Frequently Asked Question

What is a brake caliper?
A brake caliper is a crucial piece of a vehicle's braking system. Most modern vehicles have a caliper at each wheel. The caliper's specific task is to press the pads into contact with the rotor in order to slow down the spin of the wheel — in turn slowing or stopping your vehicle. Brake calipers are immensely important for stopping, as failure will cause severely reduced stopping ability.
How does a brake caliper work?
When you step on the brake pedal, a few things must happen in order for your vehicle to slow down. Let's take a simplified look at how the caliper works as part of the brake system.
Stepping on the pedal creates enough force to shove a piston into the brake fluid in the master cylinder. This fluid can't compress, so it flows under pressure through the brake lines to the calipers. The pressurized brake fluid pushes a small piston. Some vehicles have multiple pistons particularly high-end sports cars. The brake fluid is pushed inside the caliper, forcing it to move the brake pad into contact with the flat surface of the brake rotor.
The brake rotor is spinning with the wheel, effectively bolted to it. Both the brake pad and rotor are designed for maximum friction. This friction the caliper creates slows the rotor as it turns kinetic energy into heat, in turn causing the wheel to slow its spin, thus slowing the vehicle.
StopParts Calipers Installation
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Brake calipers are crucial components component of brake systems. They are made from cast Iron and Aluminum.
Calipers are subjected to extreme heat generated by braking Hydraulic pressure. Severe road conditions and elements on the road. The life Cycle of a caliper depends on driver-stopping habits, extreme hot and cold conditions, towing, road salt, or chemicals for the northern states.
Cast iron brake calipers
Historically cast iron has been used by manufacturers to make brake calipers. It is cost-effective, and stress-resistant.
Aluminum brake calipers

Many automakers began to use aluminum instead of cast iron for their disc brake calipers as aluminum is 65% lighter than iron, and aluminum forgings and alloys can have the same structural strength as iron components. The automakers liked the weight reduction because it helped boost gas mileage. However, they did not count on the problem posed by galvanic corrosion.


In the case of aluminum disc brake calipers, galvanic corrosion occurs at the inlet and bleeder. At the inlet, you have the aluminum casting, the steel banjo bolt and hose block, and the copper washers used to seal the banjo bolt and hose block. The electrolyte is a mixture of sodium chloride (salt) and water. At the bleeder, you have the same situation between the aluminum casting and the steel bleeder screw.


The galvanic corrosion on aluminum disc brake calipers occurs most frequently on the sealing surface around the inlet hole on the aluminum casting. The aluminum is the anode and loses electrons to the copper washer and steel hose block and banjo bolt. The result is excessive pitting around the inlet, potentially causing a break in the seal (and possible leak) between the copper washer and the aluminum casting.


In many cases, aluminum castings cannot be rebuilt because of the excessive pitting around the inlet. Technicians need to do a close inspection of the calipers coming off the vehicle to determine if the sealing surface around the inlet is pitted, resulting in a scrap.

Indicators you may need to replace your brake calipers
Brake calipers are designed to last 5+ years. The longevity of the brake caliper is greatly determined by the driving and maintenance habits of the vehicle owner. Below are common signs that you may need to replace your brake calipers.
  • VEHICLE PULLS TO ONE SIDE WHEN DRIVING OR BRAKING
  • REDUCED BRAKING POWER, IF YOU NOTICE THAT YOUR VEHICLE TAKES LONGER TO STOP OR THE BRAKING POWER IS WEAKER THAN USUAL, IT COULD INDICATE A PROBLEM WITH THE BRAKE CALIPERS.
  • UNEVENLY WORN-DOWN BRAKE PADS
  • LEAKING BRAKE FLUID
At StopParts, our mission is to provide top-quality performance brake calipers for every vehicle on the road. Providing our customer base peace of mind and optimal brake experience.
Should brake calipers be replaced in pairs?
When one brake caliper fails or wears out, whether to replace it alone or in pairs arises. The consensus among car manufacturers and mechanics is that replacing brake calipers in pairs is best for several reasons.
  • First, replacing both calipers ensures that they have matching levels of wear, preventing uneven braking performance.
  • Second, replacing one brake caliper and leaving the other old one can create an imbalanced brake system that affects the vehicle's handling and safety.
Finally, replacing both calipers simultaneously saves time and money in the long run, as the labor cost of replacing one caliper is nearly identical to replacing two. Therefore, replacing brake calipers in pairs is recommended to maintain safe and proper braking performance.