running into some trouble this afternoon. i have a 4" rubber donut that i am supposed to put into the hub of my 4" sewer pipe and will be fed by my 3" drain via a 4"x3" reducer (according to the plumbing guy at HD). for the life of me, i cannot get short 4" seciton of pvc into the gasket while it is in the hub, no matter how hard i try. it seem it is just a hair to large. i even tried sanding down the pvc, but that is not working at all. after doing some research online, i found this picture ( http://www.terrylove.com/images/replace_lead_bend.jpg
) it looks like they have the 3" going into the rubber gasket. However, i do not know if that hub is off a 3" or 4" pipe.
I guess my question is - do i come out of the rubber donut, gasket, whatever you want to call it with the 4" pvc or the 3"??
Might be a stupid question, but i'm stuck . thanks for your help :-)