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Joe_Way's avatar
Joe_Way
Explorer
Apr 16, 2016

Sewer Connection Problem

ON EDIT--I found the correct fitting online, at a reasonable price. Scroll down or click here.

Is it just me, or do others have problems with the newer 90 degree two-piece threaded connectors? Seems like maybe 3/4 of the parks we have been to in the last couple of years have a threaded 4" drain recessed slightly into a concrete apron. Our Rhino Extreme right angle connector drags on the concrete before the threads are snug, or sometimes even before I can get the threads started. If the drain is not plumb, sometimes I can get enough thread engagement to be secure by removing the right angle part from the threaded part, and picking the highest side when re-engaging the right angle. A couple of times I have had to deliberately cross-thread the adapter, which secures it in place but does not seal. After looking at the illustrations of other brands such as Dominator, Blueline, and Valterra, I suspect they have the same issue with the 4" threads.

I looked in the home stores and on-line for a 3"x4" threaded ABS bushing, but couldn't find any. So I made one from a 4" MPTxhub fitting and a 3" FPTxhub fitting. It takes a lathe, either metal or wood, to do this, but for those who have one or know someone who has one, it's a fairly straight-forward project.

I cut off all but about 1/2" of the hub on the 4" fitting, leaving a "handle" with which to grab the fitting for removal. Then I turned down the threaded end of the 3" fitting to a snug slip fit in the 4" fitting. In the case of the fittings I bought at Ace Hardware, the diameter was about 3.785". After machining I cut off the hub from the 3" fitting leaving only the threads. Then I glued one into the other, being sure to keep the taper of the 3" threads in the right direction.

Photos: Fittings as bought, after modification, and after gluing.





  • Real nice DYI!

    I always carry one of those rubber sewer donuts.

    Works good with the Rhino. I just stick the Rhino threaded coupling into the rubber donut for those dumps that have the concrete it adds just the right height and still seals the dump. And also lets you use the rhino coupling for dumps that have no threads at all.

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