How to Diagnose Differential & Driveline Noises

Slide Show

We don’t know which sounds worse—car guys singing show tunes in the shower or a howling differential. While there is no help for our singing, we can help you diagnose the sounds coming from a differential gone bad.

A clunk, whine, or howl can signal a worn-out pinion gear, bad bearings, or a faulty gear installation. Sometimes, the noise is not differential-related, but is caused by other driveline or axle components. This guide will help you match up the noise you’re hearing with the differential or axle component making it, or at least get you in the ballpark.

We also have a couple of good tutorials on setting up rear axle gears: Pumpkin Stuffin' (Ford 9 inch) and Nothing Beats a Strong Rear-End (Ford 8.8). But watch out—you just might learn something.

Noise: Howl while decelerating (gears previously quiet)
Cause: Loose pinion bearing preload

Noise: Howl with whir or rumble while accelerating at any speed (gears previously quiet)
Cause:  Worn rear pinion bearing or worn gear set

Noise: Howl without whir or rumble while accelerating at any speed (gears previously quiet)
Cause:  Worn gear set due to lack of lubrication or overloading

Noise: Howling while accelerating over a small speed range (gears previously quiet)
Cause: Worn gear set due to lack of lubrication or overloading

Noise: Howling after gear set installation
Cause:  Faulty gears or improper installation

Noise:  Low-pitch rumble at all speeds over 20 miles per hour
Cause: Worn carrier bearings

Noise: Whirring during acceleration/deceleration at about 10 miles per hour
Cause: Worn pinion bearings

Noise: Banging or clunking while making a turn, backing up, or rapid deceleration (like on a freeway off-ramp). Noise gets worse in warmer weather
Cause: Posi chatter due to improper lubrication; worn clutches or spider gears; improper assembly

Noise: Banging, crunching, or popping while making a turn. Noise not affected by temperature
Cause: Badly worn or broken spider gears

Noise:  Banging or heavy clicking every 2-3 feet during acceleration and deceleration
Cause:  Damaged or broken pinion gear tooth or teeth

Noise: Banging or heavy clicking every 2-3 feet during acceleration or deceleration, but not both
Cause:  High spot or heavy chip on pinion gear tooth

Noise: Banging or heavy clicking every 8 feet during acceleration and deceleration
Cause:  Damaged or broken ring gear tooth or teeth

Noise: Banging or heavy clicking every 8 feet during acceleration or deceleration, but not both
Cause: High spot or heavy chip on ring gear tooth

Noise:  Clicking while decelerating from 20 miles per hour to a complete stop
Cause:Worn carrier case-side gear bores

Noise:  Rumble or clicking that gets worse during hard turns
Cause: Bad wheel bearings

Noise: Driveline squeaking or grinding at any speed
Cause:  Worn or damaged U-joints

Noise:Clunking when depressing the throttle pedal (takeoff)
Cause: Worn U-joints; worn spider gears; worn axle splines; excessive gear backlash; loose yoke splines; worn slip yoke splines

Noise: Clunk immediately after taking off from a stop
Cause: Worn slip yoke splines

Noise: Steady vibration that increases with speed
Cause: Worn U-joint or out-of-balance driveshaft

Noise:  Cyclic vibration that varies in intensity. Intensity increases at a specific speed range, worsens during deceleration
Cause: Pinion angle too low (not parallel with front yoke on driveshaft)

Tools!
If you are inclined to set up your own rear axle gears, take a look at our list of handy tools that will make the job easier—and less likely to turn into a case of the rear axle howls.