Suspension Geometry

Discussion in 'Modifications & DIY how-to' started by Greg, Oct 11, 2006.

  1. Greg

    Greg Active Member

    I've had a few questions about different types of suspensions, suspension setups, adjustments... So, I decided to try and answer a few questions for everyone.

    CAMBER
    I'll start will camber. Camber is the tilt of the tire as viewed from the front of the car. If the top of the tires lean toward the center of the car then you have negative camber. If the top of the tire tilts out away from the center of the car then you have positive camber. Adjusting camber can have a dramatic effect on the cornering of your car. Most oval track racers run negative camber on the right side of the car and positive camber on the left. Optimum camber settings will result in more speed and ideal tire wear. Camber is measured with a caster camber gauge and is usually easily adjusted with shims or adjustable upper a-arms. Always check the toe when making camber or caster adjustments. Remember that poor camber settings will cause excessive tire wear. Camber settings set to extremes can reduce the braking ability of the car.

    TOE
    Toe is the pointing in or pointing out of the front wheels as viewed from the top of the car. If the front wheels point in, toward the engine, at the front edge of the wheels then you have toe in. If the front wheels point out at the front edge then you have toe out. Toe out pulls on the tie rods taking out the tiny clearances that are built into the tie rod ends.Toe can be set with a pair of toe plates that are rested on the sidewalls of the tires. A tape is placed on the toe plates in front of the tire and an additional tape behind the tire. When using toe plates a smaller tape reading on the back tape indicates toe out. For a very precise reading you can scribe a line in each front tire. Use a tire scribe and spin each of the front tires to get your straight line. You can then measure between the two scribed lines with a tape measure or with a toe bar. As with toe plates, a smaller measurement at the backside of the tire indicates toe out. On the other side, this toe bar extends past the sidewall by a few inches. A tape is used to measure from the toe bar back to the sidewall. When this system is used a smaller tape reading at the front of the tire indicates toe out.

    CASTER
    To understand caster you need to picture an imaginary line that runs from through the upper ball joint and extends through the lower ball joint. From the side view the imaginary line will tilt forward or backward. The tilting of this imaginary line is defined as caster. Caster is measured in degrees by using a caster camber gauge. If the imaginary line described above tilts towards the back of the car, at the top, then you will have positive caster. If the imaginary line tilts forward then you would have negative caster. Positive caster provides the directional stability in your car. Too much positive caster will make the steering effort difficult. Power steering will allow you to run more positive caster. Negative caster requires less steering effort but can cause the car to wander down the straightaway. The caster split helps pull the car down into the turn, helps the car turn in the center and helps it stay hooked up on exit.

    Corner Balance
    Proper chassis set up requires that the weight balance is set correctly for the car. In order to achieve proper and repeatable weight balance a quality set of electronic scales will need to be obtained. Before you begin the scaling process you should make sure that the car is ready. Fluid levels need to be topped off, stagger & tire are pressure set, ride heights adjusted, Caster adjusted, Camber set, rear end square and the toe checked. Emphasis should be placed on being ready before you begin the final scaling procedure as all of these factors will have an effect on the end result. If the car is not ready when you are setting it up, your just wasting time. Once the vehicle is ready, you can now record your wheel weights, partial weights and percentages. Check that the front to rear balance is correct and that the left side and total are where they need to be. If not then move the lead to the appropriate spot until you are happy. Readjust the ride heights if you have to move lead around. Now you can check the cross weight. If you want to add cross weight put a turn in the right front and left rear and take a turn out of the left front and right rear. On non coil over cars you may need to go two turns on the rear for every one turn on the front. By adjusting all four corners you will help maintain your ride heights. Now you can set the sway bar. With the car still on the scales you can see exactly how pre-load you are putting on the bar. Record your final settings and you are ready to go.

    If I missed anything or got anything wrong, let me know and I'll correct/add it

    Hope this helps
     
  2. miloman

    miloman Retired Admin

    some useful images i found:

    camber:
    [​IMG]

    castor:
    [​IMG]

    toe:
    [​IMG]
     
  3. Greg

    Greg Active Member

    Sorry for bringing back one of my dead threads, but with the interest as of late, I figured it was appropriate..

    *Shameless Bump*
     
  4. Alex

    Alex Community Founder Staff Member

    I think I stickied something similar already a couple years ago ?
     
  5. Greg

    Greg Active Member

    :dunno:
     

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