If you go to change your brake pads and notice uneven wear, you should be slightly alarmed. Uneven brake pad wear means that something larger is wrong and it should never be ignored. It’s important to get to the bottom of the issue before major problems occur.
In this guide, we cover the top reasons for the uneven wear on the brake pads. We will also show you how to fix it and answer your top questions.
Reasons For Uneven Brake Pad Wear
The brake pads may wear unevenly because of a stuck slide pin or stuck brake pads in the mounting bracket. It could also be due to bad brake pad quality, or a bad brake caliper piston, as well as rotor thickness variation.
Here’s a closer look at these options in-depth.
1. Stuck Slide Pin
The slide pins allow the caliper to move back and forth. Moisture and debris can build up on the pins, causing corrosion. If the pins become corroded, the caliper won’t be able to move as it should.
Stopping power will decrease when these are corroded. If left unrepaired, the pads will start to wear, but unevenly.
2. Stuck Brake Pads In The Mounting Bracket
While it’s not common for the brake pads to be stuck in the mounting bracket, it can happen and lead to uneven wear. The brake pads sit in the caliper mounting bracket during normal operation. This is more common if you live in a climate with snow and road salt.
If these aren’t installed correctly or haven’t been cleaned properly during the last brake pad replacement, the pads may get stuck in the bracket. The brake pads would get hot and start to pull to one side in addition to the excess wear.
3. Bad Brake Pad Quality
There are different types of brake pads. As with anything, you can choose to pick an inexpensive set of pads, but you generally get what you pay for. If the quality of the pads is not good, you could see uneven wear, similar to what happens with tires. It can also happen if the brake pads weren’t changed together at the same time, with one worn more than the other.
For this reason, we always recommend choosing a higher-quality option. Yes, you may pay a bit more upfront, but the better pads are going to provide many more miles of use. Plus, you shouldn’t hear as much braking noise and you will have more confidence over the stopping power.
4. Bad Or Sticking Brake Caliper Piston
The caliper pistons need to slide smoothly. If there is rust or debris on the pistons, you will get sticky calipers. In this situation, the brake pads drag on the rotor and it starts to wear funny.
There could also be a mechanical malfunction with the caliper piston. When the piston is frozen, the caliper won’t engage.
5. Rotor Thickness Variation
The brake rotors also play a part in how the pads wear. Depending on how thick the rotor is, you could notice uneven wear with the pads.
If the thickness of the rotor is uneven, the pad can’t wear evenly. You may have to replace your brake pads more frequently when you should have had the rotors resurfaced or replaced instead.
How To Fix Uneven Brake Pad Wear
You can fix uneven brake wear by repairing the malfunction that’s causing it. As professional mechanics, we’ve worked on our share of brake systems. Therefore, we can give you some advice if you want to repair it yourself.
1. Remove Brake Pads
If you plan to work on the brake system, it’s important to gather your materials ahead of time. You will need a solid floor jack and jack stands, plus some basic mechanics tools. You can follow our directions or get more guidance from the information in your car’s service manual.
- Secure the vehicle on jack stands. Find the appropriate jacking location in your owner’s manual.
- Remove the lug nuts on the wheel and put them in a safe location.
- Remove the wheel.
- Locate the two slider pins, otherwise known as the caliper bolts, that are holding the caliper.
- Remove the pins. With some vehicles, you only need to remove the lower bolt.
- You should be able to pivot the brake caliper upwards. The hydraulic line will flex but shouldn’t disconnect.
- From here, you should be able to inspect the brake pads and confirm the uneven wear.
- Slide the brake pads out of the mount. There are retaining clips that hold them in place.
With the brake pads out, you are ready to move on to the next step.
2. Clean The Sliding Surface Of The Brake Pad’s Mounting Bracket
If you notice rust or debris on the mounting bracket, now is the time to clean it up. There are multiple methods of cleaning, so use the one that you prefer.
Some people use a wire brush, while others think brake cleaner and a rag work better. You can also use sandpaper to gently remove any impurities. Just be sure to wear adequate protective gear so you aren’t breathing in brake dust or chemicals.
3. Check And Lubricate The Slide Pins
When it comes to cleaning the slide pins, we find the wire brush works great with brake cleaner. You want to remove any debris before lubricating.
Once you are ready for lubrication, choose high-quality grease. Make sure you don’t overapply any of the areas but put on a uniform coating instead.
4. Replace Brake Pads If Worn
Since the brake pads have worn unevenly, you should replace them. Even if there is thickness left, it’s best to start over, especially once you’ve figured out what’s causing the wear.
Brake pads should always be replaced in pairs. Therefore, if you are replacing the right front brake pads, you should replace the left front as well. The same is true with the rear brakes. However, you don’t need to replace the rear brakes with the front and vice versa unless they are all worn.
RELATED: Brake Pad Thickness – Minimum, New, & Ideal Thickness
5. Check The Brake Caliper Function
Since you’ve changed the brake pads, you want to make sure that the calipers are working as they should. Otherwise, you are going to have the same problem you started with. During the brake replacement, you would not have been able to move the piston if the caliper had been seized.
You can rebuild the caliper, but few people do that. It’s easier and less time-intensive to replace the defective caliper.
6. Replace Warped Brake Rotor
You have two options when dealing with a warped brake rotor. First, you could resurface them. To resurface the rotor, it is put in a machine, known as a brake lathe, for smoothing out the surface. This can only be done if there’s enough thickness left on the rotor. Additionally, it doesn’t always repair the problem, as the rotor could warp again after the process.
The other option is to replace the brake rotors. On average, this costs about $35 to $100 for the rotor, plus the labor to install it. Again, you should replace the rotors in pairs to keep everything uniform.
7. Contact A Professional
The brakes on your car are vitally important to your safety. Therefore, you should attempt any brake repairs if you don’t have the experience or the equipment to do the job right.
We recommend finding a qualified mechanic if you need the brakes worked on. Get an upfront quote that shows the cost of parts and labor. It’s okay to get several quotes if you want another opinion, but don’t choose a mechanic based on price alone. Instead, factor in the reputation of the auto repair shop too.
Is uneven brake pad wear bad?
Yes, it means that there’s something defective in the brake system or that the pads are low-quality. You may have a stuck slide pin, stuck brake pads in the mounting bracket, a bad caliper piston or a variance in the rotor thickness that needs to be repaired.
What causes uneven brake pad wear on one side?
Brake wear should occur uniformly. If it’s uneven, you may have installed low-quality pads. Otherwise, you may be dealing with rotor thickness variance, a bad caliper piston, stuck brake pads in the mounting bracket or a stuck slide pin, all of which must be repaired.
How do you stop uneven brake wear?
The only way to stop uneven wear from occurring more is to figure out what’s causing it and fix it. It could be a bad caliper piston, a stuck slide pin, rotor thickness variance or stuck brake pads in the mounting bracket. Once the brake system is working as it was intended, the uneven wear should cease.
Should inner and outer brake pads wear evenly?
When the braking system is working as it was intended, the variance between the inner and outer brake pads should be minimal. When the car has a floating caliper brake system, the inner pad will wear faster than the outer, but never more than by two to three millimeters.
Your braking system is vitally important to your on-road safety. Without functioning brakes, you are putting yourself and others at risk. If the brake pads are wearing unevenly, you want to quickly figure out what’s going on and repair it. There’s no time to waste.
If you aren’t sure how to diagnose or repair the braking system, get help from a professional. This isn’t something you want to experiment with since so much is riding on the integrity of the brakes.