Aluminum Trailer Questions

Hey everyone,
I'm planning to make an unusual trailer to tow by my motorcycle. It'll be used to haul sculpture (under 300 lbs) or two stacked 17'-long sea kayaks.
Here are the basic features:
Aluminum (I want a total weight under 150 lbs if possible) 8' long flatbed deck Tongue will be 'retractable' from 1' to 6' long. 2.5' wide 16" wheels (the sort used for motorcycle sidecars)
MY Questions:
1. What are the most important issues I may have? 2. What aluminum extrusions would be best (aluminum alloy, dimensions & wall-thickness)
THANKS!
James www.jameskelsey.com
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On Thursday, August 4, 2016 at 2:49:37 PM UTC-4, snipped-for-privacy@gmail.com wrote :

all-thickness)

It is not that I do not want to help, but I do not know where to begin. Wo uld need a lot more information to get started. You might begin by finding out what aluminium shapes you can get and the costs of each shape. How ar e you going to put the trailer together. If you are using welding, some al uminum allops are not suitable for welding. How wide is the trailer going to be? Are you going to use one piece in the center with arms out to suppo rt the deck? Is te deck going to be a structural member? Is the deck goin g to be aluminum or wood? Do you have access to a brake and can bend sheet aluminum into square tubing? -Are you going to use rivets?
Dan
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wrote:

It is not that I do not want to help, but I do not know where to begin. Would need a lot more information to get started. You might begin by finding out what aluminium shapes you can get and the costs of each shape. How are you going to put the trailer together. If you are using welding, some aluminum allops are not suitable for welding. How wide is the trailer going to be? Are you going to use one piece in the center with arms out to support the deck? Is te deck going to be a structural member? Is the deck going to be aluminum or wood? Do you have access to a brake and can bend sheet aluminum into square tubing? -Are you going to use rivets?
Dan
80/20 might be a good choice for this project. lots of options with pre-fab bits and pieces.
https://www.8020.net/ Engineering specs, etc. Examples of what people have built.
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l2632.R2.TR12.TRC2.A0.H1.X8020.TRS0&_nkw %2F20&_sacat804
Best Regards Tom.
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Thanks for the suggestion and Links, Tom. That's an interesting product and I could see it working... I'm going to investigate further.
James
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Good luck with your project, let us know how it comes out.
Best Regards Tom.
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wrote:

It is not that I do not want to help, but I do not know where to begin. Would need a lot more information to get started. You might begin by finding out what aluminium shapes you can get and the costs of each shape. How are you going to put the trailer together. If you are using welding, some aluminum allops are not suitable for welding.
True. Generally 7075 doesn't weld worth a darn.
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wrote:

This looks like a case where sitffness is the limiting parameter. It shares that with lots of structures, including race cars: If it's stiff enough, it's more than strong enough.
This suggests that steel tubing is going to be a better material than aluminum of *any* shape for such a project. There isn't a lot of basis to recommend anything fancier than 1020 steel tubing; 4130 doesn't make it any stiffer, and isn't going to do much for you unless you're going to crash it. And 1020 is easier and more reliable to weld than almost anything else.
--
Ed Huntress

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snipped-for-privacy@gmail.com wrote:

You can make it under 150 lbs without going to aluminum for the frame . Too much chance for a fatigue failure . I'd use 1x3 16ga mild steel for the frame , maybe some al diamond plate decking . Do be sure to calculate your tongue loading as you design this , last thing you need is a trailer swaying behind a bike - and speaking of bikes , if you're riding anything less than a Harley FLHT . Honda 'Wing or other heavy touring bike you're not going to be happy towing that load . Looking at your website you apparently have welding skills and some sense of load balancing . I presume you TIG ? If so you might want to consider 4140 thinwall tube for the frame ... race car frame builders use ER70S2 filler.
--
Snag
1990 FLHTCU
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All great advice, Snag. I'm aware of fatigue issues with aluminum, and I've always been curious about that issue & weight advantage (as well as thicker material needed) verses very thin steel (or stainless even).
A 2.5' x 8' deck is quite small and 300 lbs load quite low and it seems the trailer material could be very thin indeed.
James
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On Fri, 5 Aug 2016 07:32:21 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

