Total Lateral Load Transfer Distribution

[Sleeper68]

Like I said earlier, you made a change, lets see what happens. At the same time, like Lance said, your contact patch is broken. You are giving up all of your camber with body roll and so you are stuck riding on the outside edge......it is 100% a front suspension problem and your roll center is only a very small part of that.

Are you on crazy stiff shocks?

Yes we will see. I think getting the roll axis inclination like it used to be will make the car happy again, and I think it will handle better because of the improved camber gain, and thus more camber on the outside front while loaded up.

Yes the outside front contact patch is not good. That is why the car is understeering, we can all agree on that. Why the contact patch is not good is the topic of debate.



Two major car attributes changed between the two events pictured: 1. the front RC height and, 2. the camber gain curve. The camber gain curve improved so the only thing left that could cause issues is the front RC height and how it interacts with the rest of the car. To say that the roll center is a small part doesn't make sense to me because it is the only possible negative change from before.

My opinion on what we are looking at in the two later pictures is excessive jacking forces, due to a number of different things. The first major thing is the RC height. Jacking forces are determined by track width, acceleration, mass, CG height, and RC height. By moving the RC up, you increase geometric weight transfer "jacking" and decrease elastic weight transfer "sprung reaction". Because the springs are compressing less, the camber is not changing much. You can see this in the pictures. The front suspension is barely articulating. Instead the car is pivoting about the outside front tire. The second major thing is roll axis inclination. The rear is rolling about its roll axis much more than in the autox in March. The jacking forces are literally "picking the car up" and unloading the inside front. Thus, the rear is taking much more of the weight from the front. If we give that weight back to the front, from the rear, the jacking is counteracted and the front suspension articulates. From the articulation we gain camber, and the outside front is happy again. There are two ways to "give" weight back to the front, rear sway bar stiffening or rear RC height addition.

The shocks are Varishocks, the SS model. They are not very stiff IMO, probably somewhere near 0.6-0.7 damping ratio in the lower piston speeds. They are non-adjustable.

Agree completely. Your car can only go around a corner as fast as the front tires will let it. My personal theory is not much different than Donny's, get the front as good as you can get it and tune the back to balance it to the front.

What caster do you have in the car now? And what spindles?

You can only go around a corner as fast as whatever tire(s) lets go first. That could be any of the 4. In this case, it is my outside front. In other cases it could be inside front, outside rear, or inside rear if you have a FWD car (Ford Focus, Civic, etc.)

The car has about +6.1° of caster in it. Spindle is a GM short spindle. SAI is about 8.7°.