MovementSwap

Different footprints. The ETA Valjoux 7750 is 30.00 mm x 7.90 mm and the Sellita SW400-1 is 31.00 mm x 4.67 mm, so they do not share a case. This is a choice between platforms, not a swap. Published dimensions, layout and the checks before you swap one for the other.

Updated 05 September 2026.

Drop-in resolution

ETA Valjoux 7750 vs Sellita SW400-1: do they swap?

Whether the ETA Valjoux 7750 and Sellita SW400-1 share a case, and what changes if you move between them.

No drop-in

Different footprints. The ETA Valjoux 7750 is 30.00 mm x 7.90 mm and the Sellita SW400-1 is 31.00 mm x 4.67 mm, so they do not share a case. This is a choice between platforms, not a swap.

The ETA Valjoux 7750 is the reference Swiss automatic chronograph, in a large share of mechanical chronographs. The Sellita SW400-1 is a large-diameter Sellita automatic, for oversized three-hand watches.

They differ in diameter (30.00 mm vs 31.00 mm), height (7.90 mm vs 4.67 mm), calendar layout (chronograph, subdials at 6-9-12, day and date at 3 vs centre seconds, date at 3), winding behaviour. A larger 13 1/4 ligne movement at 30.00 mm x 7.90 mm with the classic 6-9-12 subdial layout. Its drop-in donors are the Sellita SW500 and SW510, which copy its dimensions and subdial positions.

Matching diameter and height is necessary but not sufficient. A donor is only a true drop-in when the dial-foot positions, hand-hole sizes, stem length and calendar layout also match. Two movements can share a case and still need a new dial, re-broached hands or a cut-to-length stem.

Calibers and lookups

ETA Valjoux 775030.00 mm x 7.90 mm
Sellita SW400-131.00 mm x 4.67 mm
Donor movement for ETA Valjoux 7750drop-in lookup
Donor movement for Sellita SW400-1drop-in lookup

Questions and answers

ETA Valjoux 7750 vs Sellita SW400-1: do they swap?

Different footprints. The ETA Valjoux 7750 is 30.00 mm x 7.90 mm and the Sellita SW400-1 is 31.00 mm x 4.67 mm, so they do not share a case. This is a choice between platforms, not a swap.