Originally Posted by theisgroup
the extended one give you a little more ackerman. it put the steering turnbuckles closer to the rear of the car. generally the t2 has plent of ackerman using the standard set.
Having the steering turnbuckles closer to the rear of the car provides less
ackermann effect. Less ackerman means that the difference in steering arcs between the inside and outside wheels will be reduced.
I tend to think about, and work on, both ackerman and front toe-out together. In combination, each of them has a significant effect on initial steering response and mid corner front end grip. This is due to the fact that the front end is loaded with weight in both situations. They also affect corner exit, but to a lesser degree in comparison since the cars weight is shifted rearward.
What I've found on carpet is that if you desire quick initial steering response (aggressive corner entry), its best to set the front toe-out to 1.0d or even 1.5d and then use the least amount of ackerman. This is accomplished by placing the servo saver in the forward position and mounting the steering turnbuckles in a third hole on the steering blocks closer to the rear of the car. Using this configuration (front toe-out at 1.0d) the difference between the inside and outside steering arcs should be around 2.0d at *useable* full lock (set L/R full lock with transmitter EPA while the car is on a setup system). You can use the old FK'04 ackerman extension plates
with the T2 OEM steering blocks to provide the third hole as well.
However, if the car seems to be too twitchy on initial steering inputs, such as at corner entry at the end of a straight (and changing shock dampening doesn't cure it), then I use the second hole on the steering blocks and set the front toe-out to 0d. This configuration increases the ackerman effect. But when used in conjunction with the reduced front toe-out, it should maintain the 2.0d difference between the inside and outside steering arcs at full lock. The new front toe-out of 0d should tone down the initial steering response of the front end (NON-aggressive corner entry) as the wheels start to turn in.
Keep in mind that all of this is subjective to the tire/surface combination, corner entry speed attained from the power of the motor, as well as other factors.
Regarding ackerman specifically, at each track I try to find the best combination of front toe-out and ackerman effect that produces enough mid-corner
front end grip, without causing the front inside wheel to drag or even cause the car to oversteer in a pendulum effect around the inside front wheel.
From what I've seen, with the combination of medium/high to high bite carpet and soft foams (double pink/orange & double/pink), having a difference of 2.0d between the inside and outside steering arcs provides the best mid corner grip (ala slip angles), without drag or oversteer.
**Edited to add**
On the setup station, I'm currently setting full lock to measure out at one of the following (high traction carpet/foam ONE-WAY setup):
Inside wheel/Outside wheel (degree of arc)
When trying a front diff, I've found that my setup required an increase in steering arcs from both wheels and the difference in arc increased slightly (I'm guessing around 2.5d). However, I never fully tested or measured the steering arcs with a front diff.