In our efforts to answer your pressing questions about the Acura you drive, we’ve stumbled upon a startlingly common topic: brakes. People tend to ask a lot of questions about their brakes, and given how important they are to the safe operation of your vehicle, providing you with answers to those questions is a top priority for us.
First, a brief glossary.
Brakes – You know what brakes do. What you might not know is that there are two kinds of brakes, drum and disc. Drum brakes were more susceptible to what’s known as brake fade, where heat and gas would build up within the drum, thereby decreasing the effectiveness of the brake. For that reason, drum brakes have mostly been phased out in favor of disc brakes. All modern Acuras have four-wheel disc braking systems.
Calipers – The wheels of your car each have a corresponding metal disc or rotor that spin along with the axle. When you step on the brake pedal, your brake calipers clamp down on the rotors, slowing your car down.
Brake pads – These are high-friction materials fitted to each side of the calipers. If your calipers and rotors interacted on a purely metal-on-metal basis, neither one would last very long, so brake pads are there to make the whole system more effective and more durable. They’re the third party mediator that helps the rotors and calipers negotiate a peaceful resolution to the physics of friction.
Friction – Friction is one of the first funny science words you learned, possibly from that episode of Magic School Bus where they were playing baseball inside a textbook. This probably should have been at the top of the glossary considering how essential a concept it is for braking.
ABS – Anti-lock braking systems are used in most modern cars and have replaced the practice of “feathering the brakes.” The whole point of braking is to bring your car to a controlled stop. If you stepped on the brake pedal and your wheels locked up, your car would start skidding and you would no longer be in control of the vehicle. ABS pumps the brakes more rapidly and effectively than you would be able to on your own, allowing you to maintain control and bringing you to a stop more quickly.
Sidebar: Keep in mind there’s no such thing as deceleration. There’s only positive and negative acceleration. If you remember that, hopefully there will be fewer angry physicists in the world.
With all that covered, we should be able to answer your questions.
Why are my brakes squealing? I’m not even going that fast.
If you’ve ever come to a sudden stop, you’ve probably heard your brakes squeal a little bit. If you’re just driving as normal, gradually braking at reasonable speeds like you were taught, you might be more concerned if you hear your brakes making noise.
You shouldn’t be, though. Cabin insulation and noise reduction technology have both come a long way, but it’s still impossible to eliminate all noise from braking. The squealing you hear is high-frequency vibration, a natural byproduct of the friction created by the rotors and calipers coming into contact. The severity of the vibration is also affected by temperature, humidity, and road conditions, so cold and wet weather can exacerbate this noise.
Most of the time it’s nothing to worry about, but if you think the squealing is abnormally loud, or if it turns into a lower grinding noise, have your brakes inspected. It might be time to change your brake pads.
Why does my car make a groaning noise when I start it in the morning?
Don’t you groan when you first get out of bed?
Just kidding. That sound is also totally normal, and it comes from the ABS. Your ABS is so sophisticated that it performs a self-check after you turn the car on and start moving (which means it probably happens more than just in the morning). That noise you hear is just the ABS humming while it checks itself in the mirror, fixing its tie and combing its hair. Think of it as a reminder that the ABS is confident and totally has your back.
Why does my brake pedal feel like it sinks when I’m pressing it down for a while?
After you’ve come to a stop at a light or a stop sign and you’re waiting to get going, you might feel your foot sink down another inch or two. As you may have guessed from the theme here, this is totally normal and it has to do with your car’s power braking function.
With the advent of disc brakes also came power brakes, which introduces a brake booster into the system. The job of the brake booster is pretty self-explanatory. It boosts the force you apply to the pedal so that you aren’t having to do a full-blown leg press every time you want to stop your car.
The brake booster works in conjunction with the natural vacuum created by the engine. This vacuum fluctuates based on a number of factors, such as obvious things like how much pressure is put on the accelerator and less obvious things like whether the air conditioning is on. When there’s more vacuum, there’s more brake boost, which can cause the brake pedal to drop some. So don’t be alarmed, this is just more complicated – and totally natural – physics at work.
If you want a more thorough explanation of how the brake booster works, we recommend this article on howstuffworks.com. There are a number of diagrams that might help you better visualize the mechanism.
We hope this guide has answered a lot of your questions about brakes and maybe even addressed some concerns you have. Of course if you’re still worried that something might be wrong with your brakes, it’s always a good idea to consult the professionals in our Parts and Service Department. Feel free to bring your car to Leith Acura where our qualified technicians will take care of you.
If you have other questions, the FAQ pages on Acura’s main site and owner’s site are a great resource, and you can also call or visit us at our dealership if you still need help.