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Default building jeep frame

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.
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Default building jeep frame


"mark" wrote in message
...
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.


I don't think a frame made of that tiny tubing would be very good.

Steve g


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Default building jeep frame

In article ,
mark wrote:

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.


Aluminum is far less stiff than steel, and doubling thickness may yield a
too-floppy frame. I would stick with steel unless you reengineer the frame.

Joe Gwinn
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"mark" wrote in message
...
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


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"Ed Huntress" wrote in message
...

"mark" wrote in message
...
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




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On Sun, 28 Feb 2010 06:52:53 -0800 (PST), mark
wrote:

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.


You do NOT ewant an aluminum frame. Perhaps stainless steel.
Aluminum frames on a jeep WILL flex. Particularly a 2X4 x1/4 tube.
ANY time aluminum flexes it is a stress, and all stresses are
cumulative. Frame life would likely be measured in months.

Steel is different. It has an elastic limit, and as long as that
loimit is not exceeded, no cumulative stress occurs.

I'd build a stainless steel TUBE frame if I was going to the trouble -
but Iron Horse (I believe that is still the name of the company)
supplies ready made replacement frames at a very reasonable price.
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Default building jeep frame

I have the full dimensions for the CJ frames, they have a LOT of bends,
brackets, and quirks to make a fabrication job pretty messy. There are
several companies that do these from 2x4" tube to replace the double
channel original. Under $2000. A quick google came up with
http://www.throttledownkustoms.com/framesCJ7.html
http://www.acmejeepparts.com/product...cessories&c=38
The galvanized versions run around $800 more IIRC

You do not want to use aluminum: flex, fatigue, and strength all work
against you.

mark wrote:
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.

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Default building jeep frame

On Feb 28, 2:18*pm, RoyJ wrote:
I have the full dimensions for the CJ frames, they have a LOT of bends,
brackets, and quirks to make a fabrication job pretty messy. There are
several companies that do these from 2x4" tube to replace the double
channel original. Under $2000. A quick google came up withhttp://www.throttledownkustoms.com/framesCJ7.htmlhttp://www.acmejeepparts.com/products/product_search.php?cn=Frames+%2...
The galvanized versions run around $800 more IIRC

You do not want to use aluminum: flex, fatigue, and strength all work
against you.



mark wrote:
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.- Hide quoted text -


- Show quoted text -


Roy, as for the bends, I am going to eliminate the arches for the leaf
springs, I have a 4" suspension lift so straight frame rails will be
fine although I will have to bring them in narrower at the front.
Around here we use 4X4 1/4 aluminum box tube to build cranes for
aquaculture boats that are constantly lifting 1500+ lbs 8'-10' out
from the hydraulic lift cylinder and I see many aluminum boat trailers
made form I beam, box tubing should be stronger. Also i have a
fiberglass body which is much lighter. Each frame rail will have the
load spread out to 4 points due to the leaf springs. Maybe if I use 4
X 4 instead, a 20' length is only ~$200.00
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mark wrote:
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.



Aluminum is a VERY poor choice for a frame of a Jeep. The frame in them
is engineered to flex and allow the suspension to operate well. That
flex in aluminum will work harden the frame in a short time and cause
failures. The welds will be the first failures and then the rails
themselves.
Even if you doubled the thickness the frame will be the weak point.

Now if you have access to stainless and a way to work with it that would
be a MUCH better choice. It would flex like the steel and retain it's
strength. The alloy of the stainless would be a BIG factor though.

Personally if I wanted a long lasting rig I would start with a custom
tube frame and a fiberglass or stainless body. One of the locals has a
set up like that.


--
Steve W.
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wrote:
On Sun, 28 Feb 2010 06:52:53 -0800 (PST), mark
wrote:

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.


You do NOT ewant an aluminum frame. Perhaps stainless steel.
Aluminum frames on a jeep WILL flex. Particularly a 2X4 x1/4 tube.
ANY time aluminum flexes it is a stress, and all stresses are
cumulative. Frame life would likely be measured in months.

Steel is different. It has an elastic limit, and as long as that
loimit is not exceeded, no cumulative stress occurs.

I'd build a stainless steel TUBE frame if I was going to the trouble -
but Iron Horse (I believe that is still the name of the company)
supplies ready made replacement frames at a very reasonable price.


Oh boy, if you can buy a frame that's the way to go. Unless you're just
determined to build your own frame for the sake of it, and have a well
equipped shop at your disposal, you'll spend less time and probably less
money buying one.

