78 Sovereign, Rear frame / body interface.

[andymeyer]

We are in the midst of fixing the rear end of our trailer - bought it this summer and found some work to do.

I've gotten the rear end pulled apart (we're only replacing the rear sheet of plywood - everything else is in great shape.) I got most of it pulled apart and looking for some input to get this back together right...

Help me understand what insane person put a sheet of steel between two layers of aluminum? Were they trying to create electricity before solar was the rage? What's the fix here? The horizontal portion of this is gone. Half of the vertical portion still exists, the other half is blooming and forcing the aluminum apart.

My thought is to :

• Remove it all together. Slide a thin strip of Al in to fill the slot.
• I assume that this piece is there to stiffen the rear straight section. Can I lay a 1/8" steel or 3/16" Al x1" slab in here horizontally in the top of the U channel to provide the same function? Or, an angle iron / angle Al in the same place?
• Flash the rear edge of the trailer to eliminate water intrusion in this area.

We've got a welder lined up to rebuild the lateral frame in back along with the last 2 - 3 feet of the right side longeron on the frame. He'll also be replacing 6 outriggers and we found another thin section on the frame that we'll have an angle or fish put in to stiffen.

What else should we be looking at while we're here? Most of our project is being discussed in the 74-79 Sovereign forum...

We're trying to get it closed up before it gets too cold to work on it. We're in SE PA (Lincoln University) and open to meeting any members who are in the area as well...

[dbj216]

Hello from Colorado: I'm working on a 75 Overlander with a similar rear body separation from the frame rails. Galvanic action between aluminum and steel is common in Airstreams. It is well displayed at belly pan rivets to the frame members.

I thing the main culprit in rear end rot of the seventies trailers in the silly piece of aluminum sheet between the frame rails to the bumper storage lid. Rain water sheets off the body, hits this aluminum sheet, and migrates into the subfloor. Let the rot begin.

My trailer had a "mild" case of rear end separation and frame sag. I had to replace the rear frame cross member, the steel body hold down plate, and the last 12" of subfloor. The mobile welder put it all back together for me and I have a firmly attached frame to body. I am leaving the decorative aluminum sheet out of my assembly. I will have an unsightly gap between my bumper lid and the body. Rain water will flow into this gap, not into my subfloor. I will flash down about an inch from the bottom of the body with aluminum. I will drill drain holes in the belly pan to let the water drain to the ground.

Here is a photo of my repair. Note the new cross member channel, the new oak subfloor patch, and the steel body hold down plate on top.

Hope this helps a bit.

David