When it’s time to replace your brake rotors, you may want to consider switching to two piece rotors. Two piece rotors bring a lot of benefits to the table.
What Are Two Piece Rotors?
Usually, OE brake discs are made from one piece of cast iron. Some brake rotor brands like GiroDisc, StopTech, and DBA have come out with a two piece rotor design.
Also called a floating disc assembly, a two piece brake rotor design has two pieces:
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A cast iron ring that will come in contact with the brake pads
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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:
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Quicker acceleration
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Shorter stopping distances
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Better cornering
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Better handling
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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. Lower Risk Of Warping
Brake rotors can get very, very hot. A rotor can exceed 1100 degrees Fahrenheit. It’s common for brake rotors to expand when they get too hot. One-piece rotors don’t heat up uniformly. To be more specific, the center section of a one-piece rotor remains cooler while the friction area heats up a lot. This uneven heating leads to thermal stresses that can cause:
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Disc warping
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Cupping of the braking surface
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Cracks
Two-piece rotors are free-floating. The cast iron disc can expand radially (outward) relative to the aluminum bell. The cast iron disc will heat up, while the aluminum bell remains cool. Two-piece rotors are less likely to warp or crack from excessive heat.
4. Increased Airflow
Some two piece rotors have an open design where the aluminum bell meets the rotor face. This allows for increased airflow.
5. 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.
