There are several different configurations of Wheel Bearings used in light vehicles, trucks, 4WD’s and trailers depending on what type of application is required.
There are primarily two styles of wheel bearings commonly used:
Ball bearings
The most common type of wheel bearings used in vehicles consists of small metal balls that rotate between two smooth rings or races. Ball bearings are known for their efficiency and ability to handle both radial and axial loads.
Tapered roller bearings
Designed to handle heavier loads and provide better resistance to shock and impact compared to ball bearings. They consist of tapered rollers held in place by a cage between two outer races.
Additionally, within these two broad categories, there are variations and specific designs depending on the vehicle’s requirements and design considerations. Some vehicles may also use specialised bearings, such as double-row ball bearings or sealed bearings, to enhance durability and performance in specific conditions.
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It’s worth noting that modern vehicles often use sealed bearings, which integrate the bearing and hub into a single unit. This design reduces maintenance requirements and simplifies replacement but may necessitate replacing the entire hub assembly if the bearing fails. When used in the area or attached to an axle, for example, attached to a rear-wheel-drive axle, some bearings can be replaced and purchased in a kit form, but some late vehicles can require a complete axle replacement.
It is critical in checking, maintaining and servicing wheel bearings especially a Tapered wheel Bearing at the correct intervals. This can vary, depending on the type of driving conditions experienced.
Maintaining wheel bearings on Light vehicles, Trucks, 4WD drives and Trailers is crucial for several reasons. Proper maintenance of wheel bearings enhances vehicle performance, safety, and longevity.
Key benefits
Enhanced safety:
- Preventing wheel detachment: well-maintained bearings prevent the risk of wheel detachment, which can be catastrophic at high speeds or during heavy loads especially on trailers. If disc brakes are fitted and if the wheel bearing hub is running out of line because of a wheel bearing collapsing it will push the brake caliper piston away from the brake disc causing an excessive downward movement of the brake pedal when the brakes are applied causing extended braking time for the vehicle to stop. The brake pedal may need to be pumped to stop the vehicle completely as this could cause a serious accident if you’re not stopping in time or at all.
- Stable handling: properly functioning bearings ensure stable and predictable handling of the vehicle, especially during cornering and off-road driving.
Improved vehicle performance:
- Smooth ride: well-lubricated and correctly adjusted bearings reduce friction, leading to a smoother and quieter ride.
- Efficient operation: properly maintained bearings minimize rolling resistance, which can improve fuel efficiency and overall vehicle performance.
Extended component life:
- Preventing premature wear: regular maintenance helps avoid excessive wear and tear on wheel bearings, which can otherwise lead to costly repairs or replacements.
- Protecting other parts: by ensuring bearings are in good condition, you also protect associated components such as the wheel hub, suspension, and drivetrain.
Cost savings:
- Avoiding expensive repairs: regular maintenance helps catch issues early before they lead to more expensive repairs or replacements.
- Reducing downtime: keeping bearings in good shape minimizes unexpected breakdowns and downtime, which can be particularly important for commercial vehicles.
Optimal load handling:
- Handling heavy loads: for trucks especially trailers and 4WD vehicles, which often carry heavy loads or tackle rough terrains, well-maintained bearings are crucial for handling and distributing loads effectively.
Enhanced off-road capability:
- Durability in harsh conditions: off-road vehicles benefit from properly maintained bearings as they endure more challenging conditions, including dirt, mud, and water. Regular maintenance ensures that the bearings continue to perform well under these stresses.
Prevention of alignment issues:
- Maintaining wheel alignment: good wheel bearings help maintain proper wheel alignment, which is important for even tire wear and overall vehicle stability.
Reduced noise:
- Quieter operation: Worn or damaged bearings can create noise that indicates an issue. Regular maintenance helps keep the vehicle operating quietly.
Maintaining wheel bearings is essential for vehicle safety, performance, and cost-efficiency. Regular inspections and timely replacements or adjustments help ensure that your truck/trailers or 4WD continues to operate smoothly and reliably.
