Difference between 1570 and 1575 movements?

[indyberetta]

All the 1575 movements I have seen are marked 1570. So what exactly is the difference in these movements? Is there any different parts on the movement for the GMT function? If so how hard is it to modify a 1570 to a 1575?

Thanks!

[Heywood]

The 5 designates a date function. I think they all are engraved as 1570 whether they have a date or not. The GMT function takes some extra parts. I have a diagram somewhere if you're serious about trying to convert one. I was planning on doing this til I found a 1575 GMT movement at a decent price. If memory serves, it requires a 24 hour wheel, a higher hour wheel, higher cannon pinion and a taller seconds pin (or whatever it's called). If your movement already has a date I think that your about half way there.

[indyberetta]

Yes, it has the date function already. I am trying to put it in my 1655 that I am currently building.

The 5 designates a date function. I think they all are engraved as 1570 whether they have a date or not. The GMT function takes some extra parts. I have a diagram somewhere if you're serious about trying to convert one. I was planning on doing this til I found a 1575 GMT movement at a decent price. If memory serves, it requires a 24 hour wheel, a higher hour wheel, higher cannon pinion and a taller seconds pin (or whatever it's called). If your movement already has a date I think that your about half way there.

[bertieng]

1655 needs a true 1570 GMT movement to work.

Conversion is not easy as finding the 24 hour wheel and parts is extremely difficult.

The best bet is go for a genuine 1575 movement with the GMT function installed.

Good luck.