Wheel Bearing Service for the do-it-your-selfers
Wheel bearing service (or repack) is very important to maintain the life of the bearings. It is needed on most front wheel bearings of rear wheel drive automobiles and on the rear wheels of many front wheel drive autos. Some newer automobiles now use a sealed bearing assembly which cannot be repacked. For the ones that are serviceable, it is most common to do this service at the same time as a brake service or mazda tonneau covers.
On trailers it is necessary to service the wheel bearing more often, to attain a long bearing life.
Always be sure to support the vehicle or trailer safely with proper axle stands.
On this service the wheels must be removed if the bearings are with a disc brake system. On a drum brake system the drums can be removed with the wheels on in most cases, but it is much easier to do with the wheels removed.
To remove the bearings the cotter pin and retaining nut are removed and then remove the outer bearing. To remove the inner bearing and seal , if you reinstall the retaining nut , with the outer bearing removed and the pull the drum or rotor off in a way that the bearing catches on the retaining nut , the seal and bearing will stay on the spindle and come out of the hub easily an without damage .
Clean all the grease from the hub and bearing races and inspect them for pitting damage or wear.
If any of these are found the bearings and races must be replaced.
If the race is ok than clean the bearings and inspect them for damage or pitting etc. If any is found the bearings and races must be replaced.
If the bearings and races are all in good condition then pack the bearings with clean new wheel bearing garage. If you place the grease in the palm of the hand and work the grease into the bearing by pushing the bearing into the grease this will get the grease into the rollers. Then put about ¼ inch coating all around the outside of the bearing.
Fill the crevice in the hub with grease at least ½ inches deep and the coat the inner bearing race with grease about ¼ inch thick. (Remember that too much grease is much better and safer than not enough) now push the bearing into the race and turn it a couple of turns. (This will also help to insure that the grease is worked into the bearings).
If the grease seal is in very good condition I could be reused but installing a new seal at this time is strongly recommended. Before installing the grease seal, fill the inner gap of the seal with wheel bearing grease. This will insure that the lip spring will stay in place during installation.
Coat the outer bearing and race with about ¼ inch of grease and install the drum or rotor on to the spindle and then install the outer bearing and turn it a couple of turns .
Now install the retaining washer and nut. It is best to use a torque wrench to adjust the wheel bearings. They should be tightened to seat the bearings and the loosened and re tightened to a light preload. A properly adjusted wheel bearing should not allow any side play of the wheel. This means, if you grab the wheel at top and bottom and try to wiggle it there should be no movement. If there is movement in the bearings the adjustment is too loose. Loose wheel bearing can cause poor handling of the vehicle and can cause loss of control on rough roads.
For trailers only, there are bearing bubby type devices available that can greatly increase wheel bearing life. These devices are installed in place of the wheel bearing cover.
They have a garage fitting which can fill with a normal grease gun. They also have a spring which moves when the proper amount of grease is installed. They are designed mainly for boat trailers but they can be used on any trailer. They are not recommended for automobiles.
A dust cover comes with these devices to protect the spring and grease fitting from water entry as well as road dirt and dust etc.
Boat trailer wheel bearings require service more often due to being submerged in the water.
On a boat trailer the bearings and hubs are normally very warm form the road trip, when the boat is put into the water. As the trailer is submerged into the cool water the warm hubs contract, creating a vacuum which can actually suck water and contaminates past the inner grease seal and into the wheel bearings. When the bearing buddy type device is greased until the spring moves, the hub is full of grease, leaving little room for water to get in. Also when the device is greased until the spring moves, this put a light pressure inside the hub, which compensates for the vacuum and holds the seal in place to prevent water entry. The devices are proven to prolong wheel bearing life when properly used.
It is still necessary to service the wheel bearing, but these devices and a great amount of protection for the wheel bearings between services.