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Old 05-21-2006, 12:09 AM   #1
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Weight Reduction Remodeling Methods

Ok this is a topic that comes up in passing within threads quite often. Seems it deserves it's own coffee table chat time.

So let's hear ways, decisions and ideas you have for lightening the weight of a trailer during remodeling. Small or large every pound counts when you are needing to count your towing bottom line. I know for some people this never comes up, for others it is a everyday struggle.
I personally have a 71 Caravel that is about to be totally redone over the next few years. One of my goals is to make it the lightest it can be and still be a fully functioning home away from home.
My thinking is that with today's community and the technology we have access too we have the chance to look at every part of our trailers and upgrade were it is warranted. We already do this in many many places, let's now give this focus to the weight issue.
I would love to hear what people have done, hopefully with before and after weights. Products you have found and want to share. Have you found a replacement for a material or technique for streamlining a part, let us know!
Let the discussion begin...
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Old 05-21-2006, 07:35 AM   #2
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Aluminum instead of steel

Aluminum wheels are lighter than the steel wheels on your Caravel, as are aluminum LP tanks. Total weight reduction for those items alone are about 15-20 pounds.
You can get a lighter A/C unit than the OEM Armstrong unit, and save another 15-20 pounds, although I think I would wait for the Armstrong to bite the dust before replacing it.
You can eliminate the 3 burner stove and oven with a two burner cooktop and small microwave, and save another 15-20 pounds.
These three suggestions could save you up to 60 pounds, if you feel they are worth the effort and expense.
You could also remove the cast iron, enamel coated sink and install a smaller single basin there, probably only saving a pound or two, but a pound here, and a pound there, will add up in a cumulative effect.
Newer fridges are probably slightly lighter, as well, but you would need to weigh a replacement before installing to be sure of this.
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Old 05-21-2006, 09:04 AM   #3
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Light Weight Partical Board

I was thinking about the same concept when I restored the inside of the GlobeTrotter.
While I was snooping around the local exotic hardwoods store looking for the ash to rebuild the gaucho and table I ran across a product called lightweight partical board. The claim is that it's 40% lighter than the regular.
I bit, and used it to rebuild the table. Weighing before and after showed it gained a pound over the plywood.
You might be able to save some weight using lighter weight wood like spruce for the framing of the cabinetry and beds. Use thinner veneer plywood and saving the oak or mahagany for the face frames.
Who knows, there may be someone out there thinking of titanium and anodized aluminum as an alternative to wood.
Tom.
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Old 05-21-2006, 09:09 AM   #4
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Aluminum Frame will give you a huge savings

Hi,

Don't know how far you're willing to go, but if your current frame is half rotted away and you are willing to go all the way, you could make a new frame out of aluminum. Aluminum is just about 1/3 the weight of steel.

I've half considered doing this with my own coach. My frame is showing some "sag" and I'm looking to redo the whole unit. I've got a friend who runs an RV frame making shop who was going to make me an 8" deep sectioned frame. This would add about 200lbs total to the weight of the coach but the frame would be about seven times stronger. It's not easy for him though, and it's been put on hold, because the industry standard size is about 6" wider than what the older Airstreams used and it wouldn't work with his production jibs.

So if I wind up doing it myself, I've been considering doing it in aluminum. I haven't priced it out yet, but with the way steel has been increasing, it may not be that much more.

Anyway, if you were to go that route, I'd recommend a channel section that's 6" deep and with 3/16" or 1/4" thick walls. 6061 would probably be OK but if you can get 2000 series it'd be alot stronger. Zinc Chromate it all after you get it together and then paint over that.

Oh yeah, you'd want to rivet it all together as well. If you weld aluminum, it wipes out the heat treat and you lose all the strength. But, it'd be easier to build it using rivets. Just design the connections so the rivets are being sheared and not loaded in tension.

Now that would be one cool aluminum trailer!
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Old 05-21-2006, 09:33 AM   #5
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An empty shell and sleeping bags. We did that. We dubed it Alumatent.
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Old 05-21-2006, 10:53 PM   #6
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hello jimgolden,

That aluminum frame sounds interesting,.i would be concerned about the strength over the span or the length of the frame.It must be capable of retaining that rigitity or rather not sagging ,or cracking ,too high a rating in hardness the possibility of cracking is a reality ,Id have to look into other industrial uses of this type to see what could work .It would be cool though.
As a person who has experience in riviting grumman olsen aluminum van bodys
I wouldn't say it is easier to rivit an aluminum frame than welding a steel one.It is possible your frame guy could reinforce your steel frame without the deeper channel thats causing it not to get done,the weight difference shouldn't be to different steel for steel ,reinforcing it in key areas versus the 8" channel ,boy that would be heavy.

