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Originally Posted by dennis68
How do you intend to "fix" the issues of bind in roll on a parallel 4-link? Since the issues bind cannot be solved using 4 parallel links there is actually a great deal of difference between a 3-link and parallel 4-link.
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If you read my post carefully, I did not say that you "fix" "binding" in a four link, I said that if the roll stiffness introduced by such binding is not large compared to springs and sway bar, it will not have a significant impact on handling. That is simple physics. Think of it this way: a sway bar works by introducing a massive amount of "binding" in roll. If the four link moves freely enough that you can lift one side of the axle housing several inches without the other side lifting, then the roll stiffness introduced by the suspension links is negligible.
Make no mistake, all suspension designs are "compromised" from the start. Three link designs are popular in competition because they are easily adjustable, but they have issues with tradeoffs between the most desirable instant center and the most desirable roll steer (same with four links). Also, the change in suspension parameters through suspension travel can be significant if the links are short (race cars tend to use very long links, because they don't worry about packaging in a rear seat area). Torque arm style three links have less of the issues mentioned above, but are less adjustable in some ways, and are heavier. And so on.
I stand by my point - it is possible to make a very good handling car, or a very evil handling car, with three links, four links, torque arm, truck arm, leaf springs, or what have you. It all depends on how well you manage the compromises associated with each to achieve the results you want. It would be great if we could have some of the kinds of discussions here about the effect of various suspension parameters (roll center, roll steer, instant center, camber gain, scrub radius, etc) and their subjective effects on handling, and how to achieve them. There are lots of such discussions on corner-carvers.com, but the atmosphere tends far too much toward the hostile.