This is an expansion of a portion of the previous page. Specifically, the procedure by which the 400 pounds per inch and 600 pounds per inch front spring rates were determined will be detailed.

That portion of the driveshaft reaction torque absorbed by the front suspension will act to unload the right rear (and, of course, load the left rear). If, however, the distribution of the weight transfer favors the right rear in the proper proportion, the unfavorable loading of the rear tires will be canceled.

It should be intuitively obvious that, if the right front has no suspension (is solid) and the chassis is assumed rigid, all of the weight transfer would initially be taken from the right front wheel loading. Extrapolating from this, we can say that...if the front suspension springs are not equal in rate...KsubR/(KsubR+KsubL) of the weight transfer will go to the right rear and KsubL/(KsubR+KsubL) will go to the left rear. (Each "sub" name refers to a spring rate.) Further, we can say that {KsubR/(KsubR+KsubL) - 1/2}, when multiplied by the weight transfer, will equal that extra right rear loading which occurs when KsubR is greater than KsubL. If the adverse wheel loading is to be fully canceled, this extra loading, when multiplied by the rear track, must equal that portion of the driveshaft reaction torque absorbed by the front suspension.

It was assumed that 40% of the total roll stiffness was at the front with the addition of the anti-roll bar, so the torque to be canceled equals 0.4 times the wheelbase (108) times the rear tire radius (14) and divided by the CG height (18), and the axle ratio (4.11). When this is divided by the rear track (60), we have that which is enclosed by {} above.

It is convenient to work with the ratio of KsubR to KsubL. So, if the numerator and denominator of KsubR/(KsubR+KsubL) are divided by KsubL, we have RATIO/(RATIO+1). Using this in the {} relationship and setting it equal to the torque to be canceled, we can solve for RATIO.

RATIO is found to be equal to 1.75. If, in the example of the previous page, spring rates of 400 and 700 pounds per inch had been used, plot "C" would have been on the abscissa (horizontal), meaning that left and right rear wheel loadings would be equal throughout the launch.

If this calculation is repeated for the "stock" example (60% of the roll stiffness at the front), RATIO is found to be almost 2.4. This would be a sizeable difference in spring rates, which leads to some comments on ride quality and handling for a car that is to be driven on the street. If, for instance, the spring rates are presently 500 pounds per inch and ride quality and handling are satisfactory, it is recommended that the left front rate be reduced and the right increased in such a manner that the average remains at 500 pounds per inch. While this will not restore the original ride, the sacrifice should be acceptable. Handling should also be acceptable. These spring combinations are, after all, not all that uncommon in oval track cars. Having said all this, I would still recommend that full cancellation...by this means alone...be reserved for the serious dragracer. In any event, changes like this should always be verified by use of the traction dyno.