Bumpsteer is the change in toe angle of the tyre during suspension articulation (such as roll or pitch).
This is an important change, which affects the steering feel.
The MX8 uses assymetrical ball joints and shims to adjust the angle of the steering links. This change affects the bumpsteer. Always remember to check your static toe angle when adjusting bumpsteer.
Invisible Speed RC video explaining bumpsteer:
https://www.youtube.com/watch?v=xOEL4bdjI2M
The height of the inner steering pivot in relation to the Ackermann plate can be adjusted by adding or removing shims (red shim shown), or by flipping the ball which in the photo would lower the steering link further.
The same methods can be used on the outboard end on the steering plates.
The MX8 standard setup suggests no shims, with the balls in the orientation shown in the image above.