Bump steer

Excessive bump steer increases tire wear and makes the vehicle more difficult to handle on rough roads.

The linearity of the bump steer curve is important and relies on the relationship of the control arms and tie rod pickup points, and the length of each part.

Other vehicles after lowering will exhibit an increase in toe change compared to stock, this results in the car feeling very "twitchy" on straight, bumpy roads, and at the same time feeling unwilling to turn requiring more driver input than normal due to an increase in roll understeer.

This results in very heavy inner tire wear on the rear wheels of a car that is heavily loaded or towing.

One reason that most trucks have live axle rear suspensions is because it completely avoids toe and camber changes with a load.

Since both wheels are connected to a single, rigid member they are incapable of having any toe angles under normal conditions.

It is possible to design a rear live axle suspension that exhibits roll oversteer but it is highly undesirable for on road use.

The linearity of the bump steer curve is important and relies on the relationship of the control arms and tie rod pickup points, and the length of each part.

If the radius arc of the tie rod is longer than stock on a front steer setup then the car will have more toe understeer.

This is because the effective length of the tie rods is affected by its static length/arc radius, its pickup points and the angle of its arc during each phase of suspension travel in relation to the control arms.