BRAKE PAD DIAGNOSTICS(2)
Inboard brake pad wear is the most common brake pad wear pattern. On a floating caliper brake system, it is normal for the inner to wear faster than the outer – but this difference should only be 2-3 mm.
More rapid inner pad wear can be caused by a seized caliper guide pin or slides. When this occurs, the piston is not floating, and equalizing force between the pads and the inner pad is doing all of the work.
Inner pad wear can also occur when the caliper piston is not returning to the rest position due to a worn seal, damage or corrosion. It can also be caused by a problem with the master cylinder.
To correct this kind of wear, take the same steps as fixing outer pad wear as well as inspect the hydraulic brake system and caliper for residual pressure and guide pin hole or piston boot for damage, respectively. If the pin holes or piston boot are corroded or damaged, they should be replaced.