That is a good question that is not answered. I don't know this to be 100% true but based on the illustration, it looks like its the mid way point between the ball joint position at rest and at the 1" bump position. I unfortunately cant say for sure though if that is actually what was or is typically done with your question as my suspension design background is all for race / track cars where we care more about geometry that gives traction with proper camber while cornering. Bump scrub is not something we are concerned with since tracks are typically significantly smother than public roads so not real reason to be concerned with bump scrub and loss of efficiency and added tire wear that it could bring. We pick our upper control arm points more based on camber gains and changes with roll center and instant center during chassis roll for the most part. Like the saying goes, with suspension, everything is a compromise with something else. If we can get a proper camber curve and have to have a bit of bump scrub, then so be it... The benefit of more traction when cornering outweighs the little loss of efficiency we might get because of a bit of bump scrub. Alll in all though, although this video seems like good information on the topic, the illustrations are very poorly done. Like for example, I doubt there is a car in existence that has the lower ball joint above the axle centerline. While it really doesn't make a difference being an illustration but it still can be deceiving for those who grasp concepts visually since its not an accurate visual representation.
Thks, this is the best intro to front end geometry I could find. I'm a retired physicist & I would like to make a home built car frame one day. ?Is there any book/website with all this derived? ; ?Also what the best intro book on the subject? If the scrub radius is not zero, you'll have torque steer. I assume no torque steer is best but you mentioned some is best (@11:48 into your video). ?Why wouldn't you want a non-zero scrub radius? Here's a video on race car front end geometry you might be interested in: th-cam.com/video/VbReLNi2JP4/w-d-xo.html
There is a way to eliminate the scrub.
Clear as mud.
This video is amazing!!
How did you come up with the placement of the Perpendicular Bisector?
That is a good question that is not answered. I don't know this to be 100% true but based on the illustration, it looks like its the mid way point between the ball joint position at rest and at the 1" bump position.
I unfortunately cant say for sure though if that is actually what was or is typically done with your question as my suspension design background is all for race / track cars where we care more about geometry that gives traction with proper camber while cornering.
Bump scrub is not something we are concerned with since tracks are typically significantly smother than public roads so not real reason to be concerned with bump scrub and loss of efficiency and added tire wear that it could bring. We pick our upper control arm points more based on camber gains and changes with roll center and instant center during chassis roll for the most part.
Like the saying goes, with suspension, everything is a compromise with something else. If we can get a proper camber curve and have to have a bit of bump scrub, then so be it... The benefit of more traction when cornering outweighs the little loss of efficiency we might get because of a bit of bump scrub.
Alll in all though, although this video seems like good information on the topic, the illustrations are very poorly done. Like for example, I doubt there is a car in existence that has the lower ball joint above the axle centerline. While it really doesn't make a difference being an illustration but it still can be deceiving for those who grasp concepts visually since its not an accurate visual representation.
Thks, this is the best intro to front end geometry I could find. I'm a retired physicist & I would like to make a home built car frame one day.
?Is there any book/website with all this derived? ; ?Also what the best intro book on the subject?
If the scrub radius is not zero, you'll have torque steer. I assume no torque steer is best but you mentioned some is best (@11:48 into your video). ?Why wouldn't you want a non-zero scrub radius?
Here's a video on race car front end geometry you might be interested in: th-cam.com/video/VbReLNi2JP4/w-d-xo.html
Chassis Engineering is a great book to start with. I know its old but it might help someone else.
Unblock your nose with some nasal spray