Originally Posted by ccrcraceway

Ackermann controls the difference in steering arcs between the front
inside and outside wheels. The inside wheel always has a tighter arc in
any corner. The amount of grip provided by the tires, in relation to the
steering arc and speed of the car, create an amount of measurement
called a “slip angle” for each wheel. For some tires you need a greater
difference in slip angles between the inner and outer wheel and for some
you need less.
The size and geometry of the servo saver on XRAY cars forces the inside
wheel to increase its turning angle at a greater rate than the outside
wheel, as the servo turns either way from center. The rate of the increase,
called Ackermann effect, can be changed by the angle of the steering
rods connecting the servo saver to the steering blocks. The straighter the
rods are in relation to each other, the more Ackermann effect will be
applied to the inside wheel.
Slip angles work differently on each wheel when the car is slowing down & pitching forward, than when the throttle is applied & the tires are pulling
the car forward. The goal in tuning Ackermann is to get the car to keep a consistent steering arc after going from off-power to on-power, while not
allowing the front inside wheel to be turned too much and drag through the corners instead of rolling through them. If the car steers well off-power
but pushes on-power, then use more Ackermann effect and decrease your transmitter EPA/dual rate. If the car steers well on-power and pushes
off-power, or if you can hear the front inside wheel chattering at mid-corner, then use less Ackermann effect and increase your transmitter EPA/dual
rate.
ADJUSTING ACKERMANN
The angle of the steering rods (and hence the Ackerman effect) can be adjusted by changing the location of the steering rods inner mounting
positions on the servo saver. This is accomplished by using Ackermann inserts.
• Least Ackermann effect: Servo saver insert with holes furthest FORWARD; steering rods most angled.
• Most Ackermann effect: Servo saver insert with holes furthest REARWARD; steering rods straightest.
We recommend using more Ackermann in low-to-medium grip conditions, and less Ackermann in medium-to-high grip conditions.