SC430 front wheel bearing replacement in detail

[Oregon John 0]

Odd front end noises when driving often lead to the need to replace wheel bearings. This can be a humming noise at speed, and more often upon turning the steering wheel a bit; the usual road noise changes.  Hopefully it hasn't gone on long enough to have a grinding effect.  I noticed a humming noise in my car at 98k miles. This seemed a little early - my Toyota pickup has never had any attention to its bearings at 285K and still rolls neatly down the road.  I actually had an experienced Lexus repair evaluate it, too, and they agreed in fact that both sides were worn.  Lexus  here wanted $850 to do both bearings [together].  The DIY cost was $140. It takes medium mechanical ability.

I decided to do the job myself, and eventually found that both sides still had lube in them.  My guess is that the bearings would still soldier on for another thousand miles at least.  But in order to really inspect the bearings, you have to open them up and destroy them.  So I opened the Lexus shop manual and got started.  

Note that these instructions are pretty similar for other Lexus models which don't have front wheel drive, and other manufacturers' as well.

The manual's listing of SST [special tools] is daunting but unnecessary; I accomplished the task with two 3-legged pullers, although I did use a machine shop's hydraulic press services since my wimpy 6-ton job would not do it.  Also, the manual omitted  some vital advice.

After the car is up on jackstands and the front wheels removed and marked as to left and right [from the driver's perspective], remove the front brake caliper as usual by taking out the two bolts and using a rope or wire to hang the caliper up out of the way.  Important:  Use a 6-point 17mm socket for this, and all subsequent nuts and bolts [not a 12-point]. You are overcoming 83 ft. lbs. of torque in some cases, and twelve-pointers will slip and round bolt corners.  Remove the rotor.  Next pull the top steering knuckle after removing the clip and unscrewing the castle nut until the bottom is even with the bolt end.  I used a small puller and it popped right off.  You also need to remove the little speed sensor wire from the hub.  All that's left are the two bolts that secure the unit to the lower ball joint.  Use a long socket handle - these are tight.

The book gives instructions to mount the hub assembly in a vice using 3 of the lug nuts and not tightening too much.  Good idea, but of  course it's not possible to then use a really long socket handle [36mm or 1-7/16" socket] to remove the big nut in back [visible after removing the dust cap].  You are undoing  more than150 ft. lbs. torque. So the other main tool you need is a GOOD air impact wrench. I use an Ingersall Rand 1/2" one with 90 pounds of air.  Set it on high and the nut comes off.  You did use a punch and tap out the staked part first, didn't you?  Lexus says this nut is to be renewed, but I re-used mine easily - re-staking is not hard. Now remove the skid control rotor [it looks like a gear] and remove the four 6mm bolts that hold on the dust cover. My larger 3-jawed puller then fitted over the spindle and was able to pull the unit apart WITH the air wrench.  It comes apart very slowly, even with that tool.  The inner bearing race is left, and my small puller again did the job with the air wrench. Note that I had to heat  one of the races with a propane torch first.

Pop out  the grease seal, then remove the large snap ring.  I used the Harbor Freight snap ring set #60593, but first reversed the tips, left to right etc. so that they pointed inward. Now the bearing is ready to be extracted. I took it to a machine shop and their 80 ton press!  Now do an important thing; the manual suggests this AFTER assembly, but if you have a problem, the spindle can be replaced before this.  Check the run-out of the hub face where the wheel studs are mounted.  You'll might just get the machine shop to do it, but if you have a gauge you can do it yourself.  The hardest part is mounting the spindle in something so it can rotate without wobbling.  I found it best to make a hole and stick the thing in it upside down, then rotate it carefully.  The gauge shouldn't deviate more than .002 inches according to the manual.  

Now replace the snap ring and put in a new seal, then grease it.  The machine shop can now put the spindle back in snugly. Back in your shop you can  install the big nut and stake it.  I found that mounting the unit  in a vice by the caliper holes worked well, while anchoring the hub spindle in back. This nut takes 143 ft. lbs., and most of our torque wrenches only go to 100, so.....   go borrow or rent a bigger one.  The rest of the re-assembly is fairly routine.  Make sure the top steering knuckle taper and hole have zero grease on them.  And it's advisable to check the car's toe-in after you are done.  You can go for a complete alignment, or do as I do and use two long straight sticks and two bricks. The only setting that kills tires is toe-in, and it's easy to check yourself.  Adjusting the rods that move the wheel assemblies on this car is easy, too, except the part in which you realize the car front is VERY close to the ground.  But you can reach the adjusters from behind the front wheels.  Or up on a lift, but that entails many more steps.

Parts needed for the job:   two bearings and two seals.

If you wish to renew the big nuts, you'll probably have to go to Lexus for them.