If you’ve had to do any brake work on your car at all recently, you might be wondering whether or not the brake pads are always in contact with the rotors. After all, doesn’t it sometimes seem like pads wear out a little too quickly?
In fact, the reality is that brake pads are not supposed to be in constant contact with the rotors. We’ll get into the nitty-gritty of why not in a second, but ultimately, pads and rotors only kiss when you plant your foot on the brake pedal. If they’re touching at any other time, your car’s braking system should be looked over by a mechanic. Failure to address braking issues can lead to a potentially catastrophic situation when you least expect it.
Before we get into why pads should only touch the rotors when you’re actively stopping, let’s take a moment to review the braking system in general.
The Braking System, Explained
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This isn’t the first time we’ve dived into how the braking system works, but considering the importance of this system, it’s always worth touching on again. Essentially, the pads and rotors are part of a larger component set that also encompasses the calipers, brake lines, and master cylinder.
When you initially step on the brake pedal, that effort first triggers the master cylinder, which, as its name suggests, works by pushing a cylinder through a chamber containing the brake fluid. That fluid is then forced out of the master cylinder and routed out through the brake lines to the calipers, which are found at all four wheels and house the brake pads. At this point, the force of the pressurized fluid forces the caliper piston to squeeze the pads against the rotors. The contact of the pads on the rotors slows the car down.
When your braking system is working properly, you’ll find smooth, linear deceleration when you press the brake pedal. That’s a sign that your brakes are working as intended and all is well with your system. Likewise, when you’re accelerating or cruising, the car should move forward straight and true, with no noticeable pulling or resistance.
When Should Brake Pads Contact the Rotors?
As we already noted, brake pads should not contact the rotors if the brake pedal is not depressed. Perhaps, depending on the factory tolerances of your specific make and model, there may be slight – and we mean slight – contact of the pad against the rotor. Anything more than that, however, is something to be concerned about. If the pads are snug against the rotors and your foot isn’t on the brake pedal, you’ve got an issue.
How Do I Know if My Brake Pads are Touching the Rotors?
You’ll know when pads and rotors are touching when they should be if you don’t have any issues accelerating or stopping. However, there are a few clear symptoms that suggest you may have an issue with a clingy brake pad.
Car Pulls to One Side
This is one of the classic symptoms of a stuck brake pad. You’ll be driving down a straight road and, rather than the car tracking true, begins to pull to one side, forcing you to make constant little corrections to keep it in line. There could be more than one cause of this, including issues with your tire alignment, but one of the common causes is a frozen or binding brake caliper. When this occurs, the caliper piston no longer retracts, keeping the pad in constant contact with the rotor.
The result is as if you were driving with the brakes engaged on that one wheel. As the rest of the wheels spin freely, the wheel inhibited by the bad caliper is fighting the friction and resistance of an actively engaged brake. You’ll feel this from the driver’s seat when the car is pulled towards the side with the guilty caliper.
Car Seems Sluggish
When brake pads are permanently making contact with the rotors, they create speed-reducing friction, making it hard for your car to accelerate. That’s great when things are working correctly, but if you have a pad that’s stuck on the rotor, you might notice that the car doesn’t want to accelerate as eagerly as normal. This is because the stuck pad is effectively slowing the car down at all times.
Excessive Heat from Wheels
Another classic sign of stuck brakes is excessive heat emanating from the wheels. This one is easy to detect: just walk around your car after a test drive. If you’ve got a wheel whose brake pads are constantly in contact with the rotors, you’ll instantly notice the heat on your legs. This will make the wheel and rotor too hot to touch.
Heat is a great indicator of this issue because heat is generated from friction. When the brakes are working correctly, the pad makes contact with the rotors and the resulting friction slows down the car by turning kinetic energy into heat. But as a car accelerates against a stuck pad, that scenario is significantly exaggerated. When the pad won’t move off a rotor, it is continuously turning energy into heat, generating extreme temperatures that you’ll notice immediately.
How Do I Fix Sticking Brake Pads?
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A word of caution here: brakes are serious business, and monkeying around with them without a good handle on car mechanics can lead to potentially disastrous results. We highly recommend leaving brake work to the experts. That said, if you know what you’re doing, you may be able to fix a seized caliper with nothing but a bit of cleaning and fiddling.1
The first thing to do is determine which pad is the issue. Once you’ve diagnosed the problem using the aforementioned symptoms, jack up the car and remove the wheel. With the wheel off, you’ll see the rotor and caliper. Unbolt the caliper and hang it off the spring so as not to put undue stress on the brake hose that’s still securing the caliper to the car.
Now take a closer look at the caliper. Pull out the pads. Are they evenly worn? Do they have sufficient surface area left on them? With the caliper removed, this is also a great opportunity to replace the brake pads.
With the pads still out, use a heavy-duty brake cleaner to clean the internals of the caliper. These cleaners will dispel any stubborn dirt and grime that built up over time and also help lubricate the caliper piston, pins, and slides. Add a little bit of brake grease or white lithium grease to further lube the caliper.
Now reassemble everything, making sure it’s all seated correctly and installed properly. With any luck, this will cure your stuck brake pads. If not, visit a shop – you may need more advanced brake work done.
Brake pads should not be continuously touching your rotors, or if so, the contact should be marginal. Anything more than light contact will create excessive friction that will cause noticeable drivability issues, including pulling, sluggish acceleration, and excessive heat. If this happens to you, try cleaning and lubing your calipers or otherwise stopping into your local mechanic for servicing. After all, the braking system is perhaps the most important component set on your vehicle and it requires replacement. You may also want to look into whether or not your local recycling center or mechanic will take your old brake pads for recycling.2
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- How To Diagnose and Fix a Seized Brake Caliper. Haynes.com. Accessed 18 Oct 2021.
- Lyu Y, Ma J, Åström AH, Wahlström J, Olofsson U. Recycling of worn out brake pads ‒ impact on tribology and environment. Sci Rep. 2020;10(1):8369. Published 2020 May 20. doi:10.1038/s41598-020-65265-w