What causes your brakes to squeak?
The front brakes on my SUV squeak. In the winter I forget about it because whoever engineered my SUV did an excellent job of soundproofing the interior. When the windows are rolled up squeaks disappear. Spring is on its way now and driving with rolled down windows has already reminded me that my brakes have not miraculously silenced themselves.
I will live with my squeaky brakes. Should you? I don’t know. In my case, I know my brake system is in good condition (squeaks and all). My brake pad choice (for heavy duty towing) caused my squeal. In your case, if they just started squeaking, it is time to get them inspected. All squeaks are not created equal.
A squeak or squeal is a high frequency vibration that humans can hear. In brake systems the range of high frequency squeal is approximately 4 000 to 16 000 cycles per second.
Both drum brake systems and disc brake systems will squeal but disc brakes are more often the source.
Many disc brake systems have brake pads that have squealers on them. A squealer is designed to tell the driver that the brakes are nearly worn out and it is time to replace them. This squealer is just a simple piece of thin steel that starts to rub on the brake rotor when the brake pad reaches a certain thickness. That thin piece of metal makes a shrill squeal when it comes in contact with the rotor.
Ignore the squealer squeal long enough and that noise will go away because once the brake material is gone there will be a much more severe rough growling noise indicating two metal surfaces are now providing your braking power and this braking power is severely compromised. Left long enough and you will quickly increase the cost of brake repair while endangering your life and others’.
If your vehicle does not use squealers as brake pad wear indicators, your braking performance is excellent and you still have plenty of brake pad material left then your squeal is similar to mine. It is an annoyance but alas, it is not endearing you with your neighbours.
This high frequency squeal involves the two major components of a disc brake system, the brake pad and the brake rotor. The brake pad when rubbing on the brake rotor is creating a vibration (squeal) that happens to be at a frequency we hear and find annoying.
Getting rid of this vibration (squeal) is sometimes tricky and sometimes expensive. It is very likely that the first set of brakes that your vehicle came with did not squeal. The engineers that designed the system had just that goal in mind. Build a brake system that stops well and doesn’t make bad noises.
Therefore when it comes time to choose new brake components when the others have worn out it is very likely that using the same or similar brake components would be the logical place to start. This is sometimes harder to do then you might think. Your vehicle’s original equipment parts might be hard to find and/or expensive.
The details of performing a brake job can also greatly influence the end result. There are many steps to performing a quality brake job that are left out in this era of doing things fast and cheap.
Attention to detail is important.
Trail’s Ron Nutini is a licensed automotive technician and graduate of mechanical engineering from UBC. E-mail: email@example.com