Goal: Understand the higher level functionality and purpose of suspension in a race vehicle
Notes from: Race Car Vehicle Dynamics
There is no single best geometry, it depends on the rest of the characteristics of the car
An independent suspension (suspension that allows each wheel to move independently of one another when subjected to an external load) is intended to control the wheel motion relative to the body of the car in only one path (up and down)
The study of independent suspension geometries is to determine how to restrain the knuckle to limited motion in five directions.
5 degrees of restraint (DOR) requires 5 tension-compression links
A-Arm = 2 links
McPherson strut = 2 links
...
Solid axle (or beam axle) requires 2 degrees of freedom (up/down and roll) → 4 DOR
Instant center - the projected imaginary pivot point of all the linkages at a specific position of the linkage
Instant axis - the front view and side view instant centers connected by an axis
Suspension Geometries
Camber Angles:
The goal is to maximize the grip by keeping the tire orientated perpendicular to the ground
Lateral tire scrub is increased when you try to optimize camber angles
Wears tires
For Solar cars, minimizing lateral scrub is arguably more important than optimizing camber for efficiency reasons
Cornering isn't as important for solar cars at the speed they are travelling at
Caster Angles:
Positive Caster helps the car to travel in a straight line if the driver takes hands off of the wheel
Adding caster also increases tire scrub
Toe Angle:
Most efficient is zero toe
Some toe can help improve stability of the vehicle at the cost of increased tire scrub
Scrub Radius:
True zero scrub radius is most efficient but can result in less stable steering feel
Rear wheel drive
Positive scrub radius in the rear suspension can help improve straight line tracking
On front
Slightly, negative scrub radius can help with maintaining stability in scenarios like sudden tire deflation or hitting standing water
 |  |  |
|---|