Question about stem tubes

[Hot Little Xixi 12]

I have a question about stem tubes.

I have a Rolex 1675 with a nice case, dial, hands and bezel/insert. Unfortunately it has a 6mm Rolex triplock crown. I want to replace it with the correct twinlock crown but the stem tube needs to be switched for the smaller crown to be fitted. I bought the correct crown and tube, and the stem tube removal tool but before I start trying to remove the old tube I'm wondering if the threads on the old tube where it goes into the case are the same as the threads on the new smaller tube or if the hole in the case will only take the bigger tube. Basically I'm asking if the different size crown/stem tubes have the same diameter threads or if they're different and I can't install a smaller tube into my case.

Edited November 23, 2023 by Hot Little Xixi

[FudgyDocker 3,505]

I suspect that there may be tutorials on this, posted by @NCRich, in the watch upgrade section. Either have a trawl through there, or maybe Rich will pop up and point you in the right direction?

[NCRich 13,756]

If the section where the threads are on the  tube is smaller then it won't fit.  I suspect its just a smaller crown with the same tube threads but the only way to really tell is to remove the one that is there and try.  If you are careful you won't damage it.

[Hot Little Xixi 12]

Thanks, I guess I'll just pull it out and see what happens.