New shower arm

I am needing to install a new shower arm because my shower head needs replacing but unfortunately the shower arm that is coming out of the wall is not normal size. At first I thought that the threads were just stripped some but upon closer inspection the threads are 7/16" instead of 1/2". I have been unable so far to find a reducer to go from one to the other and was wondering what everyone suggests. I am trying to get by with not changing out everything in the wall if possible because I will have to change most of my plumbing just to change it. My house was built in the late 50's and I have run into several problems when replacing things on the plumbing.

As far back as I can remember shower arms have always been 1/2". It sounds like you have some pieces of the old shower arm in there.

John

That's what I thought but I actually unscrewed the old arm and took it to the store and it is 7/16. The only thing I can possible think is that when the house was built it was made from pipe that was bent instead of buying the standard arm. The original shower head didn't fit well either.

There has never been 7/16" pipe. Pipe threads are tapered. What you are measuring is what is remaining of the threads of the broken shower arm.

John

I checked the joint in the wall and it is clear. The original didn't break and there is nothing in the threads. The old pipe screws back in fine but a new 1/2 one won't.

Don't know what to tell you. Pipe sizes are, and have always been 3/8"-1/2" and 3/4". Nothing in-between. Have you tried a 1/2" shower arm?

John

Yep tried one and it acts like it is too big. I have also tried a 3/8 adapter and it is too small.

There is nothing made in between the two sizes.

John