Brakes Noise Q & A

Brake Noise Problem & the Solution:
A Conversation with Montalvo Applications Specialists

Q: My brakes are squealing and I’ve tried replacing the brake pads but that makes no differences, so why are my brakes still squealing?

A: Brake squealing is caused by high-speed oscillations of “sticking and releasing” of the friction material on the rotor which in turn, causes a vibration on the rotor. Like a bow across a violin string, the pitch of the noise is affected by the physical characteristics of the gimbling components of the module (allows it to “float”) and the air pressure on the brake. Temperature has some effect on this occurring primarily due to pad surface glazing but it is also affected by humidity, speed and brake force (pneumatic load on the piston).

Q: “…What about a rotor that is slotted so that it would cool the brake pads like they do it in the auto industry?”

A: Car brakes are not designed to run continuously as Montalvo brakes are, they are designed to stop. The reason the rotors are slotted on race cars is not for pad cooling, it’s to help cool the rotor and to allow air flow into the center if it’s a vented rotor. If you were to slice a racing vented rotor, it would look a lot like two Montalvo rotors. The holes also reduce the “un-sprung” weight of the wheel assembly which is a supercritical statistic in racing as it dramatically affects handling, hence lightweight carbon wheels, etc. The friction material or brake pad by design has less thermal conductivity (contact heat transfer), density and mass than the rotor, so cooling the rotor is the controlling factor in performance as everything stays around rotor temperature.

Generally, Montalvo brakes, with the dramatically increased area on the black radiating surface of the rotor, cools much better than a car brake, unless you are running really slowly, and then you may need to have a Montalvo brake cover with a built-in fan.

The Solution

I recommend a single Teflon Brake Pad be installed on each rotor surface. So, if you have a single rotor brake you will need to have one of your brake pistons have a Teflon Pad. If it’s a double rotor, you will need one Teflon pad on each. You might be wondering, “Why Teflon pads?” The Teflon pads are made of friction material impregnated with a loading of Teflon. Teflon doesn’t really go anywhere; it doesn’t absorb moisture and oil and is a great lubricant. As the pad wears, a small deposition of Teflon is deposited on the brake rotor; this small amount of Teflon provides enough lubrication to eliminate the stick-release condition that is causing the vibration of the rotor and the resultant squealing.

The only potential negative implication of this is that the stopping power or torque of the brake will be slightly less. However, this is generally not noticed and generally better for tension control and would not be a concern unless there are some very unusually demanding E-stop conditions. Then, I would recommend we review your application closely together so we can make the proper recommendation that meets all your requirements, otherwise you won’t know the Teflon pads are there except for in the beautiful sound of silence!

Already tried this and it hasn’t instantly and permanently corrected the problem? Contact an Application Specialist today for further assistance!

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