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First, I won't discuss modifications to the internals of the steering rack itself, as it is an expensive part to replace should somthing go wrong. (Although, if you do have the know-how to mess with it, the lowest ratio it should have is around 16:1 for two turns lock-to-lock and nearly instantaneous steering input.)
Feedback - Partially related to unsprung weight of front suspension but also related to "kingpin inclination, steering offset or scrub radius, castor angle and the self-aligning torque characteristics of the front tires." (Tune to Win, Carroll Smith) If the steering offset is too great then feedback and the self-returning action will be excessive; if it is too small, then feel will be inadequate.
Increasing front track with wheel spacers increases the scrub radius by the thickness of the spacer is is unlikely to be beneficial to the steering.
Castor promotes straight-line stability, feel, and self-returning action. Positive castor causes a loaded wheel to undergo negative camber change when it is steered and thus may be used to counteract positive camber change created by chassis roll. Castor can help counteract corner entry understeer but also increases steering effort, which may not be a negative tradeoff, especially in cars with overboosted power steering.
Bump steer- You don't want to mess with it. Sure, you may be able to eke out another .2secs on the road course, but you coul dalso make the car an absolute terror to drive and just plain dangerous.
Truths about negative camber
There is such thing as too much negative camber. By making the wheel/tire go into static negative camber on a vehicle with a MacPherson strut front suspension, you are going to be counteracting the positive camber change. However, there is a level at which you over-counteract and thus the tire is always in a negative-camber situation. This is not wanted because it will both wear the tires prematurely and decrease contact patch and thus decreasing overall grip. In the rear, less negative camber (if any) is often used and, if it is used, it is usually to tweak the balance of the car. The old-school Japanese drifters used to run oni-kyan ("demon camber") so they could get their tires to spin easily even though they had very little power... but I don't recommend that to any of you.
Truths about toe
Toe-in, toe-out, or zero toe? Which should you use? The truth is that on the street, you should run factory specs. If you have access to cheap/free alignment, then maybe you should try and see what's best for you... but don't mess with rear toe. Front toe-in means stability at high speeds, but sub-par turn-in. Front toe-out means good turn-in, but the suspension feels darty at high speeds. Mess with them in very small amounts.
Questions, comments, and corrections are welcome.
Feedback - Partially related to unsprung weight of front suspension but also related to "kingpin inclination, steering offset or scrub radius, castor angle and the self-aligning torque characteristics of the front tires." (Tune to Win, Carroll Smith) If the steering offset is too great then feedback and the self-returning action will be excessive; if it is too small, then feel will be inadequate.
Increasing front track with wheel spacers increases the scrub radius by the thickness of the spacer is is unlikely to be beneficial to the steering.
Castor promotes straight-line stability, feel, and self-returning action. Positive castor causes a loaded wheel to undergo negative camber change when it is steered and thus may be used to counteract positive camber change created by chassis roll. Castor can help counteract corner entry understeer but also increases steering effort, which may not be a negative tradeoff, especially in cars with overboosted power steering.
Bump steer- You don't want to mess with it. Sure, you may be able to eke out another .2secs on the road course, but you coul dalso make the car an absolute terror to drive and just plain dangerous.
Truths about negative camber
There is such thing as too much negative camber. By making the wheel/tire go into static negative camber on a vehicle with a MacPherson strut front suspension, you are going to be counteracting the positive camber change. However, there is a level at which you over-counteract and thus the tire is always in a negative-camber situation. This is not wanted because it will both wear the tires prematurely and decrease contact patch and thus decreasing overall grip. In the rear, less negative camber (if any) is often used and, if it is used, it is usually to tweak the balance of the car. The old-school Japanese drifters used to run oni-kyan ("demon camber") so they could get their tires to spin easily even though they had very little power... but I don't recommend that to any of you.
Truths about toe
Toe-in, toe-out, or zero toe? Which should you use? The truth is that on the street, you should run factory specs. If you have access to cheap/free alignment, then maybe you should try and see what's best for you... but don't mess with rear toe. Front toe-in means stability at high speeds, but sub-par turn-in. Front toe-out means good turn-in, but the suspension feels darty at high speeds. Mess with them in very small amounts.
Questions, comments, and corrections are welcome.