Brake Pad Shims: What Are They and When Do They Need Replacement?

Most people understand the main components of a vehicle’s braking system. You have the master cylinder, lines, rotors (or drums), brake pads (or shoes), brake booster, and pedal. But one small component plays a major role when it comes to brake noise.

What are Brake Shims?

Simply put, the main function of brake pad shims is to prevent brake noise. At each corner of a vehicle, brake pads and brake rotors (or drums) sit very close to each other. The only thing that stops them from clanging together is the brake shim.

The brake pad shim is a component which goes in between the rotors and pads to prevent friction from occurring. Basically, the shims keep them aligned with each other, so they can function without generating noise.

If a brake shim were to become damaged or removed, then too many imperfections would exist between the rotors and pads. This would cause them to clang together and make strange noises. You will hear these noises each time you step on the brake pedal.

A lot of newer brake pads come with the shims already attached to them. So, if you are trying to replace your brake parts, there are brake kits available which contain both the pads and shims together.

In other kits, the shims will be separate from the pads and they will include adhesive backings that let you attach the shims to the pads. If you are new to brake pad shim installations, then you should purchase the brake pads which have the shims already attached.

Symptoms of Bad Brake Pad Shims

Most brake pad shims are constructed from a thin metal or rubber material. You can spend more money on higher grade shims that are made from titanium if you want. These will last you a lot longer than the rubber brake shims.The choice all depends on your budget and how often you use your brakes.

If you are a casual driver who only drives short distances each day, then standard low grade shims should be fine. Your vehicle may come with rubber shims already but if you ever need to replace your shims, then you have an important choice to make.

There may come a day when your brake shims end up wearing out or deteriorating from excessive use. Once that happens, you will notice some strange symptoms occur.

  • The main symptom, of course, will be a lot of loud squealing noises coming from your brakes each time you step on the brake pedal.
  • You may also notice the pedal pulsating quite frequently as you press your foot up against it.
  • The worst-case scenario will be a limited brake response, but that should only happen if your brake pads are not able to sufficiently access the brake rotors.

Just replace your shims to fix all these problems before they get worse.

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