Lower A-arms

[B.Rickard]

Hey suspension guys, Ive been looking everywhere for an answer on this and couldn't find anything solid so i figured i would just post it. Is there any advantage/disadvantage to having non-parallel lower A-arms? (just to specify these are in the rear and parallel is relative to the ground at a static load)
Thanks for any help you can give me. -Brendan

[Dave K]

it depends on what you want in terms of your kinematic roll center placement/movement to look like, as well as your camber curves. Making your lower a-arms non-parallel with the ground will give you more lateral tire scrub motion than a parallel arm, but i'm not one to say that's a bad thing i guess...

Come up with what you want your camber and roll center kinematics to look like, and then judge the pros and cons.

[J.R.]

Advantage, longer lower link possible, therefore, you can have greater difference in link lengths, so you can rapidly move your ic to get the correct camber curve. Excess scrub will allow you to get your tyres to operating temp faster also. Making them package drives your frame man nuts though, http://fsae.com/groupee_common/emoticons/icon_wink.gif

[scott_rfr]

So a little on topic little off topic. About the excess scrub you get resulting in bringing your tires up to temperature faster. I have heard both sides of the case both from students and professionals about running or not running scrub. My initial thought was that scrubbing the tire across the surface would help but I am not so sure any more. Has anyone actually tested it?

Scott

[J.R.]

I don't know how you would test it, without building two cars that have the same exact setup and multiple mounting points to check different linkages. I can't imagine that it wouldn't though, sliding something always produces heat. Or were you talking about running numbers to see how much scrub you want? In which case, probably something that I should do, but don't have time for http://fsae.com/groupee_common/emoticons/icon_wink.gif Winter break stuff....

Which school you from BTW?