Suspension and Steering Flashcards

What is the primary purpose of positive caster on a front suspension?

Answer: Directional stability and steering wheel returnability

Positive caster places the tire contact patch behind the steering axis, which keeps the vehicle tracking straight and helps the steering wheel return to center.

A vehicle pulls to the left, and the alignment readings show caster is uneven side to side. Which condition would cause this pull?

Answer: Less positive caster on the left wheel

A vehicle tends to pull toward the side with the least positive caster.

Feathered wear across the tread face of both front tires is most commonly caused by which alignment problem?

Answer: Incorrect toe setting

Too much toe-in or toe-out scrubs the tire sideways and leaves a feathered, saw-tooth wear pattern across the tread.

Which alignment angle normally cannot be adjusted and is mainly used to diagnose bent suspension parts?

Answer: Steering axis inclination (SAI)

SAI is set by the suspension's design, so an out-of-spec reading points to bent parts such as a strut, spindle, or control arm.

The included angle of a front wheel is equal to:

Answer: SAI plus camber

The included angle is the sum of steering axis inclination and camber, and comparing it side to side helps find a bent spindle or strut.

During a four-wheel alignment on a vehicle with adjustable rear toe, which should be set first?

Answer: Rear toe, to establish the thrust line

Rear toe sets the thrust line, and the front wheels are then aligned to that thrust line.

A turning radius (toe-out on turns) reading is out of specification on one side only. What is the most likely cause?

Answer: A bent steering arm

The geometry of the steering arm controls toe-out on turns, so a bent steering arm throws off the reading on that side.