Rick's Free Auto Repair Advice

How to buy the best brake rotors

Here’s how to buy the best brake rotors

There are lots of brake rotor brands on the market today and a high percentage of them are just garbage. They all look good in the box, so what’s the real difference and how do you buy the best brake rotors? Just follow these shopping rules.

Rule #1 Stick with a name brand manufacturer

Today it’s easier than at any other time to become an importer. All you need is an account at Alibaba and a clever name for your company. Alibaba sellers can custom print boxes for their rotors and land them in the U.S. or Canada for as little as $8 each. No reputable brake manufacturer would allow their names on those low grade rotors.

Here’s a list of the MAJOR players in the brake parts business

ACDelco — owned by General Motors and a Tier 1 supplier to GM
Advics —
Beck Arnley — see Dr1V division of Tenneco Automotive below
Bendix See — see MAT Holdings and TMD Friction
Brembo — A Tier 1 supplier of brake calipers for Porsche, Mercedes, Lancia, BMW, Nissan and Chrysler.
Bosch — No longer owned by Robert Bosch. It is now owned by Chassis Brakes International
Centric — see First Brands Group
Monroe — see Dr1V division of Tenneco Automotive
Pagid — See TMD Friction
Raybestos — see First Brands Group
Wagner — see Dr1V division of Tenneco Automotive

#1 Buy the rotors that are made with more metal

The key to stopping power is a high quality brake pad and a rotor with high mass and the proper cooling vanes. The two shown below are for the same vehicle. The top image shows the weight of a premium product, while the bottom photo shows the weight of an economy product. The economy rotor is 2.6-lbs lighter, or 15% less metal. When it comes to heat dissipation, mass is everything. So the economy rotor can’t dissipate heat as well as the premium unit, which means you’ll get more brake pad wear and more brake pad fade.

You obviously can’t bring a scale with you to the auto parts store, but you can compare them side by side and choose the one that’s heavier.

premium brake rotor

Premium quality brake rotor. Compare the weigh to the economy rotor

economy brake rotor

Economy Rotor’s have less metal so they don’t brake as well

#2 Compare friction ring thickness

If you look the thickness of the friction rings below, you’ll see where the economy manufacturers cut corners. The economy product has thinner friction rings.

The thinner friction ring can’t dissipate heat as well as the thicker friction ring. So it will degrade brake pad performance and wear out faster.

The thinner friction ring also means it can’t be resurfaced.

Compare rotor face thickness. The rotor with a thicker face is better.

Image showing thicker friction ring on premium brake rotor

OEM brake rotor. Compare friction ring thickness with the economy rotor

image showing the thinner friction ring on an economy brake rotor

Economy brake rotor. Notice the thinner plates friction ring compared to the better rotor

#3 Insist on factory cooling vanes

It costs more to duplicate the carmakers’ cooling vane design than it does to make straight cooling vanes.

Carmakers design these unique vane patterns for a reason; they cool better and provide better heat dissipation and better braking.

image showing different cooling vane designs

The cooling vane design makes a big different on braking efficiency

#4 The best brake rotors use high quality gray iron

Most brake rotors are made from either medium carbon (G30) or high carbon (G20) gray iron. Medium G30 is used mostly for standard passenger vehicles, while G20 is often used for light trucks and SUVs.

However, according to a recent SAE study, “Rotor gray iron material varies considerably from one supplier to another even with the same grade of rotor iron specified.” — Fine-Tuning of Rotor Gray Iron Material for Optimal Brake Performance, SAE 2016-01-1942.

That’s why it’s important to purchase brake rotors from a reputable brake parts manufacturer.

 

#5 There’s there’s the brake rotor coating issue

All brake rotors rust. That’s not a big issue for the friction ring (aka swept area) because the brake pads will wipe off the rust. But rust can also accumulate on the hat and mounting areas. Brake parts manufacturers have responded by offering electro-plated brake rotors.

You should buy premium brake rotors with electro-plating even if you don’t live in cold climates where road salt is used. Why? Because the electro-plating protects the cooling vanes from corroding, and proper cooling vane operation is critical to long rotor and pad life.

©, 2021 Rick Muscoplat

 

 

 

 

 

 

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