Car compasses are handy little accessories that can give you the general direction that you're traveling. From cheap plastic to brass and aircraft aluminum, these models tend to stick to your dashboard or windshield. However, it's important that you set the compass correctly so you know it's properly adjusted to work in your car. Fortunately, all you need is a hand compass and an adjustment tool to properly set your car compass.
Attach the car compass to either the windshield or your dashboard, wherever it's meant to be mounted. All adjustments to the car compass should be made after it has been mounted in place.
Find North with your hand compass and drive your car so it's facing north. Stop the car and look at the compass. If it is not reading exactly North, then adjust it by turning the N/S screw with the adjustment tool, or with a dime. Don't use a steel screwdriver, as this will mess with the magnets in the compass.
Turn the car to the East and once more check the direction it reads with your hand compass. Stop the vehicle and adjust the E/W screw until the compass on the car agrees with the compass in your hand.
Drive the car South. Stop and check the measurements. If the reading is off, adjust half of the error. For instance, if the car compass is off by 4 degrees, adjust it by just 2 degrees using the screws on the N/S screw. Perform this exact same operation driving West, correcting just half of the error margin that's found.
