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E39 Rear Wheel Bearings

Discussion in 'E39 (1997-2003)' started by vvassallo, Nov 17, 2008.

    vvassallo guest

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    I am in the middle of this project to replace the driver's side rear wheel bearing. I used a standard 6" bearing puller to extract the hub from the bearing and axel spline. Naturally, it came off while separating the sealed bearing, leaving the inner bearing race attached to the hub. A quick trip to the machine shop removed the race.

    Now I have the new sealed bearing and I am torn regarding installation.

    1. Do I just bolt up the new bearing to the hub mount on the car with the 4 torx bolts, then "slam" the hub into the bearing and onto the axel spline (of course using a good sledge hammer and some discretion), OR

    2. Do I need to have the new bearing pressed on to the hub shaft and then "slam" the shaft on to the spline before finally bolting the bearing assembly in place?

    So far, the machine shop is in favor of pressing the bearing on to the hub shaft. It looks easier to bolt the new bearing assembly on the arm/brake/wheel bracket, and then slide the hub shaft through it, but is this the way it is done? The machine shop is worried I will end up detaching the inside bearing race using this method.
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    mooseheadm5

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    I have not had to do one of these yet, but it looks like you would bolt on the bearing, put the shaft through the bearing, then push the hub in far enough to get the nut on, then draw the hub through the bearing using the nut. This is how you do it on an E30/36, and they have a similar setup (except the bearing presses into the suspension arm instead of bolting on.) By sandwiching the bearing races between the axle and hub, you prevent them coming apart. Stay far away from a hammer in this or you may chip the race or weaken it and cause premature failure. If you can't get the axle in the hub far enough, you may press it in as far as the outer inner race (confusing I know, but I mean the inner race that faces the outside of the car, but you probably understood that.)

    vvassallo guest

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    I see what you are suggesiting, however, on the 5-series, the hub shaft that goes nito the bearing is pretty long, about 5-6 inches and it needs to be in place nearly 2/3 of the way on the spline before the nut threads are exposed. Also, the bearing is sealed into the housing assembly, all of which bolts on to the lowe arm/hub/brake mounting plate (I got to look up the name for these parts). Kind of an odd job unless you are a machine shop or a BMW service center. Not too DIY friendly.

    The bearing runs about $125 before club discount so I am looking to not destroy it on installation. :)
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    mooseheadm5

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    I gather, then, that the hub itself goes almost all the way through both inner races. In that case, I suggest taking the hub and the bearing to the machine shop. We would use a wheel bearing press, which is a long threaded rod that has a nut and a plate to press agains the inner race on one end and a cup or plate to press agains the hub on the other. Several labored wrench turns later and the hub is home. If the machine shop has something to bear against only the inner race as they press the hub in, the bearing will be undamaged and you are good to go. That should be very cheap. Think about what would have happened if you had an E30 where you would have to do this on the car or remove the whole suspension arm and take it to the machine shop! The splined driveshaft should then go through pretty easily (clean and lightly lube the splines.)

    vvassallo guest

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    The bearing is not as you describe because it is entirely sealed to a mounting plate, but the installation is about the same. I figure to have the bearing unit pressed on to the shaft housing that fits on to the spline. Then I have to bolt the bearing to the carrier. It actually is a more robust design, just a pain to replace. You've at least convinced me of the way to proceed, although it was not where I wanted to go. :p
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    mooseheadm5

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    How do you mean? I know that it has a removeable carrier, but not sure how it is different than I imagine.

    vvassallo guest

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    Ok, I will try to use some unorthodox terms to describe the parts involved.

    The wheel and rotor are attached to a hub which has a flange that slides over the axel spline on the half shaft. The suspension arms are attached to a hub carrier that the brake caliper also bolts to. The sealed bearing and its housing are also bolted to this hub carrier on the outside face with the torx headed bolts mounting from the inboard side of the hub. Therefore, the wheel, rotor and hub flange assembly slides through the mounted-in-place wheel bearing on to the axel spline.

    My mechanic suggests that I remove the half shaft for installation. I need to have the sealed bearing pressed on to the hub flange. Then the hub flange is to be slid on to the axel spline and the whole assembly bolted in place on to the hub carrier. Lastly reconnect the half shaft to the diff.

    I will probably not do this with the half shaft off the car. We'll see how troublesome it becomes. The Bentley manual for this car is 33% off at Amazon so I bought it and will see tomorrow what the "proper" procedure is. :)

    vvassallo guest

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    Hmm, what a learning curve! Bentley says to bolt the new sealed bearing unit on to the hub carrier, then press or hammer the wheel hub on to the axel spline. Let me tell you that this is not as it seems. In fact, I am discovering that working on 5-er's seems to be oriented towards just having the dealer or a shop do the work. So many special tools; so many quirks on installation and removals. The E36 is sooooo much easier to work on.

    OK, project finally done and knowledge gained. Write me to get helpful hints!

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