GMF GMT Movement Swap / Compatibility Question

[daytonadude]

Very quick question:

I am replacing a broken movement on a GMT from GMF which has the green circles date setting mechanism. On Ali, SH3285 movements have another date setting mechanism, though from looking at the balance wheel on the GMF it looks like an SH3285.

Will an SH3285 from Ali work as a replacement?

Thanks so much everyone!

 

[KJ2020]

The AliExpress SH3285 should work bro. GMF has been known to do their own thing with GMT movements but if your dial is a 126x dial (has underside rims and is friction fit) then everything should swap over.

There were a couple different very early versions of the 3285 that were size compatible with the current SH/DDs. While the gen 3186 and 3285 have the same OD of 28.5mm, the rep 3285s are larger. So you could temp fit a rep 3135 in the case and see if there is extra room. This would help reinforce your confidence in using the replacement movement.

 

[daytonadude]

Super helpful, thanks @KJ2020 !

Weirdly, the dial is a 31xx style dial with dial feet. No ridges, which had me wondering if a VR3186 would fit the case. But the rotor runs on ball bearings and there is a fake paraflex shock setting which looks just like an SH3285. Very strange movement!

I will test out a VS3135 I have here

 

[daytonadude]

The AliExpress SH3285 should work bro. GMF has been known to do their own thing with GMT movements but if your dial is a 126x dial (has underside rims and is friction fit) then everything should swap over.

There were a couple different very early versions of the 3285 that were size compatible with the current SH/DDs. While the gen 3186 and 3285 have the same OD of 28.5mm, the rep 3285s are larger. So you could temp fit a rep 3135 in the case and see if there is extra room. This would help reinforce your confidence in using the replacement movement.

there’s a bit of extra room when fitting a VR3186 and a VS3135 - since the dial has dial feet, I’m inclined to order a VR3186 over an SH3285, but unsure about stem height (my current VR3186 stem is too short to test)

 

[KJ2020]

Stem height won't be an issue. Where are the dial feet positions? Does the GMF dial fit properly onto a 31xx movement?

Because if you have to clip the feet anyway you can just epoxy the dial onto a 3285 movement.

If you do use a 3186, you can make a custom spacer out of a crystal gasket or even some fishline. I've used both. Crystal gasket gets thinned, shortened, and notched.

Also, having a box of various length movement tabs is useful to help immobilize the movement in the case. The tabs can be positioned creatively to force the movement/dial to stay exactly where it needs to be.