Are The Shims On Brake Pads Necessary?

Brake Pad Shims are a key component in the car’s braking system. They are thin layers of rubber or metal sheets installed between the brake pads and the brake disc (bottom). The main purpose of brake pad shims is to reduce disc brake pad noise. They provide a smoother, quieter driving experience by absorbing vibration and noise.

You may ask: Are the shims on brake pads necessary? Shims on brake pads, also known as brake anti-noise shims or brake shims, are typically not absolutely necessary for the fundamental functioning of the brake system. However, they do serve a number of important purposes that can enhance the performance and durability of the brake pads.

Noise Reduction: The primary function of brake shims is to reduce noise. When brake pads are applied to the brake disc, they can generate vibration and noise due to the frictional forces involved. The shim acts as a damping layer, absorbing these vibrations and significantly reducing or eliminating the associated noise.

Thermal Insulation: Shims can also provide a degree of thermal insulation between the brake pad and the brake caliper. This helps to reduce heat transfer to the caliper, which can extend the life of the caliper components and maintain their structural integrity.

Shock Absorption: The shim layer adds a degree of cushioning or shock absorption, which can help to reduce the impact forces transmitted through the brake system during heavy braking. This can prolong the lifespan of brake components and improve overall ride comfort.

While brake shims are not strictly necessary for braking functionality, they offer numerous benefits that can enhance the driving experience and brake system durability. The addition of shims is a common practice in many modern vehicle brake systems, particularly in those designed for quiet and smooth operation.

Brake Pad Shims are thin layers of material installed between the brake pads and brake calipers (or pistons). Their main function is to reduce braking noise caused by small unevenness. OEM brake pad market and Aftermarket brake pad market There are several different types and materials of brake pad pads:

Rubber Shims

This is the most common type, made of rubber or rubber-like material, which has good flexibility and can absorb vibration and reduce noise. Common brake shims in the after-sales market mainly include woven brake shims.Here are some characteristics and benefits of rubber shims, especially woven brake shims:

1. Noise Reduction: Rubber shims are designed to dampen the vibrations that can cause brake squeal or chatter. They provide a barrier between the brake pad and the caliper, which helps to mute the noise generated during braking.

2. Vibration Absorption: The flexibility of rubber allows it to absorb vibrations from the braking process, leading to a smoother and quieter braking experience.

3. Woven Construction: Woven brake shims are made from interlaced rubber threads, which provide additional strength and durability compared to solid rubber shims. This construction can better withstand the heat and pressure of the braking system.

4. Heat Resistance: While rubber shims may not handle extreme heat as well as metal shims, they are designed to withstand the typical temperatures encountered in everyday driving conditions.

5. Compatibility: Rubber shims are compatible with most brake systems and are often the default choice for original equipment (OE) brake pads.

Metal Shims

Metal shims, typically constructed from materials like stainless steel or aluminum, serve a critical role in the braking systems of vehicles. Here’s a breakdown of their characteristics and benefits:

1. Heat Dissipation: Metal shims are particularly effective at conducting and dissipating the heat generated during braking. This property is crucial because excessive heat can lead to brake fade, which diminishes braking efficiency.

2. Durability: Being made of strong materials, metal shims are more resistant to wear and tear compared to rubber shims. This increased durability means they generally have a longer service life.

3. Stability: The rigidity of metal provides a stable support base for the brake pads, ensuring consistent contact with the brake rotor and even wear across the pad surface.

4. Noise Reduction: While metal shims might not be as effective as rubber shims in dampening noise, they can still contribute to reducing vibrations and the associated noise, especially when combined with other materials or coatings.

5. Corrosion Resistance: Stainless steel shims are resistant to corrosion, which is an important factor in brake systems that are exposed to various weather conditions and road salts, especially during winter months.

6. Strength: Metal shims can withstand higher pressures and forces compared to other materials, making them suitable for high-performance vehicles or those frequently used in demanding conditions.

7. Maintenance: Metal shims may require less frequent replacement than rubber shims due to their longevity, which can be cost-effective in the long run.

Rubber Steel Rubber Brake Shims (RSR shim)

These shims have rubber coated on a metal base to provide better damping characteristics and reduce noise.

RSR (Rubber Steel Rubber) brake pads are brake pads made of composite materials, they combine the properties of metal and rubber to provide better performance. This type of gasket usually has the following characteristics:

1. 1. Vibration and Noise Reduction: The rubber layer absorbs vibration and reduces noise, providing a quieter braking experience.

1. 2. Thermal Stability: The metal layer (usually stainless steel) provides good thermal stability, helping to maintain the shape and performance of the gasket at high temperatures.

1. 3. Durability: The metal layer increases the durability of the gasket, allowing it to withstand more wear and tear.

1. 4. Anti-corrosion: Metallic layers often have anti-corrosion properties, making them suitable for use in a variety of environmental conditions.

5. Environmentally Friendly: Some RSR gaskets may use environmentally friendly materials to reduce environmental impact.

Titanium Brake Pad Shims

Titanium Brake Pad Shims are a component specially designed for high-performance braking systems. Their main function is to reduce the heat generated by the brake pads during braking and transferred to the brake calipers. These gaskets are typically made from Grade 5 titanium alloy (6AL-4V/ASTM B348), a material that has a much lower thermal conductivity than traditional aluminum or steel gaskets, providing better insulation.

The effect of titanium alloy brake pad gaskets has been verified by actual tests. For example, laboratory testing by EBC Brakes shows that using titanium shims can reduce the amount of heat transferred through the brake pads to the calipers by approximately 90°F (~50°C)

. This significant thermal isolation helps extend the life of the brake caliper’s paint and seals and reduces overheating of the brake fluid, thereby reducing the risk of brake fade.

In practical applications, titanium brake pad spacers are considered particularly important for vehicles that frequently participate in track driving. Not only do they help protect the brake calipers from overheating, they also reduce the possibility of brake fluid boiling and brake fade, improving the overall performance and reliability of the brake system.

In conclusion

In summary, while brake shims are not strictly necessary for braking, they do offer numerous benefits that can enhance the overall performance and durability of the brake system. For many drivers, the reduced noise and improved ride comfort provided by brake shims make them a worthwhile addition to the brake system.