These next three categories can all be summed up under the term “alignment”. This refers to the alignment of your wheels relative to the vehicle and the road. Camber, caster and toe are all variables that need to be considered when setting up your alignment for the type of application you will be using your vehicle for. The goal of proper alignment is to make sure that your vehicle tires maintain as much contact with the road as possible to ensure you maintain the best grip for your functional track related needs or if you’re going for the “stance” look, these values require a lot of consideration.
Camber is a measurement of the centerline of your wheel/tire relative to the road surface. It is expressed in degrees and greatly affects the dynamics of the car. Positive camber is when the top of the tire is angled out away from the fender. Negative camber is when the top of the tire is angle in towards and possibly resting under the fender in some applications. Too much positive or negative camber would increase tire wear on the outside or the inside or your tires respectively and should also be considered when going for camber values that are on the extreme side.
Negative camber is when the top of the tire tucks or leans inwards. In a normal road situation, some degree of negative camber (usually no more than 1-2) improves handling. Camber allows the tire to apply even load to the tire and increase the contact patch during cornering. Without negative camber the tire load would transfer to the outside of the tire, reducing overall grip. Bringing your camber a hint to the negative side as we know tucks the tire slightly inward. That inward tuck helps maintain optimum grip under hard cornering, especially the inside tire during the turn. A wheel at 0 camber has a tendency to tilt slightly towards the positive under heavy cornering due to the weight transfer and inertia of the car, this slightly lifts the inside of the tire off of the road essentially reducing your effective contact patch. If your tires were already adjusted with negative camber to handle those corners, your inside tire still wants to camber positive under heavy cornering, which in turn negates the effect the positive camber change would have on your vehicle in the corner. Accounting for the camber of your wheels during cornering is a large part of maintaining the best possible contact patch with the road which gives you more grip and in turn makes you faster.
One of the downsides to large amounts of negative camber is increased inner tire wear under normal driving conditions because that portion of the tire will be experiencing more load. Large amounts of static camber will also reduce the general handling and grip during heavy acceleration and braking.
Camber is a very important factor in competitive racing. Even tire temperature is desired for optimal performance and the camber is adjusted to reach this goal. Excessive heating on the edges if the tire, both inside and out, are signs that camber needs to be adjusted. Most practical negative camper applications only adjust it by a couple of degrees. Usually 1-3 degrees of negative is all that is needed to compensate for most performance and track applications. Custom “slammed” and “VIP” style cars have much larger amounts of negative camber. This is in most cases to address clearance and rubbing issues the tires cause when the car is lowered far past the norm.
Positive camber is the opposite of negative camber, bringing the top of the tire outward and bringing the bottom of the tire inward. This type of camber is rarely used in road situations. Usually running positive camber without intent could mean an issue with your suspension setup or components. There aren’t many good things to be said about negative camber nor are there many practical applications.
As your vehicle travels across a normal road, your suspension is constantly adjusting for the bumps and dips in the road by loading and unloading the suspension components with the forces from the road. Since most suspension components are able to move independently and adjust to each other’s actions camber on your vehicle can vary. This is called “camber gain” and your vehicle’s camber gain under load needs to be considered when setting your camber before heading out to have some fun.
Caster – Negative and Positive
Caster is the measurement of how far in front of behind the steering axis is relative to the vertical axis. There are 3 types of caster, positive, neutral and negative. A properly aligned car will have it’s caster adjuster to self center under steering conditions. This is because each individual suspension component is designed to have some range of independent motion. So as your car enters a corner the caster angle of your suspension should ideally even itself out to 0 (zero) at the apex of the corner to provide maximum grip. To achieve this a slight amount of positive or negative caster is applied to compensate for the change while driving. Having your caster set to zero is great for straight line driving but under heavy load in corners, mostly higher speed applications, the caster angle tends to change toward the positive or negative. These slight changes could lead to a big difference in driving feel and are explained below.
Positive Caster is achieved by placing the steering axis in front of the neutral position. In a standard vehicle that means the top of the strut or coilover would be leaning towards the rear of the car. This force creates an alignment torque which provides a force that attempts to straighten the wheel when going forward. This generally improves the straight line handling of the car along with increasing the negative camber, both beneficial in most cases. A downside to positive caster is that that alignment torque makes turning the wheels harder but with modern power steering systems now this isn’t much of an issue. Most caster angles do not go beyond seven degrees but in some special applications they do and in most cases it is to further increase camber gain.
Negative caster is the opposite of positive and places the steering axis behind the centerline of the wheel. This is generally only found in older vehicles due to the technology at the time. Today’s cars don’t come with negative caster and this type of caster also lightens up the steering which in turn makes the car is a lot more prone to veering left or right.
Toe Angle – Toe Out and Toe In
Toe measures how far the leading edge of your tire is angled inward or outward. Not much is required to make a difference and toe is usually measured in fractions of degrees. It affects how a car reacts to steering inputs. To better visualize to angles you can just stand up straight with both of your feet point straight forward. (There is a toe joke to be made here) Now rotate your feet so your toes are closer together and your heels are farther apart. That is toe in. Toe out would be the opposite where your toes are pointing outward with your heels closer together. These are extreme examples of course but even a couple of degrees of toe in or out could drastically effect your ride quality and performance.
Toe-in is when the front edge of the tires tuck inward towards the center of the car. This improves straight line stability at highway speeds. This is because a cars front wheels have the tendency to toe out when under heavy load or acceleration. So just as with camber, adjusting your toe properly for your application will maintain the ideal contact patch on the road which as we all know is what it’s all about.
Toe-out is when the leading part of the tire is turning towards the outside of the car, making the tires separate from each other. This improves turning response at the cost of tire wear. Toe-out setups are usually reserved for special applications such as track cars as this must be adjusted along with other suspension components to dial in the setup.
A special note about toe values is that your car’s toe reacts differently depending on if it’s a FWD, RWD or 4×4 vehicles. FWD vehicles tend to toe in under acceleration. RWD vehicles tend to toe out during acceleration and the ideal 4×4 vehicle has no toe under acceleration but most 4×4’s aren’t true 50/50 power distribution 4×4’s so the vehicle has a toe relative to the dominant axle in the car. So to break it down, to maintain the ideal contact patch while driving, a slight toe out should be applied to FWD cars at rest as the wheels tend to toe in. A slight toe out should be used for RWD cars as the wheels have the tendency to toe in under load. A 4×4 vehicle ideally wouldn’t need the toe adjusted but hopefully with this knowledge you can make the proper adjustments.