Every time you activate the brakes of your BMW, the high amount of friction used to stop the vehicle is turned into great amounts of heat energy. In order for the brakes to operate efficiently, this heat must be removed from the system, and that is the job of the BMW brake disc. This part is made of metal to transfer the heat from the braking surface to where the heat can be removed by the open air. To increase the amount of surface area and, thus, the cooling efficiency, the BMW brake disc uses a series of chambers, called slots, that begin on the outside edge of the disc, and run towards the center. As the BMW brake disc turns, air is drawn into these chambers, and it absorbs the heat from the braking surface. To further increase the surface area for cooling, high-end versions of the BMW brake disc use methods such as cross-drilling and special surface groves. After many years, wear and corrosion will affect the surface of the unit, reducing the life of the brake pads, and rust or other debris may collect in the slots, reducing the cooling ability. Sometimes this type of damage to the BMW brake disc can be corrected by machining the surface of the disc and cleaning the slots thoroughly. When it becomes necessary to replace the BMW brake disc, however, you will find the correct version for most vehicles in our large online catalog, for a great price. Our version meets or exceeds all of the specifications of the original part, and it has a full warranty from the manufacturer. Ordering the new BMW brake disc is as simple as visiting our secure web site at any time, or calling one of our friendly associates, toll-free.
How to Repair a BMW Brake Disc
Like the brakes of your bicycle, your brake disc or rotor makes use of a caliper that squeezes the brake pads against the axle of your wheel, which slows their movement down. Meanwhile, the unmoving tires and their rubber traction on the road will do the rest in stopping your ride. With that said, here's what you need to do in case your brake disc is busted, warped, or significantly compromised:
Difficulty Level: Moderate
What You'll Need
- Brake spray
- Various wrenches
- Heavy rubber mallet
- Turkey baster or siphon
- Jack stands and tire chocks
- Large C-clamp to depress the caliper
- Wheel removal tools such as jack and lug wrench
- Rust buster spray if rotor is rusted to wheel axle plate
Step 1:Put your car on jack stands to hoist it up then remove the wheel. Put wheel chocks on the other wheels to keep the car from rolling. Once you gain access to the disc, check it for signs of damage to see if it needs replacement. If the rotor is thinning out or has track marks on it, that indicates the need to replace it post-haste. If the disc is smooth and level to the outside rim edges, it's fine and it's probably the brake pads that need replacement.
Step 2: Draw the brake fluid out using a siphon of some sort (or a turkey baster) from the master cylinder. Leave the cap off and remove a third of the fluid. Put it in a clean container for possible reuse.
Step 3:Compress the caliper with the C-clamp by placing one side of the clamp onto the caliper's interior side and the other end on the exterior side. Tighten the clamp by hand to depress the caliper. Keep an eye on the level in the master cylinder to avoid overflow.
Step 4:Remove the caliper by unbolting its bolts. Replace the pads along with the rotor itself to ensure smooth uncompromised braking every time. Pad removal should be done carefully if you wish to reuse or recycle them.
Step 5:If you can't set the caliper out of your way in a stable position, hang it somewhere with wire without twisting or disturbing the brake fluid line. Don't depend on the fluid line to hold the caliper up because it could get damaged itself.
Step 6:Pull the disc towards you. If it doesn't slide off smoothly, it might have some rusty edges. You might have to spray it with rust buster, tap the edges of the brake disc with a mallet, or twist hard then pull the rotor back until it comes loose.
Step 7:Slip your new rotor into place to replace your compromised stock rotor. Make sure it's placed against the axle plate and seated all the way back. Place the pads and discs within the caliper properly. Tighten the bolts of the caliper.
Step 8:Use brake spray to clean the brake disc and any leftover rust and debris from the previous rotor. Don't wipe the fluid off. Let it evaporate on its own. Make sure the rotor's surface is free of oil too.
Step 9:Put the wheel back on and do the same steps in removal and replacement of the other rotor on the same axle. Fill the master cylinder with brake fluid (whether a new fluid or the fluid you siphoned earlier).