The right fit
Fitting and servicing wheel bearings involves a series of precise steps to ensure that the bearings are installed correctly and function optimally. Here is a detailed procedure for fitting and servicing wheel bearings:
Preparation:
- Tools and equipment: gather necessary tools such as a jack, jack stands, wheel wrench, socket set, bearing puller, press, and new bearings. You may also need bearing grease, a torque wrench, and a dial indicator for measuring runout.
- Safety: ensure the vehicle is on a stable surface and engage the parking brake. Use wheel chocks to prevent the vehicle from rolling.
Remove the wheel:
- Loosen the wheel nuts slightly while the vehicle is still on the ground.
- Lift the vehicle using a jack and secure it with jack stands.
- Remove the wheel and set it aside.
Remove the brake components:
- Caliper: unbolt and remove the brake caliper. Support it with a hanger or a piece of wire to avoid stress on the brake line.
- Brake rotor: remove the brake rotor. If it’s stuck, tap it gently with a rubber mallet to free it.
Remove the hub assembly:
- Outer nut/cap: remove any dust cap or nut covering the hub assembly.
- Locking nut: if present, remove the locking nut (it could be a castle nut with a cotter pin or in a front hub in a 4WD can have a flat plate with a serious of holes which contain two or three tapered screws attaching it to the stud hub spindle stopping it from turning).
- Hub: remove the hub assembly. This might require a hub puller if it’s tightly fitted.
Remove the old tapered bearings:
- Outer bearing: remove the outer bearing from the hub assembly.
- Inner bearing: remove the inner bearing, usually requiring a bearing puller or similar tool.
Clean and inspect components:
- Clean: thoroughly clean the hub assembly, spindle, and all related components. Remove any old grease and debris.
- Inspect: check for any damage or excessive wear on the hub assembly, spindle, and other related parts. Replace any damaged components.
Install New Bearings if it is a ball race to Hub assembly mentioned in the two dot points below, normally the ball race comes pre-greased.
- Pressing bearings: using a press, carefully press the new bearings into the hub assembly. Make sure to follow the manufacturer’s specifications regarding the installation depth and orientation.
- Bearing race: ensure that the bearing races are properly seated in the hub. You may need a bearing race driver or appropriate tool for this.
Either fitting new or reusing the old Tapered Roller Bearings. Regreasing of the bearings needs to be performed as described or click on any of the internet addresses listed below.
Properly applying the correct type of grease to a tapered wheel bearing is crucial for its longevity and performance. Here’s a step-by-step guide on how to do it:
Clean your hands: thoroughly clean your hands or wear a new pair of latex gloves.
Grease placement: place a golf-ball sized amount of grease, (which requires to be the correct type of grease) into your palm.
Apply grease: using your opposite hand, push the large end of the bearing cone assembly into the grease. This forces grease between the rollers, cage, and cone.
Remember, proper lubrication significantly increases bearing life, especially in adverse conditions. So, follow these steps diligently to ensure optimal performance. For more detailed instructions, you can refer to below sites:
- blog.slsbearings.com
- timken.com
- forconstructionpros.com
Rotate Assembly: while pushing grease into the large end, rotate the entire cone assembly until the grease is evenly distributed around the small end.
Reassemble the hub: place the re-greased inner tapered bearing and dust seal into the Hub.
Reinstall the hub: the inner bearing & seal has already been installed in the hub. Install the hub assembly onto the spindle and ensure they are properly seated.
Install the outer bearing: place the outer bearing on the spindle.
Torque the nut or flat plate:
- Preload the bearings: tighten the spindle nut or the flat plate to seat the bearings properly. This is often done in two steps:
- Initial torque: tighten the nut or flat plate to a specific initial torque value to seat the bearings.
- This value is typically around 15-25 ft-lbs (20-34 Nm) for many vehicles, but you should refer to the specific vehicle’s service manual for the exact specification.
Adjust the preload:
- Back off and re-tighten:
– Back off: after the initial torque, back off (loosen) the nut by approximately 1/4 to 1/2 turn. This step is crucial to avoid overloading the bearings.
