The purpose of brake shims is to reduce the noise that comes from braking your vehicle. These anti-squeal shims are basically adhesive (or non-adhesive) pads made of either rubber or metal. They go in between the middle of the brake calipers and brake pads.
That way, the brake shims can adjust the differences and fix the imperfections between the two so that the noises are reduced or eliminated entirely. At the most, you will hear a little bit of rattling but that will be kept to a minimum.
If you were to hear loud squealing noises coming from your braking system, then it’s possible you have missing or worn out brake shims. Sometimes people will think these noises are coming from their brake rotors. But in most cases, the blame for these noises can be placed on missing brake shims.
This could happen when you purchase new brake pads because not all brake pads come with brake shims attached to them. In these situations, you need to attach the brake shims separately from the brake pads. You can re-use the old shims or purchase new ones.
You will find that some brake shims come with special adhesive material attached to them. You would simply attach the brake shims to the back of your brake pads (or hire a professional to do it for you).
Is Brake Pad Grease Necessary?
If you have brake shims installed between your brake calipers and brake pads, there may still be instances when you hear noises coming from your braking system. Again, this doesn’t necessarily mean that your brake rotors are to blame.
Usually, these noises occur because your brake shims are not lubricated enough grease or some other formulated lubricant. This will assist the shims in aligning the caliper and pads properly while reducing friction.
Just apply a thin film of grease to each shim if they have not already been lubricated. Never apply grease to the front of the brake pads!
Other Symptoms of Missing Brake Shims
Squealing noises are the most common symptom of missing shims and grease. However, you may experience other symptoms too, such as bad brake response or a pulsating brake pedal.
This is due to the brake pads not being properly aligned with the brake calipers. Because of this, the brake pads cannot adequately interact with the brake rotors to slow down the vehicle in time.
On top of that, it will wear out your brake pads and calipers quickly as well. Then you will be forced to replace your brake pads, brake calipers, and brake shims all at the same time.