Squeaky breaks are a common automotive annoyance, potentially affecting all types of vehicle. Fortunately, this is a common issue and can be easily solved. In this article, we will list possible symptoms and whether they are a cause for concern, why they squeak and how to avoid this with new pads.
Sounds that Aren’t a Cause for Concern
Not all noises are an indication of a problem. The large variety of conditions we face on the roads, as well as different brake pad compounds which can cause a range of sounds, varying from car to car. Here are a few noises you shouldn’t be concerned about:
Graunching in the Morning
If your brakes make a graunching sound the first few seconds of braking after sitting for a few days or being subjected to moisture, this is normal and not a cause for concern. When rotors are exposed to moisture this can cause the surface to rust, and when you apply the brakes it will remove the rust – which will cause the graunching sound.
Glazed Pad Surface
If you can hear squeaking after long downhill periods of driving, it’s normal as you may have glazed the surface. Friction between the pad and rotor is what slows you down, however, a by-product is heat, if the pad material gets hot enough it can smooth over the surface which results in squeaking. Notice that new pads are rough in texture, the heat from prolonged periods of braking can smooth over this surface, leaving it feeling like glass. Now you will hear squeaking due to the two smooth surfaces making contact.
Why do my New Brakes and Rotors Squeak?
Any moving part in a car can make unusual sounds and can happen through no fault of your own. This also applies to your brakes which can squeak and squeal. Modern brakes commonly use a cast-iron disk with a calliper holding two brake pads against the disk. During normal driving where the calliper is released, the brake pads can rattle or vibrate causing an annoying sound.
If you use aftermarket components, they could be using a different compound causing unusual noises. It’s hard to beat standard parts in terms of life, noise, dust production and cost. Unless you’re primarily using a car in harsh environments such as drifting and track events, manufacturer parts are ideal.
Brand new pads do normally make noise before a proper break-in procedure has been completed. This procedure is generally driving a few hundred miles whilst avoiding harsh braking, however some manufacturers recommend a different procedure especially if rotors and disks have been replaced at the same time.
Different Sounds and What They Mean
Squealing all the Time
Brakes shouldn’t be making constant noise and under normal use will only happen during engagement. If a constant squeak can be heard it should be investigated immediately. This can indicate a sticky calliper, where the brake calliper that holds the pads becomes partially stuck in the engaged position. This causes constant pressure against the rotor, excessive heat and eventually unwanted sounds.
Common symptoms aside from constant noise from the sticking calliper are excessive brake dust compared to the other side of the vehicle. Excessive heat is another symptom, you can test this by placing your hand at a safe distance from the wheel. If one side of the car is noticeably hotter compared to the other, this is a strong indicator of a sticking calliper and should be resolved as quickly as possible!
Squeaking During Use
A common cause of squeaking is new brakes being fitted alongside old, glazed rotors. A rotor is the surface a brake pad will come into contact with, under normal driving conditions this can become smooth and glazed over, like glass.
If there is sufficient material left on the rotor, a lathe should be used to remove the glazed surface at the minimum. In an ideal world, the rotor would be replaced at the same time for the best surface for braking, whilst following in the recommended break-in procedure.
Squeaking when New
New rotors can have assembly lubrication applied to the disk surface, which isn’t always cleaned off prior to installation. When the pad and disk meet, the friction between the two surfaces is what slows the car down.
If lubrication is present between the two surfaces, this can prevent normal operation due to the nature of lubrication – therefore impeding brake function and potentially causing noise.
This is normal, and even if the parts have been cleaned prior to installation squeaking, squealing and other noises can still occur. A correct break-in procedure is needed to ensure the pad and rotor has been properly bedded in.
How to Break in New Pads and Rotors
This will vary depending on the manufacturer of the components but is important to ensure proper contact between the pads and rotor, as well as eliminating hot spots and glazing.
It’s a good rule of thumb to be cautious the first 100 miles of new components. Particularly avoiding hard braking and coasting on the brakes. This will ensure the assembly doesn’t get too hot, as in extreme cases this can cause cracking.
A further 250 miles is required with slightly harder braking to fully bed in the new components. It’s still important to avoid sharp braking resulting in a full stop – however safety is more important than replaceable components, you should never avoid braking when it’s necessary to do so!
EBC has a great resource on bedding in procedures for your shiny new parts.
Preventing Brake Noise
Prevention is better than a cure, so what can do you to prevent noise?
Ensure dampening shims are fitted, which prevents direct contact between the piston of a calliper and the backing plate of the pad. Without these shims, you can expect increased noise when braking.
You can use anti-squeal adhesive on the backing plate during installation, which will stick the pad and the calliper together. This ensures the pad and piston within the calliper move as one section, which prevents rattling and movement, therefore, eliminating any noise.
A slight change to driving style by reducing harsh braking while driving where safe, can help reduce noise. Situations that result in unnecessary last minute braking, or coasting on the brakes whilst driving down steep hills can glaze the brake pad surface. When you apply the brakes with glazed pads you will hear squealing, you may have heard this from buses or large vehicles.