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I raised this question with several experienced mechanics and parts people and got surprisingly poor answers! It seems to me that most professionals only know a bad brake pad when a customer subsequently complaints of excessive noise, dust or premature wear. There are probably some China made brake pads that are of such poor quality that everyone can tell with the naked eye. This one here for one, looks a little dubious to me.



But is it generally possible to look at a brake pad and tell if it's good quality in every respect, before it is fitted to a car?

As with so much else in life, brake pads represent a compromise between different properties. A brake pad that is really good in one aspect is typically poor in another aspect. E.g. a very durable brake pad will tend to be very hard and consequently very noisy and it may also cause excessive wear on the rotors. So a good brake pad is one which scores high on several of the attributes that you deem most important.

The friction part of a brake pad is made from a mix of different materials which can be grouped in descending order according to the softness of the material: organic, ceramic and semi-metallic. Every type usually has some of the other materials mixed in as well and an organic brake pad can contain up to 20% metallic ingredients. A semi-metallic pad will often contain ceramic components. In fact there can be up to 50 materials that go into the mix on the friction material.

The following attributes are important for brake pads for passenger cars:

1. Braking ability
2. Noise
3. Dust
4. Durability
5. Price

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Braking ability
I don?t know about the US, but all pads sold in the EU must follow ECE Regulation 90, which a.o. prescribes that the braking performance must be very close to the car manufacturer's original brake pads, + / - 15%. This is measured in coefficient of friction (cF), which typically lies between 0.35 to 0.45 and for most brake pads for passenger car use, the braking ability isn?t an issue. You will rarely be able to find information about the coefficient of friction when you buy brake pads,

This article is about passenger cars for street use, but permit me a little Segway. You can easily get brake pads with much higher cF but they are not suitable for street use. A passenger car brake develops fade at temperatures around 315-380° C (600-700° F) whereas a racing brake pad resists fade until it reaches temperatures around 700-800° C (1300-1500° F). Racing brake pads can have a cF up to a whopping 0.68 but conversely it doesn?t work so well at low temperatures, which is outright dangerous for street use and to boot it is rather costly.

Ceramic pads can withstand higher heat than semi-metallic pads. That sounds good, but if you haven?t correspondingly upgraded the rotors, you may subject the rotors to more heat than they can handle and consequently warp the rotors. Some ceramic brake pads reportedly also works best when a little warmth has been worked up in them but that certainly doesn?t apply for all.

Can you see the quality? Not with the naked eye, but the stopping power is fine if the pads are certified with the ECE R90 standard.

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Noise
The softer the material, the less noise, The soft material molds to the brake disc and fills bumps so that the brake pad does not bounce across the surface of the disc and creates resonance in the material, which makes brakes howl. Ergo, a soft brake pad is quiet and a hard brake pad may be noisy. Ceramic pads are sufficiently soft to be noiseless. There are thankfully production techniques to modify noise characteristics of the harder friction materials. This includes

- Chamfering the sides of the pad.
- Include a shim, or relatively soft plate which is typically made of metal, rubber, or titanium, which sits between the caliper piston and the brake pad.
- Cut a groove in the middle of the brake pad to drain gasses, dust and heat from the surface and reduce stiffness.

Can you see the quality? You can see if the brake pad is chamfered, grooved or has a shim. You can also read on the box, whether the material is organic or ceramic.

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Dust
Brake dust drives many owners of expensive alloy wheels nuts. One might think that soft, organic brake pads give of more dust and semi-metallic pads have also had a reputation for being very dusty, which was certainly the case when they first hit the market as a replacement to asbestos pads. However, it isn?t these attributes that are the most important determinants when it comes to dust, but rather the resin adhesive used in the friction material. Unfortunately it isn?t possible to see with the naked eye, just which type of resin was used with a particular brake pad. If a low dust brake pad is your main criteria, then go with a ceramic brake pad as they give off less dust. More importantly, the dust color is white instead of black and thus a lot less visible on those fancy alu rims.

Can you see the quality? No, but the box should tell you whether it is a ceramic brake pad.

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Durability
A soft material will wear quicker and needs to be changed more often. A hard material lasts longer but can also do more damage to the rotors.

Can you see the quality? The box should state whether the material is semi-metallic or ceramic which ensures better durability.

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Price
Obviously a more complicated friction mix and a more processed surface will add a little cost; say 4 dollars instead of 2. A good quality shim, like a 3M shim, will add another 80 cents to the production cost. The brake pad may also come with a mounting kit and sensor which should add another 2 dollars. All these aspects taken into account, a poor quality brake pad might cost 5 dollars and a good quality brake pad should only cost 7-8 dollars for a set, but you wont be able to buy it for that price, unfortunately, as the importer and dealer will want to make their cut. Ceramic brake pads may cost another 50% in production costs.

Can you see the quality? Well, look at the invoice and decide whether you?ve paid a reasonable premium to the importer and dealer for their efforts.

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Conclusion
Back to the original question: what makes for a good brake pad? If you are ok with switching brake pads every 5,000 miles and you want to go soft on the rotors, you might want an organic brake pad. If you want durability and low dust and you?re less concerned with price, look for a ceramic brake pad. For most drivers, a semi-metallic brake pad presents the best value proposition but try to make sure is has one or more of the noise reducing attributes, such as a shim or that it is chamfered and/or grooved.

Below are a few illustrations of the various attributes I mentioned above.



Comments are much appreciated

leese8080

Wow. Thank you for your time and research on this matter. This is very informative and I have learned a lot.

Awesome Alpina wheels you got there.

NavarroOne

Much appreciated.

525iEnjoy

Noise in addition

is also a by product of poor installation, brake dust build up. Brake dust building up is probably in my opinion the main culprit especially on all German cars. Close second is bad technique on initial install of pads. The squeaking we hear is the by product of high pitch vibrations from the piston hitting the pads or the pads sliding in the carrier or the mounting points inside the piston and carrier where the pad rests or the anti rattle spring rattling. Brake dust get into any of those areas i mentioned can cause squeaking. And climates changes can cause the squeak.