ABS to Cast Iron Hub

[DVDiva]

Is there any other way to connect ABS 3" DWV (for a toilet) to an existing 3" Cast Iron hub besides using a rubber donut? We are trying to make the connection and we can't get the ABS to fit with the donut. We have tried putting the donut on the ABS and then hammering it into the cast iron (the ABS just ends up popping out), and we have tried putting the donut in the cast iron with lots of soap on the inside, but the ABS still won't go in.

Any other suggestions? We are really frustrated! Thanks!

[finnegan]

If you have room, I would cut the hub off and connect with a no hub coupling. If that is not an option, they make an ABS fitting which is intended to be inserted into a cast iron hub and then packed with a compound. I have never used it, but I am pretty certain I have seen the compound. You can always use lead, but that would not be much fun.

[DVDiva]

Thanks for the response. My husband shaved off the little ridges around the rubber donut which seemed to make it fit with the ABS into the hub. He used a car jack to slowly apply pressure to the ABS pipe to get it to slide into the rubber donut. Quite unorthodox, but it worked! We double-checked that the joint didn't leak and it seems to be working fine.

[hmmdinger]

I completely empathize with your troubles, DVDiva. That's the EXACT situation I was in a couple of weeks ago. Rubber adapter would fit on the pipe fine, and would fit into the hub fine, but try and get all three to work together...FORGET IT.

Trimming down the ridges of the adapter was the only thing that ended up working for me as well. I used a drill and a wire brush.

After all that, the pipe going into the hub is still VERY snug. I have total confidence in it.