Adjusting Wheel Bearings – What You Need To Know
Usually after every 12,000 miles, wheel bearings should be removed and carefully inspected for any inconsistency that could affect the functioning of the wheel. Wheel safety guidelines suggest that wheel bearings should be adjusted after every 12,000 miles and repacked with grease after every 36,000 miles.
Influence of Design
Bearings which are installed on undriven wheels i.e. the rear wheels of front-wheel-drive cars and front wheels of rear-wheel-drive cars are known to have a similar design.
The hub nuts placed on driven wheels, which have their independent suspension, are tightened to a high torque setting. As a result, the bearings which are used on driven wheels require less adjustment than those installed on undriven wheels.
The method of adjusting bearings which are fixed on driven wheels varies from vehicle to vehicle. The bearings which are installed on rear wheels on a live axle are not frequently or easily replaced. It takes a few extra steps compared to the replacement procedure of unitized bearings.
Adjusting Non-Driven Bearings
The bearings which are installed on non-driven wheels should be adjusted in the following two situations:
- The hub nut should be tightened, if found to be loose.
- The hub nut should be loosened, if found to be too tight.
To carry out the procedure, the wheel must be attached to the car and an axle stand should be used to raise the car so as to provide the right angles required for making adjustments to the bearing.
The bearings cannot be adjusted without removing the wheel trim. In certain vehicles, the wheel may need to be taken out before the trim can be removed. However, before adjusting the bearings, the wheel has to be installed back in its place. The wheels on which no maintenance work is to be performed should be chocked so as to prevent the car from moving.
The wheels on which the handbrakes are applied should be serviced only after releasing the handbrake. The dust cap should be removed carefully using two medium sized screwdrivers. The screwdriver should be placed between the raised flange and the hub’s surface. With a swift inward motion of the screwdriver’s handle, the dust cap can be taken off without causing damage to the hub’s surface or the dust cap.
If a cap has not been removed for a long time or the vehicle’s condition won’t allow for the dust cap to be taken out, it can be hammered off without causing much damage to it. Even if the cap does get damaged, it can be conveniently replaced as they are inexpensive.
The hub nut that you encounter after having taken off the wheel trim and the dust cap decides what your approach should be and which tool you may have to use to carry out the necessary maintenance task.
The hub can be any one of the following types:
- A castellated nut i.e. a nut which has notches cut into one of its ends. Each notch or slot is also threaded from the inside. The nut is retained in its position by a split pin.
- It can also be a plain nut with a castellated retainer fastened over it and held in its place once again by a split pin.
- Another way the hub can be secured is by ‘peening’. In this method, the outer edge of the metal is punched until it spreads over the surface. It acts as a seal on the threaded axle end.
- There is also another type which has been used in certain models of VW. It makes use of a nut with a threaded collar which is squeezed tight by a bolt. Wrenches with predefined sockets may not be of much help when unfastening them. However, pliers with adjustable grip over nuts such as self locking wrenches can be used to turn them.
In order to remove the fastened nut, you should use a wrench with a socket that fits the nut well. In case the nut has been held in position by a split pin, you should have a right-sized pin ready for its replacement. The same goes with a peened nut as it too gets damaged in the process of removing it. For a peened nut you must make use of a cold chisel and hammer.
The nut and axle end should have some grease on their surface. If they are found to be dirty, the bearings should be taken out. Using clean grease, the bearing should be repacked in the right quantity.
Traces of metal are a sign of disintegration and the bearing should be replaced at once.
The torque wrench should be correctly calibrated according to the hub nut. The calibration differs depending on the type of vehicle and can range from 11 to 60 lb ft (or 1.5 to 8.3 kg m).
It should be noted that the adjustment should be done strictly according to the service manual provided to you or as advised by a local dealer.
Now the wheel must be turned slowly using one hand, in the forward direction of travel. At this point you should carefully tighten the hub nut in accordance with the torque set on other wheels. It has been done correctly if the wheel is able to rotate smoothly.
When the nut becomes too tight, you may notice that the wheel is dragging or its movement is facing resistance as a result of moving too close to the surface on which it has been mounted.
Adjusting Driven Bearings
High torque settings are generally applied to the hub nuts of driven wheels which are not mounted on live axles. It can range from 150-200 lb ft (or 21-25 kg m). The wheel should be in contact with the ground and it should be under the weight when the final tightening is being carried out. Care must be taken to ensure that the calibration of torque is exactly as per guidelines.
Contact us today to increase the safety of your wheels. Parma Group strive to improve the wheel safety of vehicles on the road and provide all the products to ensure the safe movement of huge fleets involved in business operations.