Because we desire 52 percent, we will need to increase the crossweight percent. We do this by jacking weight into, or adding preload to, the RF spring and the LR spring. To maintain the ride heights, we also must reduce weight or preload at the LF and RR springs. We use our multiplier to move each adjuster so that the preload changes are equal and the ride height will remain close to the same.
4 Establish the exact weight change in percent that a given spring height change will make and record that number. To do this, we add five rounds of pre-load to the RF. We also take five rounds times the multiplier for the front of 1.25 × 5 = 6.25 rounds out of the LF. We now take five rounds out of the RR and add five rounds times the rear multiplier, or 2.0 × 5 = 10 rounds to the LR. The crossweight percent will have changed to, say 55.4 percent.
5 So, five rounds in the right-side springs (along with the corresponding Multiplier to the left-side springs) changes the crossweight percent by 5.6 percent, which is 1.12 percent per round, or 0.89 rounds per percent of crossweight. That is equal to 7/8 turn of the adjuster. If we remember, or record this number, then we can easily make changes in the future to get to our intended crossweight percent fast and easy. For our example, we need to go from 49.8 to 54 percent.
So we multiply the difference, or 4.2 percent, by 1.12 and we get 4.7 rounds of right side change to the spring pre-load, or 43/4 rounds. The left side changes, of course, will be 4.75 times the multiplier for front or rear. We should now be at, or near, the desired crossweight percent.
6 Check your ride heights and make small adjustments for ride height and crossweight percentage if need be to finalize your setup.
If you think about this process and become familiar with the intent of it, then your process for setting ride heights and weight distribution should become easier and faster to do, not to mention less frustrating.
Carrying Ride Heights to the Track
Now that the car has the correct ride heights and weight distribution for your setup, you need to make sure those don't change at the track. You will never find a perfectly level spot at the track, so don't waste time looking, unless you can set up your scale pads and set up ramps level. But this is almost never the case.
And don't ever believe the track scales. They are never level. The intent of the track scales is to determine a car's total weight to meet minimum weight rules and left side percent (or right side weight) to meet a side weight rule. Crossweight is of no concern to the track officials. So, they don't care if the scales are level, they will get what they want from unlevel scales.
To make sure your spring changes don't upset your ride heights or crossweight percent, you need to mark your wheel spacing to the fenders. Here is what you do.
1. Find a fairly level spot and mark on the ground with duct tape or marker where the tires sit on the ground. Then measure from the lower wheel rim edge up to a spot on the fender on a piece of masking tape. I usually mark an even inch and write that inch number on the tape. Do this at every wheel.
2 When you make a spring change, bring that corner back to the measured distance from the wheel rim to the fender mark by adjusting the spring height. Do not adjust any other wheel's spacing. Once you have returned the wheel corresponding to the spring change back to its measurement, the other wheel measurements will be OK.
For the teams that run very...
For the teams that run very soft front springs, adjusting for ride height and wheel weights can be very hard due to the extreme amount of pre-load on the springs. We have a method that might make this process easier for you. See our Sidebar for a description of the method.
Once you have set your ride...
Once you have set your ride heights and weights, it's a good idea to tape the adjuster rings so that they will not move during the race or when the car is jacked up to change tires, and so on.