For some technicians, it is a standard operating procedure to remove the caliper bracket and head to the shop’s bench grinder to clean up the surfaces with a wire wheel. Some technician will grind the ears of the brake pads so they will fit into the lands on the bracket. For most late-model vehicles, you could be doing more harm than good.
Many original equipment (OE) and aftermarket calipers and brake pads have surfaces that are plated or treated with coatings to prevent corrosion. By grinding away the surface on the brake caliper or pad, you could be creating a corrosion problem that was not there before.
In a recent technical service bulletin, BMW does not recommend cleaning the caliper bracket pad guides with a wire brush or bench grinder. Instead, the recommended cleaning them with a solvent and apply a thin layer of brake paste or high-temperature brake lubricant. This method is recommended because the bracket is plated with an anti-corrosion layer that can be removed with a bench grinder or file.
Brake pads can have a galvanized finish that needs to remain intact to protect the brake pad backing plate against corrosion. If you encounter a brake pad that does not fit in the caliper bracket, first inspect the caliper bracket for debris and that the abutment clips are fully seated. Also, make sure the pads are in the correct position. Some brake pad sets have inboard and outboard brake pads.
If the pad still will not fit, look at the ears or ends of the brake pad for any signs of deformation or remnants of the stamping process. Some low-quality brake pad manufacturers will use worn stamping dies. A worn stamping die will not produce oversized caliper ears that will not fit in the caliper bracket. Some brake pad manufacturers will not perform secondary processes to ensure the final dimensions of the brake pad. Also, some manufacturers will apply to much paint to the brake pad.
You are better off returning the set of brake pads and purchasing a high-quality set of brake pads than trying to make a substandard pad fit.
Just remember that before you head off to the bench grinder or are about to pull a file from your toolbox, try cleaning up the caliper bracket with a solvent, rag or nylon brush.