Suspension Camber Angle

In this brief article, we will discuss the importance of Camber Angle in a suspension, the different Camber settings in a car and ways to control Camber in the suspension.

What is wheel Camber in a suspension?

By Definition, the wheel Camber angle, at any corner of a vehicle, is the angle measured in the front elevation of a vehicle between the tire’s Center line and the vertical line perpendicular to the road surface.

Camber Angle is an instantaneous vehicle dynamics parameter used to define Tire behavior. It is one of the parameters that influence the handling characteristics of a vehicle. The amount of lateral force grip that a tire can generate during cornering under limit conditions, is largely dependent on the Camber angle at that particular instant.

What is Negative and Positive Camber?

Negative camber means that the top of the tire leans towards the body or inwards. Negative Camber means more tire grip and is a desirable condition.

What is Camber Gain?

Camber gain is defined as the difference in camber angle per unit vertical travel of the suspension at the wheel center. Negative Camber gain means that camber will become more negative if the wheel is moved vertically upwards.

What are the different Measures of Camber in a suspension?

The two different measures of Camber in a suspension are:

• Static Camber
• Dynamic Camber

Static camber is the camber angle setting that is in-built in the suspension at normal ride height. This will be a value recommended by the service instruction of each vehicle manufacturer. Everytime the car goes in for re-alignment, the alignment shop measures this static camber and sets it back to the recommended static camber value.

Dynamic camber is defined as the instantaneous camber angle at the tire as the vehicle goes through different maneuvers like acceleration, braking, and cornering. 

Dynamic camber = (static camber) +/- (camber gain)

Camber gain is mostly a non-linear characteristic and is a consequence of suspension geometry. 

What Camber Settings are normally used for cars?

The normal range for Camber settings are:

• Road cars 

• Drift cars

Drift cars require entirely different settings as compared to normal Road cars because of 

• the controllable oversteer requirement,
• the high tire sideslip angles that the tires undergo throughout the race, and
• A reasonable amount of tire-life so that the tires can survive multiple races in a day

The Front Camber would mimic the settings of a Road race car at approximately 3 – 4° in order to extract maximum lateral tire  grip.

The rear camber in drift cars needs to be in the range of 0-0.5° in order for the tire contact to be near-perpendicular to the road and also maximize forward grip, while ensuring minimal tire wear.

What is the significance of Wheel Camber Angle?

• Each Tire model comes with its own characteristic curve of Lateral grip (or Tire Side Force) vs. Vehicle Sideslip angle, which changes with variation in tire Camber Angles.

• What a typical car tire’s plot of lateral grip vs. Vehicle Sideslip angle shows is that
  • As the tire Camber Angle goes more into Negative, the Tire’s capacity for Tire Side Force decreases
  • Conversely, as the tire Camber Angle goes more and more into Positive, the Tire’s capacity for Tire Side Force increases

• What this pattern implies is that in order to get the maximum grip out of the outside tires during extreme cornering especially in performance-oriented cars, negative camber at limit conditions is important characteristic
• Without the right amount of negative camber, in a cornering situation, the tire would load up the outer edge of the tire and result in a lesser than adequate grip.
• There is, however, a downside to adding too much negative camber into the suspension geometry. Even though negative Camber benefits Cornering, beyond a certain point, increasing negative camber will reduce the tire’s grip under straight-line acceleration as well as braking. 
• It is therefore important to have a healthy balance between negative and positive camber in order to ensure good overall handling performance. For most cars a Camber setting of around 0 – 0.5° of negative camber is recommended for a good balance of cornering grip, braking grip, and tire wear.

How can Wheel Camber be Controlled in a Suspension?

• One of the biggest advantages in the Double wishbone is the ability to control Camber Characteristics of the wheel while it travels up and down by adjusting the lengths of the upper and lower control arms. By shortening the length of the upper control arm with respect to the lower control arm, the amount of camber gain can be increased substantially.
• In a double wishbone suspension, it is also possible to have a negative Camber gain characteristic all throughout from full bump to full rebound.
• While cornering, if the outside tire moves parallel to the car’s vertical line, the outside tires will tend to have a positive camber to the road. 

Conclusion

In this brief article, we have discussed the importance of Camber Angle in a suspension, the different Camber settings in a car and ways to control Camber in the suspension.