Roof dents appearing

[Silverflames]

Hey all,


I just finished a rear end separation rear about 6 months ago. On our camping trip this weekend, dents are appearing on the roof around the area of the AC unit. When the sun goes down and the metal cools down the dents go away. I had put some jack stands under and thought that might have been the problem. Now it's just still n 4 wheels and the tongue jack. Any ideas?

[perryg114]

I expect someone stood there and bent something a little and it pops out when it cools off. Not much you can do from the outside.

Perry

[eubank]

You know, we had some of those near the AC on our 67. You can easily pop them out with a toilet plunger, but they just pop right back in. So I thought and thought and thought. Considered expanding foam inside the wall, but that's hard to control and could wind up doing more damage than good. And finally came up with an alternative: I bought some small springs from the hardware store, removed some interior rivets below the dent, and wound the springs into the rivet holes just enough to put some mild push upward on the dent. Cut off excess spring, push through the remainder, and reinstall the rivets.


Lynn

[Silverflames]

Originally Posted by eubank

You know, we had some of those near the AC on our 67. You can easily pop them out with a toilet plunger, but they just pop right back in. So I thought and thought and thought. Considered expanding foam inside the wall, but that's hard to control and could wind up doing more damage than good. And finally came up with an alternative: I bought some small springs from the hardware store, removed some interior rivets below the dent, and wound the springs into the rivet holes just enough to put some mild push upward on the dent. Cut off excess spring, push through the remainder, and reinstall the rivets.


Lynn

Would your dents come and go with the heat?

[eubank]

Nope, they just kind of stayed put. On the other hand, we don't exactly get a lot of hot days here.

Lynn

[Wazbro]

The aluminum may have been stretched by someone walking on the roof and/or the rear end sag that you repaired (back of trailer being held up by roof).

Some have complained about the same thing (dented/warped when warm/in sun fine when cool) on the sides of new Airstreams, others have no problem with it. My theory/guess is the new trailers with this problem were built when the factory was colder so the aluminum was contracted when cut to size and riveted in place.

[Silverflames]

Originally Posted by perryg114

I expect someone stood there and bent something a little and it pops out when it cools off. Not much you can do from the outside.

Perry

Yea after the roof cooled, looking closer there is is two slight dents there. They just look much worse when the metal is heated up. I also cut out a 14 " hole and framed it in for the AC in that's area. The top is rounded, except for the AC section and it is forced straight. I wonder if that could be making the problem worse?

[Silverflames]

Ok guys and gals, I might be way over thinking this thing, and making myself crazy. I measured the rear frame of the bumper truck area, were I replaced the frame to fix the rear end separation. It appears that there is about a .25" difference from the driver's side and the passenger side (after being bolted down). I measured from the top of the frame for the bumper trunk to the bottom of the aluminum skin. It looks like the curb side is a little lower. It's not much right under the rear trunk area, but gets larger further you get closer to the edge of the trailer. You can't even notice with the naked eye.

I measured from the ground, and there was about a 3/8-1/2 (uneven ground) height difference from the bottom of the frame rails. Could this much of a difference be causing the body to twist in the heat? I have been trying to image how a slight twist (one side being to high or to low) could effect the shell, and cause dents in the middle of the trailer on the driver's side, and 3/4 of the way down on the curb side.

Only to make things more colluded, while repairing the rear frame, I set the bathroom on fire. So there may also be some heat damage. But that is nowhere near the AC and middle part of the trailer.?...

Also It should be noted that while I have the trailer back in shade the dents are pretty much gone.

Well any thoughts would be great. I'm hesitant on moving forward with the flooring and new bulkheads.

[Belegedhel]

When you did your rear frame repair/replacement, how much beefier did you leave the frame? One proposed explanation I would have is that once the (original) frame and shell form a unit, the whole thing is engineered to expand and contract at roughly the same rate.

Perhaps you have beefed up the rear of the frame so that it no longer expands and contracts at the same rate as the shell, or maybe, you have stiffened it up. When the shell gets hot, instead of the entire trailer growing a fraction longer, maybe the shell is expanding further/more rapidly than the frame in which case it is causing the roof to buckle, since it has nowhere to go.

I might soon have the same problem, as I stiffened up the rear of my frame during a RES repair as well.

good luck

[Belegedhel]

If you still have access to the bolts that attach the rear C-channel to the subfloor, you might try loosening them up and see if it makes any difference--just for the sake of experimentation. You might also try standing on the rear bumper when the dents appear and see if some weight back there helps stretch them out.

[dkottum]

The aluminum probably stretched some with the rear separation, and you have pushed it back with the repair.

Aluminum expands and contracts with the heat of direct sunlight and shade. Our new Airstream "oil cans" in the sun. The least of our concerns.

If this is the problem, and it probably is, I wouldn't lose a wink of sleep over it.

doug k

[Silverflames]

Originally Posted by Belegedhel

When you did your rear frame repair/replacement, how much beefier did you leave the frame? One proposed explanation I would have is that once the (original) frame and shell form a unit, the whole thing is engineered to expand and contract at roughly the same rate.

Perhaps you have beefed up the rear of the frame so that it no longer expands and contracts at the same rate as the shell, or maybe, you have stiffened it up. When the shell gets hot, instead of the entire trailer growing a fraction longer, maybe the shell is expanding further/more rapidly than the frame in which case it is causing the roof to buckle, since it has nowhere to go.

I might soon have the same problem, as I stiffened up the rear of my frame during a RES repair as well.

good luck

Yea, I am the master of over kill. Every part of the main frame rail I have replaced has been with galv 1/4" thick 5" tall C channel, and I added 3" more inches of depth to the frame from the back wheels to the trunk area. So the the frame is pretty ridged 8" tall. All tied together with 1/2 " SS bolts.

You bring up a good point about the frame not expanding like the rest of the body. Possibly compounding with the body that has been stretched from years of a giggly lose back end. That is much more likely to cause the dents than the body being twisted. I'm guess I'm just worrying over nothing here. Loosening the bolts and setting it in the sun is a good idea.

[Silverflames]

I just wanted to add a pick of the frame.


The second is before I bolted it down.

[Belegedhel]

Looks like good work--quite burly! Do you notice any other (possible) effects of a more-ridgid-than-original frame (ie., popped rivets, skin cracks, etc.?

[Silverflames]

No cracks, popped rivets, or other issues so far. Since it has been home and in the shade all the dents have gone away. When we set it up at the camp site I lowered the AS down on car stands, and then added some pressure on the tongue jack. I'm wondering if putting so much weight just under the door and with the new more rigid frame twisted the body up? Or if its just stretched metal expanding with no place to go. Just sitting in my yard, in the shade it looks fine.

Another thought it could be the AC unit. When I framed it in its pretty square and flat, vs the curved roof. Most of the dents are right there..

The black is the new 1/4" main rails, the striped 1/8" angle to cover the holding tanks, and the open/white is the original main rails. They are much thinner, and More flexible.

[Lumatic]

You could have a cracked frame above the axles.

[Silverflames]

Originally Posted by Lumatic

You could have a cracked frame above the axles.

Yea t thought about that.... That's what another idea that was bugging me. More frame work.. Scary thought. I still have the belly pan off on the Back end, I'll try to check.