Worn wheel bearings will affect the braking efficiency, suspension and critical braking safety characteristics of a vehicle, especially at high speeds. It is advisable to check the wheel bearings on a regular basis, every 12 to 24 months. You can do this by raising the wheel off the ground using a jack. Hold the wheel by hand at the top and bottom of the wheel and rock the wheel inwards and outwards. If the wheel has more than 1 centimetre of lateral movement, then the wheel bearing needs to be replaced.
A wheel bearing kit consists of the following:
- 1 x Inner wheel bearing and race
- 1 x Outer wheel bearing and race
- 1 x Grease seal
- 1 x Sachet of grease
- 1 x Split pin
- 1 x Lock nut (where applicable)
Apply the hand brake to secure the vehicle. This will prevent the vehicle from moving forwards or backwards while supported by the safety trestles.
Loosen the front or rear wheel securing nuts and jack the front or rear wheels of the vehicle off the ground. Install a trestle on each side of the vehicle as safety supports underneath the vehicle. Remove the securing nuts and the front wheels.
Remove the brake calliper from the strut assembly. Next remove the grease cap using a flat-note chisel and hammer. Remove the split pin and loosen the castle nut. The hub assembly will now be free and can be removed from the shaft. The outer wheel bearing and washer will be loose and can be easily removed.
Remove the old grease seal from the hub assembly. This can be done by levering the used oil seal with a screwdriver or levering bar. Wash the hub assembly thoroughly. There will be two visible securing indentations on opposite sides of the hub assembly, 180 degrees apart.
Insert a small punch on the one indentation and gently tap with a hammer. Repeat this procedure on the opposite indentation until the bearing race is completely removed. Be careful not to cause any indentation or burrs as this will hinder correct fitment of the new bearing kit. Follow the same procedure on the opposite wheel so that both wheel bearings are removed.
Use a hydraulic press to install the new bearing races. Ensure that the correct size jig sleeve or socket is used. Should you not have a hydraulic press available, a hammer and flat punch or socket can be used. These should be used with great care so that the tapered shaft area is not scratched or damaged, as this will result in high spots that will damage the new bearing races when fitted.
Place a small amount of grease in the palm of your hand and then hold the bearing in your other hand. Tap the bearing into the new grease and ensure the grease packs in between the bearing cage and the rollers around the full circumference of the new bearing. Squeeze the remaining grease into the hub cover and insert the greased bearing into the hub, tapping until it fits correctly. Turn the hub over and install the new outer bearing and washer into the hub.
Fit the hub assembly into the shaft and tighten the securing nut. This will correct the required bearing preload. Turn the hub assembly gradually while tightening the securing nut. When the bearing begins to bind while you are tightening, loosen the nut slightly until the bearing rotates freely again, then allow the relevant spanner or bar to drop freely on its own weight. The preload on the bearings will now be within the required preload specifications. Re-install the new split pin and refit the grease cap, or dust cover.
Re-fit all components in reverse order of removal. Ensure that all the relevant components are cleaned prior to installation, especially all of the relevant securing bolts. Apply the same step-by-step process above to replaced the opposite wheel bearing.
Re-fit the wheels of the vehicle, and pump the brake pedal a few times to ensure that all the relevant components re-adjust and centralize themselves. Remove the trestles and lower the vehicle to the ground. Tighten all securing nuts for the wheels.
USEFUL TIP 1:
It is advisable to replace the wheel bearings on either side of an axle at the same time. This ensures that wheel bearings operate at equal levels of wear and tear.
USEFUL TIP 2:
Always test drive your vehicle after replacing the wheel bearings. This will ensure that all the relevant components are operating within the required specifications.
USEFUL TIP 3:
It is advisable to have the wheel alignment checked following the replacement of wheel bearings. This will ensure that all the safety critical components operate in equilibrium with each other.