Is an aluminium chassis a smart choice?

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Is an aluminium chassis a smart choice?

Postby Adam-is-Teardropping » Fri Jul 31, 2020 4:56 am

Hi Everyone,

Long time lurker and first time poster! I am in the process of designing and building my first teardrop trailer and I am pretty torn on going with aluminium or steel for the chassis. A lot of weight savings comes with the aluminium, but I am a little concerned with stress fractures originating at the welds over time. Having a bunch of stuff bolted together just seems like to many points of failure for me. I don't think flexion in the frame will be a problem as the cabin bolted to the frame provides a lot of resistance to bending.

I do have access to skilled welders who would build the aluminium or steel chassis for me, but they are not designers and do not have experience with lower weight vehicles. Anyone with an aluminium trailer chassis care to comment on how it has performed? and more interestingly, how it is built? My trailer design sits 146" tongue to tail. The camper itself is 107" long and 62.5" wide.

The other big perk of going with aluminium is not having to do any surface finishing of the frame. With mild steel I would need to get it powder coated. For this reason to me there both come in at roughly the same cost.

Any documents that I could reference would be greatly appreciated in designing this. I really seem to be stuck at this point as all resources I have found are for much heavier duty trailers.

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Re: Is an aluminium chassis a smart choice?

Postby John61CT » Fri Jul 31, 2020 6:38 am

I've only got close to the boat trailer designs, and the huge advantage, there besides the ratio of trailer weight to load carried

is the lack of corrosion.

Decades later the steel ones are dead, unless basically restored & repainted / re-galved

while the aluminum is whole without needing that maintenance.

The connection points with steel need care, high tech sealants like Tefgel, plastic washers and sheet barriers, or galvanic corrosion emerges quickly in the wet.

But these are big expensive jobs produced well by only a few places at ten grand and up, custom would be more.

Little units like under 5000lb capacity people don't seem as willing to spend so shorter lived galv steel dominates there.

US engineers would be liability shy of a non-commercial project, maybe a Chinese / Indian shop could be found online. . .
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Re: Is an aluminium chassis a smart choice?

Postby TimC » Fri Jul 31, 2020 8:12 am

Last edited by TimC on Tue Aug 04, 2020 9:57 am, edited 2 times in total.
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Re: Is an aluminium chassis a smart choice?

Postby Socal Tom » Fri Jul 31, 2020 8:29 am

Aluminum still corrodes, and anywhere that vibrates will eventually work harden which makes it brittle. Unless the frame and trailer are well designed and tested the risk of failure is higher. If you were buying something mass produced and the design had been on the market for years, I'd say go for it, but for a home built, I'd be concerned.
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Re: Is an aluminium chassis a smart choice?

Postby tony.latham » Fri Jul 31, 2020 8:53 am

I think any (proffesional) fabricator can create a fine steel trailer that will last longer than any of us. But I can't say that about designing and crafting one out of aluminum. Someone would have to have his ducks in a straight line. Unless you can find a craftsman that has specialized in fabricating aluminum trailers, stay away.

That's my two-bits.



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Re: Is an aluminium chassis a smart choice?

Postby Philip » Sat Aug 01, 2020 5:16 pm

I used to work in a Fab/welding shop. The rule with alumin. Its not if its going to crack. Its when is it going to. Light alumin and road vibrations. Its going to crack sooner or later. When it happens it will take a very good welder to repair it. With many miles of road debris hitting it. It will be thinner from age and all the debris blasting it sees. There is no such thing as a one pass weld on it. Its almost impossible to get it clean enough to weld. You have to make a pass to burn the debris out of the crack. Then if your lucky the second pass takes.

I would recommend a steel frame. Remember in your travels with the trailer. You can find many people that can glue a steel frame back together. You might not find a local that can repair a alumin frame.
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Re: Is an aluminium chassis a smart choice?

Postby gudmund » Sat Aug 01, 2020 10:21 pm

I 'second' what was just said...... Note, aluminum, 'pound for pound' is more rigid than steel which would make for a stiffer frame = but very little is saved in weight (example = aluminum vehicle wheels, very stiff and yes they help in handling being they flex less - but are they that much lighter in weight?? = NO.) Also, it would take more mass of aluminum in the producing of frame material so as not to end up with as much cracking but, cracks will still happen in due time. Case in point = bicycle frames made of aluminum have mass/thickness used in their tube material and end up weighing as much as a steel frame, so what is the gain in using it over steel? = stiffness less flex .. along with the "wise" suggestion of keeping a close watch for cracking over time..... Aircraft, yes aluminum is very common in it's build-up, but the welding of it?? = just about never!! rivets/riveting are used always (and now with the advent of carbon fiber = it's the cooking, gluing and screwing them all together - Boeing 787 - and bicycles frames) .............
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Re: Is an aluminium chassis a smart choice?

Postby friz » Sun Aug 02, 2020 1:56 pm

Steel has an almost unlimited fatigue life. Aluminum has a short fatigue life. Aluminum has to be engineered or over built to avoid stress risers and reduce fatigue.

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