this tech article we will discuss replacement of the front brake pads on the
E36 BMW 3 Series. While this tech article is specific to the E36 models, it
applies to most other BMW models with floating calipers as well.
Are your brakes
starting to squeak? Has the ďbrake liningsĒ light come on? These are
indications that the brakes need service. The good news is that replacing
your brakes is a relatively easy procedure that you can perform in your own
garage in just a few hours.
With the car still on the ground,
the first step is to loosen the front wheel lug bolts but do not
remove them. Just loosen them, then snug them up. Next, jack up the car in a
safe manner. Itís a good idea
to use Wayneís article here for reference on safe ways of jacking up the
Once the car is up
in the air, remove the wheels and you will see the disc brake assembly. Look
at the backside of the caliper. Youíll see an electrical connection coming
out of the driverís side front caliper. This is the wire harness for the
rear brake wear sensor. Unplug this sensor where it plugs into the harness.
remove the brake pad retaining spring on the front of the caliper. Use a
screwdriver to pry this spring off. Now look at the back of the caliper. You
will notice two plastic inserts inside two rubber grommets at the top and
the bottom of the caliper. You will need to remove these in order to
continue. Use a screwdriver to pry them out. Directly beneath these inserts
are two 7mm Allen bolts. Use a 7mm Allen key to remove these bolts. Once
removed, you will be able to pull the caliper off the rotor.
take a look at the old brake pads. You can see how worn they are from the
pics. Compare these to the new pads. Notice the brake wear sensor on the old
pads. This will give you a good idea of how the sensor works. Essentially
when the pads wear down to a certain point, it wears away the outside cover
of the sensor, eventually wearing it down to the point where the metal strip
inside contacts the rotor, and completes the electrical circuit, and the
light on the dash illuminates. We will be replacing these sensors as well.
next step is to remove the brake rotors. You need to remove them in order to
have them surfaced. Re-surfacing brake rotors is important. Failure
to re-surface brake rotors can cause the brakes not seat properly or even
overheat.. Re-surfacing insures that the new pads will seat properly.
Any decent auto parts shop can re-surface your brake rotors for usually
around $5 a rotor.
Keep in mind, however that brake rotors, by law, can only be
re-surfaced a certain amount of times before you exceed the amount of
material that can be removed. This is done for safety reasons. If you have
exceeded the amount of material that can be removed, youíll have to
purchase new rotors.
order to remove the brake rotors, remove
the Allen head bolt that holds the rotor to the hub. You may have some
trouble removing these without stripping the bolt so I recommend that you
soak the bolt in a good penetrant spray for a few hours prior to loosening
the bolt. This will help prevent against stripped or damaged threads, and a
potential nightmare that will send you screaming over the edge. (Ask me how
I know thisÖ.)
The next step to
remove the rotors is to remove the brake caliper bracket that sits on the
back of the hub. You will notice two large bolts holding it to the hub.
Remove these two bolts, and remove the caliper bracket. The brake rotor
should now come free.
you have the brake rotors removed, take them to the auto parts store,
machine shop, etc. and have them re-surfaced. Obviously, take another car to
the store, as youíll find your brakes donít work with the brake discs
removed from the car.
is a good time to clean everything. Youíll want to use a good quality
brake cleaner to make sure that the calipers and surrounding parts are clean
and free of dirt and grime. Grease on the brake discs can cause brake
the brake discs surfaced, you can now start re-installing the components.
Put the surfaced rotors back on
the hubs, and make sure to line up the holes, so that the brake disc
hold-down Allen bolt will
thread in. Itís a good idea to put a dab of anti-seize compound on one
side of the threads to prevent stripping the next time you remove the brake
that the rotors are installed, itís time to compress the caliper pistons.
Youíll want to do this in order for the new brake pads to fit. As the old
brake discs wear, the piston gradually comes more and more out of the
caliper, making it impossible for the new pads to fit.
order to compress the pistons, first remove the brake fluid reservoir cap,
this will relieve the pressure on the system, and make it easier for you to
push the pistons. Next, use a large C-clamp as shown in the photo, to slowly
push the piston back into the caliper. The caliper pistons should slide back
with a minimal amount of force.
Now, install the new
brake wear sensor in place. keep in mind that there
is only one brake wear sensor on the right front. The sensor simply clips
onto the brake pad as shown in this photo.
the calipers are compressed, re-install the caliper bracket on the hub and
make sure the bolts are tight. BMW recommends you torque them to 65 ft/lbs.
Next, place the new
brake pads on the lower caliper mounting plate as shown. When they are in
place, carefully place the caliper over the pads. You may notice a bit of
resistance in doing this because of the new springs that hold the new pads
in place. Just use a little force to push the caliper in position, then
install the two Allen head bolts and tighten them. Donít forget to put the
plastic grommets back in place. These grommets prevent grime and dirt from
building up on the bolts, which could eventually cause them to rust and
seize. Now reconnect the brake wear indicator on the driverís side.
You donít want
to take chances with your brakes so check and re-check everything making
sure that all bolts and fasteners are tight.
you are ready to put the wheels back on. Once they are re-installed and
tightened, take the car out and test the brakes. You should notice that they
donít stop very well at first. This is normal. Youíll need to seat the
brake pads in order for them to work well. Simply drive the car cautiously
for roughly 50 or so miles, and the brake pads will seat into the new
rotors. Itís also a good idea to pump the brake occasionally during this
time to get the rotors hot and the pads seated quicker.
Well, there you have it - it's
really not too difficult at all. If you would like
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