Many people, even enthusiasts, are not sure what a carrier assembly is. That’s why the experts at My Auto Store have decided to do something about it. In this article, we will explore what a carrier assembly is and how to buy one online.
Throughout this article, you will notice that most of the terms related to carrier assembly and its components are used interchangeably. This may be confusing at first, but if you are a car enthusiast, you will know that it is uncommon among mechanics and parts dealers to call parts by their formal names, especially when there is an assembly involved. That said, let’s start with the formal definition of the carrier assembly.
The carrier assembly, also known as the axle carrier assembly or simply differential carrier assembly, is the group of components that includes the differential casing, differential bearings, and differential assembly. For the reasons explained above, it is common to confuse the carrier assembly with its components. For example, for many, the two images shown below correspond to a carrier assembly.
Formally speaking, the figure on the left is more like a differential casing, while the figure on the right is more like a differential assembly. To clarify this point, let us turn to the following two figures.
As you can see, the entire group is the one that should really be called carrier assembly. But if so, why is it also called differential unit or differential carrier? Our experts at My Auto Store have decided to dedicate the next section to explain that topic.
The first thing you should know is that from a technical point of view, the differential is the group of gears that allow the wheels of the same axle to rotate at different speeds in curves, hence its name. The figure below will surely be familiar to people who have had the opportunity to see how a differential is serviced.
The function of the differential is critical since, in addition to allowing the wheels to turn at different speeds, they also make a significant reduction to the axle shaft rotational speed. This reduction is known as the differential ratio. You may be wondering what all this has to do with the carrier assembly. The answer is simple. Since the differential is the heart of the carrier assembly, the differential and the carrier assembly are basically the same part for many people. For the purposes of this article, it is in the interest of My Auto Store that you understand the difference between the two terms. This is important when buying parts for your car because you may not need a used carrier assembly; you may only need a used differential in many cases.
The advantages of opting for a used differential or a used carrier assembly will depend on how you use your car, its year, make, model, and type of drivetrain (2WD, 4WD, AWD). What we can tell you is that differential gears are subject to constant wear and tear, and therefore in some vehicles, they tend to fail with some frequency. When replacing the differential, it is recommended to change all the bearings and seals, so some people prefer to change the complete carrier assembly. Keep in mind that depending on the type of axle carrier assembly, this might be considerably more expensive, as some are more complex than others.
This section will introduce the different types of carrier assembly, which should not be confused with the types of car axles explained in our article Where To Buy Used Axles And Not Get Scammed.
As mentioned earlier, the heart of every carrier assembly is the differential. For this reason, it is a good idea to briefly mention the most common types of differentials.
It is worth mentioning that vehicles equipped with 4WD or AWD have all three types of carrier assemblies, as they need one to distribute torque between the front wheels, one to distribute torque between the rear wheels, and a central carrier assembly (or transfer case) to distribute torque between the front and rear axles.
Let’s briefly review the most relevant points so far. The carrier assembly comprises a large number of parts, the most important of which is the differential. The differential itself is a kind of “mini gearbox” with a unique fixed ratio for each application. Additionally, depending on the type and year of the car, it can be equipped with different types of differentials.
For all these reasons (and many others), before googling used carrier assembly for sale, you should know exactly what type of part your car needs.
Fortunately, the My Auto Store team has prepared a checklist to help you have all the relevant information at hand.
The good news is that you can get most of this information in your car’s owner’s manual. If this is not possible, you can also use a free VIN decoder. If you don’t have your car’s VIN number handy, you can locate it near the driver’s side windshield as a 16-digit alphanumeric code visible from the outside.
Finally, the team of experts at My Auto Store would like to repeat the warning we gave when we talked about used axles. We do not recommend changing the axle ratio (differential gear ratio) of your vehicle as this could increase fuel consumption, affect gearbox performance, and cause all sorts of unwanted problems.