Packing Your Wheel Bearings
By Chris Troudt
Get the bike up in the air on some sort of lift. You don't need to remove the brake rotors, so no need to worry about replacing the rotor bolts. You do need to replace the wheel bearing seals, so buy a set for the front and for the rear. Don't even think about re-using the grease seals. Get some *good* quality high temperature wheel bearing grease. Synthetic is the good stuff.
Keep track of the way the parts are stacked up. It needs to go back together *exactly* the same way it comes apart. Pay particular attention to the shims -- there's one that has a shoulder and that must go back in correctly against the inner bearing race or bad things will happen. Clean every bit of old grease out of everything. Use solvent on the bearings to get them spotless. DO NOT use compressed air to dry the bearings. This can cause them to come apart, piss you off, and perhaps even injure you. Let them set on a towel, or maybe hit them with a heat gun or hair dryer if you're in a real big hurry. They do need to be free of all solvent before you repack them with new grease.
Inspect the race surfaces and the bearing rollers for pits, scuffs, or bluing. Anything that looks suspect should be replaced. Leave race replacement up to a shop. If the bearings need replacement, the races should always be replaced too. If the inspection is OK, you need to put it all back together dry (no grease) and torque the axle nuts to spec. Don't install the new seals yet -- you'll be taking it back apart again.
This is where you check the end play. It helps if the brake caliper is removed, but it's not mandatory. You can pry the pads back a bit to get some clearance on the rotor. The idea is to have nothing causing interference so you can feel only the bearing to race contact. Grab the tire and pull it back and forth. The play should be "detectable" but not excessive. A dial indicator helps to verify the actual play against the manual, but I can usually tell by feel if it's acceptable. Don't spin the wheel around a bunch with no grease in there, just check the play.
Take it all back apart and pack the bearings with grease. Make sure the spaces between the rollers are filled. Work it in there. There are several bearing greasing tools out there that work well, but doing it successfully by hand is not difficult. Apply some grease to the outer race on one side of the wheel and install the bearing. Drive the seal in. Check the shop manual here. There is a spec for the seal location in some cases. Typically the front seals should be flush with the hub, and the back seals sit slightly below flush. My trick for getting the correct seal offset is to find a washer or two that ends up with the same dimension. Set the washers against the seal and then drive them flush with the hub. Works real slick. Flip the wheel over and install the spacer/shim stack. Then apply some grease to the outer race, install the other bearing, and finally the other seal. You don't need any grease for the spacer or shims. I do pack a little extra grease into the space between the seal and the bearing on each side after the seals have been installed. You also want a little grease on the seal lip that rides on the axle.
Now you can install the assembly back on the bike. Lightly grease the axle and slide it in. Torque the axle nut to spec. Use a *new* cotter pin. Wipe any excess grease off that squeezes out so it doesn't get flipped onto the brake rotor or pad. Check the rotation of the wheel and make sure you check the operation of the brake. You don't want to forget this step, or the first time you go for the brakes you'll encounter a lever or pedal that has nothing there until you pump it a couple times. Quite the eye-opening and ass-puckering experience (so I've heard). This job is really not too bad. Much easier than I've probably made it sound. Just take your time and consult the shop manual often. A couple cold beers won't hurt either.
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