Aluminum works differently than steel, and is not corrosion proof --
particularly when you bold a bunch of steel parts to it.

Stainless is hard to weld, and fatigues far more readily than steel.

Steel can be painted or galvanized to not rust, and works pretty darn
well for frames. Very few cars have aluminum frames for a very good reason.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com


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Tim Wescott wrote:


Steel can be painted or galvanized to not rust, and works pretty darn
well for frames.


The original spec for Land Rover (British version of Jeep) frames was to
make them in steel and galvanize. They didn't do that in production, but
a version for the Australian army called the Perentie did.
http://www.allisons.org/ll/4/LandRover/Perentie/
The chasses were welded up from rectangular section steel, looking
something like a home built.
Don't Jeep frames need to flex somewhat? I saw a bare one sitting on a
garage floor. The owner picked up one corner, and the other three
corners stayed on the floor!

Jordan
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Jordan wrote:
Tim Wescott wrote:


Steel can be painted or galvanized to not rust, and works pretty darn
well for frames.


The original spec for Land Rover (British version of Jeep) frames was to
make them in steel and galvanize. They didn't do that in production, but
a version for the Australian army called the Perentie did.
http://www.allisons.org/ll/4/LandRover/Perentie/
The chasses were welded up from rectangular section steel, looking
something like a home built.
Don't Jeep frames need to flex somewhat? I saw a bare one sitting on a
garage floor. The owner picked up one corner, and the other three
corners stayed on the floor!


They may, but I'm more inclined to believe that they're supposed to be
reinforced by the body they sit on. Model T Ford frames were quite
flexible, but by design much of the missing torsional strength came from
the bodies -- the '26 T roadster body 'subframe' is more torsionally
rigid than the frame it sits on.

In general if a car is flexing in torsion then the doors won't stay
closed, or at least won't close properly in some circumstances. Also in
general, closed car bodies are much more torsionally rigid than open
ones -- this is why convertibles generally need stronger frames than the
equivalent closed version of the same car, and why they are often a few
hundred pounds heavier.

But certainly if you take a frame that's made to flex and make it
inflexible you'd better know what you're doing, or the next thing
that'll happen will be that suspension parts will rip themselves off of
the thing. (IIRC the early Fords would rip up their body mounts when
you hot rodded them or drove them hard for long periods of time, for the
same reason).

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
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What's that Lassie? You say that mark fell down the old
rec.crafts.metalworking mine and will die if we don't mount a rescue
by Sun, 28 Feb 2010 06:52:53 -0800 (PST):

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.


you can buy a steel frame for about $2k. Galvanizing add $550.
www.quadratec.com

Other options:
skid plate
front shackle reversal setup
integrated rear receiver bumper
integrated rear receiver bumper with swing out tire carrier
custom motor mounts

--

Dan H.
northshore MA.
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"Tim Wescott" wrote in message
...
Jordan wrote:
Tim Wescott wrote:


Steel can be painted or galvanized to not rust, and works pretty darn
well for frames.


The original spec for Land Rover (British version of Jeep) frames was to
make them in steel and galvanize. They didn't do that in production, but
a version for the Australian army called the Perentie did.
http://www.allisons.org/ll/4/LandRover/Perentie/
The chasses were welded up from rectangular section steel, looking
something like a home built.
Don't Jeep frames need to flex somewhat? I saw a bare one sitting on a
garage floor. The owner picked up one corner, and the other three corners
stayed on the floor!


They may, but I'm more inclined to believe that they're supposed to be
reinforced by the body they sit on. Model T Ford frames were quite
flexible, but by design much of the missing torsional strength came from
the bodies -- the '26 T roadster body 'subframe' is more torsionally rigid
than the frame it sits on.

In general if a car is flexing in torsion then the doors won't stay
closed, or at least won't close properly in some circumstances. Also in
general, closed car bodies are much more torsionally rigid than open
ones -- this is why convertibles generally need stronger frames than the
equivalent closed version of the same car, and why they are often a few
hundred pounds heavier.

But certainly if you take a frame that's made to flex and make it
inflexible you'd better know what you're doing, or the next thing that'll
happen will be that suspension parts will rip themselves off of the thing.
(IIRC the early Fords would rip up their body mounts when you hot rodded
them or drove them hard for long periods of time, for the same reason).

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com


Right. All else being equal, the most rigid frame is the best frame -- and
torsional rigidity usually is the limiting factor -- but, as you say, the
suspension has to be made to handle the high point loads.

