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Old 04-04-2011, 11:42 AM   #1
2 Rivet Member
1967 22' Safari
1978 25' Tradewind
NEW LENOX , Illinois
Join Date: Nov 2007
Posts: 88
Adding a larger grey tank to a 78 Tradewind

I have a 1978 25 ft. TradeWind with the infamously small grey tank (like 12 gal. - rediculous!). I have recently dropped the belly pans because I had a split brake line that needed repair,,, and now I have removed the side wraps so I can wire brush and POR15 the frame as long as I am there..... And, since I am there, how about installing a bigger grey tank????? Madness.... just madness....

So, what's the easiest approach to adding more grey tank capacity?

I can add a second tank closer to the axles, but there are some drain pipe height issues to work out and, the existing grey tank will have to be replaced since I can't cut into it and I can't merge into it's discharge line.

Oh yeah, I also want to install a macerator semi-permanently.... there is just enough room for it, I think....

Does anyone out there have the drain pipe plumbing diagram from the service manual for a mid-to-late 80's, or 90's, 25 ft. TradeWind with the rear Shower Bath configuration? I am looking for ideas....

And, do I really need the foam pad under the tank? I am not winter camping (not using water when I do) and I will support the tanks independent of the bottom cover.


John H
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File Type: pdf 78 TW Shower Bath plumbing.pdf (41.4 KB, 92 views)
File Type: pdf 78 TW Shower Bath tanks.pdf (48.6 KB, 111 views)
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Old 04-04-2011, 12:37 PM   #2
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1974 31' Sovereign
Ottawa , ON
Join Date: May 2008
Posts: 11,219
Images: 25
Wow, you have a 12 gallon grey tank? That's luxury to me; ours is ten gallons!

It's my belief that you will need top access to change the tanks fabout, or just add a second grey tank because of the way the tanks are suspended on the frame rails. By that I mean remove lots of interior (oh NOO!)

But check with an expert: Member Colin H will know...
“Courage is being scared to death, but saddling up anyway.”
...John Wayne...........................
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Old 04-04-2011, 12:42 PM   #3
2 Rivet Member
1967 22' Safari
1978 25' Tradewind
NEW LENOX , Illinois
Join Date: Nov 2007
Posts: 88
I was being generous at 12 gal., you are probably right at 10 gallon. It's a damn small tank...

Top access is not what I want to hear. but no, no, no. The bottom is off, I don't want to be tearing out the inside...

John H
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Old 04-04-2011, 12:43 PM   #4
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heslinhotel's Avatar
1989 29' Excella
1979 31' Sovereign
1999 25' Safari
Youngsville , North Carolina
Join Date: Sep 2006
Posts: 326
John H,
I think you want to keep the foam pad. It will keep tank from shifting and chaffing, which will eventually lead to tank failure.
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