From: Mike and Marci Clarkenfields
Date: Sat, 19 May 2001
Subject: Wheel bearing 101- long
The best way I know to check wheel bearings is to jack the car up. Grab the wheel at 12 and 6 o'clock. Try to rock the wheel by pushing in at the top and pulling out at the bottom, then reversing. Any play is too much- go by feel more than eyeballs. If you can't take the play out by hand-tightening the nut, chances are your bearings are worn. If you clean the bearings and races, inspect the surfaces carefully. ANY pitting or cracking means the bearing is history. Obvious or uneven wear patterns on the bearings or races (dull gray rather than shiny finish) means they are close or already gone.
Wheel bearings are tapered roller bearings. When they wear, they tend to become barrel shaped rather than straight taper. Once they have achieved this barrel shape, you have to over-tighten the bearing to get the slop out the wheel. Then they fail rapidly.
Always replace the bearing and races in sets (inner and outer). DO NOT use new bearings with the old races that are pressed into the hub.
Remove wheel, caliper and rotor. Save time by removing the nut and bolt that hold the metal brake lines to the strut and use a piece of bailing wire to hang the caliper from the springs without disconnecting the brake lines. Remove the hub.
Pry out the old grease seal and remove the inner bearing. Clean all of the old grease out of the hub. I have a long drift that I use to bang the old races out of the hub. Drive out the small outer race first, then the large inner one. TAP the drift, don't try to drive the race out in one shot. Tap once, then shift the drift 180 degrees, and tap again. Repeat as necessary until the race is out.
Carefully clean the ledges inside the hub where the race seats before installing the new race. Put the hub on a block of wood. Insert the new race wide side down. Use a rubber mallet. Tap gently at 12 o'clock, then 6 o'clock, then 9 o'clock, then 3 o'clock. Repeat as necessary. Go slowly. Once the new race is flush with the hub, I use the old race as a driver. Place the old race on top of the new one and continue to tap with just enough force to move the race(s). When the new race is well seated against the ledge in the hub, you will have to grab the drift again to knock the old race that you used as a driver out of the hub. No biggy, a couple of taps and it falls out. Repeat for the other race.
Start with the inner bearing. Pack the bearings with grease by putting a blob of grease in the palm of your left hand. Hold the new bearing in your right hand, wide side down, with your fingers on the bottom and your thumb on the top. Press the bearing into the edge of the grease, cutting small slices of grese with the bearing, pushing the bearing into your palm. Keep cutting slices until the grease comes out the top of the bearing. Rotate the bearing a little bit and repeat until the whole bearing is full of grease. Smear some extra grease around the outside of the bearing. Set it on a clean surface- I use the inside of the grease can lid- and do the other bearing.
Grab a big wad of grease and build a dam of grease on the inside edge of the new races. Install your inner bearing and grease seal. Put hub on car, then install the outer bearing. Hand-tighten nut whilst turning hub. Don't use cotter key yet.
Re-install brakes and wheel.
Spin the wheel and snug the nut down with a wrench, not too tight, just enough to seat things. Back the nut off and hand tighten. When it is hand-tight, wrench-tighten to next castellation- usually about 5-15 deg. Keep turning wheel. Worst thing you can do is over-tighten the nut. Check it again after about a week of driving. Should be OK, but it should never need more than one re-tightening for the first year or two.
The front wheel bearings are probably the cheapest things on the car to replace, so I tend to change them if there is a question about their condition. The good thing is that they will let you know they are going south by howling like a banshee for a long time before they become a safety concern. But you can spin the inner race on the spindle and ruin the strut if you ignore them too long. Then your $50 job turns into a $300 ordeal.