Brake Pad Shims: Everything You Need to Know for Safer Brakes and Longer Component Life

Brake pad shims are small but critical components in your vehicle’s braking system, often overlooked until they cause problems like noise, vibration, or premature wear. These thin, flat metal, rubber, or composite strips sit between the brake pad and caliper, serving multiple roles: reducing noise, ensuring even pressure distribution, preventing corrosion, and extending the life of both pads and rotors. Without the right shims—or with worn-out ones—your brakes may feel rough, produce annoying squeals, or even fail to stop as effectively. This guide breaks down everything you need to know about brake pad shims, from their purpose and types to installation best practices and maintenance tips, so you can keep your brakes quiet, safe, and reliable.

What Exactly Are Brake Pad Shims, and Why Do They Matter?

Brake pad shims are precision-engineered spacers designed to fill microscopic gaps between the brake pad and the caliper bracket or piston. When you press the brake pedal, hydraulic pressure forces the caliper’s pistons to clamp the brake pads against the rotors, creating friction to slow the vehicle. Without shims, several issues can arise:

• ​Noise: Metal-on-metal contact between the pad and caliper can vibrate at frequencies that produce high-pitched squeals or rattles, especially at low speeds.

• ​Uneven Wear: Pads may shift or rub unevenly against the rotor, causing one side to wear faster than the other.

• ​Reduced Performance: Misalignment can lead to inconsistent braking force, increasing stopping distances.

• ​Corrosion: Gaps allow moisture and debris to collect, leading to rust on the pad backing or caliper, which weakens the brake system over time.

Shims address these problems by:

1. ​Dampening Vibration: Rubber or synthetic shims absorb vibrations between the pad and caliper.

2. ​Adjusting Clearance: Metal shims (often copper or aluminum) take up space to ensure the pad sits flush against the caliper.

3. ​Preventing Corrosion: Some shims have anti-corrosive coatings or are made from materials that resist rust.

4. ​Extending Component Life: By promoting even wear, shims help brake pads and rotors last longer, saving you money on replacements.

Types of Brake Pad Shims: Materials and Designs

Not all shims are created equal. The type you need depends on your vehicle’s make, model, brake pad material, and driving conditions. Here are the most common types:

1. ​Metal Shims (Copper, Aluminum, or Steel)​​

These rigid shims are typically thin (0.005–0.020 inches) and made from non-ferrous metals like copper or aluminum, which resist corrosion. Steel shims are less common due to their tendency to rust but may be used in heavy-duty applications.

​Best For: Vehicles with performance brakes or those driven aggressively, where precise clearance adjustment is critical. Metal shims maintain their shape under high heat, ensuring consistent performance during hard braking.

​Drawback: They conduct heat, which can transfer more warmth to the caliper and brake fluid. In extreme cases, this may lead to brake fluid boiling if not paired with high-quality fluid.

2. ​Rubber or Synthetic Shims​

Made from elastomers like nitrile rubber or polyurethane, these flexible shims act as cushions. They conform to minor imperfections in the pad or caliper surface, absorbing vibrations and reducing noise.

​Best For: Everyday passenger vehicles, especially those prone to brake squeal. Rubber shims are popular in OEM (original equipment manufacturer) setups because they’re cost-effective and quiet.

​Drawback: Over time, heat and pressure can cause them to degrade, harden, or crack. Inspect rubber shims every 15,000–20,000 miles for signs of wear.

3. ​Composite Shims​

Combining metal and rubber layers, composite shims offer the best of both worlds: rigidity for alignment and flexibility for vibration damping. Some feature adhesive backing to stay in place during installation.

​Best For: Drivers who want a balance of durability and quiet operation. They’re common in aftermarket brake pad kits for trucks and SUVs.

4. ​Adhesive-Backed vs. Non-Adhesive Shims​

Some shims come with a sticky coating to hold them in place during installation, while others require careful positioning. Adhesive-backed shims reduce the risk of misalignment, making them ideal for DIYers.

How to Choose the Right Brake Pad Shims for Your Vehicle

Selecting the correct shims isn’t just about grabbing any off the shelf—it requires attention to your vehicle’s specs and braking needs. Here’s how to pick the right ones:

1. ​Match the Vehicle Make and Model​

Brake systems vary widely between cars, trucks, and SUVs. Always check your owner’s manual or consult a parts database (like RockAuto or NAPA) for shim recommendations specific to your vehicle. Aftermarket brake pads often include shims, but if you’re replacing pads yourself, verify that the shim thickness and design match the OEM specifications.

2. ​Consider Brake Pad Material​

• ​Ceramic Pads: These low-dust, quiet pads often work best with thin rubber or composite shims to prevent noise without adding bulk.

