Aluminum link material group buy

mlcasey said:
Two things guys:
The link will be very weak at the threaded end since you are removeing material from it. This mean you need to recalcuate it as a hollow tube with the inside dia being the dia of the threads.
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Good point, and a big reason we went with 1.75" uppers... both uppers and lowers will have .375 around the threads (using 1" shank and 1.25" shank ends), and it still has quite a bit more strength than the 2" .500 DOM originally planned...on the order of ~30%.

If you do decide to run them go to mcmaster.com and get some threaded inserts or heli coils to put in this will make the threads way stronger. You may still deform the hole when you load it ive seen it happen twice in custom off road aarm app.
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Interesting, and I always wondered why the "ready made" link makers were so keen to taper the ends down so much, cut wrench flats in them, etc... Were the links you saw the deformation on tapered at the ends, by chance?
I will certainly keep the heli-coil idea in the back of my head though.

Also aluminium has a much lower fatigue life then steel. Though you may never reach it you reduce the strength everytime you land on one and bend it to the plastic deformation state and then bend it back.
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Absolutely true, and a major advantage of steel, though links are somewhat like tires, a consumable. But to me, it almost seems akin to the old grade 5 vs. grade 8 thing, with the grade 5 being the DOM..
While the DOM may live a long time when loaded to near its ~3750lb limit time and time again, the 7075's limit is between ~5000-5800lbs (depending on if you count the solid vs. tapped size), which to me means it wouldn't be 'breaking a sweat' so to speak - what do you think?

Honestly, thank you very much mlcasey, for the real input on this!! It's my belief that it's still doable and will meet my goals.. Time will tell though.
 
saf-t scissors said:
. Comp guys can justify the 20lbs of weight savings. Maybe. At least on paper.
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Comp guys are not going to run something weaker (link wise anyway) to save a few lbs. I have talked to them in person (not on the interweb) and been told the advantage is that they will bend-and straighten. Steel will bend and stay bent. When I hear someone tell me they have ran both ( steel and AL) in numerous comps, and had much better luck with AL, I'll beleive that before I beleive info from the computer, engineer's, and other various no-it-all's with limited REAL WORLD experiance.

On the other hand I have seen at least 2 break, I don't know what they were other than AL. I don't know where Rich is getting his numbers, but from what I have seen 2 inch solid steel bar will bend before 2 in .385 wall tubing. So how is 2 in solid AL stronger than 2 in .500 steel tubing?
 
Different alloy of aluminum. Same idea but different:

I can bend a piece of .080 steel about 5' long with EASE in the brake at work, (even 1/8" steel to about 3 feet).

I tried to put a minimal bend (less than 5 degrees) in a sheet of .063 T6 aluminum (about 5 ft), and it was all I could do to get that. Literally, I took more to bend that .063 T6 than any steel I have ever bent in it. The brake is only rated for 14 G though, but we bend 1/8" all the time (no longer than 4-5 feet though).
 
rockmafia said:
Comp guys are not going to run something weaker (link wise anyway) to save a few lbs. I have talked to them in person (not on the interweb) and been told the advantage is that they will bend-and straighten. Steel will bend and stay bent.
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That's a misconception due to the amount that al alloys will deflect under load. People see an AL link "bend" and recoil, and think the stuff is indestructable. Steel deflects under load too, it just doesn't move quite so readily. The problem you'll run into is that a steel link will reach plasticity with only a little bit of deflection... let's say less than 1", though it depends on the length of the link, wall thickness, alloy, temper, etc. Pull some steel bottom links off of a rig after a year or so, and while they might still be "straight", you'll see they're actually bent about a dozen different ways, only very slightly. An AL link deflects a lot more before it goes plastic. So when you bend your al link, you'll usually bend it big. That's assuming that you don't break it first. 7075 is highly susceptible to stress corrosion cracking. Every time that link touches something, you're damaging it. That's why you see these guys going "I didn't even hit it hard, and it just fawking snapped in half". Well, you're not thinking about the hundreds of times that it's been loaded prior to that.

And let's not forget to mention cost. Tacoma says he got a "good deal" at like $14 a foot. $14 a foot! That's stupid money, when there are other, cheaper options out there that are stronger. The problem is that "aluminum links" is the buzzword, and 7075 and 6061 are in the 4-link calculator, so folks just scroll their mouse wheel over to the material tab, and tells the computer that they want some AL alloy, and the computer spits out some numbers. Those numbers look good, so the brain shuts off.

That's just scratching the surface. But I think it touches on a number of different issues, and my major concerns with the whole dog-and-pony show.
 
saf-t scissors said:
And let's not forget to mention cost. Tacoma says he got a "good deal" at like $14 a foot. $14 a foot! That's stupid money, when there are other, cheaper options out there that are stronger.
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That's not really that bad considering I paid $14/ft. for 2" .500 wall DOM. I was quoted as high as $21.50/ft.

What would you suggest as a stronger, cheaper alternative?
 
