I did a search and could not find anything on this topic.

Has anyone noticed that the 90s AmStd strat black trem springs are weaker(have a lower "k" constant) than the new AmStd strat silver coloured trem springs ?

Which means that they are not interchangeable without the need to adjust the position of the trem claw. Plus when set up correctly, for the same nos. of springs it takes more force to move the trem which has the newer 2008 AmStd silver trem springs than when the same strat is set up with the 90s black trem springs.

Does anyone know why Fender changed the spec of the springs ?

Silver springs are used for vintage style 6point trems. Black springs are still used on the deluxe and i presume other 2 point systems.

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No no and no

The silver springs are also used with the "new" 2 point trem unit which has the copper infused trem block and vintage style saddles...


either way ... the silver springs are still stiffer.... I prefer the black springs