What's That Noise? Understanding Differential Noise and What You Should Do

Posted on: 19 October 2016

Your car's differential is a very complicated piece of equipment. Its job is to convert the power as provided by the engine in order to turn the wheels of the car and initiate motion. Accordingly, it has many complex parts which will wear over time. If you have a rear wheel drive car and hear some strange noises emanating from the back of your car, what could these be?

How Does a Differential Work?

It pays to have a reasonable understanding of how a differential works. The engine delivers power through internal combustion to drive the crankshaft which in turn is connected to the main drive shaft. This turning driveshaft has to deliver the power effectively to the driven wheels, but it is turning at a different frequency and at right angles to your car's rear axle. It also has to deal with the fact that the inside wheel of the car will be turning at different speeds to the outside wheel as the vehicle goes around a corner.

Your rear differential has a number of different gears to help it achieve these tasks, each of which has teeth which are locked into other gears. The differential is intended to function according to the angle and orientation of the gears in relation to each other.

What Causes Problems?

One of the most common issues is low levels of lubrication in and around these gears. Sometimes these gears can jump out of place, which can also give rise to issues and noises.


If the sound you can hear coming from the back of your vehicle is a howling noise, this indicates that the components in your differential are wearing. If the noise only appears when you are slowing down, it's likely that the pinion bearing preload component is loose. If the howling only appears when you are accelerating, this may indicate that the gears are out of alignment or are beginning to wear out.


If you notice rumbling noises, this could be the result of carrier bearings that are worn. If these noises are intermittent or come at varying speeds, then it's likely that the pinion bearings are the culprit.

If you notice your rumbling noise while you are slowly turning the car, this is a sure sign that the wheel bearings are on the way out. If in this situation you notice banging or clunking noises, this could indicate broken spider gears or a worn limited slip clutch.


If you notice a clunking noise on a regular basis, this could be a broken pinion gear or a ring gear that's damaged.

What Should You Do?

Armed with this type of information, you should be able to go in for diff repairs and tell your mechanic what you believe the problem may be according to the location and type of noise that you're hearing, which should give him or her a head start in fixing the problem.