Anti-Geometry

Anti-Geometry is suspension geometry that is intended to reduce the dive or squat of the car. Anti-geometry includes anti-dive and anti-squat (as well as anti-lift which will not be covered as it is not applicable). Wheel loading remains the same regardless of anti-geometry because the total longitudinal load transfer under acceleration or braking is a function of wheelbase, forces and center of gravity height. Anti-geometry changes amount of load going through the springs and the pitch of the car. Thus, it is largely used for aero benefits.

Side View Swing Arms

Side View Swing Arms shown as the red lines. Red dots are instant centers.

To determine anti-geometry, a side view swing arm must be generated. Draw a line from the 2 mounting points of each front control arm rearward until they touch. Then, draw a line from the 2 mounting points of each rear control arm forwards until they touch. These 2 points are called instant centers. From each instant center, draw a line to its respective wheel's contact patch. This line is the Side View Swing Arm (SVSA).

Anti-Squat

Anti-squat limits the compression of the rear suspension under acceleration. Anti-squat is expressed as a percentage. 100% anti squat represents no rear suspension compression under acceleration. % Anti Squat is calculated using:

$\mathrm{\%}AntiSquat=\frac{SVSAheight/SVSAlength}{h/L}*100$

Where:

• SVSAheight is the height of the rear instant center from the ground
• SVSAheight is the rear Side View Swing Arm horizontal length
• h is the height of the center of gravity
• L is the wheelbase length

Anti-Dive

Things needed to calculate % anti dive

Anti-dive limits the compression of the front suspension under braking. Anti-dive is expressed as a percentage. 100% anti dive represents no front suspension compression under braking. % Anti Dive is calculated using:

$\mathrm{\%}AntiDive=\mathrm{\%}FrontBraking*SVSAheight/SVSAlength*L/h*100$

Where:

• SVSAheight is the height of the front instant center from the ground
• SVSAheight is the front Side View Swing Arm horizontal length
• h is the height of the center of gravity
• L is the wheelbase length
• %FrontBraking is the percentage of braking done by the front brake, also known as the brake bias.