Brake Pad Thickness: How to Check for Worn Out
It is crucial to check your brake pad thickness regularly to ensure safe braking and prevent expensive repairs down the road. Worn out brake pads can seriously compromise your ability to stop and lead to dangerous situations on the road. Thin brake pads may emit a high-pitched squealing or scraping noise when applied, indicating that a change is needed. This article provides an overview of how to properly inspect brake pad thickness so you know when replacement is required. Driving with brake pads that are too worn poses serious risks, like longer stopping distances, brake fade, and rotors becoming damaged. Stay safe by frequently checking brake components and having worn pads swapped out right away.
What are Brake Pads
Brake pads are a key component in disc brake systems, which are the most common type of brakes in vehicles today. The purpose of brake pads is to create friction with the rotor in order to slow down and stop the wheels from spinning. When the brakes are applied, hydraulic pressure pushes the brake pads against the rotor, creating friction that converts the kinetic energy of the moving wheels into heat energy, slowing the vehicle down (How Brake Pads Work).
Most brake pads today are composed of a metal backing plate layered with friction material such as fibers, bonding agents, lubricants and fillers. Common friction materials include semi-metallic, low-metallic NAO, and ceramic compounds (Everything You Need to Know About Brake Pads). The pads provide the friction while the rotor dissipates the heat and slows the wheel down. The difference between the brake pad and rotor is that the pad contacts the rotor under pressure to create braking force through friction, while the rotor is the disc that spins with the wheel that the pad clamps down on.
Recommended Brake Pad Thickness
The minimum safe thickness for brake pads is typically 1/8 inch or around 3mm according to industry standards. Most mechanics recommend replacing brake pads once they wear down to this level to ensure safe and effective braking performance. Going below this minimum thickness can compromise braking ability and be dangerous. Some specs for minimum thickness include:
The Automotive Maintenance & Repair Association (AMRA) spec is 2/32 inch or 1.5mm minimum thickness for safe operation (https://www.trodo.com/blog/when-to-replace-brake-pads-minimum-safe-thickness).
According to Toyota, the standard is to replace front brake pads when worn to 3mm and rear brake pads when worn to 2mm (https://www.autonationmobileservice.com/i/blog/brake-pad-thickness/).
While specific recommendations vary slightly, 1/8 inch or 3mm is considered the absolute bare minimum thickness for safe braking. Going below this risks brake failure and should prompt immediate replacement of the brake pads.
How Brake Pads Wear Down
There are several factors that contribute to brake pad wear, causing them to wear out more quickly in some situations:
Driving Style – Aggressive driving with heavy braking wears pads faster. Frequent stop-and-go driving also increases wear. Gentle braking allows pads to last longer.
Conditions – Environmental factors like cold, heat, moisture and salt on roads can accelerate wear. Pads wear faster in winter conditions.
Vehicle Weight – The heavier the vehicle and cargo load, the more force required when braking, wearing pads faster.
Inner vs. Outer Pad Wear – Inner pads wear slightly faster because they do more work with steering and weight transfer. Outer pads still receive significant wear.
Monitoring pad thickness and driving habits can maximize pad life. But gradual wear is normal from friction braking.
Checking Pad Thickness
There are a few ways to check the thickness of your brake pads without fully removing the wheels and calipers:
Visually inspect the brake pads through the openings in your wheel rims or brake calipers. Pads less than 4mm thick likely need to be replaced soon.
Use a small flashlight to better see the brake pad material thickness. Look for signs of thin, worn down pads.
For a more exact measurement, remove the wheels and place a brake pad gauge between the brake pad and rotor to measure the thickness. New pads are typically 10-12mm thick.
There should be at least 3mm of pad thickness remaining for safe braking. Pads worn down to the metal backing plate must be replaced immediately.
When to Replace Brake Pads
Brake pads should be regularly inspected to ensure they are not worn down too far. Waiting too long to replace worn brake pads can be dangerous and lead to brake failure. Some warning signs that your brake pads need to be replaced include:
- Squealing or screeching noises when braking – This high-pitched noise means the brake pads are worn and no longer smooth.
- Vibrating steering wheel when braking – Can indicate uneven brake pad wear.
- Longer stopping distances – As pads wear down, you’ll need to press the brake pedal farther to stop the vehicle.
- Brake pedal pulsations – Can signal warped rotors caused by worn pads.
As a general guideline, brake pads should be replaced every 25,000 to 65,000 miles. However, driving habits and conditions can affect brake pad life. Aggressive braking, stop-and-go traffic, hot climates, towing, etc. will wear pads faster. Regular brake inspections are the best way to gauge pad life.
Waiting too long after the pads are worn down to the metal backing plate can damage rotors and calipers. Metal on metal contact without the brake pad material to absorb friction will lead to overheating and brake failure. Replacing pads before they are completely worn helps prevent more expensive brake repairs down the road.
