Squealing or squeaking brakes are a common occurrence when you’re at the track, but when you’re sitting in peak hour traffic on your way to work or in the city for a night out, the high pitched squeal can not only be annoying but even a little embarrassing!
Common Causes of Squealing Brakes
1. Worn Brake Pads
Squealing brakes can occur for a variety of reasons, with the first and foremost being worn out brake pads. Most brake pads have a small metal finger on the side of them which protrudes about 2mm past the backing plate. Once your brake pads have worn out, the metal finger begins to contact the brake disc. This results in that high pitched squeak we’ve all heard at one time or another. The manufacturer does this so that you’re prompted to have your brakes looked at and changed.
2. Glazed Brake Pads
The other very common cause of squeaking brakes is the pads becoming ‘glazed’. All brake pads are constructed with an optimum operating temperature range. A good road pad that would be well suited to commuting to and from work or in start-stop traffic would have a low operating temperature (approx. 0-300 degrees Celsius). Performance orientated pads operate around the 400-800 degrees Celsius range, while dedicated race pads operate from 1000 degrees Celsius and up.
When a brake pad is forced to work beyond its ideal temperature range, this can lead to glazing. The brake pads material begins to break down and crystallise or harden. This results in a surface of very similar hardness and very low friction coefficient contacting each other, producing that same squealing noise. Performance brake pads are typically made of a different compound with a higher friction coefficient. This is why they are prone to squealing at low temperatures and are known for being harsh on brake discs.
During this glazing process, the brake pads friction material can break down causing the friction material to adhere to the discs surface. This results in a pulsating brake pedal when slowing from speed as the discs typically flat surface now has high and low spots. Contrary to popular belief this is a common cause of brake run out, and as long as your discs are not below their specified minimum thickness they can be machined or cleaned to rectify this.
A less common cause of brake squeal (although not uncommon) is when small stones/contaminants become stuck between the brake pad and disc. It’s easily fixed by quickly removing the pads and making sure they are free of grit. However, if you leave it unattended, this can result in the stone/contaminant cutting a groove into your disc as it pushes into the disc itself.
So there you have it. An in-depth look into the reasons why your brakes may be squeaking. Think it might be time for a tune-up? Head on over to Spares Box and check out our range of brakes and our Mid-Year Mega Sale! Saving up to 20% off!