The wheel hub unit (wheel hub bearing) of an automobile is a key component that connects the wheels and suspension, responsible for carrying the weight of the vehicle and transmitting driving force. Its performance directly affects driving safety and comfort. The following are detailed maintenance methods, covering daily inspections, regular maintenance, and troubleshooting:
1. Precautions for daily inspection and use
Abnormal noise monitoring
Symptoms: continuous buzzing, metal friction, or intermittent clicking sounds while driving. Reason: Internal wear of the bearing, insufficient lubrication, or foreign object intrusion.
Solution: Immediately stop and check to avoid further driving that may cause complete damage to the bearings or detachment of the wheel hub.
.Temperature anomaly perception
Method: After parking, lightly touch the wheel hub with your hand (pay attention to preventing scalding). If the temperature is significantly higher than other wheels, it may be due to increased bearing friction or brake system failure.
.Attention: High temperature may be accompanied by grease deterioration, further inspection is required.
. Observation of driving stabilitySymptoms: steering wheel shaking, vehicle deviation, or body shaking during braking.
.Reason: Excessive bearing clearance, wheel hub out of roundness, or loose suspension components.
.Handling: Go to a professional repair shop for four-wheel alignment and bearing inspection.
.Avoid wading through water and muddy roads
Risk: Water and sediment can invade the bearing seal ring, accelerating the emulsification failure of lubricating grease.
.Suggestion: Drive at low speed and lightly apply the brakes after passing through flooded roads, using frictional heat to evaporate water.
.2. Regular maintenance process
1. Suggested maintenance cycle
Ordinary family cars: every 50000-80000 kilometers or 3-5 years (whichever comes first).
. High performance/heavy-duty vehicles: every 30000 to 50000 kilometers or 2-3 years. Severe working conditions (dusty, humid): shortened to 20000-30000 kilometers.2. Maintenance steps
(1) Disassembly and cleaning
Raise the vehicle and provide safe support, then remove the wheels.
. Use specialized tools to remove brake discs and calipers (to avoid pulling brake oil pipes). Clean the surface oil stains of the wheel hub unit and blow off the internal dust with compressed air (pay attention to eye protection).(2) Bearing inspection
Visual inspection: Check whether the sealing ring is damaged, cracked, or leaking oil.
.Rotation test: manually rotate the wheel hub and observe for any jamming, abnormal noise, or axial clearance (should be ≤ 0.05mm).
. Professional testing: Use a dial gauge to measure radial/axial runout. If it exceeds the standard, it needs to be replaced.(3) Lubricating grease replacement
Selection:
High temperature environment: Use lithium based composite grease (such as NLGI No. 2), with a temperature resistance range of -20 ℃~150 ℃.
.Wet environment: Choose calcium based grease or polyurea based grease for excellent waterproof performance.
.Filling amount:
Open type bearings: Fill to 1/2-2/3 of the space capacity.
. Sealed bearings: If the sealing ring is intact, there is no need to supplement it; If opened, it needs to be refilled.Method:
Use a grease gun to slowly inject from the oil injection hole, while rotating the wheel hub to evenly distribute the lubricating grease.
.Avoid overfilling that may cause the sealing ring to extrude or high-temperature grease leakage.
(4) Reinstall and debug
Install a new sealing ring (if the original is damaged), ensuring an interference fit with the outer ring of the bearing.
.Tighten the wheel hub nuts in diagonal order, and refer to the vehicle manual for torque values (such as 110-140N · m for common vehicle models). After installing the brake components, conduct a road test and recheck the bolt tightness.