Ladder frames have an advantage for trucks and other utility vehicles in
that they can accommodate different bodies with little extra work.
Otherwise, they're generally antiques. One of the best chassis engineering
books ever written said, in 1962 or thereabouts, that perimeter frames,
particularly ladder frames made from open sections, were obsolete for
passenger vehicles.

The Jeep is an engineering anachronism, but a loveable one that still does
its intended job.

--
Ed Huntress


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Nothing wrong with a rigid chassis if you have enough suspension
articulation...

http://www.youtube.com/watch?v=w_F7QrR4Ur8


Jon


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dan wrote:
What's that Lassie? You say that mark fell down the old
rec.crafts.metalworking mine and will die if we don't mount a rescue
by Sun, 28 Feb 2010 06:52:53 -0800 (PST):

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.


you can buy a steel frame for about $2k. Galvanizing add $550.
www.quadratec.com

Other options:
skid plate
front shackle reversal setup
integrated rear receiver bumper
integrated rear receiver bumper with swing out tire carrier
custom motor mounts

That's a decent price. I can only think of three reasons you wouldn't
want to jump on it:

1: You just have to build your own frame, for emotional reasons -- I
mean, building stuff is _fun_, right?

2: You're long on shop space, tools, and time, but for whatever reason
you don't have much cash right now.

3: You're doing something absolutely new and unique, the hottest of hot
****, and that requires a custom frame (see 1). But even there, getting
a made-frame for $2k, modifying it, and having it galvanized might be a
wiser course.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
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Jon Anderson wrote:
Nothing wrong with a rigid chassis if you have enough suspension
articulation...

http://www.youtube.com/watch?v=w_F7QrR4Ur8


Even when taken to extremes.

My dad used to brag that with posi-trac and careful driving he could get
his '59 El Camino stuck in places where the four wheel drive brush
rigs (with less intrepid drivers) couldn't even get close to pull him out.

But I don't think they had one of those...

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
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On Sun, 28 Feb 2010 22:49:46 GMT, Jordan
wrote:



*Snip*
..
Don't Jeep frames need to flex somewhat? I saw a bare one sitting on a
garage floor. The owner picked up one corner, and the other three
corners stayed on the floor!

Jordan



CJ frames up till the late 70's were mostly un-boxed c cahannel & were
very flexy. Most people building up an early CJ foe seroius off-road
activities will completely box thier frames for the added stiffness &
t prevent cracking at stress points, htey rely on up-graded
suspensions to keep all 4 on the ground.

H.
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On Sun, 28 Feb 2010 10:54:39 -0800 (PST), mark
wrote:

*Snip*


- Show quoted text -


Roy, as for the bends, I am going to eliminate the arches for the leaf
springs, I have a 4" suspension lift so straight frame rails will be
fine although I will have to bring them in narrower at the front.


*Snip*

Eliminating the arches is gonna hurt come articulation time

Plus it's going to complicate the body mounting, the front & rear
kick-ups arn't there just for the arches.

As for an aluminuim chassis in general-

http://www.fishing.net.nz/asp_forums...an-o-worms.gif

Live in an occaiasionally damp area? Aluminum+steel+damp= galvanic
corosion = a bitch.

Build your own if you want, lots of people have done it successfully
but you'll be a lot happier with the results if you go galvanized
steel.

Hit up the Early CJ5 "intermediate " (yes, I know lates aren't
intermediates & certainly arn't "earlies" & CJ7's arn't 5's but
they're a fairly tolerent bunch) forums-

http://www.earlycj5.com/forums/forumdisplay.php?f=19

& do a search on frames, lots of good info from people who have been
where you're going.

H..
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Tim Wescott wrote:

My dad used to brag that with posi-trac and careful driving he could get
his '59 El Camino stuck in places where the four wheel drive brush rigs
(with less intrepid drivers) couldn't even get close to pull him out.


Early 80's, I had a 510 Datsun 4 door. I'd once looked through the
Datsun racing parts catalog, and saw the suspension kit for rally cars.
Well, never bought the kit, but I did fit 14" Z wheels which gave a good
bit more ground clearance. I used to drive all over the woods with it.
One nice summer day, I'm crawling along a rocky trail, sunglasses on,
Coke in one hand with my elbow out the window, Led Zeppelin blaring on
the stereo. Around the corner comes a string of Jeeps, out doing some
manly 4x4 trailing.

