Understanding Caster and Camber for Suspension Setup
As we progress further and further into our favorite 4-wheeled hobbies, we often find ourselves in tricky situations and finding the solution to said situations is not so clear. Nothing rings more true for novice and rookie racers, whether on the dirt oval or ripping around the road course.
Being new to the racing scene is difficult – you may not have any close relationships built with your fellow racers to be able to lean on them for help or it may just be that you are not sure they will give away all the setup secrets that they had to learn the hard way. Have no fear; hopefully, by the time you're done reading through this short article, you will understand some basic race suspension and geometry that will enable you to find a better setup for your next visit to the race track.
This article was written to help any automotive enthusiast better understand caster and camber theory/adjustments and how those translate to real-world scenarios in basic racing applications as well as being valuable to setting up your street suspension, too.
Caster is best described as a vertical line that runs through the 2 pivot points in your car or trucks suspension. Most often, these pivot points are the upper and lower ball joints in your double A-arm style suspension system. If your vehicle of choice utilizes a McPherson strut style front suspension, then your 2 pivot points would be the lower ball joint and the strut tower mount. Caster is changed by rolling that vertical line forward, resulting in negative caster or by rolling that vertical line backward, resulting in positive caster.
Caster angles are built into your suspension. As mentioned above, they are made up of those pivot points that make up your suspension. That being said, changing this angle is generally more mechanically intensive, as it will require changing out the hard parts that make up your suspension. Caster angles are generally used to improve a vehicle’s steering balance and front-end cornering stability. Caster also will help with high-speed stability.
Almost always, the more positive caster you have built into your race car or street car, the better. By making positive caster gains, you will notice it may become more difficult to steer. This is because as we gain positive caster, steering effort also increases. This downside (if you can even call it that) usually goes unnoticed in any vehicle with a power steering setup, but if you are rocking manual steering, it may be a good idea to research some fore-arm exercises as well! Gaining positive caster will further increase straight-line tracking and will also increase the tire lean angle when cornering.
Generally speaking – you want more positive caster in most situations. The benefits far outweigh the negatives and almost always when new suspension systems are discovered/designed, they include a host of things that increase positive caster, which results in a race car or street car feeling incredibly stable and “glued” to the corners!
Camber is equally important to your setup recipe, whether you are racing in any form or just out enjoying street driving. You want your car to handle well and be “predictable”. Camber is how far the tire slants away from a perfect vertical line when looking at your car or truck from the front. It is measured in degrees, just like caster, and is more easily adjusted to suit various track conditions, layouts, various street driving scenarios, driving styles, etc. This is usually the bread and butter for all those tenured racing gurus lurking around your local race tracks. Negative camber is when the top of a tire tilts inward, toward the center of the vehicle. Positive camber is when the top of the tire tilts outward, away from the center of the vehicle.
Camber is a bit more difficult to tell you to always go this way or that. It really does depend on a multitude of factors, including driver input and what he/she prefers. In terms of racing applications, a driver that tends to enter the corners aggressively, carrying a lot of speed will benefit from more negative camber, as the increase will further help the retain cornering grip, stability, and decrease tire wear. On the flip side, a more timid driver would enter the corner at a slower speed; with this same negative camber, the result would be a harsh increase in tire wear along the inside edges of the front tires. Large increases in negative camber can be bad and finding the sweet spot is the goal that every driver will be faced with. Too much negative camber will cause your car or truck to lose straight-line stability and grip in quick acceleration and quick stop situations. Keep an eye out at the race track next time, as I can almost guarantee that the cars winning that night will have a noticeable negative camber setup.
Caster and camber can be hard to master. It’s a very simple formula on the surface, but it becomes when trying to decide what is right for you, your driving style, and your vehicle. A lot of people tend to believe that they have to have the best of the best in terms of equipment to win races, when in reality if you can master these proven racing concepts, success will come. Your car will handle better, become more predictable, and with the right setup will eventually feel effortless when racing your way to victory!