Cost of Replacing Brake Pads
The cost to replace brake pads can vary greatly depending on the type of pads you choose and whether other brake components need to be replaced as well. According to AAA, just replacing the brake pads on either the front or rear wheels would run $100-$300, while replacing pads on both axles would be $200-$600.
Getting a full brake job done that includes new pads, rotors, and calipers on all wheels could cost between $400 on the low end up to $800 or more for premium parts and labor, according to Jiffy Lube. This represents a significant cost increase over just swapping the pads.
The type of brake pad material chosen also impacts cost. Ceramic pads often cost more upfront but can offer better braking performance and last longer. Basic organic pads are cheaper but wear faster. Semi-metallic pads offer a middle ground in terms of cost and longevity.
Experts recommend inspecting brake pads regularly and replacing them when they near the end of their service life, even if performance hasn’t declined yet. This preventative maintenance can avoid more expensive brake repairs down the road. Replacing pads early while rotors are still in good shape also reduces costs compared to machining or replacing rotors later.
How to Replace Brake Pads
Replacing brake pads is a straightforward job that can be done at home with some basic mechanical skills and tools. Here is an overview of the brake pad replacement process:
You’ll need a floor jack, jack stands, lug wrench, brake pad spreader tool, brake caliper wind-back tool, brake cleaner, rubber mallet, torque wrench, and new brake pads. Ensure you have all tools and supplies before beginning.
First, lift the vehicle using the floor jack and secure it on jack stands. Remove the wheels to access the brake caliper and rotor area. Use the wind-back tool to retract the brake caliper piston. This pushes the caliper off the rotor so the old pads can slide out.
Clean the caliper area with brake cleaner. Install the new pads and secure them with the pad spreader tool. Push the caliper piston back in and re-mount the caliper onto the rotor. Reinstall the wheels and lower the vehicle.
It’s crucial to pump the brake pedal until firm pressure is felt after the job is complete. This sets the new pad position. Finally, make sure to bed-in the new brake pads by driving for a few miles and braking normally without heavy stops.
Key tips when changing brake pads:
- Consult a vehicle repair manual for the proper pad replacement steps.
- Never push brake caliper pistons in by hand – use the wind-back tool.
- Replace pads in axle sets – both wheels at once for even braking.
- Tighten lug nuts carefully with a torque wrench.
- Avoid brake fluid contact with eyes and skin.
Take precautions to complete this maintenance safely. With proper tools and care, DIY brake pad replacement can save on repair costs.
Brake Pad Brands
When it comes to brake pads, the brand you choose matters. Some of the most trusted and recommended brands include Bosch, Akebono, Wagner, Raybestos, and Brembo.
Bosch is consistently rated as one of the best brake pad brands. Their brake pads offer excellent durability and braking power. Bosch pads also tend to be on the quieter side. However, they do come at a slightly higher cost than other brands.
Akebono is known for manufacturing high-performance ceramic brake pads. These pads offer increased braking power along with low dust and noise. The tradeoff is that they can be more expensive than semi-metallic pads.
Wagner and Raybestos produce reliable brake pads at an affordable price point. These tend to be good options for daily drivers who want dependable braking without paying a premium. However, some drivers report more noise from these pads compared to premium brands.
For high-performance vehicles, Brembo is often considered the gold standard. Brembo pads offer incredible stopping power for track days and competitive driving. But this level of performance comes at a steep price, making Brembo impractical for normal street use.
When choosing the best brake pad brand for your needs, consider factors like driving style, vehicle type, budget, and desired qualities like noise, dust, and longevity. Consulting consumer reports and forums can help narrow down the top brands for your specific situation.
Maintaining Healthy Brakes
Proper brake maintenance between replacements is crucial for keeping your brakes in good working order and avoiding problems down the road. Here are some tips for maintaining healthy brakes:
Clean and lubricate brake hardware regularly. Brake slides, pins, shims, and caliper bolts should be cleaned with brake cleaner to remove dirt, debris, and corrosion. Apply high temperature brake lubricant to these components to prevent binding and ensure smooth brake operation (1).
Inspect brake hoses and lines periodically. Look for cracking, chafing, leaks, and corrosion. Damaged brake hoses can lead to brake failure and should be replaced immediately (2).
“Bed-in” new brake pads and rotors. When installing new brake pads and rotors, follow the bedding-in procedure. This involves making a series of light stops to transfer an even layer of friction material onto the new rotors. Bedding in properly conditions the brake pads for maximum performance and longevity (3).
Avoid sitting with your foot on the brake pedal during long stops. This can overheat the brakes and cause premature wear. Overheated brakes are also less effective at slowing your vehicle.
Check brake fluid levels monthly. Low fluid levels can indicate a leak in the brake system. Top off with DOT 3 or DOT 4 brake fluid as needed, being careful not to spill any on painted surfaces as it will damage the finish (1,2).