How Brake Shims Work

Brake shims prevent the pads and rotors from clanging against each other.
Brake shims prevent the pads and rotors from clanging against each other.
©iStockphoto/Brent Melton

Brake shims are thin layers of rubber or metal that fit between the brake pads and the rotors to correct small imperfections that cause brake noise. They function just like shims in cabinetry: If the kitchen floor of an old house is a little crooked, the cabinet installer will add a couple of thin, wooden shims to level out the cabinets. Brake shims work much the same way to adjust otherwise normal brakes.

On the most basic level, for many new vehicles with new brake parts, brake shims function as anti-rattle pads. They keep the pads and rotors from banging against each other or squealing. Some brake part kits come with the shims already attached to the brake pads; some come with separate shims that have adhesive backings, which need to be affixed to the back of the brake pads. Other shims must be purchased separately and attached to the pads with double-sided tape.

In an­y case, brake shims are easy to use and install, and they can make a big difference in the way that the brake parts work together. While most are made from rubber, it's possible to upgrade to something like titanium brake shims. Let's take a look at these as an option for a brake shim upgrade.


Titanium Brake Shims

Brakes are tested under extreme conditions. Titanium brake shims work as heat shields to maintain braking power.
Brakes are tested under extreme conditions. Titanium brake shims work as heat shields to maintain braking power.
Peter Ginter/Science Faction/Getty Images

When brakes are under stress, they get hot. Real hot. Just think how hot the brake parts on a racecar get when coming out of a straight stretch to enter a corner. Rubber can quickly turn to goo in that situation, or in any heavy braking scenario. The heat created from the friction of the hard-working brakes can actually boil the hydraulic brake fluid, which even further reduces stopping power. That's where titanium brake shims come in.

Titanium brake shims work like heat shields to prevent the heat of the braking effort from affecting the other brake parts. Manufacturers often use a titanium alloy in the brake shims to keep costs down, as titanium can be very expensive.

While rubber brake shims can be stuck to the back of brake pads using two-sided tape, titanium brake shims are usually secured by other means. They often have holes at the top and thread onto the caliper pins. They still fit between the brake pads and the rotors, but they function less as noise dampeners and more as heat shields.

­Keeping the brake parts as cool as possible means a longer life for brake parts and fewer brake fluid changes. Brake shims are great for cars, but what about motorcycles? Can one brake part make a difference in the safety of a bike? Of course it can. Read on to find out how.

Motorcycle Brake Shims

Motorcycle brake shims help with alignment and reduce noise.
Motorcycle brake shims help with alignment and reduce noise.
White Cross Productions/Photographer's Choice/Getty Images

In addition to shielding heat and reducing noise, motorcycle brake shims are an important alignment aid. If a wheel isn't perfectly centered, a motorcycle brake shim inserted between the brake and rotor can bring it to true.

Since motorcycles don't usually generate the kind of heat that racecars do, the types of motorcycle brake shims you'll find are usually of the stick-on rubber variety, rather than titanium. These rubber brake shims reduce noise and vibration, making for a more comfortable ride. They also protect the brake pistons from overheating, which improves safety.

The shims also function to snug the friction surface of the brake pads against the rotors. The more of the friction surface that comes into contact with the rotors, the more stopping power the brake parts will be able to generate.

Though the humble brake shim serves a simple purpose and sometimes is an underestimated brake part, its assistance in wheel alignment and bettering maximum braking power is important. It helps reduce uneven wear and tear on brakes and increases the safety, giving both bike and rider a smoother and more comfortable ride.

­If you have a need for speed and want to know more about the brake shim or another brake part, shimmy on over to the next page.

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More Great Links


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