Suspension and Steering Flashcards

A front tire shows excessive wear on both outer edges of the tread with the center in good condition. What is the most likely cause?

Answer: Underinflation

Underinflation lets the tread center cave in so the shoulders carry the load and wear faster.

What is the main purpose of positive caster?

Answer: To provide directional stability and steering wheel returnability

Positive caster puts the load ahead of the tire contact patch, giving straight-line stability and self-centering.

With all other angles equal, a vehicle will tend to pull toward the side with:

Answer: Less positive caster

A vehicle pulls toward the side with less positive caster and toward the side with more positive camber.

Steering axis inclination (SAI) is measured as the angle between true vertical and a line drawn through the:

Answer: Upper and lower steering pivot points

SAI is the inward tilt of the steering axis through the upper and lower pivots, viewed from the front.

The included angle is equal to:

Answer: SAI plus camber

Included angle is the sum of SAI and camber and is used to diagnose bent parts.

On a short-long arm suspension, SAI is within specification but both camber and included angle are out of specification. Which part is most likely bent?

Answer: Steering knuckle (spindle)

A correct SAI with incorrect camber and included angle points to a bent spindle.

Thrust angle is the angle between the vehicle's geometric centerline and the:

Answer: Direction the rear wheels point

Thrust angle is set by rear wheel total toe, and a nonzero value makes the vehicle 'dog track' and the steering wheel sit off-center.