Center of Gravity (CG) is defined as that point about which, if the body were suspended from it, all parts of the body would have equilibrium ..i.e.. without tendency to rotate. it is the 3D balance point of the race car. all acceleration forces acting on a body can be considered to act through the CG of that body..we have the cg to be as low as we can get it.
Mass Centroid- is related to Cg ..sort of...ifin we slice the car into a series of sections, like a loaf of bread, each slice would have its own CG...if, in a side view, we draw a line connecting each sliced CG..we have the Mass Centroid Axis..not really a straight line but close to it.
it gives an indication of the distribution of the vehicles mass in the vertical plane.
Roll Center of the suspension is that point , in the traverse plane of the axles, about which sprung mass of that tend of the vehicle will roll under influence of centrifugal force. It is determined by drawing a line from the tire contact patch to a point in space that is the intersection of the upper and lower suspension arm linkage angles.
The CG and RC are located at different points. Usully the CG is many inches above the RC. CG can be change by moving " weight " around on the chassis.. The RC is changed by modifying how the upper and lower control arms mount to the chassis. Correct changes will improve the weight transfer to the rear tires thus improving traction.
lot of other stuff goin on here.. race car math of some is on my post in General Physics post " Race Car Physics" 31 Dec 2008
Finding the center of gravity height can be done in several ways, none of which are accomplished very easily and without some work. Presented here is the easiest method. The center of gravity height is calculated by weighing the car when level and then raising the car at least 10 inches at the rear and weighing the front again. Replace each shock absorber with a solid link to eliminate suspension travel
You need a set of electronic scales. You also need a set of blocks o eight inches tall. 10 inch is better.
First, weigh the car normally, then record the total weight (T) and the total number of pounds on the front tires-nose weight (N).
Jack up the rear of the car..CAREFULLY! Then carefully place the blocks under the rear scales (you may find it useful to lock your rear axle). Now record your new nose weight (NI). Next, subtract your original nose weight (N) from your new, lifted nose weight (NI) and you will have the difference (Nd).
Figure it out using your calculator…
a. Multiply the nose difference (Nd) x 1660= (A)
b. Multiply the total weight (T) x 8 (the height of the blocks)=(B)
c. Divide your previous numbers, A by B, and this equals (C)
d. Add this number, C, to your axle centerline height or spindle center, and the number you obtain is your vertical center of gravity.
CGH= WB x FWc / TW x Tan of angle
Center of Gravity Height Formula
Definition of Variables
CGH - Center of Gravity Height
WB - Wheelbase (inches)
TW - Total weight
FW1 - Front weight LEVEL
FW2 - Front weight RAISED
FWc - FW2 - FW1 (change in weights)
HT - Height raised (inches)
Adj - Adjacent side (see below)
Tan q - Tangent of angle (see below)
CLF - Left Front tire circumference
CRF - Right Front tire circumference
C - (CLF + CRF) / 2 (average circumference)
r - Axle Height
