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Old 11-03-2015, 07:57 PM   #15
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I think by perimeter frame, they actually mean a "sub frame" in addition to the main frame. If not, then I'm not sure how that would work...

I suggest you build the main frame conventionally with two deeper main rails running the length of it, minus the A-frame up front. They should be about 4' apart. Say 6" deep box section or 8" deep I-beam section.

Weld the outriggers to these main rails, along with cross pieces every so often up the middle between the two main rails.

Across the tops of the outriggers, you don't need a frame so much as you'd want like a 6" wide plate, 0.125" would be fine, that would go all the way around the outer perimeter of the coach. The plate lays flat. The outside edge would just match the outside line of the trailer all around. The inside would extend inwards about 6".

To this 6" wide plate, along the outer edge, you would bolt down a channel. The channel would provide the stiffness that the flexibility of the plate might not give....but the plate doesn't have to be super heavy...the channel is strong in that direction.

The shell would bolt to this channel.

The floor would then sit inside the shell, on top of the 4-5" or so of plate that is remaining inside the shell. It's like an edge carrying platform all the way around. The center is carried by the outriggers and the cross pieces between the two main rails. Your tanks and stuff go in that space in the middle.

With the two main rails, your axles can mount conventionally.

If you dispense with the two main rails and try to just do a heavy frame around the outside, how would you attach the axles?

Personally, I'd ditch the rubber axles as well and go back to leaf springs. Unless you're going through the jungles of Africa or South America, leafs work great and they don't wear out.

On the axles, get heavy duty ones with big brakes (or even go disks with an electric over hydraulic unit...but not really necessary....just get the big drums) and heavy bearings but springs adjusted for the weight of your coach. Also put real shock absorbers on it.

Run 16" or better yet 17" wheels with E rated truck tires, and never look back.
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Old 11-09-2015, 05:43 PM   #16
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The perimeter frame would be a upside down "U" channel with 3/4" legs. Where ever it crosses a outrigger, a plate would need to be welded to the bottom. A flange then could be welded to the inside vertical leg for the plywood floor would rest on. The regular "C" channel would be bolted to this framework with a barrier in between the two dissimilar metals.
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Old 11-11-2015, 08:47 AM   #17
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Just read perryg114's thread from 2013. There was talk of using angle iron as a perimeter frame. Also saw tubular material bolted to the out riggers in an unrelated blog about frames. How difficult would it be to duplicate the end C channels in heavier steel u channel? Thanks again


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Old 11-11-2015, 08:51 AM   #18
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Perry, what was the end verdict and result of your frame discussion?


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Old 11-11-2015, 04:43 PM   #19
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Quote:
Originally Posted by Bullit View Post
Just read perryg114's thread from 2013. There was talk of using angle iron as a perimeter frame. Also saw tubular material bolted to the out riggers in an unrelated blog about frames. How difficult would it be to duplicate the end C channels in heavier steel u channel? Thanks again


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It would be labor intensive. Most likely have to take out Pie shaped wedges and weld.
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Old 11-12-2015, 06:14 AM   #20
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Would it be possible to cut a plate that would match the circumference of the trailer (matching the C channel) and weld that to the top of the out riggers? How thick would it have to be in order to accomplish a similar effect? The floor could sit inside the plate and the C channel. I like the idea of more outriggers and top plate, perimeter framing.


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Old 11-12-2015, 07:39 AM   #21
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As this has been nothing but an idea bouncing around inside my head and I have have not actually done it, (I don't think it has been done by any forum members) some engineering will have to be done to figure out how thick a flat plat would have to be to replace a channel. Or just add more outriggers
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Old 11-12-2015, 06:50 PM   #22
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I think more out riggers has been discussed at length and adding them is sort of a forgone conclusion. Channel or angle would be easy on the sides, it's the ends that bother me. In such a short trailer the ends must provide the majority of the strength. Thanks again for your patients and advise.


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Old 11-12-2015, 07:51 PM   #23
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Forums are great for discussing new ideas. I would guess that your frame is so bad that you need to take the skin off and build a new trailer. Frame repairs with the skin on are easy to do.

Redesigning can be very challenging, plenty of design decisions that aren't apparent until you change the design. It is amazing how just moving one thing can ripple around the whole layout.

Good luck.
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Old 11-12-2015, 08:16 PM   #24
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Yup, it's the corners that's the challenge.
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Old 11-14-2015, 06:41 PM   #25
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A perimeter frame would be connecting outriggers together and yes the corners would be hard without hydraulic benders. The object here is to provide a real structure for the shell and for it to be supported every few inches instead of at a few points at the front and back and at the tip of an out rigger. Yes it is overkill but you would not need to worry about a bike hanging off the back of the trailer.

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Old 11-15-2015, 07:30 AM   #26
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The problem with the Airstream is that it is an Aircraft fuselage that has been cut in half. The floor and frame are an attempt to replace that missing half. The shell is really strong because of a large moment of inertia. The frame is pretty strong but not as strong as the shell. If you can keep both of them from moving relative to each other, you make a very strong structure. The out riggers only contact the shell in a few places and since they are cantilevered, they don't have much strength. At most they support the floor at keep the shell from bulging out when stressed. Better support at the back and front all the way around the corners would probably be the easiest way to gain strength. We had one guy on here, Steve, who did something like this and I think another guy who actually built a perimeter frame. I will see if I can find some of these links and post them.

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Old 11-15-2015, 03:40 PM   #27
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Thanks Perry, I am a relative novice at all this and am definitely standing on the shoulders of Giants who have tons of previous knowledge, skills and most of all experience. I am absolutely going to have a frame built and want to try and get it right the for the first and hopefully the last time. I am currently leaning toward an 8 inch main rail with similar cross members. More outriggers and a top plate that will act as a perimeter frame. I will need to solidify a plan prior to talking to the trailer frame builder so long this conversation advice and sedate is very helpful.


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Old 11-17-2015, 04:43 PM   #28
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Depends on what you plan to do with the trailer as to how crazy you go on beefing it up. I have not had problems with my center bath. Rear bath might be another issue. Newer trailers had better full box beams. If you do what you are talking about, you could probably have a back porch on it or a big storage box. You need to be aware of tongue weight and beef up axles for the weight of the heavier frame. Good luck.


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