Caster Settings

Slide 1: 

CASTER SETTINGS   Caster controls how well the car turns. If you are looking at your car from the side, caster is the angle of an imaginary line between the upper and lower ball joints relative to vertical. If that line is angled so that the top leans toward the back of the car, that's positive caster. If the top of the line leans toward the front of the car, that's negative caster. Positive caster makes the car feel more stable and resists turning. If you are turning a car that has positive caster on both front wheels and you let go of the steering wheel, it will automatically straighten up. Negative caster does the opposite and usually makes the car feel darty. Racers rarely run negative caster.   Measuring caster is straightforward. Begin by locating the car on a flat, level surface. Make sure the wheels are pointed straight ahead. If you have toe-in set on the car, the toe needs to be returned to zero for now. It also helps to have turn plates underneath the front wheels to reduce turning resistance (easy to make turn plates….you will need 4- 12”x12” floor tiles(most home improvement centers sell left overs for .50 each) and a box of salt(free from the kitchen if you don’t get caught). Place 1 tile under each front tire, then sprinkle a liberal amount of salt and place the other tile on top. The salt acts a ball bearing and is easy to clean up.

Slide 2: 

CASTER SETTINGS (PAGE 2)   Start by placing the stick against the wheel and extend stands. Place the gauge instead of sitting up, turned on its side. Zero the gauge. Remove the stick and gauge from wheel and turn the steering wheel (right or left) ¾ of a turn, (I use pin stripe to mark the steering wheel at 12 o’clock) hold gauge against the wheel and make note of the degree, example 12.4 V Now turn back to center and make the turn in the opposite direction ¾ of a turn and install gauge and you will have a reading example 14.3 V This indicates 2.1 degree of positive caster. .   By turning the wheel a preset amount, you do not have to have turn plates or measure in degrees. I turn the wheel three quarters of a full turn since that is the most a racer will typically turn the steering wheel on the racetrack. If you are using turn plates, some gauge manufacturers recommend 20 degrees while other says 10-15 degrees. It really does not matter as long as you are consistent and turn the tires the same amount every time you check the caster. If you are using the tiles, you can use the corners as a reference for the bracket that extends out but you are relying on site only. Whether you turn the wheels to the right or left to begin the process also is not important as long as you are consistent.   I know this sounds confusing at first but once you have checked your caster once or twice it is really the easiest way we have found.