Scott
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Old 05-22-2006, 07:09 AM   #7
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Be aware that I am asking these question to spur idea's for everyone not just my trailer. Thanks for the conversation.

Overlander63- i have done or already plan on doing everything you listed, so we are on the same page there.

Jim- Have you looked at the strength comparisons with a Alum. frame? is that really a workable option? Are you saying you would rivet the frame itself? Although i think this is too far for me to go right now, I'm fascinated. One of my goals with finding new materials to use is to make the whole trailer as maintenance free as i can. This means i am researching non wood floor options and i have always wished i could rid myself and my TT of steel.

Tom- I am looking to find totally new things to make cabinets out of. metal or cool plastic fronts are likely for the Caravel, there is no love loss with wood and myself. I have been thinking of ways to make the lightest weight frames too, will talk more about some ideas in another post. Sorry the particle board didn't end up quite as light as hoped, i guess 40% lighter than really really heavy is still pretty heavy.

Keep it coming, what have people already done? what have you done that maybe turned out a heavy bad choice?
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Old 05-22-2006, 07:20 AM   #8
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The floor, the floor. Composite panels to replace the floor. Buy a vacuum bag, enough Balsa wood, ect to make your own floor. Could incorporate a teak Wood panel for the finished floor. This is the money is no object blow away all vintage tourists option. You would want to do a little reasearch but I think polyester is the appropriate resin rather than epoxy, but I'm still trying to figure that out.
Could use a similar approach to wall sections, bed frame, ect.
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Old 05-22-2006, 08:24 PM   #9
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More on the aluminum frame

Howdy all,

Big truck and trailer companies make aluminum frames all the time. My dad retired from Mack and they offered aluminum frames for years.

The steel they make virtually all auto frames out of is 36 ksi, or rather it has a yield stress of 36,000 psi. I'm sure Airstream uses the same steel.

2000 series aluminum, which is what most airplanes are made of has a yield stress of about 45,000 psi, so it's actually half again stronger. 2000 series aluminum has pretty good fatigue properties, not too bad corrosion properties, and pretty good strength properties. 2024 is the most common alloy used in this series. It is a good all around alloy. If you're going to use just one alloy to build your plane, this is the one.

If you are willing to sacrifice some strength for improved corrosion performance, you'll want to use 6000 series aluminum. Here, 6061 is the common alloy. It has a yield stress of around 30-35,000 psi, so it's about the same strength as the steel commonly used in the auto industry. It has very good corrosion resistance, very good fatigue resistance, but is lesser in strength.

If you want superb strength over all else, look to the 7000 series aluminum alloys. 7075 was the old standby for years for high stress applications, having a yield stress of over 70,000 psi. The downside is that 7000 series, in general, is more corrosion prone, and it's far more fatigue prone. You have to keep an eye on it for cracks, but it's the one to use for highly stressed areas. Now, about 10-15 years ago they came up with a new wonder alloy, 7050, which has the strength of the 7000 series but with the superior fatigue and corrosion proofness of the 2000 series.

I am not sure exactly what Mack used, but most of the ones I've seen advertised said they used 6000 series. I'm sure it was for corrosion protection. Boeings don't deal with much road salt... I saw a big flat bed trailer just the other day with an aluminum frame.

Aluminum is just over a third the weight of steel. You're going to have to use heavier gauge metal to prevent local buckling than you do with steel, but you'd still wind up with a frame weighing about half what the OEM one did.

I don't know how to weld very well, so for me personally, riveting would be easier. But if you know how to weld, it'd be easier to weld up a steel frame. You can weld aluminum, but if you do, it reduces the metal to it's base strength, which is much lower, like 12,000 psi. If you design it to operate at that stress level, then it's just fine. But if you want to use the higher strength aluminums, you can't weld it or you'll ruin the heat treat (like T3 or T6, etc.) that gives it its strength. That's why they don't weld airplanes much. Boeing was looking at friction welding, but I'm not sure how far they got with it and I don't think they used it much in structural areas. Still just good old fashioned driven rivets.

Aluminum will corrode, but if you treat it (zinc chromate, powder coat, etc.), you should be in good shape. The only concern I would have is where the tongue mount plate fits to the A-frame up front, but you could do things to accomodate this. Thick plating and heavy painting between the steel tongue plate and the A-frame and the use of stainless bolts would probably take care of the galvanic corrosion.

I'd make new body mount channel and bolt it directly to the outriggers and not through the floor. I'd make the channel out of .040 or .050 aluminum plate. Get a guy with a brake to bend it. Actually, I'd run a 1/4" aluminum plate 6" wide all the way around the perimeter and then bolt the body mount channel through this plate and to the outriggers, with the overhang of the plate to the inside. I'd then run the floor out to and over this plate, butting up against the body, and bolting to this plate on the edge. Now if I ever needed to redo the floor, no more pulling the body. And no galvanic corrosion of the body mount channel to the outriggers because it's all aluminum.

