i have a odd question

[cowboy63b]

everyone knows how with 7075 alum links they are drilled and tapped to accept rod ends, i assume the same can be done with hex solid stock?


i was thinking 1.5" for the uppers and 2" for the lowers. also, would cold rolled be better or hot rolled?


this is where i would be getting the material.....http://www.onlinemetals.com/merchant...41&top_cat=197

one of my buddies in San Antonio orders from there and we had it tested and everything is legit.

[rstrucks]

Going for the worlds heaviest links?

Stick with DOM or aluminum.

[cowboy63b]

point taken.

[ATL ZJ]

the best is 3ft of allthread with female johnny joints

[dyn0mitemat]

I've considered going with solid 2" steel stock, but can't bring myself to add that much more weight under the beast

[cowboy63b]

the best is 3ft of allthread with female johnny joints

smart guy.

[JohnBoulderCO]

I've considered going with solid 2" steel stock, but can't bring myself to add that much more weight under the beast

Why? You quickly get diminishing returns on strength as the wall thickness increases and then you are just adding weight.

[AgitatedPancake]

if your worried about strength do 2.5" .375 and never look back. 2" .250 DOM bends easily enough

[zjeepin]

if you're going with the 2.5' diameter just go with 2.5x .250 or .375 square and save a bunch of money..

[cowboy63b]

well the front is 2"x.250 DOM, im not too worried about them, but i do drag the ass end over rocks, logs, and whatever else the diff reaches out and grabs, so im more concerned about the rear lowers bending.

[cowboy63b]

i was thinking if i did .250 walled lowers, i *should* be able to get away with .188 uppers, unless i decide to drag those as well.

if it helps, im swapping to waggy 44's and bigest tire this will ever see is gonna be a 35.

[ATL ZJ]

x2 on the big diameter square. You don't even need that thick- it's cheap and super strong. Took me 3+ years of punishment a zj would not survive to bend my 2.5" square 1/4 wall lowers.

FWIW I also run 1.75" .120 wall DOM uppers and have had no problems. just don't make them super long.

[5.9 ANDY]

im swapping to waggy 44's and bigest tire this will ever see is gonna be a 35.

yeh, right, thats what we all said.

[zjeepin]

im running a set of .120 wall uppers in the rear as well.. no issues

I bent 2 sets of 2x.250 DOM front links.. you will bend them too and you'll be rebuilding the arms and spending this money all over again...

[SirFuego]

FWIW, I think there is something to Clayton's reasoning for using square tubing (2x2x1/4"). I'm not easy on my junk and it looks like Cam was running square tubing for a while, too -- we know he's not easy on them either. I have a buddy running a Clayton's kit in his XJ. He did manage to bend a couple of the arms, but that was after 4 years or so of abuse with the last two being driven basically with an on/off skinny pedal in the rocks. The arms he did bend were not horribly bent and he continued to abuse them without failure. I know a few other guys that bent round lower links (to the point that they needed to be replaced) on lighter vehicles in a much shorter timeframe.

I don't want this to turn into a DOM vs. Square debate for lower arms, but I'm just passing along what I've seen.

The worst abuse upper arms will see is possibly hitting the floorboards. More likely than not, a joint or mount will fail before the tubing itself since the upper just sees drivetrain torque that smaller tubing should be able to handle. You did something special if you did happen to get a rock to bend/damage an upper link.

[zjeepin]

Cam and i both are running square lowers.. the 2.5x.250 flavor (several others in our group run square lowers as well).. I've bent them ever so slightly but my links are super long and i drive my junk pretty hard.

I'm a strong advocate because i've spent so much money on dom arms just to bend them prematurely IMO and have to spend the money and time all over again to rebuild them..

[ajmorell]

I don't want this to turn into a DOM vs. Square debate for lower arms, but I'm just passing along what I've seen.

Jared, you know should as well as anyone else that there is an inherent strength advantage to square/rectangular tubing compared to round.....

[AgitatedPancake]

Honestly I agree, I'd much rather square tube links. My claytons lowers have held up to the abuse so far. They are starting to arc slightly, but they're still straight enough for me. They've survived bending the 1.25" shank of one of my rear johnny joints too.

This is all while watching my friend with a much lighter solid axled bronco 2 on 35"s bend both 2" .250 DOM lowers pretty heavily.

If mine ever bend enough for replacement, I'd probably bump up to 2.5" .250 square links too

[SirFuego]

Jared, you know should as well as anyone else that there is an inherent strength advantage to square/rectangular tubing compared to round.....

Yeah it's been a while since doing all those calculations, but I've found that people tend to not trust equations unless they see empirical evidence that it's really true.

Especially in a hobby where (a) it's tough to generalize "strength" since there are usually so many other factors that come into play that can't be easily captured by the equations and (b) a lot of people don't know much or care to ever learn about moment of inertia or other theory-based math.

A local shop owner once told me a while back that "materials don't create strength, shapes do".

