'79 rear bumper lid and compartment improvement?

[blickcd]

I'll be replacing some rotted flooring in my rear bedroom within the next few weeks. Will be removing some belly skin and wraps as required to get to the elevator bolts, painting frame, welding in replacement metal as needed and who knows what else.

Anyway, I had this nutty idea to eliminate that metal strip that the bumper lid hinge attaches to, having some vertical piece down in the bumper area that the hinge attaches to vertically if you understand... Then replace the belly sink below the storage compartment with expanded metal.

This would leave a slot in between the rear body and the bumper lid that rain water could freely flow down and out through the storage compartment, hopefully eliminating the chance of the floor rotting again.

I've done a search for any photos of this design but it seems no one has tried it, and posted photos.

I am looking for any comments or ideas for how most people improve this problematic area.

Thanks,
Christopher

[AlinCal]

I am in the process of rehabing the bumper storage myself, No real changes to design other than having a stainless steel box or tray if you will that will fit between the frame rails were it will be caulked in place catching the water that flows down through the hinge and door, in the bottom of the tray I will have a couple short drain tubes that will pass through the belly pan material(witch was rotten pretty bad on our trailer). I have taken off the belt rail and caulked that area as well as the aluminum piece that goes between the shell and lid.
The reason I chose this path was to not allow water to the frame rails and cross member at all.
I think your idea with the expanded metal is better than Airstreams idea of the belly pan (with a couple 1/4" holes) being the floor of the compartment.

[blickcd]

Alin,

I like your idea, although I'd be concerned about the drain tubes getting clogged over time with bits of debris.

[AlinCal]

They will be more like 1" ss tube, possibly larger now that you got me thinking .

[Streamracer]

The rear bumper compartment catches a lot of dust in mine so how much dirt and water would blow up in there in everyday driving? Looks to me everything will get pretty grimey. Give it a try and let us know how it works out.

[blickcd]

Here is somewhat of an update:

After much thought I came up with what I think is an easy and cheap solution.

With the rear bumper off and belly skin pulled down a bit for better access, I ran a bead of latex caulk (because I had an old tube of the stuff on hand) on the underside of that aluminum strip that the bumper lid hinge connects to.

As you know, water will leak in at the hinge and it wants to stick to the bottom of the aluminum, and roll back to the vertical frame end plate where it can wick in under the floor. My thought was the that even a sloppy bead of caulk would create something for water to drip off of so it would never reach the frame.

Then it rained. Actually it was a rather impressive storm. Still getting water coming in between the bottom of that aluminum strip and the top of the rear vertical steel plate.

So I did a test. With the bumper removed so I could look up from below, bumper lid in the closed position, I had my wife run the garden hose in a gentle shower down the rear wall of the trailer. Water just poured in at the hinge and all dripped off the caulk. None got inside.

Maybe the wind has to come into the mix. Note that the bumper was on during the storm, but there are gaps between it and the frame where wind could get in and swirl around...

Stay tuned. I guess.

[blickcd]

I found the source of that last leak. The aluminum strip that the bumper lid hinge is connected to, it has a long slot of corrosion in it above the steel cross member.

You really need a mirror and flashlight to see the edges if it and where the water comes in.

When I do my floor and frame repairs, this strip of aluminum will be replaced with a new one, which yes will eventually corrode, but will last another 38 years and be water tight for most of them.

[blickcd]

Here is what I did for a solution. While this does work, you need to separate the frame and body to do it. I was replacing some rotted subfloor at the back, so was temporarily separated and was able to remove the remains of the aluminum strip that the lid hinge connects to.

The repairs of the floor and rusty frame may show up in my blog later. Just before bolting the shell to the frame, I covered the frame rails at the point of connection and rear cross member with some sill flashing. Its like a thick wide tape made of tar with a foil face, used to cover the sills of rough openings for windows and doors in regular construction.

I will also mention that the edges of the new sub floor were coated on the edge, and about one foot in top bottom, with West Systems epoxy. Also covered on the edges just before assembly with some heavy foil tape, the real duct tape.

After everything was bolted together and the banana wraps were back on, before installing the trim, I took some regular thin aluminum flashing, which comes in a roll, and cut a thin strip, long enough to fit between the frame rails.

The strip was pop riveted to the lower back edge of the shell. A thin bead of vulkum was applied first. The bottom edge of this flashing is maybe 1" below the bottom of the sub floor.

At the frame rails, some other flashing pieces were made and pop riveted into place. These overlap the frame rails and the previous flashing. Once again all vulkumed up.

The trim channel goes on. The top of my flashings are just below the mid point of that trim channel. Now any water running down the back of the trailer can't run back under the floor. Of course, on the inside, any exposed pop rivets were gooed over with vulkum.

For the bumper lid hinge attachment, I took a scrap aluminum door jam that might be 3/16" thick and cut a piece that was concave on one edge so it would butt up and tuck slightly under the trim channel. This required a cardboard template, and a lot of test fitting, filing, grinding, etc.

Once the fit was perfect, or close enough, holes were drilled for bolts for the hinge, and pop rivets for the springs. I would later add a few other bolt holes right on either side of each spring, as they wanted to deform the aluminum strip.

This assembly was then bolted through the original holes in the frame rails, one bolt at each end. Rain water can get into the bumper compartment through the crack between the trim channel and the hinge mounting plate, also through the hinge itself, but any water rolling forward will hit the new flashing and drain out the existing holes in the belly skin of the bumper compartment.

I've been through a number of storms, the interior still partially gutted, and the belly skin off, after this flashing and lid install, so I know that no rain water is getting in.

A lot of work, but if you are doing some repairs at the back, this might be worth adding to the list.

Oh, I can't take all the credit for this flashing design. It read a description somewhere here on the forums, no photos though, and this was what I interpreted. Hopefully the pics sum up my description. At the time of this post I don't have a photo of the final thing, but really it just looks like the factory install. Only difference is it won't leak and rot the floor over time.

[Dingo Girl]

Originally Posted by blickcd

I'll be replacing some rotted flooring in my rear bedroom within the next few weeks. Will be removing some belly skin and wraps as required to get to the elevator bolts, painting frame, welding in replacement metal as needed and who knows what else.

Anyway, I had this nutty idea to eliminate that metal strip that the bumper lid hinge attaches to, having some vertical piece down in the bumper area that the hinge attaches to vertically if you understand... Then replace the belly sink below the storage compartment with expanded metal.

This would leave a slot in between the rear body and the bumper lid that rain water could freely flow down and out through the storage compartment, hopefully eliminating the chance of the floor rotting again.

I've done a search for any photos of this design but it seems no one has tried it, and posted photos.

I am looking for any comments or ideas for how most people improve this problematic area.

Thanks,
Christopher

this is what I did on my 67. The lid is held closed with 4 Earth magnets attached to the aluminum with a great product called Sugru. The floor of the bumper trunk is 1/8" perforated aluminum.

[HiJoeSilver]

Nice work!

I'm in the process of re overhauling my rear too. I think you took pictures of the flashing on my trailer, as well as the thin strip to fit between lid hinge and shell. I folded my flashing forward under the floor/hold down plate. Same tabs on the frame sticking out though I cut mine shorter and caulked under them. I have a tank pan that sticks out back there and drain pipes. I split the tank pan at the last cross member so water running down there wouldn't want to run directly into the pan and rust the new one through like the old one. Had to rebuild the storage pan too, used aluminum sheet metal having to go around the plumbing, now it'll hold my regular and an extension sewer hose and sewer connectors. Going to get it sprayed with linex or rhino at some point.