Drivers use the term “camber” when discussing vehicle performance and handling. However, it may sound daunting if you’re a new driver or car enthusiast. What complicates matters further is the terms “positive” and “negative” camber.
What exactly is camber, particularly positive vs. negative camber, and how can each affect your driving? This blog post aims to answer your questions.
What is Camber?
The Camber is the inward and outward tilt of the tire and wheel assembly (viewed from the front of the vehicle). Each manufacturer sets a specific camber alignment for every vehicle it produces, which might be either positive, negative, or zero (0º).
When the camber is at the correct angle, the tire and wheel will roll straight. However, the camber can go out of alignment over time. When the top of the tire is leaning inward (toward the vehicle), it is a negative camber. Positive camber has the top of the tire tilting outward (away from the vehicle).
There are two types of camber angles—positive and negative—each helping vehicles perform specific tasks.
What is Positive Camber?
Positive camber is when the top of the wheel tilts outward, away from the vehicle’s center. This configuration improves a car’s stability and handling on uneven terrain. This setting is ideal for heavy-duty vehicles such as trucks or tractors.
However, excessive positive camber can cause a vehicle to drift, making it difficult to drive within a lane. It can also accelerate wear on the front tires’ outer edges, significantly shortening their lifespan.
What is Negative Camber?
Negative camber involves the top of the wheel tilting inward toward the vehicle’s center. For many reasons, most car manufacturers set a negative camber in modern models.
First, this setup improves handling and road grip, providing an equal load throughout the contact patch. It also minimizes tire vibration and allows for better cornering at high speeds.
Similar to positive camber, excessive negative camber poses many risks. It can lead to oversteering and make a vehicle move toward any road irregularities or bumps. It can also quickly wear a tire’s inside shoulder.
Not all effects of negative camber are good though; some, like excessive outer tire wear, are undesirable for street cars.
#1. Decreased Straight-Line Stability.
Negative camber can cause decreased stability when driving in a straight line due to camber thrust. This occurs when negative camber wheels naturally propel the vehicle towards its midline.
If one tire loses grip the vehicle is pushed by the other tire towards the tire with the lost grip, leading to unintentional turning.
Excessive negative camber can cause the wheels to tramline, or follow cracks in the road. It also worsens acceleration and braking in a straight line. The vehicle is often too sensitive to the crown of the road (curvature designed for water drainage to the sides of the road).
#2. Stability While Turning.
Performance cars need increased stability when turning, as turns are done at much higher speeds than normal. When the contact patch of the tire on the road is as large as possible during the turn, the wheels grab and hold onto the road better.
Static negative camber increases the contact patch on the outside front tire during a turn which increases grip and speed of turning.
This offsets the tendency of the outside front tire to roll onto its outer edge (positive camber) because of body roll during the turn, which would reduce grip by decreasing the contact patch size.
The inner front tire doesn’t need the contact patch to be as large as the outside front tire because the weight of the vehicle is mostly over the outer wheels during a turn, which is good since the camber becomes more negative on the inner wheel during that same turn.
In fact, NASCAR drivers always turn left (driving a counter-clockwise loop), so their cars have negative camber on the right wheels and positive camber on the left wheels. This is terrible for driving straight but perfect for their type of racing!
#3. Changes in Tire Wear.
Negative camber increases the tire wear under normal driving conditions, usually with mostly straight driving.
However, performance drivers do not need to replace their performance tires as often when doing a lot of cornering since negative camber decreases the relative tire wear under these conditions.
#4. Increased Suspension Wear.
Bushings and other components of the suspension may experience increased wear with negative camber because of how forces act on these parts.
How Car Camber Affects Handling?
When a car travels in a straight line on a level road, a neutral camber angle is ideal because the tire and pavement meet evenly to create a large contact patch.
However, when you drive into a corner, the tire will naturally start to roll onto its sidewall, thereby lessening the contact with the road. The result is a smaller contact patch, which means grip drops and handling suffers.
Since we all encounter different road surfaces and countless twists and turns during our daily travels, vehicle engineers must compromise on a camber angle that works best in many scenarios. For that reason, most modern cars feature a slightly negative camber angle.
A modified classic Datsun 240Z displays a more extreme example of a negative camber angle in the photo above. So adjusted, this 240Z adds contact patch and grip in corners, helping it to go faster through them.
Adjusting Camber
Camber is best measured by a professional with specialized equipment, such as an alignment rack. It can also be measured (albeit less accurately) with a bubble level and a camber gauge.
Before measuring, the joints in the suspension should be checked to ensure they are within spec as that can throw off the measurements. Inappropriate camber for the vehicle and its use can result in excessive tire wear, poor stability, or other handling issues.
Performance drivers adjusting camber on their vehicles often also want to know how the contact patch changes. This is measured by a pyrometer, also known as a non-contact infrared thermometer.
It’s essentially a thermometer which measures the tire temperature deep within the tread immediately after the car takes a corner. The contact patch in the turn will be hotter due to friction.
The way the camber is adjusted depends on the type of suspension. Camber plates are easily adjustable which makes them flexible for different driving conditions (i.e. driving on the highway to an autocross event, autocrossing, then driving home).
High-quality camber bolts are often used to align cars that have been bent due to a collision. Other times the length of the control arms can be adjusted to change the camber.
Since changing the camber affects the other suspension angles (toe and caster) and suspension components as well, all of these should be checked after the camber is adjusted to ensure measurements are within spec.