this final article on wheel bearing replacement, we will focus on the steps
involved in changing the rear wheel bearings on the 1984-91 BMW E30 3
Series. Are you starting to hear a grinding, wobbling noise coming from your
rear wheels? Have you noticed a wheel that shakes when you drive? Chances
are the wheel bearings may be starting to fail. With most of the E36s now
reaching over 150,000 miles or more, the wheel bearings may be starting to
show their age. In this tech article, I will go over the steps involved with
removing the old wheel bearings and installing the new units. It is a
relatively easy procedure and should be able to be performed in a few hours.
To replace the rear
bearings, we will need to remove the drive axles from the car. To begin, we
will need to first pry the center caps off the rear wheels while it is still
on the ground. Now look inside, you should see the drive axle retaining nut.
We will need to loosen this nut with the car on the ground. This will help
you gain enough leverage to get it off, as it is torqued in excess of 150
ft/lbs. In many cases, it may be easier to simply use an impact wrench. Get
the nut loose but do not remove it. Be
sure to use plenty of penetrant spray such as WD-40 while loosening the nut.
This will prevent stripping or seizing.
Once the car is firmly secured on jack stands, the next step is to
remove the lug bolts on the rear wheels and take the wheels off. Now, look
at where the drive axles are bolted onto the differential. There are six
Torx head bolts that hold each axle to the differential. Before you remove
them, its a really good idea to clean them off to get any dirt of grease
out of the bolt heads. Any good brake cleaner should work perfectly. We
dont have to get them spotless, however just enough to where we wont
have the Allen key from popping out. Its also a good idea to hit the
bolts with WD-40 or good penetrating oil. Typically, I like to let the spray
sit overnight, to let the oil work itself into the threads. This will make
it much easier to remove the bolts, not to mention preventing stripping and
seizing when you hit them with the wrench. Now remove all the bolts. The
drive axles will now be free of the differential. Use a piece of rope or
stiff wire to hang the drive axles to the car and keep them from crashing
remove the axle retaining nut on the outside of the wheels and remove the
lock plate underneath. Now, to get the axles out of the car, we will need to
use a puller to push them out of the trailing arm hubs. Use the lug bolts to
secure the puller to the hub and then tighten the center bolt to push the
drive axle out. Now remove the drive axles from the car.
Now, look behind
the brake caliper and disconnect the ABS speed sensors on both wheels. Also
disconnect the brake wear indicator sensor on the passengers side wheel.
Now look at the back of the brake calipers. You will see two rubber grommets
with a plastic plug installed in them. Pry out these plastic plugs. Directly
beneath them, you will see a 7mm Allen head bolt. Use a 7mm Allen head key
to loosen then remove both bolts on each wheel. Look on the front of the
caliper and pry off the brake retaining clips using a flat-head screwdriver.
Now you will be able to pull the brake calipers off the mounting bracket.
Use a zip-tie or wire to suspend the brake caliper. Do not let the
caliper hang by the brake lines, you may rip the lines. Now, remove the two
19mm bolts that hold the caliper mounting bracket to the hub, and remove the
caliper mounting brackets.
now must remove the brake rotors. This is done by first removing the small
Allen head set screw in the front of the rotor. You may find it helpful to
spray these bolts with a good penetrant spray like WD-40 and let them sit
overnight. This will prevent the screws from stripping or seizing. Remove
the screws and pull the rotors off the hubs.
remove the bearing retainer circlip. Use a pair of circlip pliers to get
this out. Now, using an impact style puller, pop the bearing assembly out of
the trailing arm. Once out, look on the inside of the bearing housing and
clean it thoroughly. This will help you when you install the new bearing
assembly. Its also a good idea to clean off all brake components, nuts
bolts, and other mounting hardware.
re-install the brake rotors, and use a new set screw to hold it in place.
The old set screws are designed for one use only and can snap or break if
you try to re-use them. Put the new set screws in and torque them to 12
ft./lbs. Next, fit the brake caliper mounting brackets over the rotor and
bolt them back on to the hub. Torque the bolts to 81 ft./lbs. Now cut the
zip-ties holding the rotors and place the brake pads into the calipers.
Place the calipers back onto the mounting bracket and re-install the Allen
head bolts that hold them in place and tighten the bolts down. Re-install
the plastic plugs over the bolts on the rear of the caliper. Now re-install
the caliper retaining clip on the front of the calipers. Re-connect the ABS
pulse sensors and the brake wear indicator on the drivers side.
Take the axles back
to the car and crawl underneath. Now coat the spines of the drive axles
with oil and slide the drive flange back into the trailing arm hub. It may
take some effort to get the axle in there, but just keep at it, and it will
slide in. Install a new lock plate on the other side of the hub, and thread
the drive axle retaining nut back on, but do not tighten it just yet.
position the inner CV joints in place and stick a screwdriver through one of
the threaded holes. This will keep the joint in place while we thread the
bolts in. But before we thread in the bolts, clean them. When I say clean I
mean remove all grease and grime. The more clean the bolts are, the less
chance there is of them loosening up over time. Once clean, put a dab of
loc-tite on the threads and thread them in. Dont forget to remove the
screwdriver as well. Now torque the bolts to 47 ft./lbs. If they are M8 size
or torque them 74 ft./lbs if they are M10 size.
put the wheels back on the car and re-install the lug bolts but do not
tighten just yet. Just get them snugged up. Now jack the car up again, and
remove the jack stands from under the car. Now lower the car, and once on
the ground, tightens the lug bolts.
last step is to tighten the drive axle retaining nuts. We have to do this on
the ground, as the amount of torque we put on this nut is enough to possibly
knock the car off the jack stands. You may even have to use an impact wrench
to get it tight. Torque this nut to 184 ft./lbs. (221 ft./lbs. on M3 models)
now put the center caps back on.
Well, there you have it - it's
really not too difficult at all. If you would like
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Gousha III adds that one should make sure the parking brake is
not engaged, as it makes the job much easier.