For measuring camber, just...
For measuring camber, just read the amount on the vial for a manual gauge or the display on a digital gauge. Make sure to calibrate your gauge before using. The Intercomp Caster and Camber gauges used in these photos are bubble type and digital. The caster and camber readings came out the same for both gauges. Make sure the car is at ride height with all of the weight in the car including the driver. Air the tires up to operating pressures. The setting for camber may need to change once the car is run hard and the tire temperatures have been evaluated at maximum operating levels.
Dive, or bump, is only part of the answer. Chassis roll has an effect that adds or subtracts from what dive does. So, what we really need to know is what the dynamic camber ends up at after the car dives and rolls, just like the chassis does in the turns.
The left front always loses a lot of camber, so we need to allow for that in setting the amount of static camber. Generally, if we end up with between 1/2 to 1 degree of positive camber at the LF wheel after the car dives and rolls, then that tire will have the dynamic camber that it needs.
The RF camber change is a little different. We can design our car so that the RF camber doesn't change after dive and roll for more conventional setups. This is actually exactly what that tire wants for most short track applications. The reason for this is that as we enter the turn, the RF tire takes a set fairly quickly. If the camber continues to change after that initial set, then the tire will give up traction and the car will usually push.
In order for your car to have...
In order for your car to have near zero bumpsteer, two conditions need to exist. A line drawn through the centers of rotation of the ends of the tie rod needs to point at, and travel through, the instant center and the tie rod length needs to be the specific distance between the inner mounts and the ball joints as shown.
For some of the present day setups for both asphalt and now on dirt, teams are running softer springs that result in much more dive. This causes much more camber change associated with dive and we therefore need to make adjustments to our static camber settings to compensate.
The right upper control arm angle mostly controls the RF camber change. So we try to work with that control arm angle first. Once we have the minimal camber change from dive and roll, we leave that angle alone as we check our frontend for moment center location and adjust the left upper arm angle as needed.
We can measure camber change by several different methods. In the shop, we can set the chassis ride heights just as they would be at mid-turn on the racetrack and then directly measure the camber at each wheel. To do this, we will need to know the shock travel at mid-turn, which is very hard to estimate.
If we look at the shock travel indicators on the shaft of the shock, they will always tell us total shock travel which includes braking, going over bumps, banking changes such as exiting the racetrack. So, an estimate based on how the car looks on the track could provide the best information as to the mid-turn attitude.
If the tie rod is aligned...
If the tie rod is aligned pointing above the instant center, the wheel will bump out when moving up and bump in when moving down. The arc it follows will not be correct in relation to the arc of the ball joints.
Once the caster and cambers have been set, it's now time to adjust our bumpsteer. As the front wheels move up and down, we want the front wheels to maintain a particular direction and not steer. It's most important for the wheels to have minimal bumpsteer when we are negotiating the turns. There are certain elements of the construction of the frontend components that will make this happen.
The angles of the upper and lower control arms, meaning a line extending through the center of rotation of the ball joints and inner mounts of each arm, intersect at a point we call the instant center (IC). This is one of the components used to determine the moment center location. In order to have near zero bumpsteer, we need to have the tie rods on each side point toward the IC for its side. This is one of two criteria for near zero BS.
The other thing we need is for the tie rod to be a specific length. That length must be equal to the distance formed by 1) a line extending through the centers of rotation of the tie-rod ends, and 2) the tie-rod line intersection with a) lines extending through both the upper and lower ball joints, and b) the plane that passes through the inner chassis mounts. This can get a little complicated because although the ball joints do form a single line, the chassis mounts form a plane because of the position of the front and rear mounts.