Replacing wheel bearings
Wheel bearings are critical to the safe operation of any vehicle. These small components primarily "bear" the load of a mounted wheel/tire assembly, working to reduce friction during wheel rotation.
Wheel bearing problems
Although bearings can last 100,000 miles or more, these mechanical elements can wear out over time. When this occurs, a driver will usually notice scraping noises as the vehicle is in motion in addition to experiencing a degree of wheel "shimmy" as one or more hub/wheel/tire assemblies wobble slightly under rotation.
However, although these symptoms tend to represent bearing problems, suspension and brake issues also sound and behave similarly. So, check your vehicle before driving with existing bearing issues. Park the vehicle, simultaneously grasp the top edges of each individual tire assembly and attempt to push and pull the entire unit backward and forward. If a bearing issue exists, you will usually feel a slight movement when executing this process, further suggesting that you are on the right track. If not, then something else is probably due for expanded mechanical investigation.
While the process of replacing one or more wheel bearings represents a fairly straightforward set of steps, it is first important to understand that there are two dissimilar bearing philosophies available in today’s market. In the former case, vehicles utilize a fully integrated approach, and consequently, the bearings themselves cannot be maintained, replaced, lubricated or "re-packed" individually. In this event, the entire bearing structure must be replaced as a single unit, thereby providing for a particularly simple replacement process.
On the other hand, some vehicles still utilize a traditional approach based on the utilization of an outer bearing case, which typically houses four individual ball bearings that can be maintained accordingly. Since the latter approach offers a more expansive replacement experience, we will use this method as a task baseline.
- To begin, ensure that you park the vehicle on a flat surface, put the car in "park" (if you have an automatic transmission), or in first gear (if you have a manual transmission), and set the parking brake. This helps to limit any potential movement when lifting the wheel/tire assembly off the ground.
- To further enhance safety, use wheel chocks on all non-involved wheel/tire assemblies in order to help prevent the vehicle from moving suddenly.
- Loosen the lug nuts of the faulty wheel/tire assembly while still under suspension load. Once this process is complete, jack the car off the ground while ensuring easy access to the wheel/tire assembly. Once the assembly is clear, remove the lug nuts.
- Remove the wheel/tire assembly and set it aside.
- Remove the brake calipers (for a disc assembly) or the entire drum assembly in the latter case.
- Remove the integrated dust cover, its security cotter pin and the castle nut.
- Gently remove the disc or drum assembly.
- Unscrew each lug bolt and remove the hub from the stub axle.
- The bearing assembly is enclosed within the hub itself, so you will have to open the hub assembly in order to gain access to the bearing assembly.
- Using a hub puller, open the hub “clamshell,” allowing access to the bearing enclosure.
- Once you have access to the bearing area, use a chisel, hammer or grinder to remove and replace the bearing races and clean the knuckle.
- Remove any old grease, grime or other unwanted ferrous material using a degreaser and lots of shop rags.
- Once you believe that the hub backplane is cleaned appropriately, replace the races. Maintain the old bearings or replace the races with new bearings using a bearing packer, and then liberally apply grease to all internal components.
- Replace all previous hub and brake assemblies in reverse order.
- Finally, replace the wheel/tire assembly, and you’re ready to go.
This step-by-step list is general, showing how a typical process might work, but each vehicle is different. Therefore, research and consider your own car, and your own mechanical capabilities, before attempting this DIY task.
Rick Carlton has been writing on consumer automotive and professional motorsports topics since 1984. His writing has been featured in numerous news, magazine and online publications.