Rear End Sag on 2005 28' CCD

[tyggeln]

My apologies for starting a new thread, if it belongs somewhere else. I've been following the thread below on cracked/broken frames just after the axle for 22' CCDs.

I've got a 2005 28' CCD. I measured the tongue weight with a Sherline scale and came up with 1050 lbs (empty propane tanks). I tow with a (seemingly reasonable) Yukon 3/4 ton plus 1200 lb equalizer WD hitch. My A-frame may or may not be bent. My trailer I guess has more than a couple things wrong...

http://www.airforums.com/forums/f36/...-48105-17.html

I've followed threads on rear sag, and floor rot and rear separation and the appearance of my TT has me a bit worried. So yesterday I made measurements. After carefully leveling the trailer (making height fwd of axle and just fwd of entry door). Including the height of the tape measure, the rear end frame was about three inches lower than at the center of the trailer. Although my wife can't tell, I have the definite feeling of going downhill when moving aft into the bedroom area. I don't seem to have a large number of rivets popping loose so perhaps that's a good sign.

I've attached a side view. There does not appear to be separation at the rear end, but I've got more inspections to perform.

Full disclosure: in order to reduce tongue weight, I used to usually put all my heavy stuff in the rear storage. I've since moved the heavy telescope gear under the bed and closer to the axles (AP 1200 Mount is 119 lbs, Celestron 14 OTA 48 lbs, Monolith pedestal is approx 50 more, three counterweights stored in the front of the bed are 3x18lbs or 54 more lbs plus battery 41 lbs.) Add about 150 lbs for clothes etc that invariably ends up aft and about 460 lbs while towing is aft of the rear axle. from elementary physics, and the distribution of the load, this applies the same moment as about 200 lbs hung off the back bumper.

Couple of questions assuming I can keep weight distributed to the axle area;

1) Does it need to be fixed?
2) If so, how much typically will this cost to fix and what is the general procedure?
3) If so, can it be towed/used while I save for the repair?

I'll add photos as I get them to look for more damage.

Chris

[ROBERT CROSS]

Chris,

I've 'kinda followed that outrigger/frame failure thread also.

From your pic it sure looks like the rear is drooping, (not related to the outriggers).
If in fact the frame is bent the cause could very well be the extra weight you were carrying in the rear.
I have always been told, and do load anything heavy in the front of the coach for proper balance. Forward weight can be transferred back to the axles with the WD bars. No stress on the rear of the frame.

It would seem though that if the frame WAS bent you would see some buckled skin evidence popped or loose rivets.

Anything showing up inside? Flooring, cabinets, that would indicate a droopy rear.

Comparison...our 25 Classic "loaded" for 'dock'n. 15960lb combined wt.
1175lb tongue wt. 7640lb trlr axle wt. hitched with WD set.

Bob

[perryg114]

Well look down the side and see if the seam is running down hill. Also you can get a cheap laser pointer and sight the floor with it. A laser level will do as well. You can level it and make measurements from the laser to the floor. If you have a lot of sag the floor won't be flat left to right either. The floor will be lower in the center and high at the edges. This gets worse the more sag you have as the outriggers begin to bend. Depending on what you find, I would pull the belly skins and look for cracks. If the outriggers are not bent real bad I would expect a few hundred to fix. Welding a small square plate just behind the axel is not going to fix the problem. You really need something that is going to span a foot or so on each side of that crack that is almost as strong as the original frame. Making welds at 45 degree angles will help as well. If something is going to break it will break at a weld or other area of stress concentration like a hole or cross member location or axel attach points.

Perry

[tyggeln]

Originally Posted by ROBERT CROSS

Chris,

I've 'kinda followed that outrigger/frame failure thread also.

From your pic it sure looks like the rear is drooping, (not related to the outriggers).
If in fact the frame is bent the cause could very well be the extra weight you were carrying in the rear.
I have always been told, and do load anything heavy in the front of the coach for proper balance. Forward weight can be transferred back to the axles with the WD bars. No stress on the rear of the frame.

It would seem though that if the frame WAS bent you would see some buckled skin evidence popped or loose rivets.

Anything showing up inside? Flooring, cabinets, that would indicate a droopy rear.

Comparison...our 25 Classic "loaded" for 'dock'n. 15960lb combined wt.
1175lb tongue wt. 7640lb trlr axle wt. hitched with WD set.

