Brake & Front
Recently, we were moving around a 2016 Kia Soul in the Brake & Front End Garage for a video shoot. All of a sudden, the right rear wheel locked up solid. The diagnostic minds in the garage started to come up with a cause based on what we were seeing. The people standing around blamed the parking brake, ABS isolation solenoids and even the brake line developing an internal flap restriction. It was not until the wheel was pulled that we saw the state of the brake pads and rotors.
The inspection hole can only tell you so much about the condition of the brake pads.
After the caliper was pried off with a screwdriver, we saw the condition of the brake pads. The friction material was worn down to 4mm and was getting close to the wear sensors on both sides. The inboard pad on the right side was missing half of the friction material.
The inboard pad with the missing material was wedged between the caliper bracket and rotor. This is what caused the rotor and wheel to lock. When the caliper bracket was removed, the friction material on the outboard pad fell off the backing plate.
So, what caused this failure? The Soul in question had only 65,000 miles. The owner’s commute is on freeways 90 percent of the time. But, it is a question of exposure to a very corrosive environment over four years. The corrosion did attack the backing plate, shim and surfaces that make contact with the bracket. But, the area of the backing plate to which the friction material attaches received the most significant corrosion. The corrosion caused the friction material to delaminate from the backing plate.
This is a difficult condition to spot using normal inspection methods. The typical failure starts at the ends of the brake pads. Small pieces can break off the ends and can be seen between the caliper bracket and rotor. Some failures leave the fraction material intact, but you can slide a feeler gauge between the backing plate and friction material.