The look on their faces at the sight of my 510 was priceless...

I did get myself in trouble once on a trail too steep to back up. I
walked down and saw there was a nice flat area to turn around and get a
run back. But there was some major erosion in between. Getting down was
no problem, but it took about an hour of filling the ruts with rocks and
branches to get back out.


Jon


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Howard Eisenhauer wrote:

CJ frames up till the late 70's were mostly un-boxed c cahannel & were
very flexy. Most people building up an early CJ foe seroius off-road
activities will completely box thier frames for the added stiffness &
t prevent cracking at stress points, htey rely on up-graded
suspensions to keep all 4 on the ground.


A boxed frame will still flex, be it steel or aluminum. Here's a thought
to ponder. I know some guys take small wire or buzz box welders out on
the trail. It's sometimes possible to patch a cracked frame enough to
get home. But that's steel. How many guys take a TIG welder out on the
trail?

But hey, give it a go. Nothing like empirical testing... G


Jon


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On Sun, 28 Feb 2010 18:32:00 -0800, Jon Anderson
wrote:

Howard Eisenhauer wrote:

CJ frames up till the late 70's were mostly un-boxed c cahannel & were
very flexy. Most people building up an early CJ foe seroius off-road
activities will completely box thier frames for the added stiffness &
t prevent cracking at stress points, htey rely on up-graded
suspensions to keep all 4 on the ground.


A boxed frame will still flex, be it steel or aluminum. Here's a thought
to ponder. I know some guys take small wire or buzz box welders out on
the trail. It's sometimes possible to patch a cracked frame enough to
get home. But that's steel. How many guys take a TIG welder out on the
trail?

But hey, give it a go. Nothing like empirical testing... G


Jon


Indeed they do but no-where's near as much as an un-boxed frame, and
after they flex for a few decades they do tend to crack, especially
around the front cross member & spring perches

http://www.tantel.ca/Images/The%20Sl...RACK%20A_1.JPG


There is a school of thought that says the frames were designed to
flex, another says they were made that way to keep the weight & cost
down for the wartime jeeps, but then the MBs & GPWs wern't expected to
have a long lifetime to begin with.

I D-plated mine instead of boxing but I'm trying to keep things as
stock looking as possible-

http://www.tantel.ca/Images/The%20Sl..._D-plate-1.jpg

http://www.tantel.ca/Images/The%20Sl..._D-plate-2.jpg


Good point about the trail welding though.

H.
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On Feb 28, 9:16*pm, "Paul Hovnanian P.E." wrote:
...
On my Landcruiser, all cross members (except for one) and attachment
points are riveted to the frame rails. This allows them to flex w.r.t
each other and not build up bending torque. ...
Paul Hovnanian


Why is a riveted joint more flexible?

jsw
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On Mar 1, 8:16*am, Jim Wilkins wrote:
On Feb 28, 9:16*pm, "Paul Hovnanian P.E." wrote:

...
On my Landcruiser, all cross members (except for one) and attachment
points are riveted to the frame rails. This allows them to flex w.r.t
each other and not build up bending torque. ...
Paul Hovnanian


Why is a riveted joint more flexible?

jsw


This Jeep is not for rock crawling or very uneven ground, 99% of it's
life will be on paved roads so there will not be extreme flexing
involved. As for buying one, by the time it got to me it on the east
coast of Canada, with shipping, exchange rate, tax, galvanizing
option, brockerage fees it would be closer to $3000.00.
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wrote in message
...
On Sun, 28 Feb 2010 06:52:53 -0800 (PST), mark
wrote:

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.


You do NOT ewant an aluminum frame. Perhaps stainless steel.
Aluminum frames on a jeep WILL flex. Particularly a 2X4 x1/4 tube.
ANY time aluminum flexes it is a stress, and all stresses are
cumulative. Frame life would likely be measured in months.

Steel is different. It has an elastic limit, and as long as that
loimit is not exceeded, no cumulative stress occurs.

I'd build a stainless steel TUBE frame if I was going to the trouble -
but Iron Horse (I believe that is still the name of the company)
supplies ready made replacement frames at a very reasonable price.


Why not aluminum? I have an aluminum boat trailer. Works very well. 3400#
boat. The Covette has an aluminum frame as well as the Cadillac bodied
Vette. Look at a Corvette and see what they use. Airplanes have aluminum
frames. And as long as you design well, the flex should not be a problem.




