Wesley PC-325-6SA - Manual (Page 39)

39 Owner’s Manual and Service Guide – PMT Series
TRANSAXLE TROUBLESHOOTING
PROBLEM DIAGNOSIS
Most drive axle problems fall into the categories of noise, vibration, leaks and failure to transmit power.
Problem diagnosis normally begins with the customer’s complaint, which should include an exact description of the type of
noise or vibration and when it occurs. This is followed up by a road test over various types of road surfaces through the speeds
where the complaint occurs.
It should be remembered that some sounds will appear to come from locations other than the real source of the problem.
Sounds in the drive shaft, exhaust system, and body floor pan can do this, making it more difficult to locate the problem source.
Condition Probable Cause
Noise in all driving modes Road and tires, wheel bearings
Noise changes with type of road surface Road and tires
Noise tone towers with car speed Tires
Noise louder on turns Differential pinion and side gears, axle wheel bearings
Noise in one or more driving modes Ring and pinion gears
Clunk on change of speed or direction of power flow Worn differential shaft or thrust washers; worn U-joints
Wheel noise Wheel loose; faulty or bad wheel bearing
Vibration Damaged drive shaft, missing drive shaft balance weight,
worn or out-of-balance wheels, loose wheel lug nuts,
worn U-joints, loose spring U-bolts, loose/broken spring,
damaged axle shaft bearings, loose pinion gear nut,
excessive pinion yoke run-out, bent axle shaft
Differential gears scored Insufficient lubrication, improper grade of lubricant,
lubricant contamination, excessive spinning of wheels
Loss of lubricant Lubricant level too high, worn axle shaft seals, cracked
differential housing, worn drive pinion gear shaft seal,
scored and worn yoke, axle cover not properly sealed,
plugged vent or vent tube.
Axle overheating Lubricant level to low, incorrect grade of lubricant,
contaminated lubricant, bearing preload too high,
excessive gear wear, insufficient ring gear backlash
Gear teeth broke Overloading, erratic clutch operation, wheel spinning,
improper adjustment
Axle gear noise Insufficient lubricant, incorrect backlash, improper tooth
contact, worn/damaged gears
Axle noise Insufficient lubricant, improper ring gear and drive pinion
gear adjustment, unmatched ring gear and drive pinion
gear, worn teeth on ring gear or drive pinion gear, loose
drive pinion gear shaft bearings, loose differential
bearings, misalign ring and pinion gear, loose differential
bearing crap-screws, worn bearings
Limited slip differential The most common problem is a “chatter” noise when
turning corners. The probable cause is incorrect or
contaminated lubricant, or lack of “friction modifier”
additive in the lubricant. Worn or damaged plates and
discs; plates and discs improperly assembled.