wheel rate vs ball joint rate

[artcat]

A few of the internet calculators spit out BJ rate, but I'm assuming this is not the same as wheel rate if the center of the contact patch is not under the BJ. Do I just re-calculate the motion ratio from the wheel center?

 

[NormPeterson]

Consider the point that the BJ and the contact patch are instantaneously rotating about.


Norm

 

[hemipanter]

If you give me a mail, hemipanter@hemipanter.se I will mail you back my own excel counter for wheelrate calculation, that will take all the A-arm geometry in to concideration.
Formula and image is going with it.
Regards
Goran Malmberg