Aluminum expedition trailer
- Thread starter Jeep
- Start date
Man i have been thinking about an aluminum trailer myself. I also want to build it all from aluminum, ie: frame, body, independent suspension. I have the tools and abilities but just dont understand the brittle aluminum weld problem. I see big rig trailers, custom car hauler trailers, and other types of trailers all the time with aluminum frames. Its not like our trailers carry anywhere near the weight of these either so whats the big deal? That is a sweet trailer. The design I have in my head is similar with a few changes.
R_Lefebvre
Expedition Leader
That's not a bad point.
Now, one difference might be the grade of aluminum they use. 6061 is the only thing I can get around here. Now, it's weldable, but I bet there are better grades out there that they may be using?
I have an all-aluminum Triton Seadoo trailer. It weight I think 300lbs or something, and is rated to carry a 1000lb machine, and they're well respected.
Martyn
Supporting Sponsor, Overland Certified OC0018
You have to think of the environment that the trailers are being used in and what type of stresses are being applied in each situation.
Trailers on wash board are in high stress high frequency vibration situations. As I tell everyone it's wash board that kills trailers not rock crawling or extreme off-roading.
Most trailers stay on the pavement, the most stress they get is from the load they are carrying and the occasional pot hole. Big rigs have some of the most sophisticated suspension on the road, they run large tires with lots of depth between the road and the rim, so they are extremely well designed for what they do.
When you start to scale things down for a small off-road trailer aluminum starts to be a headache.
You have to build aluminum very rigid especially in a short package. A 40' trailer with a 16" I beam that is 5/8" thick will safely flex quite a bit and those nice trailers are usually riding on air. You can build a small frame out of aluminum, design your frame so the weld points have the least amount of stress, 2x3 or 2x4x.250 tongue and perimeter frame and you will be ok. Use large spanning mounting brackets for suspension to eliminate flexing but like Martyn said, the washboard roads and vibration will do more damage than anything else. Almost all tubular extrusions are 6061 which is good stuff, when you weld aluminum you reduce the hardness into the 40 series range around the weld (like 4043) which is a utility grade aluminum and is very soft, forms real easy hence you lose the 6061 quality around the weld area. An aluminum frame will easily be double the cost of steel as well.
I work in a sheet metal warehouse. I have lots of contact with fabricators who build these types of things eveyday. I trust these guys because of there experience. One of them built Epcot Center, which is all aluminum framed. I spoke with three yesterday inquiring about this very question. They all said it is an issue that is easily remedied with gussets. Gussets at all welds would divide the stress one weld revieves by three, greatly extending the life of the weld. In my head I have the idea of how I wanted to build the frame. They all confirmed that my design would be the best way to construct an aluminum frame. No offense to anyone who has or builds and air bag suspension but I wouldnt have one. For the money invested in an air bag set up one could easily put a set of little quality built coilovers under there. Coilovers also have a lot less failure rate and your eliminating wiring, air pumps, leaky bags, leaky air lines, and the controls. All which take up space on your rig or trailer. Also coilovers are just as versitile and adjustable. Im not trying to argue with anyone btw I just dont usually jump on the "it cant be done" band wagon, till I prove it to myself.
Another point on vibration. I drive 1hr to work everyday on the interstate. I observe lots of trailers. I see tons of out of round tires on these things. I can see the shake from the trailer as well as the tires. I have driven cars with out of round tires and there is a definite vibration from them on paved roads. So to a degree wouldnt that turn a paved road situation into a wash board situation? These trailers go thousands of miles like that. I do agree that most large trailers are riding on air. But given that fact wouldnt and air bag suspension on our trailers solve the problem? If so then all of this debate over weld strength is useless in the event someone would want an air bag suspension.
R_Lefebvre
Expedition Leader
I also wonder how much those big trailers are welded vs. being mechanically fastened. Bolts avoid the problem of heat affected zone weakening. For example, airplanes are riveted, not welded.
Next time your next to one check it out. Welds everywhere. Its not just the big trailers though, Uhaul and Featherlight are two companies that come to mind with aluminum framed trailers. I dont know the brands but I also have two drag racing buddies that have custom built all aluminum trailers for thier drag cars.
Bullseye240
Adventurer
A lot of class 8 trucks and trailers are fastened with "Huck Bolts". They look like old style carriage bolts until you notice that those aren’t threads but rings on the stem of the bolts. The "nut" is crimped onto the bolt with a "gun" that pulls the stem of the bolt and forces the nut into a cone and then snaps the bolt off flush or close to it with the nut" They allow the joint to flex a little without the worry of unthreading the fastener. If you look at the rear suspension on the trucks most are held on that way. Something to think about next time one is alongside you. I don’t know if you still can buy a class 8truck with an aluminum frame, but I know you used to be able to.
D
Deleted member 9101
Guest
Thats just sick.. in a very good way
Martyn
Supporting Sponsor, Overland Certified OC0018
Air systems have their issues, but their performance out weighs any of the problems. It's a very simple system air bag, air line, elbow, valve. A bicycle pump will fill the system.
I'm a big fan of coil overs, not as responsive, adjustability is really a function of getting a spring with the correct rating and then it's up to you how often you want to crawl under the trailer and tighten or loosen the adjuster ring. Experience leads me to believe people don't do it that often.
Are there issues with coil overs, yes. They add around $250.00 to the price of the suspension, they need a remote reservoir so the shock doesn't overheat, and the shock can be damaged if the coil is not correctly adjusted for load.
There just isn't a perfect system.
On the issue of comparing vibration in the on-road environment to an off-road environment. It all seems so simple and easy to compare one to the other in theory, but so complex once you test the trailer off-road.