Causes And Identification of Abnormal Brake Pad Wear

Brake pads are core components of a vehicle's braking system, and their wear rate and uniformity are directly related to driving safety. Under normal circumstances, brake pads should wear evenly and within their service life (typically 30,000-60,000 kilometers). If abnormal wear, uneven wear, or cracks occur, the cause should be promptly investigated. The following detailed analysis covers "Causes of Abnormal Wear" and "Quick Identification Methods" to help vehicle owners detect problems early.

1. Common Causes of Abnormal Brake Pad Wear

(1) Wear Caused by Braking System Malfunction

• Brake Caliper Seizure: Rust or insufficient lubrication can cause the caliper piston or guide pin to become stuck, resulting in prolonged, light contact between the brake pad and the brake disc. This friction persists even when the brakes are not applied, causing excessive wear on one side or a single brake pad (common in rainy weather or on vehicles parked for extended periods).

• Brake Line Leakage/Air Intake: Brake fluid leakage or air in the line can lead to uneven braking pressure, placing excessive force on some brake pads and causing "uneven wear" (e.g., the left front wheel wears faster than the right front wheel).

• ABS system malfunction: When the ABS pump or sensor is malfunctioning, the contact angle and force between the brake pad and the brake disc during braking become unstable, potentially causing localized excessive friction and irregular wear patterns.

(2) Impact of driving habits and road conditions

• Frequent sudden braking or prolonged heavy loading: Sudden braking causes a sudden increase in friction between the brake pad and the brake disc, exacerbating wear. Prolonged braking with a full load or towing a heavy object increases the braking load, causing wear to be 30%-50% faster than when the vehicle is unladen.

• Frequent braking on mountain roads or steep slopes: Frequent braking on downhill slopes causes the brake pads to remain at high temperatures, which can lead to hardening or carbonization of the material due to overheating, accelerating wear and even causing abnormal wear after "thermal decay."

• Frequent braking while following a vehicle at low speeds: In congested urban traffic, frequent light braking can cause the brake pads to enter a semi-friction state, preventing timely heat dissipation and potentially causing uneven wear.

(3) Parts Quality and Installation Issues

• Inadequate Brake Pad Material: Low-quality brake pads contain excessive impurities, uneven friction material density, or excessive metal content. This can lead to rapid wear (possibly requiring replacement within 20,000 kilometers) and easily scratch the brake disc.

• Improper Installation: Incorrectly adjusted clearance between the brake pad and caliper, loose retaining screws, or failure to apply high-temperature grease as required can cause misaligned braking force and unilateral or localized excessive wear.

• Poor Brake Disc Condition: Deep grooves, deformation, or rust on the brake disc surface can exacerbate abnormal brake pad wear (e.g., "grooved" wear marks on the pad surface).

(4) Environmental and Maintenance Factors

• Corrosion in Harsh Environments: Prolonged driving in rainy, muddy, or coastal areas can expose brake pads to moisture and salt corrosion, leading to edge oxidation, detachment, and "chip-like" wear.

• Failure to Regularly Maintain the Braking System: Brake fluid that has not been replaced for an extended period (over two years) can deteriorate, affecting braking pressure. Lack of lubrication on the caliper guide pins can cause poor return of the brake pads and exacerbate wear.

2. How to Identify Abnormal Brake Pad Wear

(1) Visual Observation

• Thickness: Normal brake pad thickness is approximately 10-12mm. Wear below 3mm requires replacement. If the thickness difference between the two brake pads on the same axle exceeds 2mm (e.g., 3mm on the left front and 6mm on the right front), this indicates abnormal "uneven wear."

• Surface Condition: Normal wear should indicate a smooth surface. The following conditions are abnormal:

Deep grooves, cracks, or "dents" in certain areas;

Obvious chipping or flaking on the edges;

Blackening or carbonization of the surface (caused by high temperatures).

• Dust Distribution: Dust generated by brake pad wear should adhere evenly to the wheel hub. If there is significantly less dust on one side than on the other, this may indicate binding or abnormal wear of the corresponding brake pad.

(2) Driving Experience

• Abnormal Braking Squeak: A "squealing" or "scratching" sound when lightly applying the brakes (excluding the normal sound of a new pad breaking in) may indicate uneven brake pad wear or direct contact between the metal lining and the brake disc.

• Soft/Slippery Braking: A longer pedal stroke and reduced braking force when braking may indicate excessive brake pad wear. Sideways vehicle deviation during braking is often due to abnormal brake pad wear on one side or a caliper malfunction.

• Brake Judder: Noticeable shaking of the steering wheel or vehicle body during braking may indicate uneven wear of the brake pad, leading to unstable friction coefficient, or brake disc deformation due to wear.

(3) Tool Inspection Method

• Caliper Measurement: Use a vernier caliper to measure the remaining thickness of the brake pad and compare it to the standard value in the vehicle manual. A value below the lower limit indicates abnormal wear.

• Brake Test: Lightly apply the brakes on a safe road surface to observe even contact between the brake disc and pad (you can use the tire-to-road friction marks to assist in this assessment). Deeper brake marks on one side may indicate abnormal brake pad wear.

Abnormal brake pad wear is a serious concern. Ignoring it can lead to serious consequences such as brake failure and brake disc damage. During daily driving, it's recommended to visually inspect the condition of your brake pads monthly and perform a maintenance inspection of the brake system (including calipers, discs, and brake fluid) every 20,000 kilometers. Furthermore, develop a habit of driving smoothly and avoiding frequent, sudden braking to reduce the risk of abnormal wear. If abnormal wear is discovered, promptly investigate the cause and, if necessary, replace the brake pads and repair any related faulty components to ensure safe braking.And when you replace brake pads or other brake parts,you need to choose reliable and high-performance brake pads,which can make you safer.Our EV is a reliable brake parts supplier,you can visit our website:https://www.evfriction.com.  Or you can call us by +86-13363216781,and email us by jessicabrakes12@gmail.com if you want to order or consult.