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Rear bearing replacement with pics

Discussion in 'FJ Cruiser' started by BMThiker, Oct 3, 2017.

  1. BMThiker

    BMThiker I aim to misbehave Moderator SILVER Star

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    At just over 200K on the odo, I suspected it was time to replace the rear bearings. I've been checking them periodically at the gas pump by putting my hand on the center of the hub to gauge relative temperature. The passenger side has been feeling a bit warmer than usual and it's been around 90-100K since I last changed it. So I decided to go ahead and take care of this before my trip to Hot Springs in a couple weeks. If the bearing fails, it's not the kind of thing you can easily fix on the side of the road or even in an average garage for that matter. Also, if it fails catastrophically, it could damage your wheel speed sensor.

    This job requires special tools and at least a 20T hydraulic press, both of which I had access to. You could fabricate your own tool used for separating the shaft from the hub assembly, but that is another project for another discussion. From the pictures below you'll see that it's a fairly simple approach, but would require some careful fabrication.

    For starters, I'll say that I already had spare axle shaft assemblies that came from a parted out FJC. This at least allowed me to work on my replacements without being decommissioned. For that reason, the steps may be non-linear for those that are going to attempt this job on their "live" axles. I am starting with the axles already on the bench with the wheel sensor already removed.

    Step 1, remove the circle-clip.
    RearBearing (1).JPG

    Step 2, assembly of the "special service tool". The mounting plate on this tool is reversible so that it can be used on each side. Line the plate up with the bolt pattern on the hub face and then mount the plate to the shaft section of the tool. Then the tool gets mounted to the axle...
    RearBearing (2).JPG

    Step 3, using the 17mm nuts from the back of the unit bearing, you will bolt the extraction tool to the hub face. The idea is to set the tool in the bridge of the press so that the axle shaft can be pushed down by the piston, thus separating the retaining ring and bearings from the hub base.
    RearBearing (3).JPG
    RearBearing (4).JPG

    Step 4, Now we're ready for the press. That retaining ring is a real monster and I would recommend that you proceed with much caution during this process. The retaining ring is not a reusable part, but because of its location/position it is really hard to get a cutoff tool in there to assist in this process. I doubt that even penetrating oil would make a difference here.

    But, alas, it did break free. As you will note there is still the outer bearing race attached to the axle shaft. Everything in the lower half of this picture can be tossed into the recycling bin. (save the ball bearings for your slingshot pouch)
    RearBearing (5).JPG

    Next up, shattering a race...
     
    1911 likes this.
  2. NorthFJ

    NorthFJ

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    Awesome write-up....great job.
     
  3. lgrt

    lgrt

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    nice work... for those who don't have a press... you can take the axle to a local machine shop and they'll pull the old bearing and press in the new one making this a bit more DIY for average garage guys. Of course then you don't have a reason to buy a press, so you might want to ignore that advice :)
     
  4. BMThiker

    BMThiker I aim to misbehave Moderator SILVER Star

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    Let me back up to the last photo. Once the shaft is cleared on the press, the hub unit itself is still lightly pressed into the dust shield for the rotor. Some light tapping with a mallet should break it free as pictured in the bottom right above. The 4 lugs should stay in the dust shield piece.

    Step 5, cracking the race on the axle shaft. Here's where a cutoff wheel comes in handy. Make several slices into the race. Be careful not to cut into the shaft itself, but get as close as you can and cut as deep as you can with the disc you have. I suggest wearing long sleeves and a full face mask for this task. The race material is very brittle and little pieces (shards) tend to fly in the tangent of the cutoff wheel. Once you made the cuts (and before you toss the face mask to the side) hit your cuts with a cold chisel and small sledge hammer. It shouldn't take more than a few whacks to crack the race clean through - they really are that hard/brittle.
    RearBearing (6).JPG

    Step 6, set the new unit bearing into the dust shield bracket and firmly run the 17mm nuts down on the lugs so that they fully seat.
    It should look like this from each side.
    RearBearing (7).JPG
    RearBearing (8).JPG


    Step 7, now it's time to press the unit bearing assembly onto the shaft. It's a good time to take some steel wool to the shaft to smooth out any pitting where the old bearing and retaining ring were. The dust shield on the end of the axle shaft will have accumulated a fair amount of grime, so take it to the parts washer and give it a good scrub so you don't get any excess dust inside the bearings.

    Taking a steel tube that matches the diameter of the bearing face and is longer than the axle shaft, you will press the assembly into place. Keep in mind that the outer ring of the bearing face is the magnetic tone ring, so choose a tube that is smaller than the tone ring diameter but bigger than the axle shaft diameter. Here's my setup right before it goes in the press.
    RearBearing (9).JPG

    Since the 6 wheel lug nuts are vulnerable here, make sure you support the hub from the center and edges. You do not want to press your six lugs out while attempting to press the unit bearing assembly in place. And, if any of your wheel lug nuts look buggered up, now is the time to replace them. They are not impossible to service once the unit bearing is fully seated, but certainly easier.

    RearBearing (10).JPG
     
  5. BMThiker

    BMThiker I aim to misbehave Moderator SILVER Star

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    The last step is seating the bearing retainer ring over the axle shaft. It is just a repeat of the last step, but your press may groan a bit more and you may wince a little with each bump of the press. Again, it would be prudent to find that full face shield and wear it as you monitor the progress of the press. There is a slightly domed washer that goes under the retainer ring and I think its purpose is to provide a set preload when the retainer ring is in position. You'll know the position because it will have just cleared the cutout for the circle clip. Once you get the circle clip in place you are done. All that's left is returning the axle to the axle housing. I suggest you replace the oil seal on the end of the axle housing tube as well.

    RearBearing (11).JPG RearBearing (12).JPG
     
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  6. LouisianaFJ

    LouisianaFJ

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    like your press tool, good idea to make it "reversable" for both sides
    ended up just bringing one to local dealer to have it done when i helped a friend
     
  7. NorthFJ

    NorthFJ

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    @BMThiker, besides the heat on the hubs did you notice any other signs of wear (bearing howl etc)?
    How were the bearings that you pulled out?

    With the amount on our ODO you've now got me wondering if we should be looking at doing the same.
    There was some heat buildup on one side (slight, certainly not hot) but i found a caliper guide pin that was
    bunged up so i did the back brakes last week.
    We haven't taken the truck for a good run yet to see if that's were the heat was being generated from (though i suspect it is).
     
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