"Ed Huntress" wrote in message
...

"mark" wrote in message
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My original jeep CJ-7 frame has rusted out and I was thinking of
building a new one from aluminum. Would 2 X 4 X 1/4 wall (if that is
even available) box tubing have the equivalent strength of the stock
1/8" wall steel frame? I would like aluminum because it will last
forever, no need of any paints etc..., very easy to work with and
cheaper than building a steel one and having it galvanized. My second
choice would be stainless 1/8" box tubing.

This looks familiar, Mark. Didn't you post this same question here three
or four years ago? Someone posted something similar.

Anyway, as Joe Gwinn says, aluminum has 1/3 the stiffness of steel,
roughly 1/3 the strength for low alloys of each, and weighs 1/3 as much. A
box section tube doesn't take advantage of aluminum's low density, so
there is no weight advantage in using aluminum in this way. To get equal
strength in the same section (2 x 4), the aluminum tube will have to have
walls that are 3X as thick as the steel one.

I don't know Jeep frames but if the frame isn't boxed (in other words, if
it's a U-channel or top-hat section rather than a rectangular tube), and
if you use box-section aluminum to replace it, it will be a great deal
stiffer and stronger. But that's because the tube is stiffer and stronger,
not because it's aluminum.

All in all, aluminum sounds like it's a lot more trouble than it's worth.
Welding that thick section and producing a *strong* weld with it will be
no picnic, unless you're an expert. It will cost a lot more for the
material. I can't speak for the galvanizing but I thought that hot-dipping
a frame was supposed to be a reasonable cost proposition.

I'm sure you'll get other opinions.

--
Ed Huntress

During our 8 year tour in the Marshall Islands where you can corrode a glass
thermometer, we saw jeeps made of Stainless Steel that were made in the
Phillipines. No rust.. People that owned them were not excessively rich.
Don't know what they cost, but looking back we should have bought and
shipped a couple of them to the US .

Stu Fields