| When a wheel bearing goes out on a vehicle, it mayor may not give much warning. Typical clues include noise from the vicinity of the wheel, possibly some steering wander or looseness in the steering, and/or some abnormal tread wear on the front tires. Also, an ABS light could illuminate. Any time a customer has one of these complaints, you should carefully inspect the front tires, suspension and steering linkage to find out what's causing the problem. If the problem turns out to be play or roughness in the front wheel bearings, the fix is a new set of bearings. As a rule, there should be no perceptible play in the wheel bearing if you are pulling and tugging on a wheel 12 and 6 o'clock, but up to .010 inch of. play in the front bearings may be acceptable on some old vehicles cars and trucks with adjustable bearings. Vehicles are changing and it is becoming harder for even the strongest and most sensitive technicians to notice any play when it is on a lift. In some cases, a testdrive is the only way to condemn a bearing. Also, the only clue to the condition of a bearing maybe an erratic wheel speed sensor code that has caused the ABS light to come on. | | Bearings are very sensitive to hits and bumps. If the bearing or the seal in some way is damaged, it will lead to a reduced lifetime. A clean environment is very important when changing bearings. Particles entering the bearing will also reduce the lifetime of the bearing. It is most likely that the bearing dropped on a floor (or mishandled in a similar way) is severely damaged and should be replaced. Some wheel bearings have the capacity, under normal conditions, to last the lifetime of the car. Abnormal loadings or hits when driving, as well as influence from other components can cause damage to occur. The damage gradually becomes worse and sooner or later the bearing breaks down. | | In the late 1970s, the hub bearing began to appear on front-wheel-drive vehicles. This was a sealed, lubricated for life, pre-adjusted bearing with a mounting flange attached to the strut knuckle or rear axle flange and a hub for the rotor, wheel and CV joint. Other versions consist of a hub and bearing set that mount on a rear axle spindle or steering knuckle. The bearing could be either ball or roller type. Passenger car and light truck hub bearings are not adjustable. The hub is directly affected by the condition of the bearing. The driver may first notice a noise coming from the wheel of the vehicle when the steering wheel is turned. There will be noticeable end play when the wheel is unloaded. A check using a dial indicator will show an end play greater than 0.004 inch (0.100mm). Bearing end play can also affect a wheel speed sensor and cause an intermittent ABS trouble code. If the bearing flange has a runout, that runout will be magnified at the rotor friction surface. A runout of 0.0005 inch (0.00254 mm) at the bearing flange could result in a 0.001 inch (0.0025 mm) runout at the rotor friction surface. A wheel bearing is the most critical component of a braking system. It positions the wheel and rotor to the caliper, the wheel and drum to the backing plate, and controls the input to the wheel speed sensor. As Electronic Stability Control (ESC) braking systems become more complex, the wheel bearing will still be the central component to the system's operation. These changes will require greater care in the servicing of the total suspension system. When replacing a hub unit, the replacement unit might feel stiff and difficult to turn. Do not return the bearing. Some hub units and sealed bearing are being filled with a special grease that prevents damage while the bearing is being shipped. The grease is designed to have a high viscosity during shipping so the balls or rollers do not destroy the surfaces of races. After the bearing is installed, the certain elements in the grease break down and the bearing turns normally. | | If there's play in sealed bearings, replacement is necessary. Depending on what type of bearings are used, installation may be relatively easy or a chore. Sealed wheel bearings that bolt to the knuckle or can be easily separated from the knuckle shouldn't give you much trouble. On the inside of some bearing assemblies, there is a finger to help keep dirt and other contaminants out of the bearings. Be careful not to bend or damage this during installation. Also, make sure the mating surfaces in the knuckle are clean and free of nicks before installing the new bearing. Inspect the splines on the CV shaft for damage. If the vehicle uses a prevailing torque hub nut, don't reuse the old hub nut on the axle. Install a new one and torque to specifications. It is nearly impossible to give a general torque specification for a locking nut. There can be large differences depending on bearing type and housing. Use the torque given by the car manufacturer's recommendations. |
FAQs
If left unaddressed, you might lose control of your vehicle, develop braking problems, and the wheels can also come off. Unusual noises, uneven tire wear, steering wheel vibrations, abnormal side pull, and an illuminated ABS warning light are telltale signs of a bad wheel bearing.
