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What Are Two Piece Rotors?

A two piece brake rotor design has two pieces:

  1. A cast iron ring that will come in contact with the brake pads

  2. A center piece called a bell (or a hat), usually made of aluminum

The aluminum bell makes up the hub section of the disc assembly. It directly bolts on the cast iron ring. When bolted together, these two pieces act as a normal brake rotor.

The two piece design allows for a floating mount system. There are several benefits two a two piece rotor as compared to a conventional rotor.

The Benefits Of Two Piece Rotors.


Having a set of two piece rotors on your vehicle is beneficial in many different ways. Let’s discuss the biggest benefits of two piece rotors;

1. Reduced Weight

Aluminum weighs a whole lot less than cast iron. With an aluminum center, a two piece rotor weighs less than a one piece rotor. The center of the rotor is a great place to save a lot of weight. The location is both unsprung and rotating.

The less your rotors weigh, the better the benefits:

  • Quicker acceleration

  • Shorter stopping distances

  • Better cornering

  • Better handling

  • Improved fuel economy

2. Better Heat Dissipation

The aluminum bell and the cast iron ring are two separate pieces. That means most of the heat from the cast iron ring isn’t transferred to the aluminum bell. Therefore, the vehicle’s hub and wheel bearings are not subject to extreme heat. This helps the wheel bearings last much longer.

3. Increased Airflow

Some two piece rotors have an open design where the aluminum bell meets the rotor face. This allows for increased airflow.

4. Cost Savings

Two piece rotors can be cheaper to replace than one piece rotors. As long as the aluminum bell is still in good shape, you can replace only the cast iron ring and reuse the bell. When replacing just the rotor, you should always replace the mounting hardware.

What is Solid Rotors?

Solid brake rotors are usually machined from a single piece of raw material, like cast iron. Although more exotic materials are available particularly when it involves racing or street performance requirements.
Solid discs usually appear at the rear of the vehicle.

What is Vented Rotors?

Vented brake rotor designs are thicker CNC-machined cast-iron discs that have a hollow vent or channel between the front and rear rotor surfaces. This allows for enhanced heat dissipation.

Vented discs usually appear at the front. This configuration helps deal with increased heat/gas dissipation involved with enhanced weight levied by front-engine placement, along with the fact that most cars are brake-biased toward the front, usually on the basis of a 60/40 brake-balance ratio.

Performance brake systems are usually all-vented configurations since resistance to heat and gas can make the difference between controlling a hard-braking evolution or ending up in the kitty litter – upside down, hanging from the straps. As you might expect, all-vented configurations are usually more expensive than mixed-disc systems.

In the end, your choice of rotors depends on your vehicle and driving habits. If you’re not sure what you need, contact us and we will be glad to assist.

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