Thetford C402C cassette doesn't mate with flange

Discussion in 'Port-A-Potties / Cassette Toilets / Bath Houses' started by Erik Walthinsen, May 22, 2019.

  1. Erik Walthinsen

    Erik Walthinsen New Member

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    I've spent a few hours futzing around with the seal and other things on the toilet in our recently acquired and as-yet unused (next week!) tent trailer.

    The fundamental problem seems to be that when I slide the cassette into the slot, it's a good 1/8-1/4" too low to catch the flange, so it ends up sitting underneath it with a significant gap, and leaking like crazy. If I'm *very* careful about sliding it in, I can sometimes get it to catch the flange, but that's rare. Even then the seal isn't good enough to have water standing in the bowl for *any* time at all, though I suppose that's pretty much a given for this kind of toilet (meaning very careful training ahead for our 4yo...).

    It looks like I'm going to have to find some kind of narrow shim (1/2" wide by ~3/16" thick) that I can install under where the cassette wheels would slide, so I can get the whole thing inserted at the right height to catch the flange.

    Has anybody else run into this problem? Based on how the pieces are molded, I don't see how this could be an installation failure, so I'm at a loss as to how this can happen without every unit ever made having the same problem...
     
  2. Orchid

    Orchid Sharp Shootin' Grandma

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    Is the floor under the cassette solid? I can't see any other way this problem could happen.
     
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  3. Erik Walthinsen

    Erik Walthinsen New Member

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    Yeah, it's solid, but the cassette fits into a plastic frame that's *part* of the main toilet frame itself... The floor could sag underneath and it wouldn't (shouldn't?) alter the relative dimensions of the lower frame and the flange.
     
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  4. Orchid

    Orchid Sharp Shootin' Grandma

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    I knew the cassette slides into a frame, just never realized it was all connected. I suppose it's safe to say that hubby empties the cassette most often. When I'm in there, it's usually just to add flush water.

    That's a really interesting problem that you have. As you said, not sure how it would be possible without it being the same on every other unit made. Ours seals well. Sorry I couldn't be any help. Hope someone here has the answer.
     
  5. SteveP

    SteveP Well-Known Member

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    I'd look at the wheel assemblies. Do the wheels seem to be loose, maybe wobbly? Mine aren't.

    The shims are probably your best short term fix. You shouldn't leave water in the bowl, it's not needed and only makes a mess.

    https://www.thetford.com/parts/cassette/
     
  6. Sjm9911

    Sjm9911 Well-Known Member

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    If you go to the sight above and get the manual for your model it should have a trouble shooting guide in it. If not, i would shim the whole thing if its off. I can check mine maybe tomorrow night , take some pictures. I can compare.
     
  7. SteveP

    SteveP Well-Known Member

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    Make sure it still latches in place after you shim it. That could be an even bigger problem.
     

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