'66 Biscayne- chassis adjustment for better traction-

[Larry Merk]

Originally Posted by 66cayne

Ahh! the engineering approach. Thanks for the spreadsheet. I have a couple of questions about the variables. How do you calculate the vehicle center of gravity (is it half of the car's height?)? Also, the suspension geometry x, y, z, dimensions for control arm lengths. I know what the length is of each of my stock arms is but not sure how that converts to an x,y, z dimension.

66cayne,

Put the car on jackstands, take off the rear wheels, and measure.

Open the spreadsheet and hover your mouse over the X, Y, and Z data entry cells. It will display a description of the measurement needed such as "height from ground" or "forward from rear axle center line." Enter the numbers in the appropriate cell and you will see a graphical depiction of your rear suspension with a top view and side view. It should be obvious from the plot if your numbers represent your suspension geometry. You can then modify mounting point locations to see how the change affects instant center and other dimensions.

Before using this spreadsheet we wondered why our car (and others) squat on acceleration. The spreadsheet showed us the stock instant center was behind the rear bumper.

Of course the final test is to run the car and see how it works at the track. We made a couple of adjustments and quickly found the sweet spot where the car really worked well. Good luck.