How to tie copper to ABS DWV?

So I have old revent and drain lines that I've cut off that were 1-1/4" copper DWV, which seems to be somewhat rare. I have to tie this to 1-1/2" ABS to build a new section for a moved sink.

Question is, what's the best way to do this?

I found some Fernco reducing couplings at the local Big Box, but I heard from the local plumbing plan reviewer that neoprene couplings must be the shielded type (presumably to protect from punctures). Fernco supposedly makes a shielded reducing neoprene coupler, but I can't find it at my local supply house.

My other idea is to sweat on a copper 1-1/4 to 1-1/2 reducer and a stub of 1-1/2 copper and then use a straight shielded coupler. But copper DWV is hard to find too.

Removing the 1-1/4 entirely is very difficult, because that would mean cutting out the tees from the stack completely, and then I have to build the stack in plastic, and then the 3" plastic fitting hubs wouldn't fit in a 2x4 wall, and... yuk, not fun.

What do people typically do in a situation like this???

What you need is a the Proflex coupling by Fernco part# 3001-1125 or Mission's shielded coupling part# CK-1125. This will take you from 1-1/2" ABS to 1-1/4" copper. If your local plumbing supply house doesn't have one in stock they can order one for you.

Good luck!

drains

If the drains are 1 1/4" like you say, then you are stuck. You cannot "increase" the drain size without creating major complications down the road.

So how can I un-stick myself?

Rio -- thanks, I eventually found two of those.

Trouble is, they don't really look very soil-friendly on the inside to go in the direction I would need them to run. There are rough transitions in there that look like they would create clogs. I think that's what hj is thinking of.

hj -- any ideas on unsticking myself? Know anywhere that sells 1-1/4" copper DWV and fittings? The one place around here that has copper DWV at all only goes down to 1-1/2.

Surely I'm not the very first person in the world with this problem...I assume this sizing was standard back in the 60's because the lav traps used to be 1-1/4" also.

-P