SUSPENSION DIAGNOSIS 2A-3
DIAGNOSIS
GENERAL DIAGNOSIS
Checks
Loosened Mountings
Damaged or Worn wheel Bearing
Damaged Shock Absorber
Damaged TireAction
Retightening
Replace
Replace
Replace
Abnormal Noises
Checks
Broken Stabilizer Bar
Faulty Shock AbsorberAction
Replace
Replace
Vehicle Rolling
Checks
Over Inflated Tire
Faulty Shock Absorber
Loosened wheel Nut
Bent or Broken Coil Spring
Damaged Tire
Worn BushingAction
Pressure Adjustment
Replace
Tighten as Specified
Replace
Replace
Replace
Poor Riding
Problems in the steering, the suspension, the tires, and
the wheels involve several systems. Consider all systems
when you diagnose a complaint. Some problems, such
as abnormal or excessive tire wear and scuffed tires,
may by the result of hard driving. Always road test thevehicle first. If possible, do this road test with the
customer.
Proceed with the following preliminary checks. Correct
any substandard conditions.
Checks
Incorrect Wheel Alignment
Excessive Resistance of Lower Arm Ball Joint
Insufficient Tire Pressure
Faulty Power Steering
Action
Repair
Replace
Adjust
Repair or Replace
Hard Steering
Checks
Deformed Arm Assembly
Worn Bushing
Bent or Broken Coil Spring
Difference Between L/H & R/H HeightsAction
Replace
Replace
Replace
Adjust
Vehicle Pulls to Right or Left
WHEEL ALIGNMENT 2B-5
VIBRATION DIAGNOSIS
Wheel imbalance causes most highway speed vibration
problems. A vibration can remain after dynamic
balancing because:
lA tire is out of round.
lA rim is out of round.
lA tire stiffness variation exists.
Measuring tire and wheel free runout will uncover only
part of the problem, All three causes, known as loaded
radial runout, must be checked using method of
substituting known good tire and wheel assemblies on
the problem vehicle.
Preliminary Checks
Prior to performing any work, always road test the car
and perform a careful visual inspection for:
lObvious tire and wheel runout.
lObvious drive axle runout.
lImproper tire inflation.
lIncorrect trim height.
lBent or damaged wheels.
lDebris build-up on the tire or the wheel.
lIrregular or excessive tire wear.
lImproper tire bead seating on the rim,
lImperfections in the tires, including: tread
deformations, separations, or bulges from impact
damage. Slight sidewall indentations are normal and
will not affect ride quality.
Tire Balancing
Balance is the easiest procedure to perform and should
be done first if the vibration occurs at high speeds. Do
an off-vehicle, two-plane dynamic balance first to correct
any imbalance in the tire and wheel assembly.
An on-vehicle finish balance will correct any brake drum,
rotor, or wheel cover imbalance, If balancing does not
correct the high-speed vibration, or if the vibration occurs
at low speeds, runout is the probable cause.
