negative kingpin

[andsund]

I'v been looking at using negative kingpin inclination, but im trying to grasp the negative effects of it!

with negative KPI we get negative camber due to steering on both wheels.

but will u lose the steering stability by getting negative KPI? can seem to find anyone that uses this!

[acedeuce802]

Have you designed a rough draft of your negative KPI suspension? Have you put it in a kinematics software? Do you know how much the KPI actually affects the camber, compared to the caster affect? Have you thought about packaging an upright?

To take from this thread (http://fsae.com/eve/forums/a/tpc/f/125607348/m/70220475151?r=70220475151#70220475151): camber variation = KPI Angle x (1-cos(Steering angle))- Caster angle x Sin (steering angle). To help me comprehend this, I put this formula in Excel, and played around with different caster and KPI values, as well as different steer angles. Make sure to know what your typical steer angle is, because that plays a large factor in how much KPI affects the camber change.

[Fyhr]

How much scrub are you aiming for?

How does the negative KPI influence required steering effort?

[andsund]

Thanks for the idea, The negative kingpin didnt give me much of negative camber. I just wondered why no one uses it. Since I cant find any negative kinematic effect but only as pontus points out the scrub gets larger.

Another thought was the wheel stability KPI gives when you use conventional KPI(positive) is reversed in negative KPI and forces the wheel to turn when the wheels starts to turn. As it feels a little crazy to go for negative KPI it must be some factor that convinces all the teams to go positive KPI. I was just wondering about the effects and if anyone had tried it! would be interesting to test in dymola or adams car(we dont have =/)

[PatClarke]

Since I cant find any negative kinematic effect

Andsund, you haven't looked hard enough! Think about why KPI is used and then think about the counter effects!

Pat