Brake Pad Shims Installation: Procedure, Needed Tools & More
Brake pad shims are small pieces of steel or aluminum that sit between the brake pads and caliper. Their purpose is to reduce brake noise, vibration (NVH), and heat transfer. By creating a barrier between the pad backing plate and caliper, shims reduce the transfer of vibration that can cause irritating brake squeal. They also reflect heat back into the pad, helping to keep the calipers cooler and preventing brake fade. Shims come pre-installed on most new brake pads, but may need to be transferred over or replaced when installing new pads. This guide will cover when and how to install new brake pad shims.
When to Install Shims
Brake pad shims help reduce brake noise and vibration by preventing metal-to-metal contact between the brake pad backing plate and caliper bracket. Some signs that your vehicle may need new brake pad shims include:
Squealing or squeaking noises when braking – This high-pitched noise is typically caused by vibration of the brake pad. Installing shims dampens vibration and eliminates the squeal.
Vibration when braking – Excessive vibration during braking can indicate the pad is moving or vibrating in the caliper bracket. Shims provide a buffer to prevent this movement.
Roughness during braking – If you feel roughness or pulsation when applying the brakes, damaged or missing shims could be allowing the pad to move and cause uneven braking.
Loose brake pads – Without shims, pads can move and rattle inside the caliper bracket. Shims hold the pads snugly in place.
If your brake pads are due for replacement, it’s a good idea to install new shims at the same time. Most vehicles require shims on both leading and trailing brake pads. Refer to your vehicle maintenance schedule to determine when to replace shims.
Tools Needed
To complete a brake pad shim installation, you will need some basic tools including:
- Socket set – Needed to remove the caliper bolts and wheel lug nuts.
- Screwdrivers – Used to remove clips or screws securing the pads and shims.
- Brake cleaner – Helps clean away any debris or oil on the brake parts.
- Gloves – Protect your hands from brake dust and fluids.
- C-clamp or brake caliper tool – Pushes the caliper piston back into place.
- Torque wrench – Ensures proper tightening of bolts to specifications.
- Brake grease – Lubricates contact points on the caliper and pads.
Having these basic tools on hand will make the brake pad shim installation process much smoother. Always refer to your vehicle’s factory service manual for the exact tools required for your specific make and model.
Removing the Wheels
The first step in replacing brake pads is to remove the wheels to access the brake caliper and pads. This involves jacking up the vehicle and removing the lug nuts that secure the wheels.
Use a jack to raise the vehicle high enough so that the wheels are lifted off the ground. Place jack stands under the vehicle for security. Then, using a lug wrench, loosen each lug nut securing the wheel. Once all lug nuts are loosened, you can remove the wheel from the vehicle.
Be sure to block the wheels that remain on the ground to prevent the vehicle from rolling. The emergency brake should also be engaged for further security. With the wheels removed, you’ll have access to the brake components to begin replacing the pads.
Source: https://www.youtube.com/watch?v=VbNLdcH8Gqo
Removing the Caliper
Before installing new brake pad shims, you’ll need to remove the caliper that holds the brake pads in place. Here are the steps for properly removing the caliper:
Begin by locating the bolts that hold the caliper in place. There are usually two bolts on the back of the caliper. Use a socket wrench to loosen and remove these bolts.
With the bolts removed, you can now detach the caliper from the brake assembly. Be very careful when handling the caliper, as it can be quite heavy. You don’t want it to drop and become damaged.
Use a bungee cord or some other support to hang the removed caliper securely out of the way. This will allow you access to the brake pads while keeping the caliper protected. Make sure it is hung securely and will not fall during the shim installation process.
With the caliper safely hung out of the way, you can now access the brake pads and proceed with replacing them and installing new shims.
Removing the Old Pads
After removing the caliper, you can now access and remove the old brake pads. First, locate the pad retaining pins that hold each pad in place. Carefully remove these pins and set them aside. The old pads should now slide out easily.
Inspect the back of the pads for any shims that may be present. Shims are small thin pieces of metal that help reduce brake noise. If your old pads have shims attached, gently pry them off and set them aside. You’ll be reusing these shims when installing the new pads. According to Edmunds, “Slide out the old brake pads” during this step. Be mindful not to damage them as you remove the old pads from the caliper bracket.
With the old pads removed, now is a good time to inspect the brake rotor surface. Look for any grooves, glazing, or uneven wear. If the rotors look worn, you may need to replace them as well for optimal brake performance.
Installing the New Shims
Before installing the new shims, you’ll want to thoroughly clean the caliper bracket where the brake pads sit. Use a wire brush or sandpaper to remove any debris or rust buildup. The shims need to make flush contact with the caliper bracket in order to work properly.
Refer to your vehicle repair manual for the proper shim orientation and placement. Usually the shims will go in between the caliper bracket and the brake pads. The shims may have a tab or projection on one side – this side should face the caliper bracket. Alternatively, the shims may be flat on both sides. In this case, orientation doesn’t matter as much.
Make sure the shims are sitting flat against the caliper bracket before installing the pads. You may need to bend or adjust the shims slightly to get them to sit flush. Proper shim installation is crucial, as incorrectly installed shims can lead to brake noise, uneven pad wear, and poor braking performance.
Installing the New Pads
When installing new brake pads, it’s crucial to orient them properly in the caliper bracket. The pads will have markings indicating which side should face the rotor. Aligning the pads incorrectly can lead to reduced braking power and premature wear.
Many pads come with hardware clips that help hold them in place. Remove any old clips and install new ones included with the brake pads per the manufacturer instructions. The clips slide over the outer edge of the pads.
Before inserting the new pads into the caliper bracket, apply a thin layer of high temperature brake lubricant on the contact points where the pads slide. This helps reduce noise and ensures smooth movement within the caliper. Avoid getting grease on the rotor contact surface of the brake pads. This video shows how to properly lubricate the brake pad slides and shims.
Reinstalling the Caliper
After installing the new brake pads and shims, you can reinstall the caliper. It’s crucial that the caliper bolts are torqued to the vehicle manufacturer’s specs, usually around 30-40 ft-lbs. Using a torque wrench helps ensure proper tightness.
With the caliper back in place, inspect the brake fluid reservoir under the hood. If the level has dropped significantly, top it off with fresh, clean brake fluid (like DOT 3 or DOT 4). Avoid mixing different types of brake fluid.
To complete the job, bleed the brakes to remove any air bubbles that may have gotten into the lines when working on the caliper. Air in the lines can cause a soft or spongy brake pedal feel. Bleed each wheel cylinder one at a time, starting with the one furthest from the master cylinder. Have a friend pump the brakes while you open and close the bleeder valve. Catch the old fluid in a container. Repeat the process until you have clean, bubble-free fluid coming out.
After bleeding the brakes, test them at low speeds to ensure proper operation before taking the vehicle out on the road. The brakes should feel firm and stop the vehicle like normal.
Conclusion
After the brake pads and shims have been installed, it is crucial to properly bed in the new pads. This involves taking the vehicle up to speed and braking several times in succession to transfer an even layer of brake material onto the brake rotor surface. Follow the bedding procedure recommended by the brake pad manufacturer.
Signs that the new brake pads and shims have been installed correctly include:
- No brake squealing or other noises when coming to a stop
- Firm brake pedal feel with no sponginess or loss of pressure
- No vibration in the brake pedal when braking
- No looseness or rattling from the caliper bracket
- Brake pad retaining clips and hardware installed securely
If any issues are noticed after install, the brake system should be inspected again to ensure proper installation of all components. With quality parts installed correctly, the new brake pads and shims should provide miles of smooth, quiet braking performance.