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mark wrote:
On Mar 1, 8:16 am, Jim Wilkins wrote:
On Feb 28, 9:16 pm, "Paul Hovnanian P.E." wrote:

...
On my Landcruiser, all cross members (except for one) and attachment
points are riveted to the frame rails. This allows them to flex w.r.t
each other and not build up bending torque. ...
Paul Hovnanian

Why is a riveted joint more flexible?

jsw


This Jeep is not for rock crawling or very uneven ground, 99% of it's
life will be on paved roads so there will not be extreme flexing
involved. As for buying one, by the time it got to me it on the east
coast of Canada, with shipping, exchange rate, tax, galvanizing
option, brockerage fees it would be closer to $3000.00.


Ooh -- ouch. Everyone assumes (well, at least I did, and I didn't see
qualifications to the contrary) that someone who's posting is local.

OK -- build it yourself. But use mild steel. Unless you're _really_
out in the boonies there should be reachable outfits that do
galvanizing. If not, mix up some zinc chromate epoxy primer (if you can
still get _that_) and roll it around inside all of the frame rails when
you're done with the build up.

Be sure it's square and straight, or your doors will _never_ fit.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
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Tim Wescott wrote:
mark wrote:
On Mar 1, 8:16 am, Jim Wilkins wrote:
On Feb 28, 9:16 pm, "Paul Hovnanian P.E." wrote:

...
On my Landcruiser, all cross members (except for one) and attachment
points are riveted to the frame rails. This allows them to flex w.r.t
each other and not build up bending torque. ...
Paul Hovnanian
Why is a riveted joint more flexible?

jsw


This Jeep is not for rock crawling or very uneven ground, 99% of it's
life will be on paved roads so there will not be extreme flexing
involved. As for buying one, by the time it got to me it on the east
coast of Canada, with shipping, exchange rate, tax, galvanizing
option, brockerage fees it would be closer to $3000.00.


Ooh -- ouch. Everyone assumes (well, at least I did, and I didn't see
qualifications to the contrary) that someone who's posting is local.

OK -- build it yourself. But use mild steel. Unless you're _really_
out in the boonies there should be reachable outfits that do
galvanizing. If not, mix up some zinc chromate epoxy primer (if you
can still get _that_) and roll it around inside all of the frame rails
when you're done with the build up.

Be sure it's square and straight, or your doors will _never_ fit.

If box section then you need to provide drain holes for the zinc to
enter and exit. A guy I knew had a box section chassis galvanised and
the company didn't drain it well, they charged by weight so he got a
bigger bill than originally estimated and couldn't carry the chassis
easily any more. So get a fixed price or make sure it can be drained
easily. A company near me gets Marcos chassis galvanised, talking to the
owner he said it took them a few goes and a tame galvaniser to get the
drain procedure right but the Marcos chassis is somewhat more
complicated than a ladder frame Jeep chassis.
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"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.


Boat trailers are rarely twisted the way that off-road vehicles routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)
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"RAM³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.


Boat trailers are rarely twisted the way that off-road vehicles routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)


Hell, I raced a vette, steel chassis, and it got to rock clrawing a couple
times. :) And boat trailers are regularly towed over uneven ground.


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On 01 Mar 2010 22:02:21 GMT, "RAM³"
wrote:

"Bill McKee" wrote in
om:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.


Aircraft have aluminum monocoque construction. Any plane with a frame
has steel (or wood) frame.

Aluminum bicycle frames have a very limited lifespan.
The corvette uses a "space frame" which is significantly different in
concept, design, and stress, than a Jeep Ladder frame.

Boat trailers are rarely twisted the way that off-road vehicles routinely
are.

Boat trailers are triangular so by basic design see very little
flexing.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)




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"Bill McKee" wrote in
m:

Hell, I raced a vette, steel chassis, and it got to rock clrawing a
couple times. :) And boat trailers are regularly towed over uneven
ground.


With only 1 wheel in contact with the ground while the boat was loaded and
tied down and the tow vehicle at tilted in the opposite direction?

I doubt it.

"Uneven" is a long way from "rock crawling" and your 3,400# boat is
unlikely to be towed over "Jeep" roads on an all-Aluminum trailer with any
regularity.

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"Bill McKee" wrote in message
m...

"RAM³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.


Boat trailers are rarely twisted the way that off-road vehicles routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)


Hell, I raced a vette, steel chassis, and it got to rock clrawing a couple
times. :) And boat trailers are regularly towed over uneven ground.


