Suspension - Diagnosis and Testing

Preliminary Inspection

1. 1
   Road test the vehicle.
   

   • If any suspension alignment or ride height concerns exist, REFER to the Symptom Chart: Suspension System.

   • Verify the customer concern by road testing on a smooth road. If any vibrations are present, REFER to the Symptom Chart: NVH.
2. 2
   Inspect the tires.
   

   • Check the tire pressures at all normal vehicle loads and on cold tires. REFER to the VC label.

   • Make sure all tire sizes match the specification. REFER to the VC label.

   • Inspect the tires for uneven wear and damage. INSTALL new tires as necessary.
3. 3
   Inspect the chassis and underbody.
   

   • Remove excessive accumulations of dirt, mud or road debris from the chassis and underbody.

   • Front or rear suspension components.

   • Suspension mount(s).

   • Improperly seated spring(s).

   • Shock absorber(s).

   • Struts.

   • Suspension bushing(s).

   • Steering system components.

   • Wheel bearing and wheel hub.
4. 4
   Check aftermarket accessories.
   

   • Check for aftermarket modifications to the steering, suspension, wheel and tire components (such as competition or heavy duty). The specifications provided in this manual do not apply to vehicles equipped with aftermarket accessories.

Symptom Chart: Suspension System

The diagnosis in this manual assumes a certain level of skill and knowledge of Ford-approved diagnostic procedures.
REFER TO: Diagnostic Methods (100-00 General Information, Description and Operation).

• If the cause of the observed or recorded condition is found, correct the cause (if possible) before proceeding to the next step.
• If the concern is not visually evident, REFER to the Symptom Chart or REFER to the NVH Symptom Chart.

Symptom Chart: NVH

The diagnosis in this manual assumes a certain level of skill and knowledge of Ford-approved diagnostic procedures.
REFER TO: Diagnostic Methods (100-00 General Information, Description and Operation).

Noise, Vibration and Harshness (NVH) symptoms should be diagnosed using the available diagnostic tools. For a list of these tools, see the explanation of their use and the glossary of common terms, Glossary of Terms.
REFER TO: Noise, Vibration and Harshness (NVH) (100-04 Noise, Vibration and Harshness, Description and Operation).
Since any one of several systems may be the cause of the symptom, it may be necessary to use a process of elimination diagnostic approach to identify the responsible system. If it is not the causing system of the symptom, REFER TO: Noise, Vibration and Harshness (NVH) (100-04 Noise, Vibration and Harshness, Diagnosis and Testing).
for the next probable system and continue diagnosis.

Pinpoint Tests

Vehicle Pulls, Drift

Diagnostic Overview

The diagnosis in this manual assumes a certain level of skill and knowledge of Ford-approved diagnostic procedures.
REFER TO: Diagnostic Methods (100-00 General Information, Description and Operation).

Possible Causes

• Unevenly loaded vehicle
• Tire Pressure
• Tire forces
• Brake drag
• Incorrect vehicle alignment
• Bent/damaged vehicle components
• Steering

Component Tests

Ball Joint Inspection

1. 1
   Before checking the ball joints for wear, check the wheel bearings. If necessary, install a new wheel bearing.
   REFER TO: Front Wheel Bearing and Wheel Hub (204-01 Front Suspension, Removal and Installation).
2. 2
   Raise and support the vehicle by the frame so the wheels hang in their natural position.
   REFER TO: Lifting and Jacking - Overview (100-02 Jacking and Lifting, Description and Operation).
3. 3
   Inspect the ball joint and ball joint dust boot for damage.
   

   • If the ball joint or ball joint dust boot is damaged, install a new lower control arm as necessary.
     REFER TO: Lower Control Arm (204-01 Front Suspension, Removal and Installation).
4. 4

   NOTICE: Do not use any tools or equipment to move the wheel and tire assembly or suspension components when checking for relative movement. Suspension damage may occur. Using tools or equipment will also create relative movement that may not be present when hand force is used. Relative movement must be measured using hand force only.

   Inspect the ball joint for relative movement by alternately pulling down and pushing up on the lower control arm by hand. Note any relative vertical movement between the steering knuckle and the lower control arm at the lower ball joint.
   

   • If no relative movement is felt or seen, the ball joint is good. Do not install a new lower control arm.

   • If relative movement is detected, go to step 5.
5. 5
   To measure ball joint deflection, attach a suitable dial indicator with a flexible lever between the lower control arm and the steering knuckle or ball joint stud.

6. Measure the ball joint deflection while an assistant manually pushes the lower control arm up and down.
   
   • If the deflection exceeds the specification, install a new lower control arm.
     Refer to: Lower Control Arm (204-01 Front Suspension, Removal and Installation).
   • If the measurement is within specification, no further action is required.