Cam, Trey -- how did you setup the rod ends for 2.5" square tubing? Did you find square tube adapters somewhere tapped for the rod ends, or did you do something else?

[zjeepin]

Cam, Trey -- how did you setup the rod ends for 2.5" square tubing? Did you find square tube adapters somewhere tapped for the rod ends, or did you do something else?

I made my tube adapters, I cant remember if there are any 2.5" tube adapters on the market or not..

[SirFuego]

Jared, you know should as well as anyone else that there is an inherent strength advantage to square/rectangular tubing compared to round.....

OK, so the geek in me couldn't help but to try to theoretically answer the question what size of tubing 2" solid stock would be "equivalent" to in terms of strength regardless of the evidence already establish in this thread. As many know, when you are comparing the same material (and same length), the moment of inertia (MOI) can be used to compare the relative strengths of the different shapes. You can find calculators online to do these calculations and read all about it, but for the sake of this discussion a higher MOI means that it's more resistant to bending and deflection.

You can see in the attached picture, it has MOI (and area) calculations for square and round tubing of different thicknesses. I know that not all combinations are actually available, but I included them for comparison. Notice how the MOI flattens out for each tubing size, so there comes a point that adding more material is basically just adding weight.

For example, cowboy was asking about 2" solid stock (which in the table above is round 2" tubing with a 1" wall thickness). If you take a look at that data point on the graph and draw a horizontal line over to the Y-Axis, any data point that lies above that line will be stronger than 2" solid stock. You can see that the data point for 2x2x1/4 is also above that line -- indicating that it's stronger.

Or you can look at the table to get the actual numbers. 2" solid stock has a MOI of 0.785in^4. 2x2x1/4 square tubing (same as Clayton's arms) has a MOI of 0.911in^4. You will also see that the 2x2x1/4 has a significantly smaller area which means that it'll be lighter, too.

[cowboy63b]

so based off of your graph, square tube is stonger than round tube of the same diameter with less wall thickness.

makes sense seeing that a square shape is stonger than a circle.

[SirFuego]

Basically, yes. Also take note how quickly the MOI increases as you increase diameter/height as well.

That said, this comparison I did is only valid for the same material. Once you start comparing different materials (such as comparing strength/weight of chromoly vs "normal" steel vs aluminum), you need to take other parameters into account for comparison since the strength and density of the material plays a role in overall strength and weight.

I also must say that those numbers are there purely for comparison purposes to illustrate how wall thickness can at some point be compensated for by diameter and/or shape without using as much weight. In reality there may not be "much" difference between an MOI of 0.8 and 0.9 for the forces the lower control arms will see (for example), so there isn't much sense getting caught up in targeting a specific number. The trends shown by the graph are much more important than the actual numbers. I would just use 2x2x1/4 as a baseline for comparison purposes and work from there.

[Kraqa]

Rock Crawler used to use solid arms with little success.

Solid will not resist bending as well as a hollow structure. The beauty of 7075 aluminum is that it has a good memory and will spring back. Where steel will keep its new shape.

The square to round debate is a good one. Square links are stronger in one direction than the other. Where round is universally strong in any application. I would not run 2.5 x2.5 links IMO they are probably the most ghetto links you can get. 2x2x.25 links are cheep and don’t look that bad.

I’m a fan of round. I run 2” x .375 wall and have yet to bend one, that they are expensive. In my next build I’m going with a round tube/plate fabricated hybrid rear trailing arm with the rest of the links being aluminum. the round tube for the trailing arms will be 2” x .188 wall. The aluminum will be 2” 7075 lowers and 1.5” 7075 uppers.

[ajmorell]

OK, so the geek in me couldn't help but to try to theoretically answer the question what size of tubing 2" solid stock would be "equivalent" to in terms of strength regardless of the evidence already establish in this thread. As many know, when you are comparing the same material (and same length), the moment of inertia (MOI) can be used to compare the relative strengths of the different shapes. You can find calculators online to do these calculations and read all about it, but for the sake of this discussion a higher MOI means that it's more resistant to bending and deflection.

You can see in the attached picture, it has MOI (and area) calculations for square and round tubing of different thicknesses. I know that not all combinations are actually available, but I included them for comparison. Notice how the MOI flattens out for each tubing size, so there comes a point that adding more material is basically just adding weight.

For example, cowboy was asking about 2" solid stock (which in the table above is round 2" tubing with a 1" wall thickness). If you take a look at that data point on the graph and draw a horizontal line over to the Y-Axis, any data point that lies above that line will be stronger than 2" solid stock. You can see that the data point for 2x2x1/4 is also above that line -- indicating that it's stronger.

Or you can look at the table to get the actual numbers. 2" solid stock has a MOI of 0.785in^4. 2x2x1/4 square tubing (same as Clayton's arms) has a MOI of 0.911in^4. You will also see that the 2x2x1/4 has a significantly smaller area which means that it'll be lighter, too.

Haha, nice work. I didn't mean to open that can of worms but that is good info for sure.