Brake clunk noise

What causes a brake clunk noise when applying brakes?

A brake clunk noise can be caused by loose caliper bolts, loose caliper bracket bolts, missing or worn abutment clips or a worn abutment. Here’s how to check and correct brake clunk noise.

Understand brake pad movement during application

When you apply your brakes, the brake pads move in to squeeze the spinning brake rotor. The rotating motion of the rotor combined with the squeezing movement forces the “ears” of the brake pad backing plate against the abutment area. In late model brake designs, car makers install stainless steel abutment clips between the backing plate ears and the abutment. The clips dampen brake pad vibration and reduce abutment wear.

But even with routine clip replacement, the abutment area can still develop wear spots and those wear spots allow the brake pad to move too much during brake application, causing a brake clunk sound.

Check all bolts for correct torque

If you’re hearing a brake clunk noise during application, start by checking the caliper bolt and abutment/bracket bolt torque.

Next check abutment clips and the brake abutment areas

The abutment’s job is to stop the brake pad from moving. The abutment clip’s job is to prevent vibration transmission to the vehicle and to prevent abutment wear. The abutment is prone to rust and wear.

Brake caliper abutment areas are prone to rust and wear

Example of abutment wear. This worn “dimple” area allows extra pad movement during braking, resulting in a brake clunk or thunk sound. Replace the abutment

High heat degrades the spring tension of the anti-rattle clips and rust can cause the brake pad “ears” to bind. Always replace anti-rattle clips when you replace brake pads

To eliminate brake clunk

Replace worn caliper brackets/abutment. Lubricate the “land” area under the clips to reduce corrosion and wear. Install new anti-rattle clips. Lubricate the top portion of the clip to allow the pad ears to slide easily.

©, 2020 Rick Muscoplat