What Are Brake Pad Shims? (and Symptoms of Bad/Missing Shims)
Most people are familiar with the main components of a vehicle’s braking system: the master cylinder, lines, rotor (or drum), brake pads (or shoes), brake booster, and pedal.
But when it comes to brake noise, one small part plays a big role. Here’s everything you need to know about brake pad discs (also known as anti-squeal discs). What is a brake disc? Simply put, the main function of a brake pad disc is to prevent brake noise. At every corner of the vehicle, the brake pads and the brake disc (or drum) are placed very close to each other. The only thing that prevents them from meshing is the brake disc.
The brake pad disc is the part that is sandwiched between the brake caliper and the brake pad to prevent friction. Basically, the washers keep the brake rotors in place so that they can function without making any strange noises.
These anti-squeak washers are adhesive or non-adhesive rubber or metal pads. They are placed between the brake caliper and the center of the brake pads.
When the brake disc is damaged or dislodged, it creates excessive unevenness between the rotor and the pads. This causes them to hit each other and creates strange noises. I hear this noise every time I press the brake pedal.
Can I install brake pads without the washers?Yes, you can install brake pads without the washers, but it is usually recommended to use the washers. Washers are designed to reduce noise and vibration, but do not affect the performance of the brake pads themselves.
For example, a discussion on Honda-Tech states that washers are only for reducing noise and vibration, and do not affect performance. However, it is important to note that you can drive without the washer, but using a washer will prevent squealing and allow for quieter driving.
Do I need brake pad grease?
Even if the brake disc is installed between the brake caliper and the brake pad, you may hear noises from the brake system. Again, this is not necessarily the fault of the brake rotor.
Usually, such noises are caused by the brake disc not being sufficiently coated with grease or other lubricants. This helps the washers properly align the caliper and pads while reducing friction. Simply apply a thin layer of grease to each washer if they are not already lubricated. Never grease the front of the brake pads.
Why do some brake pads come with washers? Many new brake pads come with washers already installed. So if you are looking to replace your brake parts, there are brake kits available that include both pads and washers.
In other kits, the washers come separate from the brake pads and have an adhesive backing that allows the washers to be attached to the brake pads. If this is your first time installing brake pad washers, consider buying brake pads that already have the washers installed.
Types of Brake Pad Washers
There are a few main types of brake pad washers, each of which serves a slightly different function.
Rubber Washers
Rubber washers are very common and are installed between the brake pad and the caliper piston. They are made of flexible rubber or rubberized plastic.
The natural flexibility of rubber helps insulate the pads from vibrations and noise caused by metal parts rubbing against each other. Rubber washers come in a variety of thicknesses, but are usually around 0.5mm to 2mm thick.
Metal discs
Metal discs are also used between the brake pads and pistons. However, they are made from thin sheets of steel or aluminium, and are therefore harder than rubber washers. Metal discs may be coated or uncoated.
The thickness and coating of the metal disc affect its insulating capabilities. Thicker washers, about 1.5mm thicker, provide more noise and vibration damping. Coated washers also help reduce friction between metal parts. Some vehicles require specific configurations to tune braking performance.
Isolation Washers
Finally, there are insulation washers that are attached to the brake pad support plate itself. These help to dampen vibrations emanating from the pad surface by adding mass. Insulating glass is made of materials such as fiberglass or rubberized plastic, approximately 3-5 mm thick. In some high-performance covers, it is built into a carrier plate.
Can brake pad discs be reused? In most cases, old windows can be reused as long as they are in good condition. You will need to clean them with brake cleaner and a cloth or paper towel before fitting them with new pads. Symptoms of a Broken or Missing Brake Disc
Brake discs can wear out or deteriorate from excessive use. When this happens, you’ll notice some strange symptoms. Missing discs on your brake pads can also cause the same symptoms.
#1 – Brake Noise
The main symptom, of course, is a loud squealing or grinding noise you hear from your brakes every time you press the brake pedal. If you recently installed new brake pads and are now hearing squealing noises when you apply the brakes, it’s time to double-check for missing discs.
#2 – Pulsating brake pedal
You may also notice a pulsating brake pedal when you press your foot on it. This is because a faulty or missing brake rotor causes the brake pads and caliper to be out of alignment.
#3 – Poor brake response
In the worst case scenario, you will have limited brake response, which only happens if the brake pads don’t have enough access to the brake rotor. This is caused by the brake pads and caliper not being properly aligned.
Because of this, the brake pads cannot adequately interact with the brake rotors to slow down the vehicle in time. On top of that, this can also wear out your brake pads and calipers quicker than normal.