The word “camber” comes up frequently in discussions regarding vehicle performance and handling. If you’re a new driver or car enthusiast, it can sound intimidating. Then there’s the terms “positive” and “negative” camber too!
Just what is camber in regards to positive vs. negative camber anyways, and how could that affect your driving? This blog post is here to answer your questions!
What is Camber?
Camber is the inward and outward angles of the tire and wheel assembly (looking from the front of the vehicle). Each manufacturer has designated a camber alignment for every one of its vehicles, which can be either positive or negative, or zero (0ยบ).
If the camber is at the proper angle, the tire and wheel will roll straight. However, the camber can go out of alignment over time. When the top of the tire leans inward (toward the vehicle), it is a negative camber. Conversely, in positive camber, the tire has the top leaning outward (away from the vehicle).
There are two camber angles: Positive camber and negative camber, and both angles help vehicles to perform tasks.
What is Positive Camber?
Positive camber occurs when the top of the wheel is tilted outward (away from the centerline of the vehicle). Positive camber increases a car’s stability and handling on uneven surfaces. This orientation is best for heavy-duty cars such as trucks or tractors.
Too much positive camber will cause a vehicle to drift, hence difficult to drive within a lane. Excessive positive camber can also wear the front tires’ outer edge out quicker and shorten their life expectancy.
What is Negative Camber?
Negative camber is when the top of the wheel tilts inward toward the center of the vehicle. For a variety of reasons, most car manufacturers set a negative camber in modern-day models.
First and foremost, this setup helps improve handling, road grip, and creates an even load in the contact patch. It also helps absorb tire vibration and aids in higher-speed cornering.
Similar to positive camber, negative camber carries many risks when excessive. Negative camber can lead to oversteering, cause the vehicle to steer toward potholes and bumps in the road, and cause inside shoulder wear on tires.
Not every impact of negative camber is positive. Some degrade performance, like excessive wear on the outer side of the tire, which is exceptionally adverse for street cars.
#1. Reduces Straight-Line Stability.
Negative camber can create less stability while driving in a straight line because of something called camber thrust. Camber thrust occurs when negative camber wheels are pulling towards the car’s midline naturally.
If you have one tire losing grip, the other tire just pushes the whole vehicle towards the tire that lost grip and creates unintentional turning.
Extreme negative camber keeps the wheels tramlining or tracking along the cracks in the road. It also further worsens acceleration and braking while driving straight. The vehicle typically becomes too sensitive to the crown of the road (the curve of the road designed for drainage of water to the sides of the road).
#2. Stability while Turning.
High-performance cars need heightened stability when turning since turns are usually done at significantly higher speeds than normal driving. If the contact patch of the tire on the road can be as large as possible while turning, the tires can hold on to the road significantly better.
Static negative camber will effectively increase the amount of contact patch on the outside front tire when turning, which facilitates additional grip and speed of turn.
Static negative camber also helps counteract the tendency of the outside front tire rolling onto its outer edge (positive camber) because of body roll during the turn, which would reduce grip by reducing of contact patch size.
The inside front tire does not have to maintain contact patch size like the outside front tire does because most of the weight of the vehicle is over the outer tires when the vehicle is turning, which is great because, in fact, the camber becomes more negative for the inner wheel during that same turn.
In the case of a NASCAR driver, they always turn left (counter-clockwise loop); therefore, the right wheels would have negative camber and the left wheels would have positive camber. This would be terrible if trying to drive the vehicle straight, but just fine for their style of racing experience!
#3. Change in Tire Wear.
Negative camber increases tire wear under “normal” driving conditions, where the driver has primarily been driving straight.
However, for performance-oriented drivers, they replace their performance tires less under significant cornering, because negative camber decreases relative tire wear under those cornering conditions!
#4. Increased Wear on the suspension.
Bushings and other suspension components may have increased wear with a negative camber because of how the forces are acting on the suspension components.
How Does Car Camber Affect Handling?
When a car is traveling in a straight line on flat pavement, a neutral camber angle is ideal so that the tire and pavement interface evenly, resulting in a large contact patch.
But once you turn into a corner, the tire will roll over to the sidewall, ultimately reducing the amount of contact you have with the road to create a small contact patch. A small contact patch = grip drops, and handling is negatively affected.
Because we all drive on variably less-than-smooth surfaces and different corner orientations whenever we drive, vehicle engineers have to make compromises on a camber angle to suit the use of the vehicle. For this reason, you will generally find a slight negative camber on most modern cars.
An example of the modified classic Datsun 240Z above, a more extreme example of a negative camber angle. In this case, the angle was adjusted so that this 240Z maximizes contact patch and grip in corners, enabling it to corner faster.
Adjusting Camber
Camber angles are best measured by a technician and specialized equipment (an alignment rack). It can also be measured more rudimentarily (but less accurately) with a bubble level and a camber gauge.
However, before measuring camber, you should ensure the suspension joints are all in spec because worn suspension can affect performance in a car. Inappropriate camber for the vehicle and vehicle use will increase tire wear, stability issues, and other handling problems.
Performance drivers who are changing camber on their vehicles will also want to know how the contact patch changes. Contact patch temperatures are measured with a pyrometer that is referred to as a non-contact infrared temperature gauge.
In essence, it is a thermometer that measures the temperature of the tire tread surface deep within the compound right after the car turns; the contact patch will be hotter than the rest of the tire because of friction.
The way the camber will be adjusted depends on what type of suspension system is installed on the car. You typically find camber plates that can be easily set to different camber angles; i.e., driving on the highway to an autocross event, racing the autocross, driving home.
High-quality camber bolts are also used to align a vehicle that may have been involved in a collision. And it is possible to adjust the length of the control arms to change camber.
All suspension angles, camber angle, toe, and caster and suspension components will be affected by changing camber angle, therefore, all suspension components and angles should be checked/confirmed after adjusting camber angle to ensure angles are within spec.