– Re-tighten: re-torque the nut or flat plate to a lower, specified preload setting. This is often around 10-15 ft-lbs (14-20 Nm) but varies by vehicle. - Final Assembly:
– Locking mechanism: if the vehicle has a locking mechanism, such as a cotter pin or locking washer with three tapered screws, install it to prevent the spindle nut from loosening.
– Reinstall dust cap: place the dust cap over the spindle nut to protect the bearing from contaminants. - Reinstall the brake components:
– Brake rotor: reinstall the brake rotor. Make sure it sits flush against the hub.
– Caliper: reattach the brake caliper and secure it with bolts. Ensure the caliper is correctly aligned with the rotor. - Check and test then reinstall the wheel:
– Place the wheel back onto the hub.
– Hand-tighten the wheel nuts initially.
– Manually spin the wheel to ensure it rotates smoothly and quietly.
– Lower the vehicle from the jack stands and do a final tightening of the wheel nuts to the manufacturer’s torque specifications using a torque wrench.
– If applicable, check the wheel alignment or have it checked by a professional.
– Conduct a test drive to ensure that everything functions correctly and listen for any unusual noises.
Important tips
- Manufacturer’s specifications: always follow the vehicle manufacturer’s specifications and recommendations for torque settings and installation procedures.
- Use quality parts: use high-quality bearings and components to ensure longevity and reliability.
- Use proper tools: use a calibrated torque wrench and a dial indicator for accurate measurements.
By following the above steps, you can ensure that your wheel bearings are fitted and serviced correctly, contributing to the safe and efficient operation of your vehicle.
It has been alleged that there have been at times where trucks are catching fire on the side of major highways, because of major failure with wheel bearings subjected to lack of maintenance.
It has been noted where there has been a real concern about trucks catching fire due to wheel bearings failing, though such incidents are relatively rare compared to other causes of vehicle fires. Here’s how a failing wheel bearing can potentially lead to a fire:
Heat generation and friction:
- Excessive heat: when a wheel bearing begins to fail, it can generate excessive heat due to increased friction. This friction heat can be significant, especially if the bearing is severely worn or damaged.
- Grease degradation: wheel bearings are typically lubricated with grease. As a bearing fails and generates more heat, the grease can break down, potentially leading to a loss of lubrication and further increasing friction and heat.
Fire hazard mechanisms:
- Combustion of grease: if the temperature of the wheel bearing and surrounding components becomes high enough, it could cause the bearing grease to ignite. Although wheel bearing grease is generally formulated to withstand high temperatures, prolonged overheating can lead to the grease becoming flammable.
- Contact with flammable materials: in some cases, if the vehicle is carrying flammable materials or debris accumulates near the wheel area, the risk of a fire increases if there’s sufficient heat generated by a failing bearing.
Heat transfer to other components:
- Heat transfer: excessive heat from a failed bearing can transfer to other nearby components, such as brake lines, tires, and even fuel lines in extreme cases. This can potentially lead to fires if the heat reaches flammable materials or components.
Signs of failing wheel bearings:
- Unusual noises: grinding or squealing noises can indicate a failing bearing.
- Vibration: excessive vibration in the wheel or steering wheel can be a sign of bearing problems.
- Heat: overheating of the wheel hub area can indicate issues with the bearing.
Prevention and maintenance:
- Regular inspections: regularly inspect and maintain wheel bearings as part of routine vehicle maintenance. This includes checking for signs of wear, proper lubrication, and replacing bearings as needed.
- Proper installation: ensure that wheel bearings are installed correctly and to the manufacturer’s specifications to avoid premature failure.
- Immediate attention to symptoms: address any symptoms of bearing failure immediately to prevent further damage and reduce the risk of overheating or fire.
While it is not common, the failure of wheel bearings can potentially contribute to a fire hazard due to excessive heat and friction.
Proper maintenance is the key to everything and timely inspection and or replacement of wheel bearings are essential to minimising this risk and ensuring vehicle safety.
If you suspect issues with your wheel bearings, it’s important to have them inspected and repaired by a professional to prevent potential hazards.
Please be advised that the information provided in this article is only a guideline and you should always seek expert advice and have ensure all work is carried out by a licensed professional