How would you check for correct adjustment of the wheel bearings? ›
You should be able to feel the barest hint of play. The wheel should also still turn smoothly. On some cars (including the VW with hub collar), a screwdriver is used to probe alongside the hub nut at the thrust washer behind it. If you can just move the washer, the adjustment is correct.
How to tell which wheel bearing is bad? ›
How do you tell which wheel bearing is bad, front or back? The easiest way to test your wheel bearing is to Jack up each wheel in turn. The hold the wheel top and bottom and try to rock it back and forth, if its stiff then the bearing is fine, if it moves then the bearing has wear and needs replacing.
How do you know when a bearing has enough grease? ›
Check the grease level by pressing on the edge of the spring-loaded piston. If you can move or rock the piston, the hub has enough grease. Don't add anymore. If the piston doesn't move, you need to add more grease.
How does a car act with a bad wheel bearing? ›
Bad wheel bearings can cause the steering wheel to vibrate. The intensity increases as the vehicle speed increases and the vehicle turns to the left or right. However, the vibration could be linked to an out-of-round tire (there could be a flat spot on the tire) or a tire that is no longer balanced.
How do you physically check for a bad wheel bearing? ›
Jack up the car and put one hand at 12 o'clock and the other one at 6 o'clock, then try to push and pull and the tire and see if there's any “play” or movement. If so, you will probably have bad bearings. You would also probably hear them while going down the road making a humming or grinding sound.
What is the most suitable way to test a wheel bearing for noise? ›
To do a DIY diagnosis, you'll need to jack the car up and spin the wheels individually to see which one is noisy. It's also worth rocking the wheel from side to side and up and down to check for clonks and movement.
What happens if you put too much preload on a wheel bearing? ›
Setting the preload too high will overload the bearing, lead to higher friction and nega-tively influence bearing life. When determining preload, the preload force required to provide an optimum com- bination of stiffness, bearing service life and operational reliability should be calculated first.
What is one of the first signs of bearing failure? ›
The first sign of bearing failure is excessive vibration. Following this, the bearing will begin to heat up past acceptable levels and produce excessive noises, either high-pitched or grinding.
How do I know if my wheel bearing is CV or axle? ›
To tell the difference between a bad wheel bearing and a bad CV joint, listen to the noise. If you hear a grinding, growling, or rumbling noise coming from the affected wheel, it's a bad wheel bearing. If you hear a clicking noise coming from the affected wheel when turning, it's a bad CV joint.
Adding too much or too little grease is one of the most common mistakes made in our industry. As we've discussed already, too much grease builds up and eventually causes increased friction and pressure, and that causes excess heat. Too little of grease has the same life-shortening effect on bearings too.
What happens if you put too much grease in a wheel bearing? ›
Too much grease volume in a bearing cavity will cause the rotating bearing elements to begin churning the grease. Churning can be compared to walking along the beach. If you reach ankle-deep water, it is easy to move (equivalent to running torque).
How many pumps of grease for a bearing? ›
A general rule of thumb is to pump grease equal to about 1/3 to 1/2 the volume of space between the inside and outside races of the bearing.
How long can you drive on a damaged wheel bearing? ›
Typically, you shouldn't exceed 1,000 miles on a bad wheel bearing. Driving for distances longer than 1,000 miles could lead to serious complications with your vehicle. Continuing to put stress on this wheel bearing will also hurt the hub, CV joint, and even the transmission.
Can a wheel fall off with a bad bearing? ›
If your wheel bearing fails, it can cause the wheel to stop while you are driving or possibly even to fall off. At the very least, before a wheel falls off, a failed wheel bearing can/will cause significant damage to your vehicle, so it's very important to keep an eye on these and keep them maintained.
