. Apparently trying to get a new sealed barrel is very difficult or basically impossible. The weird aspect is they also list a mainspring in the list?

Longines_Longines 431.pdf

[Anza]

Thanks for the guidance.  I’ve also thought it odd that mainsprings are available for a sealed barrel.  I just finished up a Longines 345 with similar sealed barrel.  Apparently it’s possible to gently shave the top off the center rivet and open it like a normal barrel, but I only wanted to do that as last resort.