I suggest you guys look into carbon fiber and other composites...
 
i paid $10 a foot for my 2.25 .385 wall and i cant in imagine how the al. could be stronger, but it would be:bling:
 
tw89yj said:
That's not really that bad considering I paid $14/ft. for 2" .500 wall DOM. I was quoted as high as $21.50/ft.
What would you suggest as a stronger, cheaper alternative?
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Fawk, I dunno... how about some 2.5" 1/4 wall? Should be about $7/ft... maybe $8. It's stronger and lighter than 2"x.500. You'd save like 8-10# per link. 2.25x380 is stronger, too. I don't think $10/ft is a great price, but it's an odd size, too.
 
Cheapest price I found around for 2.5" .250 was $8 from Carwash on the PBB.. locally it was FAR more. so, add in shipping from him, then try to find tubing insert that is for 2" ID tube to a 1.25" thread. I haven't really looked to hard for one, but you could bet it will be $15 or so each.
 
I mean, I think my biggest gripe is with the general lack of thought that's going on. If you want to run AL links, then fine. But nobody's even stopped to consider the consequences of that... either out of complacency or ignorance, I dunno.
 
Yo,

One fly in the ointment. Aluminum has no endurance limit meaning if you stress it enough times, it will fail. Stressing steel below a threshold that is a function of its intrinsic properties will not lead to a fatigue failure. That is why aircraft aluminum parts must be replaced at predetermined intervals.

MY $0.02
 
So Saf-t.. If I'm reading right, your 2 big reasons for not liking it is:

1: That it will deflect more easily (about 3x as easily)
2: SCC and also general fatigue

1 is somewhat mitigated IMO in that it will have to sustain almost 50% more force to reach yield (plasticity).. Yes, it'll deflect, but it won't stay that way until you hit something BIG.. big enough to have destroyed that .500 DOM a loooong time ago. But it *should* sustain multiple hit that would yield the DOM.

2: Nothing I can say other than what's the life expectancy of a lower link on a rock buggy no matter what the material? (Jim, Scott, Greg, shaddup..i can hear you already "As little as Rich wheels, a lifetime!" :flipoff2: ) 1 year, 2 years MAYBE? I would be very surprised if SCC would play a role by then, considering a prime example I ran into while doing research was the landing skid on a Huey..
Average airframe prefix I remember seeing was mid 60's. Stored outside primarily, flown for thousands upon thousands of hours, and flexed every time it lands... Shit, they let ya do auto-rotations to the ground in those.. (Blackhawks will auto-rotate, but the landings aren't very kind to the airframe or occupants - no auto's to the ground in a 60)

Just because I don't have a degree from a technical university doesn't mean that -
A: I don't know what in the hell I'm talking about.
B: I don't know people that DO know what the hell they're talking about, (both MIT engineer-types and real-world usage types)
C: I don't know how to do research.
D: I don't weigh the pros and cons.

How's this:
DISCLAIMER TO ANYONE FOLLOWING THIS:
Aluminum links will NOT last as long as as steel link. It will fatigue over time, and may break, killing you, your family, and possibly a busload of nuns. If it doesn't brealk, it will likely deform upon impact. Whether it springs back or not is a function of a multitude of factors beyond this discussion. :beer:
 
Rubber links actually can absorb more energy than aluminum or steel, and are virtually impossible to break. That is my final answer.
 
Rich said:
DISCLAIMER TO ANYONE FOLLOWING THIS:
Aluminum links will NOT last as long as as steel link. It will fatigue over time, and may break, killing you, your family, and possibly a busload of nuns. If it doesn't brealk, it will likely deform upon impact. Whether it springs back or not is a function of a multitude of factors beyond this discussion. :beer:
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That's main reason I still have a 12' stick of 2 1/2" solid aluminum bar standing in the corner of my shop. I wanted to have the really light weight bling links, but the fatigue part is what scared me away. With my steel lower links I can see when one bends a little it isn't going to just shatter one day in the middle of the trail. My lower links have bent slightly on everything I've had but I've never had one bend to the point where it couldn't be driven. Mine are 2" .385 wall dom lowers,they have a slight curve to them now but they haven't really gotten any worse after multiple wheeling trips.
 
jeepinmatt said:
Rubber links actually can absorb more energy than aluminum or steel, and are virtually impossible to break. That is my final answer.
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[foghorn leghorn voice]boy, I say boy, has you considered wood? Wood is straight and light and will last a damn long time. Plus if needed jus chop down a tree and replace on thee trail[/stupid voice]

I think the only way to settle this is a link off...

We need 2 identical buggies, with opposing materials and a trip to DPG, Tellico, Callalantee, Uwha...never mind neither would break, and we wheel until a link breaks. Broken link owner buys beer for the board
 
SkyHiK5 said:
[
I think the only way to settle this is a link off...
We need 2 identical buggies, with opposing materials and a trip to DPG, Tellico, Callalantee, Uwha...never mind neither would break, and we wheel until a link breaks. Broken link owner buys beer for the board
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Good luck getting any wheeling like that out of these two, at least anytime soon for one of them.
 
Question is.. who is the "no time soon" and who is the other? :p
 
saf-t scissors said:
Fawk, I dunno... how about some 2.5" 1/4 wall? Should be about $7/ft... maybe $8. It's stronger and lighter than 2"x.500. You'd save like 8-10# per link. 2.25x380 is stronger, too. I don't think $10/ft is a great price, but it's an odd size, too.
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what can u get dom for? i thought i got a deal
 
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