BMW E46 service brakes consist of hydraulic brake calipers, one at each wheel. When the brake pedal is pressed, brake pads inside the calipers clamp the brake rotors (or discs) and slow down the vehicle. The parking or emergency brake uses an entirely separate braking system. A pair of mechanically operated cables attached to the parking brake handle actuates parking brake shoes inside the rear wheel drums (which are integral with the rear brake rotors). I cover procedures for parking brake cable adjustment and brake shoe replacement in separate tech articles.
You should check your brake rotors every major service that you perform on your BMW. Inspect your brake rotors for cracks, scoring and replace them if you have a pulsation when braking. Brake rotors can look good and still be worn out. If there is a ridge around the edge of the brake rotor, this is a good sign that they are worn out. Measure the brake rotor thickness to determine if they need replacing using a micrometer. When measuring, measure in a few different spots and use the lowest number. Factory BMW rotors have minimum thickness stamped on the brake rotor hub flange.
- Front brake rotor minimum thickness: All models except M3 20.4 mm (0.80 in) M3 26.4 mm (1.04 in)
- Rear brake rotor minimum thickness: All models except M3 17.4 mm (0.68 in) M3 18.4 mm (0.73 in)
It is also a good idea to inspect and replace your brake pads when replacing the brake rotors. See our Pelican Parts technical article on Replacing Your Brake Pads. Remember to always replace your brake rotors in pairs per axle.
Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.
Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you are working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.
Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.
Lift and support the axle of the vehicle. See our Pelican parts technical article on Jacking Up Your BMW. Remove the wheels on the axle you are replacing the brake rotors on.
Using a flathead screwdriver, slowly push the brake caliper piston in. This allows the brake caliper to be pulled off the brake rotor easily.
Working from behind the brake caliper. Remove the two 16mm brake caliper bracket mounting bolts (green arrows). Remove the brake caliper bracket from the wheel carrier and leave it hanging using a Zip Tie or a metal coat hanger. Do not allow caliper to solely hang by the brake hose.
Next, using a 6mm Allen bit, remove the brake rotor mounting fastener. Then remove the brake rotor from the hub.