Have you ever slowed down your car at a stop sign or red light and heard a strange groaning or moaning noise coming from the brakes?
This type of brake noise at low speeds can be alarming, but is actually quite common and usually indicates that some brake maintenance is needed. Identifying the root cause of the noise quickly and performing the right repairs is key to restoring safe and quiet braking.
In this article, we’ll explore the common causes of groaning brake noises and what you can do to resolve the issue.
What Causes Brake Groaning at Low Speeds?
Brakes can make all kinds of noises, including squeaking, grinding, humming, and groaning. Groaning noises are often heard when braking at lower speeds around 10-25 mph.
This type of noise indicates that your brake pads are no longer smoothly gliding across the rotor surface. Instead, vibrations between the pad and rotor create a droning or groaning sound.
There are several common culprits of brake groan at low speeds:
- Glazed brake pads: Over time, brake pad material can become glazed over from heat cycling. This causes the pads to stop gripping effectively and slip across the rotor surface instead.
- Worn brake pads/rotors: If brake pad material is wearing thin or rotors are excessively worn, braking performance will suffer. The lack of adequate grip between pads and rotors can lead to groaning vibrations.
- Brake dust/debris buildup: Built up debris between pad/rotor surfaces prevents smooth contact and can cause noise.
- Corroded/rusted rotors: Rust, corrosion or hot spots on rotors creates uneven braking surfaces. Groaning can occur as the pads pass over damaged areas.
- Sticking/frozen calipers: Calipers that do not retract properly after braking create drag that leads to vibrations.
- Warped rotors: Extreme heat cycles can warp rotors over time. The high and low spots of a warped rotor generate noise as pads pass over them.
- Hydraulic system issues: Problems with brake fluid or hydraulic components can cause calipers to not engage/disengage properly, also creating noise.
While groaning brake noises at low speeds are usually more of an annoyance than a safety issue, it’s still smart to address the problem promptly. Allowing brake noises to continue long-term will likely lead to more serious wear and damage.
Dangers of Ignoring Groaning Brake Noises
Those droning groaning noises coming from your brakes are trying to tell you something – don’t ignore them! Here are some of the potential consequences of allowing brake groan to go unchecked:
- Reduced braking power: Pads and rotors are the friction surfaces that provide stopping power. As they wear and corrode, braking performance declines. Groaning noises indicate degraded braking surfaces.
- Complete brake failure: In a worst case scenario, severely damaged brake components can actually fail completely, causing complete loss of braking. This would make it impossible to stop the vehicle.
- Vehicle damage: Worn brake pads can damage rotor surfaces as metal backing plates make contact with rotors. Caliper issues may cause heat damage and leaks.
- Increased stopping distance: Brakes that groan have reduced effectiveness, meaning it will take you longer to come to a complete stop. This increases risk of an accident.
- Difficult vehicle control: Groaning brakes are likely to be “grabby” and vibrate when applied. This can make controlling the vehicle more difficult.
The bottom line? Don’t take chances with your brakes. Stopping safely and reliably should be your top priority. Use brake groaning as a warning sign to have your brakes checked out.
How to Diagnose the Cause of Brake Groaning
If your brakes start groaning at low speeds, how do you pinpoint the exact cause? Here is a step-by-step diagnostic process:
Step 1: Visual Inspection
Start by thoroughly examining the visible components of your brakes:
- Check for brake pad wear – are pads getting thin?
- Look for debris embedded in pads/rotors.
- Check rotors for grooves, discoloration, rust and other signs of wear/damage.
- Scan hydraulic components for leaks/damage.
- Ensure caliper pins can move freely.
Any issues identified here will help you isolate the root cause of the groaning noise.
Step 2: Low Speed Test Drive
Now take the vehicle on a low speed (10-25 mph) test drive, mimicking your normal in-town driving:
- Apply the brakes lightly at first, then more firmly.
- Does the groan occur right away or only with heavier braking?
- Does it occur constantly or only once per stop?
- Is the noise more prominent with braking, acceleration, turning or straight driving?
Make notes on when the groan happens to provide helpful clues.
Step 3: High Speed Test
Accelerate the vehicle to highway speeds and make a few hard stops from 50+ mph.
- Does the groaning go away at higher speeds? If so, that can indicate a buildup or corrosion issue.
- Does it get louder? That may signal warped or damaged rotors.
Again, document your observations for analysis.
Step 4: Wheel Analysis
Jack up each wheel and spin it slowly while listening/looking for issues:
- Touch pads to check for uneven or excessive wear.
- Note any cracks, rust or discoloration on rotors.
- Watch calipers to ensure they fully retract after braking.
By process of elimination from your inspections, you should now have a solid diagnosis of what is causing the groaning noise so it can be properly repaired.
How to Fix Groaning Brake Noises
Once the root cause of brake groaning is identified, the appropriate fix can be made:
- Glazed pads: Sand or replace pads to renew friction surface.
- Worn pads/rotors: Replace pads and resurface or replace rotors.
- Debris buildup: Clean pads, rotors and calipers with brake cleaning spray.
- Corroded/rusted rotors: Resurface or replace rotors. Prevent future rust with brake lubricant.
- Caliper issues: Lubricate/replace caliper slides and pins if sticking. Replace caliper if frozen or otherwise non-functional.
- Warped rotors: Resurface or replace warped rotors.
- Hydraulic problems: Repair leaks, change brake fluid, replace damaged components.
Be sure to follow a proper brake job process including:
- Proper tool use to avoid damage
- Bedding in new pads/rotors
- Road testing before regular use
- Checking fluid levels
Consult a brake specialist for major repairs like replacing calipers or hydraulic components.
Here are a few mistakes to avoid when correcting brake groaning issues:
- Assuming groaning noise will simply go away on its own
- Using cheap aftermarket pads with poor friction
- Not cleaning/lubricating important hardware
- Forgetting to pump brakes to set new pads after service
- Neglecting to bed-in pads and rotors properly
Take the time to fix groaning brakes right the first time and you’ll be rewarded with smooth, quiet braking once again.
When to Seek Professional Brake Service
While some brake groaning issues can be DIY repairs, more complex problems are best left to professional brake technicians. Seek out professional brake service if:
- Groaning occurs along with other noises like grinding or squeaking
- There are signs of hydraulic brake fluid leaks
- Rotors are deeply grooved, cracked or damaged
- Caliper repair or replacement is required
- Brake system warning lights are illuminated on the dash
- You lack the knowledge, tools or ability for safe brake service
The pros have the expertise and equipment needed for precise brake diagnosis and repair. It’s worth the cost for reliable, long-lasting results.
Brake Groaning Safety Tips
Hopefully this overview gives you a better understanding of what causes brakes to groan and how to fix them. Here are a few final brake safety reminders:
- Be proactive about brake inspections and service to prevent noises
- Stop driving immediately if brakes start making unusual noises
- Avoid “riding” your brakes by resting your foot on the pedal
- Don’t continue driving on groaning brakes – have them serviced promptly
- Bed-in all new brake pads and rotors properly before regular use
- Follow your vehicle owner’s manual maintenance schedule
Well-maintained brakes will provide safe, smooth, quiet operation for thousands of miles. Consider brake groaning as an early warning system to get your brakes checked out. With the right diagnosis and repair, you’ll have the reliable braking performance you need. Stay safe out there!