Advise Please Rear Hold Down Plate

[Tony S]

Hi all,

I hope some one can help me. How do I get the old rotted out hold down plate out. More challenging I suspect how to get the new one back in?

I have cut away the old sealant and the rivets are drilled out and/ wacked with a sharp chisel. But the plate isn’t moving. Could someone told me how they did it

Mine is a 1973 vintage

In advance many thanks

Tony

[Tony S]

Howdy folks

I got the old eat n away hold plate out. It fell apart or bent it straight. Now the hard part. Anybody got one back in without taking out the buck rivets? How?

Any help would be appreciated. I will post pics when I get to my camera.

Thanks

Tony

[barts]

Clearly the line of rivets connecting the skin to the C channel in the rear have to come out, since those go through the steel plate.

I tore out the bathroom to fix the rotted floor, so I was able to remove and replace the hold down plate from the inside, rotating it around the C channel and under the floor. You'll need to loosen and remove all the bolts holding the C channel to the floor, of course, since those go through the steel plate as well.

I replaced mine with stainless. I didn't have access to a brake, so I use a chunk of heavy angle and lots of c-clamps and a large soft hammer to bend the stainless sheet to the desired degree, walking the blows up and down the bend line. Not perfect from a cosmetic standpoint, but w/ any luck no one will see it for another 40 years , by which time it will be Someone Else's Problem (TM).

I've appended a drawing of our fix; since the aluminum skin was badly corroded around the C channel I added a doubler behind the original skin. I also added an additional row of rivets 6" or so above the floor to tie everything together. It's rock solid now . Note also that the plate that holds the hinges for the rear storage compartment must not be used; figure out something else, because that is the source of most of the trouble with these years of trailers; the sealant goes under the trim and water wicks under the floor, where it sits against the plywood and steel hold down plate - presto, instant rust and soon, rotted floors and rusted tiedown bolts.

[Tony S]

Thanks Barts great information and thanks for the drawing. You gave me some of this information as an answer to an earlier post which gave me an idea of how to approach it. The addition info and drawing will pretty much do the trick.

I think it will help a lot of others, too.

I too am planning to go with stainless steel. My skin is corroded some around the c channel and I will add a doubler.

QUESTIONS: Did you use buck rivets for the new row of rivets, 6” above floor?

Did you use a particular aluminum to reinforcing for the skin?


Tony

[Chuck]

Originally Posted by barts

...figure out something else, ...

and what did you do for this?

[Tony S]

Chuck what did you do on yours?

Tony

[Chuck]

well...nothing, yet. That's why I asked.

There's a fair amount of corrosion on the skin back there along the rivet line; The plate itself has some, but I can't see that much of it. My bil replaced the rear cross member last fall; the hold down plate is still riveted in as it was by the factory. He said it didn't look bad.
I'm inclined to take it out, anyway, and do as is described above. I've been squeemish about it because I don't have rivet-bucking skills (or tools), so not sure if I'd be able to get it back in! (lol).
I was thinking I should just bite the bullet, and go for it; while I'm at it, un-buck the rivets holding the shell to the u-channel and slip a strip of flashing in between the outer skin and u-channel that will hang down and cover the exposed plywood floor edge.
The real puzzle, though, is how to close out the bumper cover, and protect the plywood floor edge along the back of the trailer. The area between the outer edge of the hold-down plate to the outside edge of the frame rails is not a straight line, so you can't use a straight piece of 90-degree angle flashing.

[barts]

Originally Posted by Tony S

Thanks Barts great information and thanks for the drawing. You gave me some of this information as an answer to an earlier post which gave me an idea of how to approach it. The addition info and drawing will pretty much do the trick.

I think it will help a lot of others, too.

I too am planning to go with stainless steel. My skin is corroded some around the c channel and I will add a doubler.

QUESTIONS: Did you use buck rivets for the new row of rivets, 6” above floor?

Did you use a particular aluminum to reinforcing for the skin?


Tony

Yes, I used buck rivets. If you have the air hammer, it's not difficult although practicing a little on something less visible won't hurt. I'd
never buck riveted before by

I had a piece of 50XX series sheet, prob. 050 or so, that I used as a doubler. 6061 would work also - it just needs to be corrosion resistant., it doesn't show. 2024 would also do, of course.

- Bart

[barts]

Originally Posted by Chuck

and what did you do for this?

Well, I used a piece of heavy 6061 T6 alumnum angle I got surplus between the frame rails. It definitely made the opening smaller, but I can still get the slinky in and out, so it works. The trick is to leave a gap so the water can drain readily into the bumper compartment and then out via the holes and gaps in the belly pan.

- Bart

[Tony S]

Thanks again Bart.

I cleaned up the corrosion with sand paper and wire brush does it need any type of treatment applied? Is what remains still active if the cause has been eliminated

I will let you know what I end up doing for the bumper box lid. Lance in his post about Abbey gets some separation H

http://www.airforums.com/forums/f36/...-73643-34.html

Shows what he did, which was leave a gap. I wonder if some step flashing set up would work as an alternative.

Tony

[wahoonc]

Originally Posted by Chuck

The real puzzle, though, is how to close out the bumper cover, and protect the plywood floor edge along the back of the trailer. The area between the outer edge of the hold-down plate to the outside edge of the frame rails is not a straight line, so you can't use a straight piece of 90-degree angle flashing.

I am going to use a flashing that is formed to fit using a shrinker/stretcher and Eco-Bender which will allow you to put a bend along a curve.

It will go in where Bart has the blue piece in his drawing.

Aaron

[Tony S]

That eco Bender is real interesting. Did you find an outlet in the USA?

Went out and bought some material for the job. Tomorrow will see about getting started.

I cleaned up the corrosion with sand paper and wire brush does it need any type of treatment applied? Is what remains still active if the cause has been eliminated?

I am going to use PVA tape around any disimilar metals. It is thick and is used to wrap gas pipes around here.

Tony

[Frank's Trailer Works]

I would like to suggest you put a barrier between the steel and aluminum. I have used phenolic sheeting a few times now.

[wahoonc]

Originally Posted by Tony S

That eco Bender is real interesting. Did you find an outlet in the USA?

Went out and bought some material for the job. Tomorrow will see about getting started.

I cleaned up the corrosion with sand paper and wire brush does it need any type of treatment applied? Is what remains still active if the cause has been eliminated?

I am going to use PVA tape around any disimilar metals. It is thick and is used to wrap gas pipes around here.

Tony

We have 3 of them at work, 2 different sizes, no clue where they came from. There used to be a company in Raleigh, NC that sold them. Did not realize my link was to a company in AU

Aaron

[Tony S]

Well made some nice progress today. Thanks for all the help

I didn't get stainless steel for the hold down but did use PVA tape as a barrier. I also use the doubler plate of aluminum, basically as per drawing. This 6" piece of Aluminum is stout it drops down below the angled hold down and will channel any water for its length below the plywood. I will do two rows of rivets through the new taller hold down plate. One as the originals, the other above them about 3 inches.

You can also see in picture the reenforced last cross member with some plate steel. The previous owner made a modification this makes it stronger than ever and steel allows some flex.

The 4th picture show the 6" aluminum doubler behind the hold down plate and above the yet to be welded plate steel over the x member.


Again thanks for the help. I hope there is not any glaring problems and the pictures helps someone else.

Tony