Bob

Bob - I have not seen buckled skin, or found a lot of popped rivets lately. The floor just aft of the bathroom/axle area seems to slope down; I can feel a ridge, but my wife cannot. Measurement is in order. No cabinets at that location, but some mismatch in the bathroom door that may be related. Shower door seems a bit tight also.

Maybe unrelated, I had issues with the overhead storage in the rear coming down, which I fixed last summer with more and bigger screws into the interior skin. That arrangement seems kind of sketchy so I have reduced the weight stored up there. Just a few pillows or down jackets allowed.

I used to carry more weight further back than I do now in the exterior compartment (now it goes fwd). Moving a 41 pound battery from the rear to the axle area is like moving 320 pounds one foot inward just aft of the axles. So any heavy components need to come out of there (truck and trailer tire chains, extra battery, two bottle jacks, 6 foot folding table which I was going to get rid of) and I've reduced the load back there by a couple hundred pounds. All I will put in there now are lynx blocks, outdoor patio rug, bow saw, shore power cable, potable hose, 4xaluminum jacks, . Probably more room for improvement. Maybe allow folding chairs. Only store wood blocks in the bumper.

The under bed storage is too attractive for storing my stargazing gear, that I'd hate to give it up. Hopefully it was the storage of heavy items in the exterior compartment that did me in, since my stargazing gear is all in the interior compartment, and mostly in the fwd half of the under bed interior compartment. If a few bicycles and a cantilevered rack can damage the frame, it seems really critical to get mass out of the exterior compartment and the overhead storage. If need be I can move the AP1200 mount and counterweights fwd to the truck bed - worth almost 180 pounds.

I also need to do what I can to reduce the acceleration at the aft end, and reducing the WD force by weaker load bars or less tension. This would also seem to help with potential A-frame damage I'm also evaluating.

I wonder, is there a spec for allowable cargo moment arm loading aft of the axles?

Chris

[tyggeln]

Perry - thanks great feedback and ideas. I have attached a view looking down the trailer. I think you can see it sagging.

I would hope that the damage is limited to a few hundred bucks and that all I need to do is to restore the level plane and then weld in structural plates or else use the airstream kit. Labor and the right setup would be the key. I haven't really taken it anywhere with this damage, and so knock on wood the damage is not severe.

I like the idea of the laser pointer/level as it will allow me to restore the level real time. My plan would be to raise the frame on blocks and fine tune with wood shims. Any thoughts on this method for regaining alignment?

Chris

[perryg114]

It looks ok to me. There has to be some finite amount of sag back there. The only way to get rid of all sag is to have some extra wheels back there. The question is whether or not you have more sag than normal. Any beam will deflect under load a finite amount. Unless there is a bend like an upsidedown leaf spring then you are going to have some sag. I don't think Airstream made the frame with an upward bend to it to compensate for sag. For example, when I cut the frame loose from the body of the trailer when I replaced the rear floor the frame dropped about 3/4 of an inch. The body supports the frame and the frame supports the body. I could jump on the frame and it would deflect more but it always came back to where it was as it should. An Airstream like an airplane is a dynamic structure. It twists and bends and distorts. If the tail did not droop some you would need to think about that.

If the rear of the floor is not more than an inch lower than where the wheels are I would say you are good. It won't hurt to beef it up even if there are no problems.


Perry

[Wabbiteer]

What's a string pulled taut down the length of the interior floor look like?

You see any movement hopping on the rear bumper (gently!)?

[tyggeln]

I haven't been back to the forum for a while...but thanks for all the helpful suggestions. I took the trailer to a un-named Airstream dealer for evaluation and estimate back in 2012 and after removing the belly skins they indeed found a cracked frame. The total damage assessment came in at about $11, 000 (!!)

A couple months later and they claimed fixed, and the dealer claimed they had beefed up the "joints" strongly to avoid any issue later. Alas, I was not happy, as the floor was still not ~flat (still a ridge under the linoleum). I talked to the insurance co (USAA) and they said for $11,000 the dealer had better make me happy.

Joint was reworked by dealer, and the floor appears to be flat (no palpable ridge under the linoleum). That was after several weeks...and yuckko when we got the rig back in June, we found that rodents had moved in while they had the belly skins off. They spent several hours cleaning and vacuuming and were glad to see us go.

The outside band still seems to be a bit out of alignment, and probably is beyond any skillset to make perfect, and the bathroom door frame seems a bit wider than it should be. I will need to work on the bathroom door as its got me worried about the latch engagement.

Nothing is ever as perfect as it was.