Brake Hardware Kits: Why Replace Clips and Shims

By Core Brake Parts Tech Team — Circleville, OH warehouse

Replace the clips, shims and springs every time you replace brake pads. That hardware is what holds a pad square to the rotor, lets it slide freely, and keeps it from rattling, and it wears out from heat and corrosion just like the friction material does. Putting fresh pads into tired hardware is one of the most common reasons a brake job comes back with noise, uneven wear or a pull.

What Brake Hardware Actually Does

On a typical floating caliper, the pads do not bolt to anything. They sit in machined channels in the caliper bracket and float there, sliding in and out a tiny amount every time you press and release the pedal. A set of small, inexpensive parts makes that motion controlled and quiet:

• Abutment clips sit between the pad ears and the bracket mounting lands. They give the pad a smooth, uniform surface to ride on and hold the inner and outer pads in position so they do not rattle.
• Anti-rattle clips and springs put light tension on the pads or caliper so they cannot chatter or shift under braking.
• Shims mount to the back of the pad backing plate. They damp vibration between the pad and the caliper piston or fingers and act as a thermal barrier.
• Pad separator (retraction) springs, used on some designs, push the pads away from the rotor after the piston retracts so the pads are not lightly dragging.
• Guide pins and boots let the caliper slide side to side so both pads clamp evenly. The rubber boots keep water and grit out and keep the lubricant in.

Most brake hardware kits bundle the clips and springs for a given caliper design. Some pads also arrive with shims already attached.

Why Old Clips and Shims Should Not Go Back In

Heat cycles take the spring out of the steel

Every stop heats the brake assembly, and every drive afterward cools it. Over thousands of those cycles, clips and springs lose their spring tempering. A clip can look fine on the bench and still have lost the tension that keeps the pad from moving. Once that happens the pad can shift, rattle, or cock slightly in its channel.

Corrosion changes how the pad slides

Caliper brackets are ferrous and rust, especially in road-salt states. Rust grows on the bracket lands and under the clips, and it can build up enough to squeeze the pad so it binds instead of sliding. Old clips that have rusted or worn a groove where the pad ear rides make the problem worse.

Shim adhesive breaks down

Some shims are held on by a pressure-sensitive adhesive. Moisture and heat eventually destroy that bond, and a shim that has shifted or partly let go no longer damps anything. Many current designs add tabs or clips so the shim cannot migrate.

New pads sit differently than worn ones

A fresh pad is much thicker than the worn one it replaces, and it sits in a different spot relative to the clips. Hardware that has taken a set around the old pad does not hold the new one the way it was designed to.

Symptoms of Worn or Missing Brake Hardware

Wagner's noise troubleshooting guidance puts it plainly: vibration is the main source of brake noise, and rust, distorted or loose parts, and heat-fatigued components are what let that vibration start. Power Stop makes the same point from the wear side: bad clips let pads shift, which leads to noise, uneven wear, pulling and binding.

How to Do the Hardware Part of a Brake Job Right

1. Remove the old clips and inspect the bracket. Wire brush the rust off the pad lands and the surfaces where the clips mount. New clips will not seat correctly on top of leftover scale.
2. Check the bracket for wear. If the pad channels are worn or the guide pin bores are out of round, the bracket needs to be replaced, not just cleaned.
3. Service the guide pins. Pull the pins, clean them, and look for rust, bending or a swollen or torn rubber sleeve. Use only a brake-specific caliper lubricant; other lubricants can make the rubber boots and sleeves swell and bind. Replace boots that are torn or flattened.
4. Install the new abutment and anti-rattle clips. They should snap in fully and the pads should slide in them without forcing.
5. Handle shims the way the pad maker specifies. Instructions differ by shim type. Wagner, for example, calls for a light coat of silicone lubricant on the back of constrained-layer shims only, and no chemical compound at all on its molded sound insulators, because chemicals can reduce their effectiveness. Follow the instructions in your pad box.
6. Fit any separator springs. They can be fiddly, which is why they get left out, but they are part of how the pads release from the rotor.
7. Clean and bed in. Clean the rotor faces, pump the pedal before moving the vehicle, and follow the pad manufacturer's break-in procedure.

What to Replace at the Same Time

Hardware is the cheapest part of a brake job, so it rarely makes sense to reuse it. While the caliper is off, look at the parts around it:

• Pads: always as an axle set. See our brake pads, or ceramic brake pads for a quiet, low-dust option.
• Rotors: if they are below minimum thickness, scored, or causing pulsation. Browse brake rotors.
• Calipers: if a piston is sticking, a boot is torn or the caliper is leaking. See replacement brake calipers.
• Brake hoses: if they are cracked or bulge under pressure. See brake hoses.

How Hard Is the Job?

If you can change brake pads, you can change the hardware; it adds only a few minutes per wheel. The work that takes real time is cleaning corrosion off the bracket and freeing a seized guide pin. Basic hand tools, a wire brush, brake cleaner, brake-specific lubricant and a torque wrench cover it. Torque the caliper bracket and guide pin bolts to the values in the factory service manual for your vehicle. If a bracket bolt or pin is seized solid, or the bracket channels are worn, that is the point where many owners hand it to a shop.

Frequently Asked Questions

Do I really need new hardware if the old clips look fine?

Yes. Clips lose spring tension from heat cycling long before they look worn, and trade guidance for technicians is to replace abutment and anti-rattle clips at every pad service even when they appear good.

Can missing shims cause brake squeal?

They can. Shims damp vibration between the pad backing plate and the caliper. A missing, shifted or unbonded shim lets that vibration through, and vibration is the main source of brake noise.

Should I grease the back of the brake pads?

It depends on the pad. Some shim types take a light coat of brake lubricant on the back, some insulators should get nothing at all, and pads without shims may call for a noise compound. Always follow the instructions that come with your pads.

What lubricant goes on caliper guide pins?

Use a lubricant made for brake caliper pins. General-purpose lubricants can attack the rubber boots and sleeves, making them swell and bind the pin.

Are brake hardware kits vehicle specific?

Yes. Clip shape follows the caliper bracket design, so match the kit to your year, make, model and axle, front or rear.

Why are my new brakes making noise with new pads?

The most common causes are reused clips, a rusty bracket under the new clips, a shim that is missing or installed wrong, or a guide pin that is not sliding freely. Check those before blaming the pads.

Sources

1. Tire Review - Brake Hardware Items Often Neglected - functions and failure modes of abutment clips, anti-rattle clips, shims and adhesive breakdown, guide pin boots, bracket corrosion and pad separators
2. MOTOR Magazine - Brake Shop: Brake Hardware - replace clips at every service, brake-only lubricant on pins, shim construction, bracket wear inspection
3. Power Stop - Do You Need New Hardware With New Brake Pads? - heating and cooling weakens hardware; bad clips let pads shift and cause noise, uneven wear and pulling
4. Wagner Brake - Brake System Noise Troubleshooting Tips - vibration as the main noise source, clips losing spring tempering, shim lubrication by shim type