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iRacing Formula
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R-04 // USER
MANUAL
angles which can be beneficial in chicances or hairpins. As well as this the more caster angle the greater the jacking effect during
cornering which will result in lifting the inside front wheel while lowering the outside front wheel. This jacking effect will also result
in the unloading and potentially lifting of the inside rear wheel which can aid in rotation around tight corners.
CAMBER
Camber is the vertical angle of the wheel relative to the center of the chassis. Negative camber is when the top of the wheel is
closer to the chassis centerline than the bottom of the wheel, positive camber is when the top of the tire is farther out than the
bottom. Due to suspension geometry and corner loads, negative camber is desired on all four wheels. Higher negative camber
values will increase the cornering force generated by the tire, but will reduce the amount of longitudinal grip the tire will have
under braking. Excessive camber values can produce very high cornering forces but will also significantly reduce tire life, so it is
important to find a balance between life and performance. Increasing front camber values will typically result in increased front
axle grip during mid to high speed cornering but will result in a loss of braking performance and necessitate a rearward shift in
brake bias to compensate.
TOE-IN
Toe is the angle of the wheel, when viewed from above, relative to the centerline of the chassis. Toe-in is when the front of the
wheel is closer to the centerline than the rear of the wheel, and Toe-out is the opposite. On the front end, adding toe-out will
increase slip in the inside tire while adding toe-in will reduce the slip. This can be used to increase straight-line stability; more toe-
out results in more straight line stability but increased rolling drag. Generally, it is best to keep to small values here due to the low
power nature of the car.
LEFT/RIGHT REAR
SPRING RATE
Similar to at the front axle, stiffer springs will result in a smaller variance in ride height between high and low load cases and will
produce superior aerodynamic performance through improved platform control at the expense of mechanical grip. This can be
particularly prominent when exiting slow speed corners with aggressive throttle application. Stiffer springs will tend to react
poorly during these instances especially so on rough tracks which will result in significant traction loss. Spring stiffness should
be matched to the needs of the racetrack and set such that the handling balance is consistent between high and low speed
cornering. As an example case, a car which suffers from high speed understeer but low speed oversteer could benefit from an
increase in rear spring stiffness. This will allow for a lower static rear height which will reduce rear weight transfer during slow
speed cornering while maintaining or even increasing the rear ride height in high speed cornering to shift the aerodynamic balance
forwards and reduce understeer. Six options for spring rate are available 88 N/mm (500 lbs/in) to 175 N/mm (1000 lbs/in).
iRACING FORMULA iR-04 // CHASSIS
