It’s safe to assume that most auto repair DIYers undertake repair projects to save the labor costs associated with repair shops. Oil changes, spark plugs, filter changes, and tire rotations make up most of these tasks, but more accomplished home mechanics might take on more serious jobs, like, engine part replacement and brake jobs. But some things are best left to the pros, like certain elements of a brake repair. Here’s an example:
Can I hand sand brake rotors? You cannot hand sand brake rotors and expect to get satisfactory results. The machining of brake rotors requires too much precision for hand sanding. Furthermore, it would take much longer to do this task by hand, even if you could achieve the exact specifications.
Some repairs, whether home or auto, are simply too daunting to be undertaken by amateurs, regardless of their skill level. Simply put, they’re worth the money. With brake jobs, you have a couple of factors to consider – cost and safety. Safety should come first, but too often does not. Having brake rotors machined by professionals is one of those jobs that are worth the money.
What Does a Brake Rotor Do?
The brake rotor is made from hardened steel and revolves with the wheel assembly. Brake pads, made of cast iron and surfaced with a textured metallic coating, apply “squeeze” the rotor when the brake pedal is pressed, and the resulting friction slows the rolling rotor and breaks the forward momentum of the car.
Since the brake pads are textured with metallic grit for resistance (friction), they are also abrasive, which means they create wear on the rotor. When the wear defaces the surface of the rotor to the point where the pads don’t make solid contact with the rotor’s surface, it’s time to replace or resurface the rotors.
Signs of Brake Wear
Except for truly dedicated DIYers, few car owners do visual inspections of their brakes. If you take your car in for tire rotations, most tire shops will take a look at your brakes. It’s a service to you, and potential revenue for them, if service is needed (and they do that service routinely). But aside from visual inspection, there are other signs that the average car owner should pay attention to.
Here are some things to look for, feel for, or listen for:
- Brake Light Comes On
- Odd Noises From Brakes
- Vibration When Braking
- Leaking Brake Fluid
- Soft, “Spongy” Feel to Brake Pedal
- Burning Smell
- Pulling to Left or Right When Brakes Applied
Why is the Brake Light On?
The sudden appearance of a light on your car’s dashboard should be treated like a red flag. If it’s the brake warning light, it’s warning you of one of two issues, both needing immediate attention:
- It’s time to check the brakes. (Usually pre-designated when the car’s onboard computer was installed.)
- There is an active problem with the brakes.
Cars made in the past few years probably have a brake light system that relies on sensors to detect brake wear that exceeds specifications. 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 descends lower and lower into a groove or rut caused by brake pad wear, the sensor will eventually touch the rotor. This triggers the system and tells it to display a light on the dash.
Generally, the brake warning light turns on before the car owner starts 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. This would be an unfortunate mistake.
What’s That Scraping Noise?
Noises from the brakes can vary in sound and in the way we hear them. There are two primary sounds, but the ways these sounds express themselves are many:
- Metallic Squeal – This occurs when the brake wear indicators directly come in contact with the rotor. These can be heard when the car is in motion, and ironically, often go away when the brakes are applied.
- Grinding, Scraping Sound – This more serious condition means the brake pads have completely eroded, and their brackets are making contact with the rotor.
Not Good Vibrations
If you feel shaking in the steering wheel when you apply the brakes, it is a likely indicator that your brake pads/rotors/both are worn to the point of needing replacement. Shaking of the wheel or whole car when the brakes are not applied could point to non-brake issues like tire balance or wheel alignment. When brake pads gouge or pit the metal rotor, it will create a bumpy surface can be felt.
Brake Fluid Leaks
Leaking brake fluid is not necessarily a case for brake wear, but it could be. Most likely, there is a problem with the master cylinder, the seals, the brake lines or fittings that deliver the brake fluid to the cylinders.
If extra pressure is required to stop, it could cause a temporary leak of brake fluids. The extra pressure could cause fluid to force open a seal for a moment. This is not the most likely scenario in this situation, but it’s worth considering.
Brake Pedals
You should be familiar enough with your car’s characteristics to know when something is wrong – or at least different. If you feel that you have to push harder on the brakes to stop, that the response is lagging or feels “spongy,” there is an issue with your brakes that needs to be checked out.
Spongy brakes don’t necessarily mean that your brake pads are worn, but that is one of the possibilities. Air, moisture, dirt, or all three may have infiltrated your brake lines or master cylinder. In any case, have this condition checked out immediately.
Something’s Burning
If you notice a “hot,” acrid, chemical burning smell immediately after slowing drastically or coming to a complete stop, the smell could be coming from your brakes. It could mean you’ve been driving with your parking brake on, or it could mean your car’s 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, and the overheating can lead to the emulsifying of the grit on the brake pads. This is a serious condition that requires immediate action.
If your brake pads have overheated to the point where their gritty coating has partially melted, you need to determine the root cause. Also, some of the residues from the brake pad could have ended up on the rotor. This is another example where hiring a pro is clearly worth the money.
Pulling to One Side
When your brakes wear unevenly, so will the braking ability of each brake. This can “pull” the car toward the stronger brake.
Turning a Rotor
Again, only the pros should attempt this procedure. It’s a common practice to prolong the life of a rotor by having it “turned,” which means to grind the surface until it is smooth again.
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.
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
