Reading and analyzing your suspension's camber curves is a very important step in improving your race car's handling.
The term Camber is used to describe the tilting of a wheel/tire. If the top of the tire is leaning outward from the car, then this is called "positive" camber. Conversely, if the top of the tire is leaning in toward the car, this is called "negative" camber.
Camber is measured in degrees of tilt. 1.5 degrees of positive camber means the top of the wheel is leaning outward 1.5 degrees. Likewise, 3 degrees of negative camber means top of the wheel is leaning inward 3 degrees.
While your car's camber is adjustable in the garage, it also changes on the race track. This is why it is important to examine the camber curve (see sample below).
Parts of the Camber Graph
The numbers on the left side of the graph
represent the up and down travel of a wheel or suspension. The line in the
middle labeled "static" is the wheel (or suspension) position when the race car
is at rest or standing still.
The negative (-) numbers represent the condition where the wheel moves downward from the frame. This could happen when the tire drops into a pothole, or when the inside of the chassis lifts as during body roll in a corner.
The positive numbers above the static line are where the wheel has moved up in relation to the chassis. This can be a case where the tire is going over a bump or when the outside of the frame drops as during body roll in a turn.
The numbers on the bottom of the graph are used to identify the wheel's camber change. The curving line on the graph is the camber change for each position of the wheel's vertical movement.
Using the static line and the "0" camber line, the graph can be divided into 4 quadrants (top left, top right, bottom left, bottom right). It is desirable to have a camber curve that is in the top left and bottom right quadrants.
Stock frames from the 60s and 70s often had camber curves that ran from the top right through the bottom left quadrant. This is very undesirable for high performance handling.
Desired Shape of Line
The next step in analyzing and improving your
camber curve after getting the line in the proper quadrants (or if you were
lucky to have it in the proper quadrants to start), is to achieve a specific
line shape on the camber graph.
Generally your camber curve should be less of a curve and more of a straight line. Ideally the line would slope uniformly from the top left to the bottom right of the graph.
Good and Bad Parts of Line
Typical stock car suspensions will have a
camber curve that looks like the one in the example. The hook part of the line
where the arrow "A" is pointed is undesirable.
If your car squeals the inside front tire in a corner, there is a good chance you have a camber curve with a hook. Short track race cars that have a camber curve (like the example) often require large amounts of positive camber in the left front tire in order for the tire temperature to be even across the face of the tire.
The region of the line marked B is a desirable shape. Notice that here the line it is flatter and less curved than at the opposite end of the line.
When analyzing your suspension, if you find a camber curve that has a flatter portion at the top, your handling could be improved by lowering your frame height. One way of thinking about this is that lowering the ride height will move the camber curve lower on the graph. This brings the better portion of the curve down to the operating range and moves the bad portion down off the graph.
Create your own graph
Just the ability to generate a camber curve can be an advantage over your competition. Having the ability to quickly try suspension changes and see how they impact your camber curves is a sizable advantage. You will need to place your car up on blocks so you can get the full travel out of your suspension. Next take the springs out of the car on the wheel that your making the graph for. Then set your camber, Using a jack place the suspension at the static number. Then note the readings when you change the tires position in the fully extended position. Use graph paper to plot your information. Next plot your information with the suspension when its compressed. Note the total movement of the wheel. You now have information at that specific camber adustment like the graph above.
You can repeat this for other camber settings to enhance your cars handling. If your not getting the even temperature across the tire you can quickly change your camber to one you have on file, you already know what the camber will be through the motions of the suspension and this will help you if you go from a high banked track to a flat track or vise versa.
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