Brake tech is a very complex and nuanced topic, so we asked the experts at Alcon Brakes to help us clarify and expand on some frequently asked questions in the braking universe. Today, they’re discussing the pros and cons of solid vs. vented brake rotors.
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Solid vs. Ventilated Brake Discs
Why do we use ventilated brake discs? It’s all about airflow and cooling.
Cool(ish) brakes are happy brakes. And when it comes to braking systems, there is a big advantage to cooling through convection.
That’s why we use a ventilated disc, because it has a greater surface area than a solid one.
If you were to test two discs with exactly the same dimensions, except that one has an air gap for ventilation, you’d see these results when run on a brake dynamometer:
- The solid disc would have a lower temperature than the ventilated disc at the end of the first stop, due to the solid rotor’s greater thermal mass.
- But! The ventilated disc would have a lower temperature at the end of a repeated stop fade test, because of the ventilated disc’s improved cooling capability seen between brake events.
- Better yet, the ventilated disc would see an equilibrium of heating and cooling earlier than the solid disc—which is a fancy way of saying the amount of heating on the disc would be equal to the rate of cooling. That means the disc won’t see higher temperatures at the end of subsequent stops.
Brake test engineers can carry out the dynamometer tests with or without additional cooling.
In theory, you can simulate the disc being in an enclosed box (as it may be on some tracked vehicles).
It’s obvious that better air flow in and around the rotor offers additional cooling, especially on higher speed applications, but you’ll still see benefits in low speed situations too.
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