Does everyone grasp the existence of the instant center?
There is another imaginary line called the antisquat line. This is a line that connects the rear tire patch and the height of the center of gravity above the center line of the front tire. I don't fully understand why this is. But we will accept that it exists, because engineers have found it.
The position of the instant center in relation to the antisquat line will have an effect on the on the behavior of the rear suspension while the wheels are spinning and applying traction to the ground.
If the instant center is located anywhere above this antisquat line, the control arms will push the rear axle into the ground. The further above the line, the harder the push. This is a resistance to squat or antisquat or positive antisquat.
If the instant center is located anywhere below this antisquat line, the control arms will pull the rear axle away from the ground, causing the vehicle to squat. The further below the line, the harder the pull. This is negative antisquat.
If the instant center is on the antisquat line, then the control arm's effect on the axle will be neutral. In the image above, this is called 100% antisquat.
Antisquat numbers above 100% are positive, numbers below 100% are negative. I don't know why this is.
This video covers too much ground and isn't as simple as I would prefer.
Pay close attention to 8:30, the red buggy followed by the green. This is what matters for us.