Trying to calculate vertical wheel travel after hitting a bump

[ace-card]

Hi everyone,

I'm studying Motorsport Engineering and am trying to do an in depth analysis of a vehicle double wishbone suspension system. I have been using Excel to model the behaviour of certain aspects, and I am currently trying to analyse the effect of a wheel hitting a bump and it's affect on camber change.

What I'm wondering is what reference point for the vertical wheel travel do you use? Is it the bottom ball joint in relation to the ground or the top ball joint? Obviously, this would be the same if the wishbones were of equal lengths and equal angles to the chassis, but what happens if they are not? This would mean that the hub and wheel would now be traveling in an arc and not straight up/down, making the ratio of travel between top and bottom different. It is this which is ultimately confusing me!

One last question...if I were to use wishbones of equal length, mounted at different angles to each other, how would this affect the motion of the wheel?

I hope I have made sense! Any suggestions would be much appreciated!

Thanks!

 

[Ranger Mike]

Welcome to the forum
i suggest you look at post on this mech eng forum
race car suspension class Jul22-09, 12:03 PM
tells about checking for Bump Steer and you arte correct..it is all about tire contact patch and camber change..get back to me ifin you got any questions

rm

 

[berkeman]

Hi everyone,

I'm studying Motorsport Engineering and am trying to do an in depth analysis of a vehicle double wishbone suspension system. I have been using Excel to model the behaviour of certain aspects, and I am currently trying to analyse the effect of a wheel hitting a bump and it's affect on camber change.

What I'm wondering is what reference point for the vertical wheel travel do you use? Is it the bottom ball joint in relation to the ground or the top ball joint? Obviously, this would be the same if the wishbones were of equal lengths and equal angles to the chassis, but what happens if they are not? This would mean that the hub and wheel would now be traveling in an arc and not straight up/down, making the ratio of travel between top and bottom different. It is this which is ultimately confusing me!

One last question...if I were to use wishbones of equal length, mounted at different angles to each other, how would this affect the motion of the wheel?

I hope I have made sense! Any suggestions would be much appreciated!

Thanks!

Here is a link to Ranger Mike's thread:

https://www.physicsforums.com/showthread.php?t=326355

.