Seiko 5740 (5740A, 5740B, 5740C) Mainspring

Genuine Generale Ressorts Swiss-made replacement mainspring for Seiko 5740A, 5740B, 5740C and related manual-wind movements. 

The Seiko 5740 family includes some of Seiko’s most interesting vintage manual-wind watches. The 5740C is particularly notable as the movement used in the Lord Marvel 36000, one of Seiko’s early high-beat watches running at 36,000 vibrations per hour. Lord Marvels are increasingly collectible.

If you’re servicing a vintage Seiko 5740 movement, a high-quality replacement mainspring is important for proper fit and performance. A poorly made mainspring can cause fitment problems with the arbor or barrel and may not deliver the amplitude expected from a properly serviced movement. Here, there’s no mystery about what you’re installing: a branded mainspring made by Generale Ressorts, a leading specialist manufacturer of watch mainsprings.

Is GR4007D compatible with the Seiko Lord Marvel 36000?

Yes, GR4007D is a replacement mainspring for the Seiko 5740 family, including the 5740C used in the Lord Marvel 36000. Because vintage Seiko movements may have undergone previous repairs or parts substitutions, compare the existing mainspring and barrel configuration before installation.

Compatible Seiko Movements

5722A
5722B
5740A
5740B
5740C

Specifications

Manufacturer: Generale Ressorts
Manufacturer Part Number: GR4007D
Type: Manual-wind mainspring, D-end
Height: 1.45 mm
Thickness: 0.125 mm
Length: 440 mm
Barrel Diameter: 10.5 mm

Amplitude Watch Parts ships from the USA, so there’s no need to worry about long shipping delays or tariffs.