NAPA - National Automotive Parts Association Certified Mechanic Suspension and Steering Questions and Answers — Questions and Answers
Question 1: A vehicle is brought in with a clunking noise from the front end, most noticeable during low-speed turns and when driving over bumps. The driver also reports that the steering feels loose. Which of the following is the MOST likely cause?
- Worn sway bar end links
- A failing power steering pump
- Worn ball joints (Correct answer)
- Incorrect tire pressure
Correct answer: Worn ball joints
Worn ball joints are a common cause of clunking or rattling noises from the front suspension, especially over bumps or during turns. The excessive play in a worn joint also leads to a loose or wandering steering feel. While sway bar links can cause noise, they typically don't affect steering feel as dramatically. A failing power steering pump would cause whining noises and stiff steering, not clunking. Incorrect tire pressure primarily affects pulling and tire wear.
Question 2: A technician is performing a wheel alignment and finds the caster angle is significantly more positive on the left front wheel than on the right. What is the MOST likely effect this will have on the vehicle's handling?
- The vehicle will pull to the right.
- The vehicle will have improved high-speed stability.
- The steering will feel lighter than usual.
- The vehicle will pull to the left. (Correct answer)
Correct answer: The vehicle will pull to the left.
Caster is the forward or rearward tilt of the steering axis. A more positive caster angle provides greater straight-line stability. When caster angles are unequal side-to-side, the vehicle will pull toward the side with the LEAST amount of positive caster. In this case, with the left side being more positive, the vehicle will pull to the right.
Question 3: Which of the following is NOT a primary component of a typical MacPherson strut assembly?
- Coil spring
- Control arm (Correct answer)
- Strut mount (bearing plate)
- Shock absorber (damper)
Correct answer: Control arm
A MacPherson strut assembly is a single unit that typically includes the shock absorber (damper), coil spring, and an upper strut mount with a bearing. The control arm is a separate suspension component that connects the bottom of the steering knuckle to the vehicle's frame or subframe.
Question 4: A customer complains of a whining or groaning noise that gets louder when turning the steering wheel, especially at low speeds. The steering also feels unusually stiff. What is the MOST probable cause of these symptoms?
- Worn outer tie rod ends
- A failing power steering pump (Correct answer)
- Low tire pressure
- Incorrect wheel alignment
Correct answer: A failing power steering pump
A whining or groaning noise during steering, combined with stiff steering effort, are classic symptoms of a failing power steering pump. This can be due to low fluid levels, air in the system, or internal wear within the pump itself. Worn tie rods cause looseness and noise but not typically whining. Low tire pressure and poor alignment cause pulling or uneven tire wear.
Question 5: In a rack and pinion steering system, what is the primary function of the inner tie rod?
- To absorb vertical impacts from the road.
- To connect the steering rack to the outer tie rod, transferring steering inputs. (Correct answer)
- To adjust the caster angle during a wheel alignment.
- To reduce body roll during cornering.
Correct answer: To connect the steering rack to the outer tie rod, transferring steering inputs.
The inner tie rod acts as a pivot and connects the movable steering rack to the outer tie rod end. When the driver turns the wheel, the rack moves side-to-side, pushing or pulling the inner tie rod, which in turn moves the outer tie rod and the steering knuckle to turn the wheels. Shock absorbers handle impacts, and caster is adjusted at the control arms or strut mounts. The sway bar controls body roll.
Question 6: A vehicle consistently pulls to the right while driving on a flat, straight road. A preliminary check shows tire pressures are correct and there are no dragging brakes. Which of the following is the most likely cause?
- A worn left-side ball joint
- A faulty power steering pressure switch
- Wheel alignment issues (Correct answer)
- A damaged CV axle
Correct answer: Wheel alignment issues
The most common cause of a vehicle consistently pulling to one side is improper wheel alignment. Angles such as camber, caster, or toe being out of specification will cause the vehicle to drift. While worn suspension parts can cause pulling, alignment is the most frequent culprit. A worn ball joint typically causes looseness or clunking, and a faulty CV axle usually creates noise or vibration, especially during turns or acceleration.
