Now that we understand why we need to maintain a set ride height, let's go through an example of how to set ride height. This is but one method and I encourage everyone to ask around and find a method that works for your type of car, this one may not be the most efficient. Do not copy these ride heights; they are only used as an example. Your car may be designed to run different ride heights than these.
1. Determine your ride heights. Ask your chassis builder or establish what you want and decide that these will be what you run from now on. For our example, we use LF 4.00, RF 4.50, LR 4.50, RR 5.00.
2. Choose a level spot in your setup area. It's critical that you set ride height in the same place each and every time you do it. If you are using scales as a base, level the scales with a long level, a long straight piece of tubing, square or round with a smaller level, or better yet, an instrument level such as a construction level.
3.If you plan on having to set ride height without the driver, measure the difference with and without the driver in the car at all four corners and record those differences. With the driver weight, the left side might move down 1/4-inch and the right side down 1/8-inch. Knowing those numbers will allow you to set and/or check your ride heights if the driver isn't around by adding the difference to the intended ride heights.
4. Prepare the car. Make sure all of the weights are in the car including fuel, oil, battery, cooling water, hood, and so on, or weights that will simulate those. The driver is optional based on No. 3.
5. Air up the tires as they will roll through tech. Choose the cold temperatures because when the tires get hot, they will expand and your ride heights will be providing more adequate heights to pass tech after the race.
6. Disconnect the sway bar. We will deal with preload on the bar later on. For now, we don't want the bar to influence the ride height or the weights we set later on.
7. Calculate the average front and rear desired ride heights. In our example, the front average is 4.25 and the rear is 4.75.
8 Read the ride heights as they exist. Record these. For our example we have LF 3.625, RF 4.75, LR 4.625, RR 5.75.
9. Calculate the average existing ride heights front and rear. We have 4.1875 front and 5.1875 rear.
10. Find the difference from the desired average ride heights. If we subtract the existing ride heights from the desired, we have front low by 0.0625-inch and the rear high by 0.4375-inch.
11. Adjust the front up by 0.0625-inch and the rear down by 0.4375-inch. Do this by making equal changes to the adjusters on each side. At the front, we will move the LF and RF adjusters up by 0.0625-inch.
12. Adjust the rear down by using the same method as in No. 11. In our example, move the LR and RR corners down by 0.4375-inch.
13. Now that we have the front-to-rear rake set, we adjust the side-to-side rake. The new existing ride heights are LF 3.6875, RF 4.8125, LR 4.1875, RR 5.3125. The LF needs to go up 0.3125 and the RF needs to go down the same amount. So we turn the RF adjuster up (to lower that corner) 2.5 turns and the LF down (to raise that corner) 2.5 turns.
14. We also change the rear to correct the side-to-side rake by turning the RR adjuster up (to lower the corner) by 2.5 turns and the LR adjuster down (to raise that corner) by 2.5 turns. Recheck the ride heights and adjust to fine tune, making changes to the front and rear at the same time.
Once we have established our...
Once we have established our ride heights and weights at the shop on a level surface, we can then record the wheel position at the track on an unlevel surface to facilitate spring changes. Mark and record the distance from the rim to a spot on the fender at each wheel. When making spring changes, return that corner to the measured distance and you will have returned that corner to the correct ride height and weight.
Another method of recording...
Another method of recording the ride height for reference is to measure from a point at the lower control arm, such as the top of the ball joint bolt, up to the frame-rail. Place a piece of tape on the tubing and mark an even inch and write that number on the tape. When you change springs, return the corner to that measurement.
Changes in ride height have...
Changes in ride height have an effect on the front geometry and the rear as well. In the rear, ride height changes affect the trailing arm angles which affect our rear steer and alignment which are critical parameters. Even the pinion angle can be affected by changes in the rear ride height. That is why we need to maintain strict control over our ride heights.