Remove belly skin -- all or nothing?

[pilgrim_still]

'73, 31', SLY, rear bath -- aka, M&MT (mildew and mouse turds)
-- the goal is a usable TT, not a restoration.

Noting a lot of flaky rust in the storage bin inside the rear bumper, and always curious about the origin of rust, I took off the rear bumper (only had to drill-out two of the four bolts). I loosened the underbelly skin to let it drop down between the trailer longitudinal frame. This released lots of small stones, rust, leaves, nut (pecan and hickory, not S.A.E.) pieces, etc.

I was going to completely remove the belly skin, but it is about 15 feet long! It extends from the rear to infront of the front axel. Sure, I can drill-out the rivets to release it, but, how would one ever replace it? You would need 2 or 3 2x6's 10 feet long and several hydraulic or screw jacks. Or, is there another way?

In the rear, I see that the angle iron (between the two longitudinal frames) that supports the rear end of the holding tank is severely rusted. Rusted, too, is the galvanized metal pan in which the holding tank rests -- but it is only rusted where it has been in contact with the angle iron. Otherwise, everything seems intact and neither rusted or corroded. I assume I can just jack-up the pan and tank, cut-out the bad areas, replace and weld in a new angle iron...or, am I being Poly-Anna?

[gerbermania]

I recommend dropping the bellypan to inspect both angle irons holding the waste tank. Cutting out a section large enough to inspect, and perhaps weld, both will be a 'waste' when you could have just dropped the belly pan.

I'm in the process of replacing both angle irons because they were rusted completely through, as was the galvanized waste tank pan resting upon them. This sounds a lot like your situation.

You may want to build that waste tank pan out of another material, or at least put something between the galvanized sheet metal and the steel angles. I am using 1/4" PVC sheet between the angles and the pan, to reduce the galvanic action.

I did this just a few weeks ago. Once I got into the process, I noticed that both angle irons holding the waste tank were severely rusted, as was the galvanized waste tank pan, where the pan rested upon the angle irons. Since you are planning on doing the rear-most angle iron, I recommend doing a thorough inspection of the forward one.

You may need to remove your BAL jacks, and drill out a few extra belly pan rivets to slide the belly pan forward enough to free it from the chassis frame. Once done, it makes the work on the waste tank much easier.

Attached is a photo of mine from above. I went a few steps further than you, though, because I also had to replace the rear section of plywood subfloor. It had the strength of, well, it didn't have any strength at all.

Christopher