The relationship between the Center of Gravity and the vehicle’s Roll Center, is a very important concept to grasp. This will help you understand how the forces acting on the vehicle through the corner affects the roll of the vehicle, which will then help you understand how to help tune your suspension because body roll translates into suspension movement.
Caster – This is the angle of tilt of a line drawn from the center of the top ball joint through to the center of the bottom ball joint, compared to vertical. Caster aids the wheels to straighten themselves out after cornering, however the more caster you have, the more that you may have to fight the steering entering a corner. If the top tilts toward the rear of the vehicle, then it has positive (+) caster. If it tilts forward toward the front, then it has negative (-) caster.
Figure 4 – Positive Caster
Caster Split – This is the difference between the caster of the front wheels. If the left front is set at +1 degree and the right front is set at +3 degrees, then your caster split is 2 degrees (Right front(+3) –Left front (+1) = 2).
Force – an influence on an object, capable of producing or tending to produce a change in movement.
Suspension Bump – Occurs when either physical track changes, such as bumps or body roll due to cornering causes the suspension to travel upward from the set ride height.
Suspension Droop (or Sag) –Occurs when either physical track changes, such as holes, grooves or body roll due to cornering causes the suspension to travel downward from the set ride height.
Suspension Travel – This is the total distance that the suspension moves from the full height of Suspension Bump to the full drop of Suspension Droop.
There are many different factors affecting the handling of your vehicle in a race or high performance application. All of these factors fit together like a puzzle, and they all interact with, and affect each other. This is the beginning of explaining the pieces so you can put them together.
We will start the series focusing on the independent front suspension. I wanted to focus on what happens with the suspension when it moves, how to evaluate your suspension, and then we can build on that by exploring how to control that movement.
While there are too many variables between track conditions, suspension possibilities, and driver abilities to determine a steadfast rule, we can give you an idea of a target area to be in when analyzing and attempting to maximize your specific suspension system and application. This will at least help to get you in the ballpark, and you can spend more of your time fine tuning it to get faster rather than spending time and money just trying to “hang on” and not crash.
I am going to attempt be straight forward with no-nonsense informative posts so you can take the information and make it work for your particular situation. This is not to be assumed as a precise engineering guide, but more as an explanation of the concepts and theory’s within the suspension.
If you are limited on mechanical or fabrication skills you need to get professionals involved!
Motorsports is a very dangerous activity and participation can, and may, lead to serious injury, or even death. Everybody involved should consult with the appropriate safety official or authority before using any information provided in any of these posts.
Welcome to the DJ2 Motorsports blog! Throughout our blog posts we hope to provide information to help you understand chassis dynamics to help you maximize the performance of your suspension.