Brake Repair

How to Tell if a Brake Caliper is Bad


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A brake caliper is one of many important parts of a braking system. Combined with brake pads, they have the enormous task of changing the vehicle's forward motion to heat which stops the vehicle. If they don't work properly, stopping the vehicle can be very difficult. How do you identify a bad brake caliper? The steps below will help you identify whether or not your brake caliper is bad. 

Step 1: Visually Inspect the Exterior and Operation of the Caliper
Visually inspect the exterior of the brake caliper. Look for cracks and brake fluid leakage. If you see cracks, the unit needs to be replaced. Areas which are leaking will be wet or have streaks. Have an assistant operate the brakes while you observe its operation. If the caliper does not move or you can still turn the rotor with the brakes applied, check whether or not brake fluid is reaching the caliper. 

Step 2: Check If Brake Fluid Is Reaching the Caliper
Locate the air bleed valve on the back side of the caliper. Attach a small hose to the valve and place the other end of the hose in a clear glass jar, half filled with clean brake fluid. Be sure the end of the hose is submerged below the brake fluid. This keeps air from getting into the system. Open the valve and have an assistant apply the brakes. If fluid flows into the container, then fluid is reaching the caliper. If you see bubbles, then there is air in the system that must be removed. If no fluid flows into the jar, check your brake lines and the master cylinder for problems. If additional fluid flows into the glass jar from the container, then the problem is the caliper. 

Step 3: Check If the Caliper Floats Properly
If the caliper moves when the brakes are applied, pay attention to how smooth the motion is. One problem could be that the floating pins need lubrication. If the caliper doesn't move, then watch to see if the brake pad itself shows any sign of attempted movement. If the pad tries to move, then the piston behind the pad is working and the caliper is not floating properly. The pins could be damaged or they need to be removed, cleaned and relubricated. 

Step 4: Check If the Piston Is Working Properly
When the brakes are applied, the piston should push on one of the brake pads, causing the caliper to float. Since a second brake pad is connected to the floating part of the caliper, the two brake pads squeeze the rotor, causing it to stop rotating. If the brake pad in front of the piston doesn't try to move when the brakes are applied, there's a problem with the piston. It's best to replace the caliper as a unit if the piston is bad.

Keeping your brake system in top condition can be a challenge. By following the steps above, you will have a better chance of locating the problem yourself, which can save you a lot of time and money.

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