Brake pads and rotor replacement, what size will work?

Tiny
KEITHTHOMAS19
  • MEMBER
  • 2016 CHEVROLET SONIC
  • 1.4L
  • 4 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
What size or kit will work for my vehicle?
Saturday, January 13th, 2024 AT 11:40 AM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
Normally we go by application when ordering brake rotors and pads, but in the case of my older Grand Caravans, they were available with optional larger brakes, and the way to tell was by wheel size. Standard brakes came on vans with 14" wheels, and the heavy duty / larger brakes came on vehicles with 15" wheels. I used to drag around an enclosed tandem-axle trailer that is larger and heavier than that van, and thanks to those larger brakes, I never needed to hook up the trailer brakes. The smaller brakes were fine for the vans, but not when pulling a big trailer.

I use the Rock Auto web site almost every day for reference, and for your car, I found the same thing. Your model is listed as being available with 15" or 17" wheels. Wagner lists different rotors for each wheel size, but the other suppliers don't make mention of wheel size.

Your car could also have rear disc or drum brakes. That variable shows up on the front brake pad and rotor sets. All original and aftermarket suppliers' friction material must maintain the original "coefficient of friction" to maintain the carefully designed-in front-to-rear brake balance. Drum brakes are "self-energizing" which simply boils down to they require much lower brake pedal effort to achieve a given stopping power. Disc brakes usually require a power brake booster to get the needed stopping power. This means the front brakes will typically be different depending on whether they have to match the high stopping power of rear drum brakes or the lower stopping power of rear disc brakes.

At least one supplier lists their front kits are for cars with rear disc and drum brakes. All of the others' listings don't require you to know which rear brakes you have. That tells me you can order any kit and it will fit.

One point of confusion comes when looking at the options, or "features" they list, like special coatings, slotted rotors, and things like that. Keep in mind there is no such thing as a replacement pad or rotor design that is going to give you more stopping power or that you'll be able to stop in a shorter distance. Remember the front and rear brakes have to be balanced. If those on either axle lock up too easily, those skidding tires will have no traction. To get traction back, you have to let up on the brake pedal to get the wheels spinning again, and that means while you're letting up on the pedal, the other wheels weren't at their maximum stopping power yet. Every aftermarket supplier must adhere to the original stopping power to maintain that balance. If one set of pads should have a higher coefficient of friction, it will be shorter or skinnier to offset that higher stopping power.

What you can get with the more expensive aftermarket pads is better heat dissipation which lowers the risk of one type of brake fade. Overheated brake pads off-gas a layer of gas that acts like little ball bearings between the rotor and pads. The brake pedal will still be high and firm, like normal, but the brakes will not slow the car as effectively as normal. Slotted rotors are an attempt to reduce the effects of off-gasing, but for most of us, that isn't necessary. If those special features had real value, they would have been incorporated when the car was built.

If you visit an auto parts store, the person there will tell you the different suppliers and / or "quality" they offer, and they will probably ask whether you have rear drum or disc brakes and the wheel size. Some will offer "good", "better", or "best". In those situations, the lowest quality you can buy is equivalent to original equipment. No supplier is going to go through all the design and production effort to make something not as good as what came on the car originally.

When you see a big difference in cost between multiple choices, the more expensive sets typically come with new hardware. For disc brakes that can include replaceable wear surfaces the calipers and pads ride on, and anti-rattle hardware. For drum brakes that usually includes all the hold-down hardware and return springs. Those get weak from age and heat, so we usually replace them with each brake job. In fact, there's a real lot more involved in a professional brake job than just slapping on a few new parts. There's a lot we do to prevent noises and vibrations, and there's a lot that can be done to accidentally cause those problems. Here's a link to article that goes into more detail for this job:

https://www.2carpros.com/articles/how-to-replace-front-brake-pads-and-rotors-fwd

Let me know if there's anything else I can help with.
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Saturday, January 13th, 2024 AT 2:01 PM

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