CHANGING BRAKE PADS

Brake pads are a wear part and therefore need to be replaced otherwise you won't be able to stop your car. Some brake pads are known as "squealers" because they have embeded screws in the pad that rub on the rotor (disk) when the pad is low. The problem with this is that it destroys your disk. Don't buy "squealers". BMW has a small electronic sensor that when worn down it will make an electrical connection with the rotor and thereby cause the brake replacement light to come on. Much better than "squealers".

EQUIPMENT, SKILL, TIME, PARTS

Tools I use: screw driver that is part of the trunk tool kit #71-11-1-179-629. Anti Squeal glue 7mm allen that fits a socket ratchet and needle nose pilers

This is a moderate skill level part to replace.

This replacement should take about hour or less since you are replacing at least two sets at a time.

Make sure your parts work for your vehicle. The parts I got are these: Front Brake Pads #34-11-6-779-652-M49 and Rear Brake Pads #34-21-6-761-240

Front Brake Sensor #34-35-6-751-311 and Rear Brake Sensor #34-35-1-164-372

STEP #1:

I have had false sensor readings in the past due to the wire from the sensor getting damaged.

Before you go to all the trouble of changing the brakes I would first check the condition of the sensor wire to make sure it is not damaged.

STEP #2:

Note that the sensor wire is held in place by the rubber lid for the brake fluid bleed valve. Be sure to route the new sensor wire this same way to avoid the wire getting damaged. Check to make sure that the brake fluid reservoir level is low enough so that it can handle having the fluid pushed back into it without the reservoir overflowing. If the reservoir is to the max then you need to take some fluid out. What I usually do is change all 4 brake pad sets at one time then I flush the brake fluid and fill the reservoir to max. That way when the reservoir is "low" that just means that my pads are worn down.

STEP #3:

After lifting the car and removing the tire you will next need to remove the spring clip that holds the brake caliper in place. The easiest way I have found to do this is to use the little screw driver like a lever arm and push the spring clip towards the caliper (in this picture that means to the right). The spring has little hooks on the arms that go into those holes and so by pressing it in you are lining the hooks up with the holes. Now you just need to pull the spring clip towards you (away from the car) to remove the clip. To re-install them you just have to squeeze towards the caliper then push in.

STEP #4:

If the sensor is damaged just yank it out. If it is still good you can either reach in there with some needle nose pilers and pull it out or you can wait until you get the pads off and do it then. Either way at this point I like to open up the caliper a bit by gently using the screw driver as a pry bar to push the piston back into the caliper. You will need this extra room to get the bigger pads in and it is easier to do at this stage. If you have a fancy tool you can wait until you have the caliper off and then use your fancy tool or some wood and a crowbar.

STEP #5:

The caliper is held on with two caliper guide bolts. The guide bolts are contained inside rubber sleeves and the rubber sleeves have a plug (or should have a plug) to keep the bolts protected from dust etc. Take the plug out and on my car I need a 7mm allen wrench to undo the bolts. The bolts are one on the top and one on the bottom. Tightening torque on these is 30 Nm (22 ft lb). The caliper slides on these guide bolts so I like to completely remove them and polish them up to make sure they are clean and smooth.

STEP #6:

Since you should not disconnect the brake line the caliper will awkwardly not touch the ground. You also don't want the weight of the calipher hanging on the brake line so you either have to have a little platfrom to rest the caliper on or use a hanging wire of some sort. In this picture I just used some sytrofoam blocks. At this point I inspect piston and make sure it is nice and clean and I finish pushing it all the way in.

STEP #7:

Personally I like using anti-squeal glue because it keeps my brakes from squeaking. It is basically a silicone rubber that you put on the parts of the brake pads that contact the caliper and it acts like a rubber gasket to absorb any vibrations that make the squeal noise.

attach the new sensor (as needed) and install the pads. Re-assemble and you are done.

BAVARIAN TINKER

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