James, one of the things you might keep in mind is the arc of the front/back of the kayaks when you go over a rounded drive or mound at the beach/river. You don't want the kayak digging into the blacktop, rocks, or dirt. Check your elevations, since the wheels will be in the center. The end will be 8.5' back from the pivot point.
How will you fasten it to the bike? 3-point mini-pintle?
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Thanks for the advice on length. While I'm going with 16" wheels, I still h aven't decided if I want the trailer deck OVER the wheels Between the wheel s. A lower center of gravity makes good sense, but the wheels will limit wi dth, and as you said, the odds of scrapping the back of the trailer/load go es up the lower it is.
As for the Hitch, still researching. I'd PREFER a hitch that pivots with th e bike's lean, but so far I've only found a proprietary system that they wo n't sell separately from their trailer (Bushtec).
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On 8/7/2016 1:07 PM, snipped-for-privacy@gmail.com wrote:

Putting the deck over the wheels sounds like a really bad center-of-mass situation. The wheels would be 30" apart, the deck about 26 - 28" high and up to 300 pounds on the deck! And the center of mass of the load might be, what, a couple of feet above the deck? That would bother me and I don't bother easily.
Bob
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wrote:

A common design has low side rails that can support wider loads. http://www.johnsontrailerco.com/single-axle-utility-trailer-wside-rails/ A neighbor brought home a garden shed that weighed at least 2500 lbs on the side rails of his double-axle trailer, certain that I could find a way to lift it off and lower it onto concrete blocks.
Atwood fold-down stabilizers are lighter alternatives to crank-down trailer tongue jacks: (Amazon.com product link shortened)
https://www.nueratrailerparts.com/
--jsw
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wrote:

Or beside the deck, with the suspension he is using.

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On Sun, 7 Aug 2016 10:07:49 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

Another possible suggestion is to tilt them a bit, ass-end up, like a stinkbug. Keep half of it low while giving clearance.

A standard ball hitch gives the least degree of movement, pintles are better, and hinged swivels the best. Build your own out of 1" square tubing? Limiting the play in _every_ joint/connection is essential, too, especially if you're not going to give it any suspension.
Ride an old suspensionless 10-speed bike 1/4 mile and you'll see why I say that. Suspension, shocks, and large tires entirely remove our awareness of the shock the extremely rough (but smooth?) roads which we travel on would otherwise give us. Trailers take a real beating.
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Hi Larry,
I'm actually planning on using a Timbren suspension system http://www.etrailer.com/Trailer-Axles/Timbren/A4RS440.html It's highly sensitive and will take most of the bounce out of the trailer.
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On Sun, 7 Aug 2016 18:08:48 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

Hey, pretty cool. Looks like air-ride bags for trailers. Good show. They look very well built, too.
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On Sun, 7 Aug 2016 18:08:48 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

Looks like a functional duplicate of the ols Austin Mini suspension system - should work pretty good - perhaps a little "strong " for the application (designed for 800 lb trailer load)
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wrote:

FYI, we have an article coming up soon on welding thinner gauges of 4130 (under 1/4", focus on tubes in the 16-gauge range), written by a specialist at Hobart. I asked him to deal with all of the myths and old-wive's tales and to give us the scientific responses to questions like pre-heat and post-heat; types of filler; etc.
I've wanted to find an expert on the subject for years, and I think I've got him. I'll let you know when it's coming.
--
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HEY ED... I remember you from the YAHOO group (is that still around?) I was just looking around online and have a question...
Stainless steel 1" x 3" x .063 tube weighs 1.7 lbs/foot Aluminum in 1" x 3" x .125 weighs 1.1 lbs/ft
Which would be better? on a 30" x 96" trailer (about 30' of material) it would be 51 lbs (SS) verses 33 lbs (AL)
Remember the trailer is only 8' long and will never carry over 300 lbs.
THANKS,
James
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