Re: Valve Stem Thread Pitch
Have you checked to see if the washer is worn or loose? Sometimes replacing or tightening the washer (if it's a "compression stop" type faucet) can fix the issue. Check both the hot and cold, as well as the mixing valve that switches between tub spout and shower head.
You're not going to be able to change the thread pitch unless the inside threads are in a cartridge than can be removed -- the pitch must match in both the outside threads on the stem and the inside threads on the valve body. And then you'll probably have to have something custom machined, which will probably be more expensive than just replacing the whole works.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.