Roll Center... Is this a problem? - Lateral-g Forums

LateNight72 · #1 03-19-2009, 07:58 PM

I do not think it is, but wanted to get some opinions before I start ordering stuff.

The thing I wanted to confirm was if it was alright that the point where my upper arms converge with the lower arm is 75.8" away from the tire centerline. Will this be a problem? I don't think it is. But wanted to confirm.

Lower Arms - 7" ~ Parallel to the ground
Roll Center - 1.5"

Thanks.

David Pozzi · #2 03-20-2009, 10:41 PM

No, I've seen much much worse than that!

terryr · #3 03-21-2009, 12:34 AM

Your camber curve will be opposite of what is wanted for handling. The tire will tip out at the top instead of in. Not much you can do unless you go to a taller spindle or mount the upper arms lower in the chassis.
GM did this for a better ride and less tire squirm. I've seen old ads where they brag about it. "yes, we've screwed up the ride so grandma won't complain."

LateNight72 · #4 03-21-2009, 01:05 AM

Quote:

Originally Posted by terryr

Your camber curve will be opposite of what is wanted for handling. The tire will tip out at the top instead of in. Not much you can do unless you go to a taller spindle or mount the upper arms lower in the chassis.
GM did this for a better ride and less tire squirm. I've seen old ads where they brag about it. "yes, we've screwed up the ride so grandma won't complain."

Its a "clean-sheet" suspension.

JRouche · #5 03-22-2009, 12:14 AM

Nice , I like your line drawing. Is the white line your lower arms? Im not even schooled in the suspension area, just learning. But I do understand your line drawing.

So Im trying to learn here. Is a shorter IC more desirable? From the sounds of it maybe? Dummy me, I thought a lil longer IC distance would help to keep the tire vertical through the suspension travel. Forgive me, just trying to get a grasp on the whole idea. But if the IC is way out there, the tire is gonna follow a simple path, too short of a IC distance and its gonna move quiet a bit?

Were you asking if the IC was too close?? Like the upper arm was tilted down too far?

Excuse my retarded questions, just trying to get an idea of where you guys think the IC should be? Long or short. I got the feeling the IC was on the shorter side. Help a guy out. Im ALL open ears at this point, I want to learn what is a desirable suspension setup.. Thanks. JR

LateNight72 · #6 03-22-2009, 01:13 AM

Quote:

Originally Posted by JRouche

Nice , I like your line drawing. Is the white line your lower arms? Im not even schooled in the suspension area, just learning. But I do understand your line drawing.
....Yes the white lines are the empirical centerline(s) of the lower arms.

So Im trying to learn here. Is a shorter IC more desirable? From the sounds of it maybe? Dummy me, I thought a lil longer IC distance would help to keep the tire vertical through the suspension travel. Forgive me, just trying to get a grasp on the whole idea. But if the IC is way out there, the tire is gonna follow a simple path, too short of a IC distance and its gonna move quiet a bit?
.... A shorter IC will give you a larger negative camber gain for every inch traveled, since the upper arms will have more angle, and the radius they travel will be more horizontally than it will vertically.

Were you asking if the IC was too close?? Like the upper arm was tilted down too far?
.... I was asking if it were okay in general.

Excuse my retarded questions, just trying to get an idea of where you guys think the IC should be? Long or short. I got the feeling the IC was on the shorter side. Help a guy out. Im ALL open ears at this point, I want to learn what is a desirable suspension setup.. Thanks. JR
.... You'll want negative camber gains to help keep the tire's entire contact patch on the road. sideloading forces mixed with body roll when turning will try to put all the force on the outside edge of the tire. You design in negative camber gain, so when the car rolls (and the suspension compresses) it angles the tire to effectively put as much tire on the road as possible. More negative camber means more force that can be applied (to a certain extent).

Hopefully Dave can give a better explanation than I can. (I suck at explaining things, God just didn't want me to be a teacher

)

terryr · #7 03-27-2009, 09:12 PM

Quote:

Originally Posted by LateNight72

Its a "clean-sheet" suspension.

Then try to make it better than factory. wink

LateNight72 · #8 03-27-2009, 09:35 PM

Quote:

Originally Posted by terryr

Then try to make it better than factory. wink

Really? No way.