• ​Semi-Metallic Pads: Harsher on rotors but durable, they may require metal shims to manage heat and vibration.

• ​Organic Pads: Made from natural fibers, they’re softer and prone to wear. Rubber shims can help extend their life by reducing friction.

3. ​Evaluate Driving Conditions​

If you frequently drive in stop-and-go traffic, tow heavy loads, or drive on mountain roads, opt for heavy-duty shims (e.g., thicker metal or composite designs) to handle increased heat and pressure. For daily commuting, standard rubber or composite shims usually suffice.

Installing Brake Pad Shims: Step-by-Step Best Practices

Improper installation is a common cause of shim failure. Follow these steps to ensure a proper fit:

1. ​Gather Tools and Materials​

You’ll need:

• New brake pads (with or without shims—check if yours come included).

• Brake shim kit (if purchasing separately).

• Jack and jack stands.

• Lug wrench.

• C-clamp or brake piston tool.

• Torque wrench.

• Brake cleaner.

• Gloves and safety glasses.

2. ​Remove the Old Brakes​

Lift the vehicle, remove the wheels, and retract the caliper pistons using a C-clamp. Be careful not to damage the brake line. Unbolt the caliper bracket and set it aside.

3. ​Clean the Caliper and Rotor​

Use brake cleaner to remove dirt, grease, and old brake dust from the caliper bracket, rotor, and pad contact points. A wire brush can help scrub away rust or debris.

4. ​Install the Shims​

• ​Metal Shims: Slide them between the pad and caliper bracket, aligning them with the pre-drilled holes or slots. Ensure they lie flat—no bending or warping.

• ​Rubber Shims: Press them into place, making sure they cover the entire contact area between the pad and bracket. Avoid stretching or tearing.

• ​Composite Shims: If adhesive-backed, peel off the backing and stick them to the pad. If not, position them as you would metal or rubber shims.

5. ​Reassemble the Brakes​

Slide the brake pads into the caliper bracket, then reattach the bracket to the steering knuckle or rotor mount. Tighten the bolts to the manufacturer’s torque specification (usually 25–35 ft-lbs for caliper brackets).

6. ​Bed-In the Brakes​

After installation, bed-in the brakes by doing 10–15 slow, hard stops from 30–40 mph. This transfers friction material from the pads to the rotor, ensuring even wear and preventing noise.

Maintaining Brake Pad Shims: When to Inspect and Replace Them

Shims don’t last forever. Even the best ones degrade over time due to heat, pressure, and exposure to road grime. Here’s how to care for them:

1. ​Regular Inspections​

Check shims every 10,000–15,000 miles or during routine brake pad replacements. Look for:

• ​Cracks or Tears: Rubber or composite shims may split, losing their ability to dampen vibration.

• ​Corrosion: Metal shims can rust, especially if exposed to salt or moisture.

• ​Misalignment: Pads that shift or rub unevenly may indicate a loose or worn shim.

2. ​When to Replace Shims​

Replace shims if:

• You notice increased brake noise (squealing, rattling).

• The pads show uneven wear (one edge thinner than the other).

• The rotors have grooves or discoloration from misalignment.

• The shims themselves are cracked, corroded, or deformed.

3. ​Pro Tip: Replace Shims with Every Brake Job​

Most mechanics recommend replacing shims whenever you replace brake pads. Even if the old shims look okay, they’ve likely lost some of their elasticity or alignment properties, which can compromise performance.

Common Questions About Brake Pad Shims

Q: Can I reuse old shims when replacing brake pads?

A: It’s not recommended. Old shims may be worn, corroded, or misshapen, leading to noise or uneven wear. Always install new shims with fresh pads.

Q: Do brake pad shims affect braking performance?

A: Yes. Misaligned or worn shims can cause the pads to drag or shift, reducing stopping power. Properly installed shims ensure even contact with the rotor, maximizing braking efficiency.

Q: Are aftermarket shims as good as OEM?

A: High-quality aftermarket shims (from brands like Akebono, Bosch, or EBC) meet or exceed OEM standards. However, avoid cheap, generic shims—they may not fit correctly or last long.

Conclusion: Don’t Overlook the Small Parts That Keep Your Brakes Safe

Brake pad shims are unsung heroes of your vehicle’s braking system. By reducing noise, preventing wear, and ensuring even pressure, they keep your brakes working reliably mile after mile. Whether you’re a DIY enthusiast or rely on a mechanic, taking the time to choose the right shims, install them correctly, and maintain them will pay off in quieter rides, longer component life, and safer stops. Remember: when it comes to brakes, no part is too small to matter.