With three points taking out the loads -- hitch and suspension supports,
which generally are paired but close -- there is no significant torsional
load on a boat trailer. It's all simple bending. You can deal with that, but
if you towed your boat 100% of the time, I think you'd develop fatigue
problems in aluminum.

The aluminum Corvette chassis are semi-space-frame with some shear panels.
The subframes resolve their loads in three dimensions. There isn't much
flexing there.

The same applies to aircraft, which often are near-monocoque. If they flex,
you die.

--
Ed Huntress


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wrote in message
...
On 01 Mar 2010 22:02:21 GMT, "RAM³"
wrote:

"Bill McKee" wrote in
news:ca6dnfBx8ZKbmxHWnZ2dnUVZ_rmdnZ2d@earthlink. com:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.


Aircraft have aluminum monocoque construction. Any plane with a frame
has steel (or wood) frame.

Aluminum bicycle frames have a very limited lifespan.
The corvette uses a "space frame" which is significantly different in
concept, design, and stress, than a Jeep Ladder frame.

Boat trailers are rarely twisted the way that off-road vehicles routinely
are.

Boat trailers are triangular so by basic design see very little
flexing.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)


I should have read your message before posting. g

--
Ed Huntress


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On Feb 28, 6:09*pm, wrote:


Steel is different. It has an elastic limit, and as long as that
loimit is not exceeded, no cumulative stress occurs.



Not completely true. If one does not exceed 50% of the elastic limit
in steel, almost no cumulative stress occurs. From
http://www.epi-eng.com/mechanical_en..._in_metals.htm

"It is a simplistic rule of thumb that, for steels having a UTS less
than 160,000 psi, the endurance limit for the material will be
approximately 45 to 50% of the UTS if the surface of the test
specimen is smooth and polished.

That relationship is shown by the line titled "50%". A very small
number of special case materials can maintain that approximate 50%
relationship above the 160,000 psi level.

However, the EL of most steels begins to fall away from the 50% line
above a UTS of about 160,000 psi, as shown by the line titled
"Polished"."

Dan


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On Mon, 1 Mar 2010 17:52:39 -0500, "Ed Huntress"
wrote:


"Bill McKee" wrote in message
om...

"RAM³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.


Boat trailers are rarely twisted the way that off-road vehicles routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)


Hell, I raced a vette, steel chassis, and it got to rock clrawing a couple
times. :) And boat trailers are regularly towed over uneven ground.


With three points taking out the loads -- hitch and suspension supports,
which generally are paired but close -- there is no significant torsional
load on a boat trailer. It's all simple bending. You can deal with that, but
if you towed your boat 100% of the time, I think you'd develop fatigue
problems in aluminum.

The aluminum Corvette chassis are semi-space-frame with some shear panels.
The subframes resolve their loads in three dimensions. There isn't much
flexing there.

The same applies to aircraft, which often are near-monocoque. If they flex,
you die.


Error.. ever see the wings on a B-52? When they taxi out for take-off
both outrigger wheels are on the ground; when they come back one
outrigger will be ten feet in the air. But not only the wings, a B-52
on the ground has large wrinkles on each side of the fuselage, forward
of the wings; flying the fuselage is smooth.


John D.
(johnbslocombatgmaildotcom)


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"John D." wrote in message
...
On Mon, 1 Mar 2010 17:52:39 -0500, "Ed Huntress"
wrote:


"Bill McKee" wrote in message
news:qZ6dnaBKsPYVoxHWnZ2dnUVZ_uudnZ2d@earthlink. com...

"RAM³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.


Boat trailers are rarely twisted the way that off-road vehicles
routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)

Hell, I raced a vette, steel chassis, and it got to rock clrawing a
couple
times. :) And boat trailers are regularly towed over uneven ground.


With three points taking out the loads -- hitch and suspension supports,
which generally are paired but close -- there is no significant torsional
load on a boat trailer. It's all simple bending. You can deal with that,
but
if you towed your boat 100% of the time, I think you'd develop fatigue
problems in aluminum.

The aluminum Corvette chassis are semi-space-frame with some shear panels.
The subframes resolve their loads in three dimensions. There isn't much
flexing there.

The same applies to aircraft, which often are near-monocoque. If they
flex,
you die.


Error.. ever see the wings on a B-52? When they taxi out for take-off
both outrigger wheels are on the ground; when they come back one
outrigger will be ten feet in the air. But not only the wings, a B-52
on the ground has large wrinkles on each side of the fuselage, forward
of the wings; flying the fuselage is smooth.


