The first generation of automotive wheel hub bearings was a widely used structure in early automobiles, typically consisting of double row tapered roller bearings that required independent installation of bearing inner and outer rings and rolling elements, as well as sealing and lubrication systems. Here are the detailed installation methods and key precautions:
1. Preparation before installation
Tools and materials preparation Special tools: bearing puller, hydraulic press, torque wrench, depth gauge, micrometer, dial gauge, magnetic gauge holder.
.Auxiliary materials: high-temperature grease (such as lithium based grease), bearing sealant (such as Loctite 515), cleaning agent (such as gasoline or specialized degreaser), dust-free cloth.
. Spare parts: new bearing inner and outer rings, roller components, sealing rings, wheel hub units (if replacement is required), locking nuts or retaining springs.Component inspection Bearing inspection: Check whether there are cracks, peeling or wear on the inner and outer rings of the bearing, and measure the clearance with a micrometer (radial clearance is usually 0.05~0.15mm).
.Check if the roller surface is smooth, without rust or pitting.
.Wheel hub inspection: Confirm that the inner diameter of the wheel hub bearing hole and the outer ring of the bearing have an interference fit (usually an interference fit of 0.01~0.03mm).
. Check whether the flange surface of the wheel hub is flat, without deformation or burrs.Steering joint inspection: Check whether the bearing seat hole of the steering joint is worn. If the wear exceeds the tolerance (such as the hole diameter expanding by more than 0.05mm), it needs to be repaired or replaced.
.Cleaning and protective agents thoroughly clean the inner and outer rings, rollers, wheel hubs, and steering knuckles of bearings, removing oil stains and metal shavings.
. After cleaning, blow dry with compressed air to avoid residual impurities affecting the bearing life. Wear dust masks and gloves during operation to prevent impurities from entering the interior of the bearing.2. Installation steps
1. Install the bearing outer ring
Method 1: Hydraulic pressing method (recommended) Place the bearing outer ring smoothly into the steering knuckle bearing seat hole, ensuring that the outer ring end face is aligned with the seat hole step.
. Use a hydraulic press to slowly and evenly press into the outer ring, with the pressure direction perpendicular to the axis, to avoid tilting and causing deformation of the outer ring. The depth of pressing should meet the requirements of the maintenance manual (usually the outer ring end face is flush or 0.5-1mm lower than the outer edge of the seat hole).Method 2: Hot fitting method (suitable for large interference fit) Heat the outer ring of the bearing to 80-100 ℃ (induction heater or oil bath heating can be used), and keep it warm for 10 minutes to allow it to expand evenly.
. Quickly insert the outer ring into the steering knuckle seat hole and lightly tap the outer ring end face with a copper hammer to place it in place, avoiding direct tapping of the roller. Cool naturally to room temperature, and the outer ring forms an interference fit with the seat hole.2. Install the bearing inner ring and roller assembly
Assemble the inner ring and rollers. Insert the roller assembly (including the cage) into the bearing inner ring to ensure that the rollers are evenly distributed and not stuck.
. Apply an appropriate amount of high-temperature grease (with a thickness of about 0.1-0.2mm) on the inner raceway and roller surface to enhance lubrication and prevent rust.Install the inner ring onto the hub and insert the assembled inner ring roller assembly into the hub journal, ensuring that the inner ring end face is in contact with the hub flange face.
.Use a hydraulic press or specialized press to press the inner ring into the wheel hub, with the pressure direction consistent with the axis to avoid tilting the inner ring.
. After pressing in, check the relative position between the inner ring and the wheel hub to ensure there is no axial movement.3. Install sealing ring
Choose sealing ring type. The first generation bearings usually use rubber skeleton sealing rings, and it is necessary to confirm that the inner diameter of the sealing ring is in interference fit with the shaft neck, and the outer diameter is in interference fit with the wheel hub.
.Install the sealing ring and apply a small amount of lubricating grease to the lip of the sealing ring to reduce installation resistance and prevent dry friction.
.Insert the sealing ring into the shaft neck and use a special tool (such as a sealing ring installation sleeve) to evenly press it in, avoiding lip flipping or cutting.
.After installation, check if the lip of the sealing ring is tightly attached to the shaft neck without any gap.
4. Install the wheel hub unit onto the steering knuckle
Adjust the bearing preload and insert the wheel hub unit (including the bearing) into the steering knuckle. Install the locking nut or retaining spring.
.Use a torque wrench to tighten the locking nut according to the manufacturer's specified torque (usually 150-250N · m), and cross tighten it 2-3 times to ensure even force distribution.
After tightening, rotate the wheel hub and check if it rotates flexibly without any jamming. At the same time, use a dial gauge to measure the axial clearance (usually 0.02~0.08mm).
.Install hub bolts or nuts and tighten them diagonally to the specified torque (usually 80-120N · m).
.Check the coaxiality between the wheel hub and the steering knuckle, and use a dial gauge to measure the end face runout (≤ 0.1mm) and radial runout (≤ 0.05mm) of the wheel hub.
.III. Key precautions
Interference fit control: The interference fit between the outer ring of the bearing and the steering knuckle, and between the inner ring and the wheel hub must be strictly matched. If it is too small, it can easily cause loosening, and if it is too large, it can cause bearing cracking or wheel hub deformation.
. If the interference fit is insufficient, a small amount of bearing sealant (such as Loctite 515) can be applied to the surface of the outer or inner ring to enhance the bonding strength. Lubrication and sealing grease should be filled to 1/3~1/2 of the bearing chamber to avoid excessive heating or insufficient lubrication. After the installation of the sealing ring, a leakage test is required: inject a small amount of lubricating grease into the bearing chamber and observe whether the lip of the sealing ring leaks oil.Pre tightening force adjustment: If the pre tightening force of the bearing is too high, it will increase friction and heat generation, while if it is too low, it will cause vibration and noise.
. When adjusting the preload force, it is necessary to refer to the maintenance manual and use specialized tools (such as a preload force measuring instrument) to ensure accuracy. Installation environment requirements: It is recommended to maintain the installation environment temperature at 15-30 ℃ to avoid high temperature causing grease deterioration or low temperature causing bearing brittleness. The entire installation process should be kept dust-free to prevent impurities from entering the bearing and causing early wear.IV. Common Problems and Solutions
After bearing installation, heating may occur due to excessive preload or insufficient lubrication. The preload needs to be readjusted and lubricating grease needs to be replenished.
.Wheel hub rotation sticking: It may be due to the tilting of the inner and outer rings of the bearing or damage to the rollers, and the bearing needs to be disassembled, inspected, and replaced.
. Sealing ring oil leakage: It may be due to damage to the lip of the sealing ring or improper installation. The sealing ring needs to be replaced and reinstalled. Early failure of bearings: It may be due to impurities entering during installation or insufficient interference fit, and thorough cleaning and reinstallation are required.