BMW 34216855004 Brake Disc, Ventilated

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If either disc requires replacement, it's essential to replace BOTH at the same time to ensure even and consistent braking. New brake pads should also be installed. Apply the parking brake, raise the front of the vehicle, support it on jackstands, and remove the appropriate front wheel. Inspect the disc surface for score marks and damage; light scratches are normal, but deep scoring may necessitate disc refinishing by an automotive machine shop. Ensure the disc isn't machined below its specified minimum thickness, which can be found stamped into the hub of the disc. If the disc is potentially warped, check it for runout using a dial indicator. Some professionals suggest resurfacing the discs during brake pad replacement for a smoother finish. Additionally, inspect the disc for cracks and wear. For removal, unscrew the bolts of the brake caliper mounting bracket, slide off the caliper assembly, and tie it to the front suspension coil spring. Mark the disc's relationship to the hub, remove the bolt securing the brake disc, and then remove the disc. For installation, ensure clean mating surfaces for the disc and hub, align marked points from removal, wipe any preservative coating from a new disc, position the caliper over the disc, and secure it. Finally, install the wheel, lower the vehicle, and depress the brake pedal a few times to ensure brake pads contact the disc. Check the brake operation before driving.

Measure the brake disc diameter on the vehicle and check it against the corresponding brake disc specifications for the front or rear brakes. Additional application information is available through parts data and the authorized BMW dealer parts department. Machine or replace brake discs in pairs per axle. Begin by raising the car and supporting it safely, then remove the wheels. Next, remove the brake caliper carrier bolts and suspend the brake caliper from the chassis using stiff wire, ensuring the hydraulic brake line remains connected. Remove the brake disc mounting screw and take off the disc, inspecting it for cracks, signs of overheating, and scoring. The minimum allowable thickness is stamped on the disc hub. Measure the disc braking surface with a micrometer at eight to ten different points, using the smallest measurement for comparison against the specifications. If the disc does not meet minimum thickness requirements or is damaged, it should be replaced. Clean the disc with brake cleaner before installation, and when installing new rear brake discs, adjust the parking brake accordingly.

To install the brake disc, follow these steps:Ensure the mating surfaces of the disc and hub are clean and flat.Align the marks made during removal and tighten the disc retaining bolt to the specified torque.If a new disc was installed, wipe any anti-corrosion preservative coating from the disc with solvent before installing the caliper.Make sure the disc mounting surface on the hub is free from dirt and corrosion.Slide the caliper into position over the disc, ensuring the brake pads slide past both sides of the disc.Tighten the caliper mounting bolts to the specified torque.Install the wheel and lower the vehicle to the ground, then tighten the wheel bolts to the specified torque.

For a thorough inspection, unbolt the caliper from the steering arm to evaluate the brake pad thickness, brake rotor, condition of the caliper seal, and condition of the caliper slider bolts.