Aluminum is expensive, but steel have about tripled in price the past couple of years. I don't know if aluminum has gone up as much or not. It might be a wash.

On the new steel frame I designed for my own trailer, it's only 1/8" thick so when I run the numbers, I'm only adding about 150-200lbs max to the overall weight of the trailer. The deeper section gets you more strength than a thicker one, for a given weight. The 8" frame is nearly 7 times stronger than the 4" one, and only adds about 170lbs. The hold up is that all of my buddy's production jigs are set up for a wider frame. 67.25" (I believe that is the figure) is the industry standard for frame spacing. Basically everybody but Airstream uses this. Airstream might even use this now, but not on the older ones. I could make this work on a newer widebodied coach, but on my '77, it's 6" more narrow than the new ones. To space the frame rails that far apart doesn't allow me enough room to fit the wheels inside the shell. I'd have to flare the fender area out like a dually pickup and I think that'd look kind of goofy. So I'm not sure if he'll be able to make me one or not. I've not pressed him, as it's a favor type deal. I'm sure he could make it, but it'd be a lot harder to sequence it in since it wouldn't work on his standard jigs.

If I did an aluminum frame, I'd use minimum 6" deep, but probably 8" deep, aluminum channel or I-beam (whichever I could get easier) with probably a 3/16" thick web and 1/4" thick flanges, with the flanges being 2" wide. I'd probably use 6000 series aluminum. It'd be as strong as the steel, but have good fatigue and corrosion proofness. If I could score 2000 series at a good deal, I'd use it. Not sure on 7000 series. If I got a good deal on it, maybe. I'd probably want it a little thicker just to avoid fatigue cracks. I'd run 1/4" thick by 2" wide strips across the top of the rails to form the tops of the outriggers, then rivet in gussets to these strips and to the frame's vertical webs, making the triangle shape. Axles would bolt on like normal. Everything else would pretty much go together the normal way. I'd use full depth angle for cross members, of about the same thickness. I'd put the lips down on most of the angles to make it easy to put in supports for holding tanks, etc. I think it'd make a heck of a frame. I'd then zinc chromate and then paint the whold thing.

I should probably just sell my '77 and buy a newer one with the 5" frame (mine has the 4" one), but I'm kind of attached to it. And, mine is showing no separation and only the beginning of the sag, so it's not bad yet. I probably shouldn't even be considering any of this, but it sure is fun to build stuff! I could probably patch it up, but it looks to me that to do it right, I have to tear out half the trailer anyway. If I'm going to go to that length, might as well do the full monty!

Anyway, hope this helps.
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Old 05-22-2006, 08:31 PM   #10
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I have owned several boat trailers with 100% aluminum frames. The only steel was in the springs, axles and brake hardware. Also, the boat trailer frames were welded, not riveted.
Also, your coach has a steel bumper, they are available in aluminum. Hey, 5 pounds is 5 pounds.
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Old 05-23-2006, 01:02 AM   #11
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Hey Jimgolden,

yor a wealth of good information ! I know trucks have aluminum frames on some as do the semi trailers .You would need to be experienced in the correct riviting type and procedures that I would think a factory would have to put that frame together and have it be structurally sound.You mention fatigue cracking and that is what I am talking about.It sounds like you have a good grasp on aluminum and its properties for sure.It sounds very expensive to do what you have described and Im certain it would be as the labor would be the big dollars ,this kind of fabrication and riviting a custom frame needs to be done correctly and a frame jig is a must here.I would go for the steel frame myself .given your knowledge ,what would be your estimate to have it built,time matrials and labor at todays rates of 65 to 85 per hour ?

Scott
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Old 05-23-2006, 11:27 AM   #12
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Materials for cabinets

Hi, I am currently looking for materials to use to replace the cabinets in my '74 Tradewind. I want light and environmentally friendly. I will also be building a dinette and replacing the flooring. I like the look of bamboo for the floor, but I am afraid it is too heavy. I have considered cork, but I find the patterns too busy in a small application. Any thoughts? Also, what is a good light wood to use for cabinets? I have seen some pretty (bamboo, birch) plywoods at the local environmental store. I would love some ideas. I have found someone experienced to do the work, as soon as I make some choices! Thanks for your ideas. Pam
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Old 05-23-2006, 11:54 AM   #13
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When I dismantled my Overlander I removed about 100 lbs of mouse droppings.
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Old 05-23-2006, 01:33 PM   #14
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Quote:
Originally Posted by greg176
When I dismantled my Overlander I removed about 100 lbs of mouse droppings.
Oh thanks!... I never thought of that possibility. Am I to think there could be this kind of evidence under the floors of my trailer? Even if I don't see anything on the interior? Yuck!
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