Brakes - Normal Operational Noises
Section Title: Brake SystemTSB No. TS 01 10265
Division: Automotive
Category: Technical
SUBJECT:
BRAKE NOISE CHARACTERISTICS DURING NORMAL OPERATION
MODEL(S):
ALL
YEAR:
ALL
This bulletin is to provide information about some brake noise characteristics heard during normal operation. Please utilize this bulletin when explaining brake noises to eliminate concerns and reduce unnecessary component replacement.
It should be considered normal for the brake system to have some noise during normal operation. This is most common with disk brake systems and will happen from time to time. It is caused by friction when the pads are stopping the brake disc from rotating.
The definition of brake noise can be different case by case, driver to driver and situation to situation. Noise can be defined as an unpleasant sound and the severity is usually affected by the sensitivity of the person hearing the noise. In general noise can be described as loud, unpleasant and disruptive sounds. Use the guidelines below carefully to accurately decide whether noise is normal or a cause for concern. If components are replaced for a normal noise the satisfaction of the driver will be adversely affected because the noise will not be eliminated.
General tips:
^ Listen to the complaint thoroughly and deeply.
^ Take the vehicle for a test drive with the owner driving to reproduce the noise.
^ Verify the nature of the noise with the driver side window down and up if possible.
^ Rear brake noise may sometimes be mistaken for front brake noise.
^ Do not replace any components without first verifying they are the cause of the concern.
^ Be sure brake pads and shoes are not worn or need replacement.
Key questions:
^ Where does the brake noise seem to originate?
^ At what speed does the noise occur?
^ Does it happen when the brakes are cold, or when you have been driving for a while?
^ Does it happen after many stops, or only after a few stops?
^ Does it happen in wet conditions such as rain, humidity or after a car wash?
The following are considered normal noise characteristics of all braking systems.These noises do not generally indicate any malfunction of the braking system or improper operation, but may be noted as an indication that it is time to bring the vehicle in for normal brake service.
1. Loud metallic squeaking noise
Typical complaint
Loud metallic squeaking noise can be heard while brake pedal is applied.
What is it and why
On vehicles equipped with pad wear indicators, an audible continuous warning can be heard when pads need replacing. This is not a malfunction. It is an indicator that service is required.
What can be done
Have the brakes inspected by a qualified Suzuki service shop immediately.
With this in mind
Always have a complete brake inspection and diagnosis performed whenever a brake concern arises. These tips are to be used to help understand normal brake conditions. It is not intended to provide diagnostics on any particular vehicle performance issue. Always take a brake noise concern seriously and do a thorough inspection to eliminate any abnormal issues.
2. Slight squeaking / squealing noise
Typical complaint
Driver complains that vehicle makes a squealing noise sometimes when applying brake pedal lightly at low to medium speed. The squealing stops when applying the brake pedal with more force.
What is it and why
The brake system normally can make a squeaking and / or squealing noise whenever applying the brake pedal. These noises are caused by the high frequency vibration of the brake pads against the rotating brake disc. Generally vibration can be an unavoidable result of friction generated by the brake component. This noise can come and go depending on the weather conditions. This type of noise is normal and cannot be eliminated under normal braking conditions.
What can be done
The level of vibration can be affected by ambient temperature and humidity, by road conditions such as dust, sand, mud and road salt. Also the thickness or condition of the brake pad plays a role in many cases. Normally adding or removing shims and applying high temperature grease between the pads and shims dampen and isolate most of the noise.
With this in mind
Have the brake system inspected and checked for pad thickness if the squealing noise is abnormally loud.
a. Replace the brake pads if the thickness of the remaining friction material will not last until the next service.
b. If the pad lining is thick enough to last until the next service; remove, clean, grease and reinstall the pad shims. Use high temperature grease.
3. Groaning noise
2-1 Groaning noise on A/T model
Typical complaint
Vehicles with automatic transmissions may have a slight groaning noise when the driver brakes to a sudden stop and then allows the vehicle to creep slowly from that stop.
What is it and why
This noise is caused by low-frequency vibration of the brake pads against the rotating brake disc.
This vibration transmits through the body components such as the suspension and the body panels.
Generally this vibration is an unavoidable result of the friction generated by the brake components.
The amount of vibration is influenced by the weather conditions. This type of noise is normal and cannot be eliminated under normal braking conditions.
What can be done
The level of vibration can be affected by ambient temperature and humidity, by road conditions such as dust, sand, mud and road salt. Also the thickness or condition of the brake pad plays a role in many cases. Normally adding or removing shims and applying high temperature grease between the pads and shims dampen and isolate most of the noise.
2-2 Groaning noise with ABS (sometimes clunk / click noise)
Typical complaint
A brief groaning noise is heard when first starting the vehicle.
What is it and why
On vehicles equipped with ABS (Anti Lock Brake System), the ABS unit emits a brief grunt or groan when the ABS unit does a self check. This self check will be completed after every engine start and may be heard once the vehicle starts moving either forward or backward.
What can be done
No action required -- this is a normal function of the ABS system.
4. Clicking noise
Typical complaint
A click noise is heard when applying the brakes after backing out of a parking space. This click is heard again when applying the brakes after driving forward a few feet. It seems to only occur after changing from forward to reverse or reverse to forward.
What is it and why
The clearance between the brake caliper bracket and the ends of the brake pads allow for heat expansion and helps avoid corrosion between the caliper bracket and brake pads. This clearance can cause the pads to hit the caliper bracket when you first apply the brakes in a new direction of travel. The single clicking noise heard is a normal characteristic of the brake system.
What can be done
No action required -- this is a normal characteristic of the brake system.
5. Grinding noise
Typical complaint
Grinding noise heard during light braking during the first few stops after first starting to drive.
What is it and why
This noise is common primarily during the first few stops on rear drum brakes and on some front disk brakes due to the formation of trace rust corrosion after the vehicle has been parked overnight. This light corrosion is typically cleared from the metal surface after a few stops.
What can be done
If the rotor surface does rust, the area under the brake pads usually remain rust free. The difference in friction between the rusted and un-rusted areas may produce a slight brake pedal pulsation, vibration and / or noise for several stops. This will improve as the brake pad friction against the rotor polishes the rust off the rotor. Usually three or four stops will polish the rotor surface.
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