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K^2
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pretend you have 2 triangulated lower links, and 2 parallel uppers in a 4 link setup.

When the axle tries to move laterally, the axle essentially "pivots" around where the lower links join.

The upper link on the side where the axle is trying to move tries to compress, while the upper link on the other side tries to extend. Because that is not possible for each to compress or extend, the axle stays put.

Now if you remove one of those upper links - as the axle tries to move laterally it will just instead rotate forward or backward since there are not equal and opposite forces holding the axle in place.

If you triangulate both lowers and the upper link, the same thing will happen. As you hit the gas, the upper link which is suppose to control torque will pull the axle sideways and over laterally since there is not another link to control the force in the opposite direction.

"One links" are not one links, they are 2 links. If you remove the panhard bar there is technically nothing to locate the axle laterally, and it will just try to swing around the pivot point like a trailer.
 

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Discussion Starter #22
maybe in something that doesn't see any kinda side loads, but this is rock crawling. With the setup you're talking about you'd need a RIDICULOUSLY HUGE crossmember to attach to, and even then I see things failing if you ever take a decent side hit, like say rolling and landing on the side of the tire, or hitting a rock with the outside tire in a turn at speed.

On our competition cars we run triangulated 4 links in the back, and on hard rolls it's not unusual to bend an upper link, or rip out tabs. We used to replace uppers on the RockHer1 fairly regularly because of this, and it had 2 huge beefy lowers, not just one.

Technically it'll work, but structurally it's far from ideal.
So far your the only one that seems to understand. And what you are saying is the very first thing that I thought of. But, in your example no 4 link with only two triangulated links would ever work. Which we know they do, so I am still curious how this would not work and that would.

Uh yes 3 links work. with a Panard bar to take the lateral forces. Campbells have twisted a couple 9" housings in 3 link set up. Thats with the upper doing only power control duty. I can't imagine how much force it takes to twist the housing especially after Shannon has trussed it. I doubt VERY highly that it would survive the additional forces of being the lateral locater as well. You trying to save weight? Be John Nelson? What?
I'm not building anything or planning to do anything. I am curious to learn.



pretend you have 2 triangulated lower links, and 2 parallel uppers in a 4 link setup.

When the axle tries to move laterally, the axle essentially "pivots" around where the lower links join.

The upper link on the side where the axle is trying to move tries to compress, while the upper link on the other side tries to extend. Because that is not possible for each to compress or extend, the axle stays put.

Now if you remove one of those upper links - as the axle tries to move laterally it will just instead rotate forward or backward since there are not equal and opposite forces holding the axle in place.

If you triangulate both lowers and the upper link, the same thing will happen. As you hit the gas, the upper link which is suppose to control torque will pull the axle sideways and over laterally since there is not another link to control the force in the opposite direction.

"One links" are not one links, they are 2 links. If you remove the panhard bar there is technically nothing to locate the axle laterally, and it will just try to swing around the pivot point like a trailer.
This example only starts to work if the upper link is still mounted on the outside of the axle. If it is mounted closer to the center like 3 links are, it does not apply. If it did, all three links would fail, panhard or not, because the traight uppers only deal with rotational force.

Wait, I might be seeing what you are saying. But no, not entirely. Wait, yes, I just saw it. It won't work at all. Thanks Kirby, the rest of you, I really expected better. :flipoff2:
 

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K^2
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So far your the only one that seems to understand. And what you are saying is the very first thing that I thought of. But, in your example no 4 link with only two triangulated links would ever work. Which we know they do, so I am still curious how this would not work and that would.



I'm not building anything or planning to do anything. I am curious to learn.





This example only starts to work if the upper link is still mounted on the outside of the axle. If it is mounted closer to the center like 3 links are, it does not apply. If it did, all three links would fail, panhard or not, because the traight uppers only deal with rotational force.

Wait, I might be seeing what you are saying. But no, not entirely. Wait, yes, I just saw it. It won't work at all. Thanks Kirby, the rest of you, I really expected better. :flipoff2:
any time :D
 

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A 4 link with one link removed is not enough to locate the axle. it will move side to side as the axle housing rotates.

Dont believe me? Put your vehicle on jack stands, take one link out, drop it down (if it stays together afterputting the weight back on it) and then try to drive out of the garage.... you wont get far.
 

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I hit a rock at speed with drive side front. The force was enough to rip the steering arm and knuckle apart, crack the axle tube and slightly bend the lower link.

Think of the force on your crossmember in your triangulated lowers set-up.

StinkBug said it best.
 

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Discussion Starter #26
I hit a rock at speed with drive side front. The force was enough to rip the steering arm and knuckle apart, crack the axle tube and slightly bend the lower link.

Think of the force on your crossmember in your triangulated lowers set-up.

StinkBug said it best.
That was a dana44 and that "rock" was actually a red plastic cup from the night before. :flipoff2:

Its not about force. It won't work at all. Kirby made it make sense to me. Which is what I was after.
 

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In 3 dimensions there are 6 axis of motion- 3 rotational and 3 linear.

You want 2 of them for your axle: 1 linear (vertical motion) and 1 rotational (articulation).

The other 4 axis you want to eliminate, and you need 4 links to do that, or combinations of links like wishbone/triangle/radius arms that can do the work of more than one link.


If you remove one link from a 4-link, then you enable one of the undesireable axis of motion. Generally you will lose wrap control or lateral control, or when the links are at an angle, some combination of both.
 

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When you google one thing and something else comes up, you end up here on an old thread. So I read through all the post and it got me thinking. Everyone talks about triangulated lowers and a straight upper. What about 2 straight lowers and one triangulated upper that goes from the frame on one side to the center point on the axle?
 
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