Inspection and Verification

Front Drive Axle

Special Tool(s):

Inspection and Verification
The technician should have a thorough knowledge of driveline system operation and accepted general driveline guidelines to detect any problems.

A gear driven unit will produce a certain amount of noise. Some noise is acceptable and audible at certain speeds or under various driving conditions.

Certain conditions, such as road conditions and weather, will amplify normal vehicle noise.

Certain axle and driveline concern symptoms are also common to the engine, transmission, wheel bearings and tire. For this reason, be sure the cause of the concern is in the axle before repairing or installing any axle components.

The following is a guide to diagnose a driveline concern:
^ Verify and document the customer concern.
^ Perform a preliminary investigation.
^ Road test the vehicle.
^ Find the cause of the problem.
^ Inspect the components.

1. Verify and document the customer concern.
1 When was it first noticed?
2 Did it appear suddenly or gradually?
3 Did anything unusual occur that would coincide with it or precede it?
4 Has the driveline system been repaired before or new components installed?
^ Check the vehicle service record. Note any repairs other than driveline, such as brakes or suspension.

5 Are there any special conditions affecting the concern or will alter the concern? For example:
^ Road speed
^ Type of road
^ Drive mode
^ Temperature
^ Vehicle loaded or unloaded

6 Is the condition constant or intermittent?
Can the concern be duplicated at any time?
7 Check for TSBs, and SSM.

2. NOTE: If the inspection reveals an obvious concern, repair the vehicle.

Do a preliminary investigation. Visually inspect for obvious signs of damage.
1 Inspect the driveshaft:
^ for build up of any foreign material.
^ for damage, such as a bent tube or missing weights.
^ U-joints, CV joints or flex couplers for wear or damage.

2 Inspect the axle:
^ for signs of leakage at the drain or fill plug, differential seal, vent or halfshaft seals.
- a plugged vent or vent tube will cause a leak.
- for damage, such as cracks, bent halfshafts or dented cover.
^ for missing fasteners.

3 Inspect other suspect components/systems:
^ inspect the suspension for broken springs, damaged shock absorbers and worn suspension bushings.
^ inspect the brake components - lines, cables and calipers.
^ inspect the tires; are they in good condition and do they match?

3. NOTE: A road test is necessary for any customer concern of noise or vibration.

Road test the vehicle.
1 During the road test, use the following driving methods to diagnose the problem. Is the concern most noticeable:
^ from a stop?
^ on shifts from REVERSE to DRIVE?
^ on turns?
- sweeping type turn.
- tight turn (to the stop).
^ in DRIVE?
- accelerating the vehicle, definite throttle depression, applying engine torque.
^ in CRUISE?
- maintain a constant speed with the throttle applied.
^ in COAST?
- decelerating with the throttle closed.

2 Record when the concern occurs. Write down the kph (mph) range at which the noise/vibration occurs.
4. Find the cause of the problem.
1 Compare the inspection and road test results with the following chart.
2 Use the following diagnostic routine chart to identify the probable cause and know what corrective actions should be taken to repair the component/vehicle and to prevent a reoccurrence.

Diagnostic Routine Chart (part 1):

Diagnostic Routine Chart (part 2):

5. NOTE: If the conclusion of the road test points to an axle assembly section (ring and pinion or differential case) concern, carry out a visual inspection of the axle.

Inspect the axle components.
1 Remove the differential housing cover. Drain the axle lubricant through a white cloth. Check the fluid for:
^ any foreign material.
^ metal particles.
^ burnt odor.

2 NOTE: When inspecting the axle, do not clean the components immediately. Cleaning may remove diagnostic evidence.

Inspect the axle components.
^ Look for:
- loose fasteners.
- notches or visible steps or grooves created by wear.
- pitting or cracking along gear contact lines.
- scuffing or deformations.
- discolorations.
- nicks or ridges on gear teeth.
^ Clean the axle components for inspection.
- Remove as much lubricant as possible with clean solvent. Wipe the components or blow them dry with compressed air.
^ Re-inspect for:
- loose fasteners.
- notches or visible steps or grooves created by wear.
- pitting or cracking along gear contact lines.
- scuffing or deformations.
- discolorations.
- nicks or ridges on gear teeth.
^ Check backlash and carry out a ring and pinion pattern test. Front Drive Axle/Differential