Tub-Shower Drain

I'm in the process of replacing a tub-shower drain with 1 1/2" ABS and it is working fine so far. Last step is to replace the P-Trap and give the whole drain some more slope for better drainage. (The current slope seem to be close to horizontal).

What is interesting is that the first part of the drain pipe itself (with overflow and drain) seems to be only 1 1/4". This if ofcourse only about a foot long, but I'm wondering if this makes the tub drain alot slower?

I was debating whether to use 1 1/2" or 2" pipe for the drain, but now when I see the 1 1/4" pipe I'm curious if that changes everything?

It is probably 1 1/2" tubular pipe - thinner walled that regular piping...
OD if 1 1/2" pipe is just short of 2"... OD of 1 1/2" tubular piping is 1 1/2"
1 1/4" pipe is what is under your lav....

I hope you are right...

I hope you are right.
The pipe is metal and I measured the OD, which is about 1.5" and I fits into the P-trap that is ABS.

The flow in the tub is somewhat slow, and I'm trying to figure out why.
I thought it was due to the skinny pipe, or the poor slope on a horizontal run.

We'll see once I can get through the pipe.

Thanks!

Mark - you were right!

It was 1/2" pipe. Unfortunately it is leaking from the tub to the pipe...I guess I need to replace the drain pipe. The plumbers putty or whatever the sealant is seem to come off.