John D.
(johnbslocombatgmaildotcom)


I don't know what the structure of a B-52 looks like, John, but it must be
far removed from a true monocoque. If a monocoque's skin wrinkled in
compression, all integrity would be gone, and it would completely collapse.

The wings contain spars -- the skin is stressed in tension but takes no
compressive loads. That's stressed-skin but not monocoque. Most metal
aircraft wings are made like that.

I was referring to the fuselage, of which there are many different designs.
As far back as the British Mosquito bomber of WWII, some aircraft have had
near-monocoque designs, which depend on the skin (which sometimes is cored
sandwiches, as on the Mosquito, and not a single sheet) to handle tensile,
compression, and shear loads. As you approach a true monocoque, any
stringers and ribs are there to help keep the skin's shape, rather than to
directly take out the major loads.

--
Ed Huntress


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On Tue, 2 Mar 2010 02:28:52 -0500, "Ed Huntress"
wrote:


"John D." wrote in message
.. .
On Mon, 1 Mar 2010 17:52:39 -0500, "Ed Huntress"
wrote:


"Bill McKee" wrote in message
news:qZ6dnaBKsPYVoxHWnZ2dnUVZ_uudnZ2d@earthlink .com...

"RAM³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.


Boat trailers are rarely twisted the way that off-road vehicles
routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)

Hell, I raced a vette, steel chassis, and it got to rock clrawing a
couple
times. :) And boat trailers are regularly towed over uneven ground.

With three points taking out the loads -- hitch and suspension supports,
which generally are paired but close -- there is no significant torsional
load on a boat trailer. It's all simple bending. You can deal with that,
but
if you towed your boat 100% of the time, I think you'd develop fatigue
problems in aluminum.

The aluminum Corvette chassis are semi-space-frame with some shear panels.
The subframes resolve their loads in three dimensions. There isn't much
flexing there.

The same applies to aircraft, which often are near-monocoque. If they
flex,
you die.


Error.. ever see the wings on a B-52? When they taxi out for take-off
both outrigger wheels are on the ground; when they come back one
outrigger will be ten feet in the air. But not only the wings, a B-52
on the ground has large wrinkles on each side of the fuselage, forward
of the wings; flying the fuselage is smooth.


John D.
(johnbslocombatgmaildotcom)


I don't know what the structure of a B-52 looks like, John, but it must be
far removed from a true monocoque. If a monocoque's skin wrinkled in
compression, all integrity would be gone, and it would completely collapse.

The wings contain spars -- the skin is stressed in tension but takes no
compressive loads. That's stressed-skin but not monocoque. Most metal
aircraft wings are made like that.

I was referring to the fuselage, of which there are many different designs.
As far back as the British Mosquito bomber of WWII, some aircraft have had
near-monocoque designs, which depend on the skin (which sometimes is cored
sandwiches, as on the Mosquito, and not a single sheet) to handle tensile,
compression, and shear loads. As you approach a true monocoque, any
stringers and ribs are there to help keep the skin's shape, rather than to
directly take out the major loads.


The only true monocoque airplane structure that I have seen is various
light aircraft and even then it is from the rear of the cockpit back
to the tail skid. The B-52 forward section is not a pure monocoque as
there is substantial structure to built the "two deck" upper and lower
areas so there are various formers and bearers but I suspect that the
skin does support a substantial amount of the load.

Are you sure that the Mosquito had a "cored" structure? I thought it
was cold molded - just layers of veneer glued together.


John D.
(johnbslocombatgmaildotcom)
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"John D." wrote in message
...
On Tue, 2 Mar 2010 02:28:52 -0500, "Ed Huntress"
wrote:


"John D." wrote in message
. ..
On Mon, 1 Mar 2010 17:52:39 -0500, "Ed Huntress"
wrote:


"Bill McKee" wrote in message
news:qZ6dnaBKsPYVoxHWnZ2dnUVZ_uudnZ2d@earthlin k.com...

"RAM³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very
well.
3400# boat. The Covette has an aluminum frame as well as the
Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex
should
not be a problem.


Boat trailers are rarely twisted the way that off-road vehicles
routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with
your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill
effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)

Hell, I raced a vette, steel chassis, and it got to rock clrawing a
couple
times. :) And boat trailers are regularly towed over uneven ground.

