Wheel Alignment

[jam_rs]

Wheel Alignment

Front toe-in: too much
■ Car darts over bumps, under heavy braking and during corner entry - is generally unstable
■ Car won't point into corners, or if extreme. May point in very quickly and then dart and wash out

Front toe-out: too much
■ Car wanders under heavy braking and may be somewhat unstable in a straight line, especially in response to single wheel or diagonal bumps and/or wind gusts
■ Car may point into corners and then refuse to take a set
■ If extreme will cause understeer tyre drag in long corners

Rear toe-in: too little
■ Power on oversteer during corner exit

Rear toe-in: too much
■ Rear feels light and unstable during corner entry. Car slides through corners rather than rolling freely

Rear toe-out: any
■ Power oversteer during corner exit and (maybe) in a straight line
■ Straight line instability

Front wheel caster or trail: too little
■ Car too sensitive (twitchy?)
■ Too little steering feel and feedback

Front wheel caster or trail: too much
■ Excessive physical steering effort accompanied by too much self return action and transmittal of road shocks to the drivers hands
■ General lack of sensitivity to steering input due to excessive force required

Front wheel caster or trail: uneven
■ Steering effort is harder in one direction than in the other
■ Car will "pull" towards the side with less caster - good on ovals, bad on road courses

Camber: too much negative
■ Inside of tyre excessively hot and/or wearing too rapidly. At the front this will show up as reduced braking capability and at the rear as reduced acceleration capability. Depending on the racetrack and the characteristics of the individual tyre, inside temperature should be 10°-25° hotter than the outside. Use a real pyrometer with a needle rather than an infra red surface temperature device.

Camber: not enough negative
■ Outside of tyre will be hot and wearing. This should never be and is almost always caused by running static positive camber at the rear in an effort to avoid the generation of excessive negative camber under the influence of aero download at high speed.
- A better solution is improved geometry and increased spring rate. Dynamic positive camber will always degrade rear tyre performance and if extreme, can cause braking instability and/or corner exit oversteer.

Bump steer, front: too much toe-in in bump
■ Car darts over bumps and understeers on corner entry

Bump steer, front: too much toe-out in bump
■ Car wanders under brakes and may dart over one wheel or diagonal bumps
■ Car may understeer after initial turn in

Bump steer, rear: too much toe-in in bump (same as solid axle steer on outside wheel)
■ Roll understeer on corner entry
■ Mid phase corner understeer
■ "Tiptoe" instability when trail braking
■ Darting on power application on corner exit

Bump steer, rear: too much toe-out in bump (same as solid axle steer on outside wheel)
■ Instability on acceleration
■ Good turn in followed by a tendency to oversteer at mid-phase and exit