Rear hold-down plate necessity?

[vhord]

I am probably going to show my ignorance (it won't be the first time) but here goes -

Today, I decided that I needed to replace the poorly fitting angle iron that I had installed for my rear hold down. It was 90 deg. angle and the piece actually needs to be about 107 deg to fit the slope on the rear end.

IMHO - After taking a closer look at this section it appeared to me that the "rear hold-down plate" actually does very little to hold the rear down. Unless my memory is failing me, what was left of the original plate fit between the bottom of the subfloor and the aluminum sheet that the trunk lid attaches to, then wrapped around and was attached to the bottom c-channel. I would think that it should be attached to the frame to give any real hold down. At least that is the way the front hold down plate is installed and I can see how that actually helps.

Maybe I am incorrectly installing it. Anyone have an opinion or solution?

[Zeppelinium]

I'm surprised that the rear hold down is not connected as well as the front one. I have only dug into the front ends, but as you know, the front hold down is part of the frame, like welded.

If I had an Airstream longer than about 22', I'd think that the shell was holding the frame up (with all the tanks in the frame, you understand) rather than the other way around. I think I'd do my best to make it very secure.

Zep

[Aerowood]

I made a new one for my GT that was originally galvanized. I made it from .063 2024-T3 but extended outboard on each side to pick up the vertical frame and then clipped it to the channel. I have a picture at home that I will post

[vhord]

Originally Posted by Aerowood

I have a picture at home that I will post

Kip,

I would be very intersted to see what you did.

Thanks.

[Aerowood]

I said I was going to post a picture didn't I? Well I had an "old timers moment" and forgot. The picture is on my home computer, so I will try to remember tonight. Basically I ran a new aluminum angle out so that it went out to the vertical ribs, then I made small "L" angles that attached the rib to the "C" channel then bolts through through the "C" channel plywood floor and then through the aft cross member. I do have a picture of the new angle here though. The new angle is underneath the plywood. I routed out the ply so that the ply would set flush to the frame. There is a large amount of sealant between the the two pieces

[aaumpine]

Aerowood,

I'm presently in the middle of removing the deck in the bow area. Do I need to remove the plate in front to enable the plywood to slide in and out, or can I leave it riveted to keep the shell at the proper height?
Aaron
Sorry about the hijack

[Aerowood]

Check out my thread below posts #75 &77. The vertical plate is welded to the frame. I did not remove rivets from the plate until after the new floor was in, as it held up the fwd portion of the shell as you surmised.


http://www.airforums.com/forums/f381...nte-26902.html

[vhord]

Originally Posted by Aerowood

Basically I ran a new aluminum angle out so that it went out to the vertical ribs, then I made small "L" angles that attached the rib to the "C" channel then bolts through through the "C" channel plywood floor and then through the aft cross member..............The new angle is underneath the plywood.

Kip,

That looks very good but I am still having a problem. Not meaning to question your method but it appears to me that if the plywood is compromised at a later date (compression or rot) then it is going to allow the shell to flex upward or downward. Maybe if it were a steel angle and it was welded to the aft crossmember then it would be held permenantly. I visualize that the rear end seperation starts small then over time it continues to worsen.

I am probably making myself clear as mud and I am also overthinking this.

Aaumpine - you may need to chamfer the front edge of your plywood to help it slide in.

[vhord]

To further clarify myself if the floor was completely removed against the front wall the shell would remain rigid. If the floor was gone in the rear the shell would flex.

[Aerowood]

You are correct, but on mine the shell is so short the problem is'nt as magnified as the longer. I think that a welded on vertical plate like the front would be an excellent upgrade

[vhord]

I wish that I had thought of this before I installed my subfloor and crossmember. I am not sure if I can still accomplish it now. The new crossmember that I installed does not line up exactly with the slope of the rear wall. At the time that was not critical.

If not then I may have to live with the original installation although I still do not feel that it does much good. Thanks for your input however. I will install the angle clips to tie the ribs down.

Either way I am going to have to do something even if it is wrong so that I can put the rear back together and get on with this project.

[Aerowood]

How about some metal spacer blocks same thickness as the floor but installed between the "C" channel and cross member. You would have to bore clearance holes in the ply to install.

[vhord]

That actually crossed my mind. If they were inserted at the bolt points that would help. Some small pieces of 3/4" square tubing might do the trick.

I have as similar problem at the front corner of my trailer. I used the old floor for a pattern but did not realize that the factory cut it short. The C-channel on one side does not completely line up with the subfloor leaving about a 3/4" gap on the outside. I have been thinking of putting a spacer between that c-channel and the outrigger for support.

I have always had 20-20 hindsight.

[Aerowood]

I ran into the same issue and just bored a new hole closer to the inside edge of the "C" channel and then put a cutoff fender washer under the head of the bolt.

You know that the second Airstream will be a lot easier, now that I've made all the mistakes on the first.

[aaumpine]

Aerowood and Vhord,
A little late (I was reading Aerowoods thread.)
Thanks for the input.

[vhord]

I decided to use the "40 year rule" on this portion of my project. If it lasted for the last forty years at age 58 why should I worry about it lasting longer than that!

Therefore, I fabricated an aluminum 1-1/2" x 2" angle (106/74 deg.) out of .100" aluminum and installed it like the original.



(BTW - I know that I have still not removed that trailer bracket from the bumper - but I will when I find one of those round-to-its!)

When I first reworked my frame I added a couple of angle iron clips to the outside of the frame.



With that additional support and with the addition of this flashing that I had previously fabricated and a little bit of Vulkem I think it might last long enough for me.

It's time to move on to bigger and better things.