Servicing Tapered Wheel Bearings !

It started as a faint squeal a few weeks ago, but lately a grinding sensation has been added to the mix. No biggie, you figure, as you accelerate up the entrance ramp you use every morning. The car probably just needs a fresh set of brake pads. Ker-runch! Suddenly, your left front wheel rockets out from under the vehicle, the nose drops, sparks spray from the chassis, and your latte goes flying out the window. The brake pedal is now useless. Wrestling with the steering wheel barely keeps you from plummeting down that ravine adjacent to the highway.
You're shaken and you're breathing heavily. But it could have been a lot worse. After all, as noted, you still are breathing.

Now, think. When's the last time you serviced those front wheel bearings?
Unlike the sealed wheel bearings we covered a few months ago, the front wheel bearings found on a typical rear-wheel-drive car or truck employ two-piece caged bearing assemblies. Good maintenance dictates that the bearings should be cleaned and repacked any time the brake disc is removed from the spindle.
A Set of Wheel Bearings Equals a Pair of Pairs
Conventional wheel bearings come in two pieces: the tapered cage assembly of rollers with the inner race, and the tapered outer race that presses into the brake disc (or drum) hub. The rollers ride on the inside tapers of both races.
But there are actually two complete bearing sets per wheel -- an inner and an outer -- and both have a separate inner race. Together, they support the entire brake disc (or drum) and wheel/tire assembly. Wheel bearings should be replaced as axle pairs. Don't just replace, for example, bad left front wheel bearings without also replacing the right front ones, regardless of their condition. You also should replace the spring-loaded seals that keep the wheel bearing grease from escaping out the backs of the hubs and dirt and water from intruding into the grease cavity. Oh yes, get a tub of wheel bearing grease, too. We paid less than $50 for everything we needed for our project car.
Get Dirty: Inspection
The first step when checking for worn wheel bearings is to get the tire off the ground. Chock the wheel on the opposite corner fore and aft. Set a safety stand under the corner you're working on after you jack it up. Grasp the whole wheel assembly at the top and bottom (12 o'clock and 6 o'clock positions) and try to rock it in and out. (Rocking side to side is more indicative of bad tie rod ends.) Also, spin the wheel and feel for roughness. A slight amount of play is expected, but any more than a few millimeters of movement at the top or bottom of the wheel as you rock it calls for a closer look. Remove the lug nuts, which probably will mean setting the wheel back down to keep it from spinning, unless you've got an air wrench or a helper to depress the brake pedal.
You'll need to remove the brake caliper, which usually requires taking out a couple of caliper bolts or some sliding pins. Hang the caliper by a piece of heavy wire to keep from damaging the rubber brake hose. If you have drum brakes, front or rear, you may need to back off the brake adjustment stars; refer to the shop manual for the specific number of notches. Now pop off the dust cap with a chisel and a light hammer tap. Then, use pliers to straighten the cotter pin. Remove the locking crown if there is one (some cars use just a castle nut) and unscrew the axle nut. Wear a mask to avoid breathing in the brake dust, or rinse the assembly with water.
While pulling the brake disc (or drum) from the spindle with one hand, catch the small outer bearing and the washer in front of it as they fall into your other hand. Pull the large inner bearing out past the grease seal from the back of the hub. You may have to pry out the seal first.
Both sets of rollers should be gooey with no signs of dirt in the grease. Rotate the cage assembly on the inner race with your fingers. Look inside the inner race and on the axle spindle for score marks. Nothing? The rollers spin true? Are the surfaces of the bearing race and rollers a little textured, but there are no chatter marks (called brinelling) or obvious wear? No blue metal from overheating due to lack of lubrication? Is the grease sticky and not like the crumbly bar of Irish Spring in your shower soap dish? If so, you can simply repack the old bearings and put it all back together. Clean the old grease -- all of it -- out of the hub, the bearings, and off the spindle, washer and nut. Follow up with mineral spirits and a small paintbrush or aerosol brake cleaner to remove the last of it. Dry any remaining solvent with a rag or compressed air.
Out With the Old, in With the New
Any signs of damage or wear, however, mean you need new bearings. Look for two indents inside the hub just behind the races, 180 degrees apart. Use a hammer and punch to carefully bang out each race from the other side of the hub, alternately tapping at one indent and then the other. A hydraulic press with the correct arbor will make short work of this. If you can't get the races loose, you can take the hub to your local machine shop and have a mechanic press them out.
Before installing the new race -- which you've carefully kept matched to its respective bearing -- make sure its land is clean and burr-free. A hydraulic shop press works best for installation, but with a certain amount of care it is possible to install the new race using a hammer and a punch. Don't scratch the tapered area that the rollers ride on. The best way to minimize any chance of doing damage is to tap in the race with a socket large enough to fit the race's circumference.
Your fresh bearings will not come out of the box pregreased. So pack each thoroughly. Put a generous dab of grease in the palm of your (clean) hand and push the grease between the rollers and the cage. Do this all around the circumference of both bearings. While your hands are slathered, cup some more grease and glob it into the disc (or drum) hub. Don't pack it full -- about 50 percent grease is plenty. Then, insert the large inner bearing into the back side of the hub. Tap the new grease seal into the back of the hub.
Reinstall the brake disc (or drum) on the spindle, insert the small outer bearing, and place the washer and thread on the nut. Run the nut home by hand, then tighten it a little more with a wrench while spinning the brake with the other hand. This seats the bearing further and sets its preload. Keep spinning while tightening. You'll feel the bearing start to bind slightly as you tighten more. Stop there.
Now back off the nut with the wrench until you feel that resist­ance dissipate, and one of the castellations on the nut lines up with the cotter pin hole. Use a new cotter pin. Don't overtighten the spindle nut. Better to keep it on the looser side than make it too tight if the cotter pin holes don't line up just right. To finish the job, fill the dust cap halfway with grease and tap it back on. Reinstall the brake caliper, then scrub the brake disc with brake cleaner to remove any grease or even handprints from the friction surface. Reinstall the wheel by torquing the lug nuts to the manufacturer's specified torque in a star pattern. Remove the safety stand, lower the vehicle and take it for a road test.


Remove the caliper and hang it nearby with a piece of wire or string to avoid damaging the rubber brake hose.


Pry off the cap without damaging it -- you'll need it again.


Pop off the brake disc and remove the bearings. Clean all the old grease off the bearings, brake and spindle with solvent.


Pop the old seal out with a pry bar or even a screwdriver, then use solvent to clean up all the old grease. Dry with a rag or compressed air.

Pack the bearings by mushing grease in between the rollers until they're completely coated.


Tap the new grease seal home and fill the cavity halfway with fresh grease.


Adjust the castellated nut by lightly tightening it and spinning the wheel. Now loosen it until the casteallations line up with the axle's crossdrilled hole. Too loose is better than too tight.


Install the cotter pin (we suggest using a new one). Then, fill the outer cap halfway with grease and tap it in.