Caster is the leaning forward or back of the tire at the top of the wheel. Do not confuse this with camber which is the inward or outward tilt of the wheel at the top. Positive caster is when the wheel is tilted back toward the rear of the vehicle. Negative caster is when the wheel is tilted forward toward the front of the vehicle.

Caster is used to provide directional steering stability. When thinking of caster, think of a tool box, TV stand, chair, or anything else that has 4 wheels on it that swivel to help you move it across the floor. When you push an object like this across the floor you'll notice that the wheels will swivel back allowing you to push forward with ease. This is positive caster. Now take those 4 swivel wheels and turn them forward 180 degrees. This is negative caster. I'm sure you know how difficult it is to push something with the wheels in this forward or negative position. Besides being difficult to push, it also has a tendency to take off in an unwanted direction until the casters spin in a positive direction. For the same reasons we want our chair to slide across the floor with ease, we want our race car to do the same. When setting your chassis you'll want to tip the top of the wheels back adding positive caster to provide you with that straight ahead directional stability. There are NO circumstances where negative caster is preferred, hence the adjustment range in ARCA SimRacing is from +1.5 through +4.0.

Proper caster adjustments will vary with each track and individual driver as well as the steering device you maybe using. (i.e. force feedback) The more positive caster the more feedback you will feel as a driver. More caster can also provide a more difficult steering effort, especially with a force feedback wheel. More positive caster will also give you a better feel for the car. More caster will allow you to make better decisions on the track about how the car is handling.

So why not crank the caster positive as far as it will go? Because too much positive caster also has it's drawbacks. When you turn a car left with positive caster the LF rises while the RF drops. This changes the weight on all 4 corners of the car. In effect you're taking cross weight out of the car the more you turn the wheel. The more positive the caster, the more cross weight there is being removed. The more cross weight you remove the looser the car will get.

In general, you'll want to run higher positive caster settings on a short track with tight corners, over a larger track with long, wide sweeping corners and long straight-aways. +4 to +5 on the RF isn't uncommon for a track like Martinsville. For Michigan or California a setting of +2 or +3 would be preferred. Higher caster settings allow you to "catch" power slides on exit a little bit easier as well.

Another element that must be considered is the caster split or caster stagger as I like to call it. Caster stagger is simply using different settings on the LF wheel than the RF. When caster settings are different, your steering will tend to pull toward the side with the least amount of caster. On tracks where your only turning left, you would want a higher positive caster setting on the RF than the LF. This more positive caster on the RF will make the car pull to the left entering the turns, which is the preferred setup for entering the corners. The higher the caster stagger you run the easier the car will turn itself into the corner. Higher stagger will also take some feel out of the car and also force you to hold your wheel to the right down a straightaway.

Caster stagger will also affect braking. If you run too much stagger at tracks that require heavy braking such as Martinsville or the road courses, you may have to add brake bias. Although a better trade-off would be just to even up the caster allowing you to brake harder without causing the car to pull to the side with the least amount of caster.

Caster stagger is NOT the only adjustment that will give you that pull to the left. Many other factors must also be considered. Camber settings, weight balance, tire stagger, tire psi, and track banking also plays an important role. Many newcomers will be uncomfortable with the pull to the left and many may even think that there wheel won't calibrate properly. This pull to the left is normal and is the preferred setup to assist drivers when entering the corners with ease. Most caster stagger settings will be between 2 and 3 degrees. In other words, if you ran 1 degree positive on the LF, you would run positive 3 or 4 on the RF. In general, tracks that are small and have tight corners will require a higher caster split to help you turn into a corner better.

Simulating the pull that a stock car gets in a game is going to yield different results for different types of controllers. To add to this variation, the Linearity setting you choose in setting up your controller, in combination with the steering ratio you choose within the setup is going to contribute in making the pull feel different from user to user.  On any given controller, setup the Linearity towards the Non Linear side (say 10%)  You will notice the need to use a lot more counter steering on the straight than somebody using 90% Linearity with the exact same setup.

Do you see real drivers using counter steering down the straights? No, because they can center the wheel on the steering shaft. Is the pull still there for them? Yes. You can get your controller to center on the straights by how you calibrate it, get rid of it entirely if you like. Will you still feel the pull? No, why? because the pull you're feeling is from the tension on the springs, bungee, or whatever your controller uses to center itself. Your controller isn't hooked up to the suspension of a stock car, so you're not going to be able to feel the dynamic pull that the suspension creates. Furthermore, your steering wheel doesn't have the range of motion as a real car.  At best you're probably getting from 240 to 270 degrees of motion, and much less on a Joystick (maybe 90 degrees if you're lucky?) A real car has what, maybe 3 to 4 full rotations from lock to lock? With this in mind the game has to have Steering Ratio values that can compensate for the lack of true lock-to-lock movement. The differences in degrees of lock to lock motion between a joystick and a wheel is why the Linearity setting makes such a big difference, it has to in order to make all types of controllers usable. You just need to find the setting that is comfortable to you.

One thing to remember in ARCA Sim Racing, a setting of 22:1 is going to require LESS steering movement than a setting of 5:1, which would be more sensitive to steering input.

Caster synopsis:

• More positive caster will loosen the chassis the more the wheel is turned through a corner.

• More positive caster will allow you to catch slides on exit a little easier.

• Caster adjustments are better felt through a force feedback wheel.

• The car will pull to the side with the lower amount of positive caster.

• The higher the caster stagger, the easier the car will turn into a corner.

• The higher the caster stagger, the easier the car will break loose braking into a corner.

• The higher the caster stagger, the less steering effort required. This will tend to give you a loose feeling upon corner entry.