Suspensions have 3 functions: ride, handling and platform control.
Ride refers to the way the car deals with track surface changes. Handling is all about vehicles dynamics and how the car reacts to speed and direction modifications. Those 2 functions are similar to what is expected from a road car's suspension system. But on a race car, suspensions must also work in accordance with the aerodynamics of the car: this is what we call platform control.
P424 suspension design was carefully defined to perform those duties through optimisation of antis, camber, caster, king pin angle, roll centre...
P424 front suspension
On P424 front suspension side view, wishbones are not parallel. The tire contact patch moves forwards and rearwards during bump and droop movement. Therefore, when the car is braking or accelerating, some of the vertical load transfer is not reacted by the pushrod and side spring assembly. This load goes through the wishbones. The vertical movement is limited under braking (anti-dive at the front, anti-rise at the rear) and under acceleration (anti-lift at the front and anti-squat at the rear) due to the reduced load going through the pushrods and side springs springs.
Advantages: reduced body movement under braking and acceleration keeps the aerodynamic balance more stable.
Disadvantages: worse riding over kerb due to jacking forces (in plane movement of tire contact patch instead of pure vertical movement). Cars with little aero downforce tend to have small amount of antis to maximize ride performance. Cars with lots of downforce (F1) have high antis to reduce the aerodynamic balance variations.
Camber angle ads some cornering potential to the tire. It is important to keep the outside tire at negative or zero camber during cornering to maximize performance. Due to body roll in cornering, some of the static camber setting is lost (offset by chassis roll angle). Suspension camber gain helps recover some of this camber angle (camber increases as the outside wheel travels in bump). The inside tire will go to positive camber during cornering but this tire has less effect on performance. Too much negative camber can lead to excessive inside shoulder temperature in straight line, especially on very fast tracks with long straights.
For safety reasons, tire manufacturers limit static camber teams can use during races. We have seen some instances of tire blowing up due to side wall blistering when temperature is too high. When this happened, restrictions on maximum static camber angle have been added from the following race.
Increasing caster angle can help cornering performance by adding extra load to the outside tire (vertical movement of the contact patch during steering). But too much caster will make the steering too heavy. Caster angle also helps give more steering feedback to the driver.
Kingpin angle adds stability to steering in straight line and under braking / acceleration. Under braking, increased scrub will tend to add toe out angle and stabilise the car (open the wheels in top view).
Same as with the antis but in front view. Wishbones are not horizontal. Some vertical loads during cornering go through the wishbones instead of pushrods and springs. The higher the roll centre, the more load is reacted through the wishbones.
Advantages: reduced roll angle during cornering, chassis more reactive during change of direction and steering input. Less aerodynamic downforce loss due to roll angle.
Drawbacks: chassis feels stiffer (less loads go through the springs), ride over kerbs is worse.