How-To Replace Rear Wheel Bearing

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Category: How-To

Published on Wednesday, 11 January 2012 04:13

Written by Jeff Lyon

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***WARNING: Do not proceed unless you are an experienced mechanic and have the appropriate tools***
***PROCEED AT YOUR OWN RISK***

Tools Used: 12 ton hydraulic press, large snap-ring pliers, flat-bladed screwdriver, cold chisel, hammer, gasket scraper, various size sockets (for press tools).
Parts Replaced: Wheel Bearing Part#: B455-33-047B, Wheel Bearing Seal Part#: G304-33-065 (Same parts left/right)

The rear wheel bearings on the Miata don't have to be replaced that often but when they do it is not a trivial job.  Since we are upping the HP by at least 50% on the Turbo SM I made sure to examine the rear wheel bearings since I was swapping out the differential and half-shafts.

With the axles out it is easy to check for play in the bearings.  The left rear bearing had about an 1/8" of play which is way too much.

After removing the upright, check the lower bolt for straightness.  The first clue is how hard was it to remove the bolt?  This bolt bends easily if the wheel experiences any side impact.  If this bolt is bent, even a little, it can rotate and change the toe settings of that wheel.

I used a 1 1/8" socket that fits right inside the bearing to press out the spindle.

Next remove the inner seal.

Next flip the upright over and remove the large retaining clip.  You can use two screwdrivers to do this or if you have a large pair of snap-ring pliers you can save 20 minutes and several cuss words.

To press out the bearing I used the largest 3/4" drive socket and a 12 ton press.  This step is the most dangerous so be careful and make sure the everything is setup square and solid.

Another tricky step is removing the inner race from the old bearing off of the spindle.  Usually a cold chisel will work to start the race sliding down the spindle shaft.  Keep rotating the spindle 180 degrees hitting on opposite sides.  There have been occasions when this hasn't worked.  If this doesn't work then option 2 is to use a cutoff wheel and make a couple of cuts into the bearing race 180 degrees apart then use a cold chisel to split the race off of the spindle shaft.

A comparison of the new and old bearing shows that the new bearing has stainless steal seal on the inside of the bearing.  This is the side of the bearing that goes down when pressing the new bearing in and will face the differential when it is all reassembled.

I used some 220 grit sandpaper to clean up the inside of the upright before installing the new bearing.  This removes any rust and dirt that may be left behind and will make installation of the new bearing easier.

I used a 4x4 to support the upright when pressing in the new bearing.  Remember to set the bearing with the stainless steal seal down.

Now the new bearing is installed.

When installing the snap-ring if you are having trouble getting the ring to seat it is most likely because the bearing is not seated all the way. 

Next to the last step is pressing the spindle back in.

The last step is to install the new inner seal and I would have a pic of that too if I had the seal.  So pic to follow soon.

Carefully install the new seal so that you don't bend the ring. 

New seal installed ready to be back on the car.

Place a light coating of grease on the half-shaft splines before installing.

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