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Old 08-13-2015, 10:45 PM   #15063
Razathorn
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Quote:
Originally Posted by Cpt.America View Post
I'm just correcting your misinformation. Relax. There's no need to be so combative. Everybody is just here to lean. You stated empirically that changing your link length at the hub doesn't change roll center, which is completely incorrect. Changing your link length or angle on either end, CHANGES the roll center of the car as it is driven around the track.

To be more specific, if the car's suspension isn't moving at all (i.e. standing still), if you ONLY lengthen the link without changing it's angle at all, the roll center doesn't change UNTIL the car starts to roll. The moment the car's suspension starts to move, the longer link has a different "curve" in which the roll center changes. Not only does it provide less camber gain, it provides a lower roll center, when the car is fully leaned over compared to a short link.

Moving on.
Believe it or not, I actually DO understand all of that. I too have ran the differences between where the RC is at rest and rolled in a suspension design simulator after changing the links around in all sorts of stupid ways. I *really* do have an in depth understanding of this subject. If you see something I've said that appears wrong, I promise you it is just a misunderstanding due to my goal of making things understandable and applicable when chassis tuning.

I really don't want to get lost in the weeds here over what I was trying to say, which is this, in extreme detail:

If your goal is to tune camber gain, make changes at the hub and not at the inside brace. There are multiple reasons this is advisable. First, the adjustments offered in/out are "half hole" and aren't nearly as dramatic as changes at the inside (that are far apart), which will REALLY jack your roll center up in addition to changing camber gain—I mean it's in a totally different world at that point for BOTH roll center AND camber gain. This is why AE came out with A/B hubs, because the A hub holes were too large of a change to be useful for camber gain tuning—anything other than middle A was junk! The second reason is that because the distance between the inner hinge pin and inner upper link is smaller than the distance between the outer hinge pin and outer link—the lever arm at the inside is already shorter than at the lever arm at the outside in nearly every modern offroad car (if the arms are level, the camber links sweep down toward the inside brace.) Any change to the inside—height, left/right, will have a larger percentage difference against the distance of the lever arm. This is only compounded by the fact that the steps in/out at the inside are HUGE.

This is why I made the following statement...
Quote:
Originally Posted by Razathorn View Post
you have to familiarize yourself with what camber gain does (the length of your link, best adjusted at the hub to not mess with roll center.)
When you change camber gain at the hub, the RC is certainly changed to SOME degree, but it is so small, it is dwarfed by the change introduced by the camber gain itself. You'll either like the camber gain change or you wont. if it feels better, then you go adjust roll center with links up/down if it feels off, but in my experience, it really doesn't need much, if any, adjustment.

Now, if you go tuning camber gain by changing the inside link, not only is the camber gain change huge, the roll center is obliterated—it's so far off the car may be undrivable (especially a 2wd buggy,) and then you really have to go MESS WITH roll center to even test your camber gain change.

That's the best I can do to clarify what I'm trying to say.

Do you agree with this assessment?

EDIT: By the way, the "ae tuning tips" thing was not directed at you at all—that came from another post, not yours.

Wayne
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