The replacement of car wheel hub units must follow rigorous steps, covering five major stages: preparation, disassembly, installation, inspection, and testing. The specific operation is as follows:
1. Preparation stage
Tool and accessory preparation
Core tools: jack (load capacity needs to match vehicle weight), socket wrench, torque wrench, rubber hammer, cleaner, anti slip plug, warning triangle, gloves, goggles.
Key accessories: wheel hub units suitable for vehicle models, wheel hub nuts/bolts, variable diameter rings (if required), rust proof lubricants.
.Safety measures: Park the vehicle on a flat and hard surface, pull up the handbrake, place warning signs, and operate in a cold state (to avoid high-temperature deformation of the wheel hub).
. Specification verificationConfirm that the dimensions (diameter/width), PCD value (bolt hole pitch diameter), center hole diameter, and offset (ET value) of the new wheel hub unit are strictly matched with the vehicle to prevent interference or shaking.
.2. Disassemble the old wheel hub unit
Pre loosen the nut
Use a socket wrench to slightly loosen the tire nut in diagonal order (when not driving) to avoid deformation of the wheel hub caused by unilateral force.
.Lift the vehicle
Align the jack with the chassis support point and slowly lift the vehicle until the tires are 2-3cm off the ground to ensure stability.
.Completely disassemble
Completely unscrew the nut and remove the old tire.
. If the hub is tightly connected to the axle, lightly tap the edge of the hub with a rubber hammer to loosen it and avoid damaging the axle head.Clean the shaft head
Remove rust and dirt from the shaft head, check if the shaft head is worn or deformed, and repair or replace it if necessary.
.3. Install new wheel hub unit
Pre treat new wheel hub
Check that the new wheel hub has no cracks or burrs, apply anti rust lubricant to the installation surface, and ensure that there are no impurities.
. Preliminary positioningAlign the new wheel hub with the shaft head, gently push it to fit, and manually tighten the nuts in diagonal order to ensure that the wheel hub and shaft head are initially fixed.
. Precise tighteningUse a torque wrench to tighten nuts in stages:
First tightening: Tighten diagonally to 50% of the standard torque (e.g. recommended 120N · m for M12 nuts on fuel vehicles, first tightening to 60N · m).
.Second tightening: Tighten again in diagonal order to 80% of the standard torque.
. Final tightening: Tighten diagonally to the standard torque value to ensure even force distribution. Attention to new energy vehicles: Due to the increase in battery weight, the nut torque needs to be appropriately increased (such as the recommended 160N · m for M14 nuts). Lower the vehicle for re inspectionRemove the jack and anti slip plug, and check the tightening status of the nut again to ensure that there is no looseness.
.4. After installation inspection
Appearance and functional inspection
Confirm that the wheel hub is not deformed or cracked, the nuts are tightened properly, and the tire pressure is normal.
.Check that there is no interference between the wheel hub, shock absorber, and caliper to ensure flexible rotation.
.Dynamic Balance Test
After installing the tires, adjust the dynamic balance by attaching balance weights (one on each side) to eliminate the risk of high-speed shaking.
.Fifth, Test Drive Verification
Low speed Test Drive
Start the vehicle and drive it at a low speed of 20-30km/h to check for any abnormal shaking, noise, or directional deviation.
.High speed re inspection
Gradually accelerate to 80-100km/h, confirm that the wheel hub unit runs smoothly without heating or abnormal noise.
.Key precautions
Operating taboos
It is strictly prohibited to use inferior wheels or mismatched specifications to avoid insufficient load-bearing capacity leading to fracture.
.The tightening nuts must be carried out in stages in diagonal order to prevent deformation of the wheel hub.
.A torque wrench must be used to avoid being too loose (prone to detachment) or too tight (damaging threads).
. Installing the shaft head without cleaning it directly can result in a loose fit and cause shaking. Neglecting the dynamic balance test may lead to high-speed loss of control. Professional adviceIf the wheel hub is deformed for repair, dynamic balance testing, or complex fault handling, it is recommended to entrust it to a professional repair shop for operation.
. Regularly clean the wheel hub (to avoid salt and sediment corrosion) and check the tightening status of the nuts to extend their service life.