Originally Posted by drmike

Ah. OK. Time for school I guess (but not condescendingly so!).

Compare these two sums:

LF+RR
RF+LR

The "cross weight" is computed this way:

CW=(RF+LR)/(LF+RF+LR+RR)

The idea here is that the cross weight should equal 0.5, or 50%. This can be adjusted to be true using the spring perch adjustments on coilover suspensions, or in the case of old solid-axle racers like "modified" dirt track cars and NASCAR stock cars, by adjusting the "wedge", or right rear upper spring perch screw jack. Even if the left side and right side sums are not equal, the cross weight can be made equal. In contrast, the left-to-right weight bias cannot be adjusted with spring perch adjustments but must be adjusted with the movement of ballast across the car.

So, why do we care about the cross weight? Because this affects the bias of the car's performance towards a left or right turn. Oval track cars are biased towards left turns, and therefore run a lot of "wedge", that is, an unbalanced cross weight. For road cars and road race cars, generally it is best to have a balanced cross weight, so that left and right turns are equally good.

So my comment is that the stock 370Z, straight from the factory, has a pretty good cross weight. Immediately we can see (assuming a sample of many Z cars showed similar measurements) that the Z is precisely put together, and that the springs are quality units. The only other way to get a nice cross weight is to use horribly soft springs, and we know that's not true.