Home 9 Differentials


Heavy-duty and medium-duty trucks tend to have problems with their rear differential gear—the gear that allows wheels to have different speeds of rotation. Differentials are especially important for trucks that are going through a turn, as they cause the wheels to have a different rate of speed and are part of what helps the vehicle stay on the road during a turn. There are a lot of different moving parts as well as electrical mechanisms that relate to your differentials, so there are multiple ways that this important structure of your vehicle can go wrong.


One of the key ways that you can pinpoint a problem to your rear differentials is through the noise that you’re hearing. A howling noise is a clear indication that something is going wrong, and usually indicates excessive wear on your differentials—often because the pinion-bearing preload is coming loose. There are various forms of howling that are problematic: howling at any speed and howling any time you’re travelling over a certain rate of speed. When your differentials howl all of the time, this is a good indication that you simply need an alignment, but howling over a certain rate of speed often indicates excessive wear and means that your differentials may need to be replaced.


A rumbling sound can also indicate excessive wear, this time on your carrier bearings. This sound could also be similar to a whirring noise. Rumbling sounds can also indicate wheel bearings that need to be replaced.

Banging And Clunking

Banging or clunking sounds can find they are caused by broken spider gears, worn positraction clutches or insufficient lubrication. However, pinion gears or a broken ring can cause clunking every few feet. Clunking sounds that happen only when you’re starting to move could be U-joints that are going out, transmission problems or an out of balance driveshaft.


While not a sound, vibrations that are steady and increase in accordance with the speed of the vehicle can find their cause in a driveshaft that is out of balance or worn U-joints—both of which need to be resolved quickly to save you big bills.

No matter the sounds that you’re hearing, the differentials are trying to tell you to quickly take care of the problem before it becomes much larger. If you can catch a bad part before it is completely ruined, or before it ruins other parts, then you’ll be saving yourself a great deal of money in the long run.

Truck Differentials

When you need to get your differentials or other parts of your heavy duty trucks checked out, come to J & W Mechanical Fleet Services. We will help you get your trucks back on the road quickly and efficiently—we work closely with our customers to make sure that heavy duty is done right.

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