Suspension Fundamentals
What is the main purpose of a vehicle’s suspension system?
To connect the frame to the wheels, support weight, and absorb road shock.
What is the primary function of springs in a suspension system?
To support the vehicle and absorb road shock.
What component connects opposite sides of the suspension to reduce body roll?
Stabilizer (sway/anti-roll) bar
What two main types of steering gears are commonly used?
Recirculating ball and rack & pinion.
What is the first step when diagnosing a suspension problem?
Verify the customer’s concern with a road test.
What are two types of weight classified in a suspension system?
Sprung and un-sprung weight
What unit is spring rate typically measured in?
Pounds per inch (lb/in) or kg/mm.
What is the purpose of a control arm?
A control arm maintains the correct wheel position and alignment as the suspension moves, ensuring stable handling and a smooth ride.
What is the function of tie rod assemblies?
Transmit steering motion while allowing suspension movement.
During a steering inspection, what is a dry park check, and what is it used to detect?
It’s used to feel and observe for looseness in steering linkage components such as tie rod ends, idler arms, and pitman arms.
What effect does torque at the drive wheels have during acceleration?
Squat at the rear suspension.
What is the main difference between fixed-rate and variable-rate coil springs?
Variable-rate springs stiffen under heavier loads; fixed-rate remain constant.
What is a torsilastic bushing, and what is its purpose?
An elastomer bushing, bonded to metal sleeves that absorbs vibration.
What tool is used to safely remove a ball joint from its tapered stud?
Ball joint separator (pickle fork or puller).
What is the bounce test, and what does it tell you about a vehicle’s suspension condition?
The bounce test is performed by pressing down firmly on the vehicle’s front or rear bumper and releasing it to observe how the body moves.
A properly functioning suspension should recover within one and a half oscillations.
If the vehicle continues to bounce, the shock absorbers or struts are weak or worn, allowing excessive spring oscillation.
What component connects the vehicle’s frame to the wheels while allowing vertical movement over bumps?
Suspension linkages and control arms.
What is the purpose of shock absorbers in a suspension system?
To control spring oscillations and prevent excessive bouncing.
What is the difference between a guiding ball joint and a load-carrying ball joint?
Guiding pivots only; Load-carrying supports vehicle weight.
What two components support the centre link and keep it level?
Pitman arm and idler arm.
Why must torsion bars, coil springs, or struts be handled with extreme caution during removal and replacement, and what is the correct safety procedure?
Because suspension springs store a large amount of energy, releasing them improperly can cause serious injury or death.
The correct procedure is to use manufacturer-approved spring compressors or unloading tools to safely control spring tension before removing any fasteners.
Explain the difference between sprung and un-sprung weight.
Sprung = supported by springs; Un-sprung = not supported (wheels, brakes)
Why must torsilastic bushings be torqued at ride height?
They must be torqued at ride height so the bushing sits in its neutral, untwisted position
Why must torsilastic bushings be torqued at ride height?
They must be torqued at ride height so the bushing sits in its neutral, untwisted position
What is bump steer, and what conditions in the steering or suspension system commonly cause it?
Bump steer occurs when a vehicle veers to one side as it travels over bumps or dips because the toe angle changes unevenly between the left and right wheels
What are two adjustments made when servicing a recirculating ball steering gear?
Thrust bearing preload and high-spot adjustment.