In this month’s Part Smart Installation Best Practices Series, MPA’s Part Smart technicians discuss phenolic resin brake caliper pistons and the need for replacement with every caliper rebuild.
Phenolic resin has been used as an alternative to steel caliper pistons for over 40 years, providing reduced heat transfer, eliminating rust, and reducing weight. Steel brake pistons can corrode, causing leaks and offer little resistance to heat transfer from the brake pad to the brake fluid. Phenolic resin is a very dense, lightweight material that acts as an insulator, preventing heat from reaching the brake fluid and caliper body.
Reducing overall brake system temperatures increases stopping efficiency and safety.
While Phenolic resin is an excellent choice for its ability to resist corrosion and extreme temperatures, it can begin to break down and become brittle over time. Micro-cracks in the pistons structure cannot be seen without destroying the piston in the process. There is no non-destructive way to test internal integrity, every test is a failure.
To eliminate concerns, Quality-Built Brake Caliper applications with Phenolic pistons have 100% new piston replacement. By new every time Quality-Built engineers have eliminated any issues with cracked or damaged components which can lead to failure. Also note that when selecting brake pads for your vehicle, the pads will be different depending on piston material.
For more information on Part Smart or to access Installation Best Practices guides for MPA’s other product lines, please visit https://getpartsmart.motorcarparts.com/partsmart or scan the QR code with your mobile device.
What does a Brake Caliper Piston do?
- The piston in your brake caliper is one of the critical components. It is responsible for forcing the brake pads and brake rotor into contact, which in turn brings your vehicle to a stop.
What is a Phenolic Piston?
- A phenolic piston is a caliper piston that has been made using phenolic plastic. Phenolic plastic is exceptionally strong, making it the perfect material for use in brake calipers as it resists heat, rust, and oxidation.
Why shouldn’t Phenolic Pistons be Reused?
- While phenolic pistons are high strength and capable of withstanding extreme pressure and temperatures, they are also susceptible to possible heat damage and stress cracking over time. It is impossible to determine or identify heat damage or stress cracking without breaking down the phenolic piston itself, which renders the piston unusable. For this reason, Motorcar Parts of America uses only brand-new Phenolic Pistons in every remanufactured Brake Caliper we produce.
Phenolic Piston Failure Symptoms:
- Uneven brake pad wear
- Heatshield damage can lead a phenolic piston to break down under excessive heat exposure.
- A cracked piston can cause a loss of pressure resulting in complete brake failure.
Note: Reusing phenolic pistons can lead to brake failure and possible injury.
Motorcar Parts of America does not recommend using any parts with reclaimed phenolic pistons.
