DIY car repairs are trending upward these days, contrary to predictions that with boomers getting too old to work on their own cars and millennials not inclined to do so, fewer car owners would be doing their own repairs. One of the most common DIY repairs is replacing brake pads, which is fairly easy, but some questions crop up.
Can you replace brake pads and not rotors? Yes, you can replace brake pads and not rotors. Eventually, however, you will have to replace the rotors. Common wisdom suggests replacing the rotors once for every two times you replace the pads. Rotors can also be “turned” – ground down smooth again.
As brakes are the first line of defense against collisions, it’s crucial to maintain them and to observe them for signs of wear. If you do any brake repairs yourself, be sure to follow proper procedures and use quality parts.
How Disc Brakes Work
In the term “disc brakes,” disc and rotor are the same thing. The disc is made from hardened steel and revolves with the wheel assembly. Pads, made of cast iron and fitted with a textured metallic coating, apply pressure to the rotor when the brake pedal is pressed and slow the turning disc until it comes to a complete stop.
Two pads apply pressure on each side of the rotor, “squeezing” it until it stops rotating. Since the pads are textured with grit for grip strength, they are also abrasive, which means they create wear on the rotor. When the wear defaces the surface of the disc to the point where the pads don’t make good contact with it, it’s time to replace or resurface the rotors.
The pads and the rotor are replaceable, and the job to accomplish these tasks is meant to be done with a minimum of disassembly and reassembly.
How to Know When A Brake Job is Called For
It’s a safe assumption that other than the most dedicated gear heads, few people take the time to do a visual inspection of their brakes on a regular basis. Indeed, it is a lot of trouble to jack up the car, remove a tire – or two, if you have two different types of brakes – and perhaps even partially remove a portion of the brake assembly.
Here are some things to look for, feel for, or listen for:
- Brake Light On
- Noises From Brakes
- Vibration or Shuddering When Braking
- Leaking Brake Fluid
- Soft Feel to Brake Pedal
- “Hot” Smell
- Pulling to One Side When Brakes Applied
Brake Light On
Unless you drive a restored ‘57 Chevy, your car has a brake warning light on the dashboard. Depending on the technology in place at the time of your car’s assembly, the brake warning light either warns you that it’s time to check the brakes or that sensors have detected a problem.
Cars made in the past two to three years likely have a sensor-driven brake light system. When everything is in good working order, electronic brake pad wear sensors glide on the end of a caliper, mere millimeters from the surface of the rotor.
But as the caliper dips lower and lower into a groove caused by brake pad wear, the sensors will eventually touch the rotor. This triggers the system to display a light on the dash indicating that the brake pads have reached the end of their life.
The brake warning light generally comes on before you start noticing any other condition that would indicate brake wear. Some car owners get a little nonchalant about the warning light, assuming that they have plenty of time to get the repair taken care of, but the longer you go without it, the faster the brake wear will occur.
Noises
Noises from the brakes can vary in sound and in presentation. There are two primary sounds:
- Metallic Squeal – This occurs when the brake wear indicators make contact with the rotor. It’s the audio version of the dashboard warning light. These can be heard when the car is in motion, and ironically, often go away when the brakes are applied.
- Grinding, Scraping Sound – This is a more serious condition. It means the brake pads have completely worn out, and their holding plates are making contact with the rotor. The distinct metal-on-metal sound should definitely not be ignored. The rotors could be damaged to the point they would have to be replaced, even though the mileage would not necessarily warrant it.
Vibration
If you feel shaking in the steering wheel when you apply the brakes, it could indicate brake pad wear. If you pads wear down evenly, you might not notice any vibration, but given enough time, the gouging of the metal rotor will create a bumpy surface that “fights back” against the pressure of the brake pads.
Leaking Brake Fluid
This is probably not a case for brake wear, but it could be. Most likely, there is a problem with the master cylinder, brake lines, or fittings.
When you apply the brakes, brake fluid rushes through tubing to the brake caliper and creates hydraulic pressure, helping force the brake pads down onto the rotor. If it’s leaking, a seal is separating or is worn to the point it can’t hold back the fluid.
Leaking brake fluid could be an indicator of brake wear if extra pressure is required to effect a stop. The extra pressure could cause fluid to force open a seal temporarily. This is not the most likely scenario in this situation, but it’s worth considering.
Spongy Feel to Brake Pedal
You should be familiar enough with your car’s characteristics to know when something is behaving differently. If you feel that your brake pedal’s travel is more than it used to be, that you have to press harder to affect a stop, that it’s one way one day and different the next, there is an issue with your brakes that needs to be checked out.
This doesn’t necessarily mean that your brake pads are worn, but that is one of the possibilities, and probably the most likely. It could mean there is air or moisture in the brake lines or master cylinder. In any case, have this condition checked out immediately.
Burning Smell
If you notice an acrid smell immediately after coming to a stop, it could be coming from your brakes. It could be you’ve been driving with your parking brake on, or it could mean your brakes are overheating.
Never drive with smoking, burning, or overheated brakes. They could cause your brake fluid to boil and release into the atmosphere, and you’ll end up with no brakes at all.
Worn brakes are susceptible to overheating.
Pulling to One Side
If your brakes wear unevenly, so will the braking ability of each brake. This uneven stopping power can “pull” the car toward the brake that’s doing the majority of the work.
Turning a Rotor
You can often prolong the life of a rotor by having it “turned.” Turning a rotor means to machine the surface until it is smooth again. This is not a DIY project.
When the scoring on a rotor is deeper than 0.5 millimeters, it must be replaced or machined perfectly flat again. The rotor can be machined by no more than two millimeters total, whether in one process or multiple turnings (which would be highly unusual). After that, the rotor must be replaced.
Extend the Life of Your Brake Pads
The way you drive has a major impact on the wear and tear on your car, including your brakes. Slow down gradually, anticipating that you’ll likely have to stop at the next intersection. Don’t rush up to the intersection at full speed, and then have to press hard on the brake pedal because the light turned red. This can lead to overheating of the brakes if repeated multiple times in a short time span.
Many modern cars have a clutch-free manual shift option. While upshifting from a stop through all the gears seems to be more trouble than it’s worth, downshifting to a stop has a great advantage. As you approach a stop sign or red light, take the transmission out of automatic and manually shift down one gear. A moment later, downshift again. This slows the car down without the brake pedal even being touched.
Sources:
https://www.autoserviceworld.com/jobbernews/millennials-re-inventing-diy-market/
https://shop.advanceautoparts.com/r/advice/cars-101/braking-fundamentals-brake-pads-rotors-and-fluid
https://en.wikipedia.org/wiki/Disc_brake
https://www.carsdirect.com/car-repair/when-should-you-turn-brake-rotors
https://www.lesschwab.com/article/never-ignore-these-8-warning-signs-of-brake-problems.html
https://www.r1concepts.com/cms/index/Why_buy_new_brake_rotors_instead_of_turning_them