With three points taking out the loads -- hitch and suspension supports,
which generally are paired but close -- there is no significant
torsional
load on a boat trailer. It's all simple bending. You can deal with that,
but
if you towed your boat 100% of the time, I think you'd develop fatigue
problems in aluminum.

The aluminum Corvette chassis are semi-space-frame with some shear
panels.
The subframes resolve their loads in three dimensions. There isn't much
flexing there.

The same applies to aircraft, which often are near-monocoque. If they
flex,
you die.

Error.. ever see the wings on a B-52? When they taxi out for take-off
both outrigger wheels are on the ground; when they come back one
outrigger will be ten feet in the air. But not only the wings, a B-52
on the ground has large wrinkles on each side of the fuselage, forward
of the wings; flying the fuselage is smooth.


John D.
(johnbslocombatgmaildotcom)


I don't know what the structure of a B-52 looks like, John, but it must be
far removed from a true monocoque. If a monocoque's skin wrinkled in
compression, all integrity would be gone, and it would completely
collapse.

The wings contain spars -- the skin is stressed in tension but takes no
compressive loads. That's stressed-skin but not monocoque. Most metal
aircraft wings are made like that.

I was referring to the fuselage, of which there are many different
designs.
As far back as the British Mosquito bomber of WWII, some aircraft have had
near-monocoque designs, which depend on the skin (which sometimes is cored
sandwiches, as on the Mosquito, and not a single sheet) to handle tensile,
compression, and shear loads. As you approach a true monocoque, any
stringers and ribs are there to help keep the skin's shape, rather than to
directly take out the major loads.


The only true monocoque airplane structure that I have seen is various
light aircraft and even then it is from the rear of the cockpit back
to the tail skid. The B-52 forward section is not a pure monocoque as
there is substantial structure to built the "two deck" upper and lower
areas so there are various formers and bearers but I suspect that the
skin does support a substantial amount of the load.

Are you sure that the Mosquito had a "cored" structure? I thought it
was cold molded - just layers of veneer glued together.


IIRC, it's wood veneer skins over an end-grain balsa core. It did have
bulkheads to maintain the fuselage's shape.

--
Ed Huntress


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John D. wrote:
On Mon, 1 Mar 2010 17:52:39 -0500, "Ed Huntress"
wrote:

"Bill McKee" wrote in message
m...
"RAM³" wrote in message
. 10...
"Bill McKee" wrote in
m:

Why not aluminum? I have an aluminum boat trailer. Works very well.
3400# boat. The Covette has an aluminum frame as well as the Cadillac
bodied Vette. Look at a Corvette and see what they use. Airplanes
have aluminum frames. And as long as you design well, the flex should
not be a problem.

Boat trailers are rarely twisted the way that off-road vehicles routinely
are.

The same thing applies to Corvettes.

After all, when was the last time that you went rock-crawling with your
'Vette? Grin

How about mud-bogging or bouncing around on deeply-rutted roads?

Jeeps are expected to do all of these and more without any ill effects.
(Getting dirty/muddy is, for a Jeep, a good thing!)
Hell, I raced a vette, steel chassis, and it got to rock clrawing a couple
times. :) And boat trailers are regularly towed over uneven ground.

With three points taking out the loads -- hitch and suspension supports,
which generally are paired but close -- there is no significant torsional
load on a boat trailer. It's all simple bending. You can deal with that, but
if you towed your boat 100% of the time, I think you'd develop fatigue
problems in aluminum.

The aluminum Corvette chassis are semi-space-frame with some shear panels.
The subframes resolve their loads in three dimensions. There isn't much
flexing there.

The same applies to aircraft, which often are near-monocoque. If they flex,
you die.


Error.. ever see the wings on a B-52? When they taxi out for take-off
both outrigger wheels are on the ground; when they come back one
outrigger will be ten feet in the air. But not only the wings, a B-52
on the ground has large wrinkles on each side of the fuselage, forward
of the wings; flying the fuselage is smooth.


For what it's worth, I was told that the fuselage
skin on a B-52 was unwrinkled until they started
flying them at 100ft off the ground at 500mph or
something...
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On Sun, 28 Feb 2010 14:10:06 -0800, Tim Wescott
wrote:



Stainless is hard to weld, and fatigues far more readily than steel.


Setting aside the question of whether SS is a good choice for the OP's
project, the common austenitic stainless steels -- 304 and 316 -- are
among the easiest materials to weld. The fatigue limit of both alloys
is in the 35 to 40 ksi range, higher than the fatigue limit for common
structural steels.

--
Ned Simmons
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