What Causes Rotors to Warp?

Brake rotors take a lot of abuse as they entirely rely on friction to slow you down. The big metal discs that form the rotors are essentially latched on to by metal brake pads that bring these dics to what can best be described as a grinding halt. This process generates an enormous amount of heat.

These rotors are completely smooth when they come out of the factory. They can become warped over time, which basically means that they lose their even and smooth surface. 

That’s due to the fact that they’re clamped down by the brake pads numerous times in a single day. This is bound to cause wear and tear which results in the warping of the rotors.

What causes brake rotors to warp?

There are a few reasons why brake rotors end up warping. Wear and tear is the simplest reason. Use them for a long time and all of that heat and friction is going to end up taking its toll on the metal. The pads grind into the rotor every single time the speed needs to be reduced. 

This same step is repeated countless times over the lifespan of the rotor. While these are solidly built and rotors are essentially big round pieces of steel, they’re not really invincible. So put a brake rotor through enough wear and tear, it’s bound to get warped. 

There are other factors that can exacerbate these issues or cause the rotors to wear out and warp much faster than you’d imagine. For example, if you drive through the mountains quite often, the brake rotors work overtime especially when you’re coming down a long hill.

In this scenario, the stresses on the rotors are much higher than they would be if the vehicle was only being used on normal roads. That’s why many offroad drivers suggest that alternate methods like engine braking be used to prevent the brakes from heating up and even possibly failing.

Most people don’t remember that brake pads aren’t something that are meant to last a lifetime. Consult the owner’s manual of your vehicle to understand the intervals after which they need to be changed. If worn out brake pads are used for prolonged periods they end up damaging the rotor.

Drilled holes vs. slotted holes

If you look at a performance car closely you’ll notice that its brake rotors look quite different from the ones on your family SUV. That’s because those cars require incredible stopping power and conventional brake rotors just don’t fit the bill. 

Brake rotors actually come in many different types and each has their own set of advantages. Drilled and slotted rotors are among the most commonly used options.

Drilled holes

Drilled rotors are a good choice for those who live in areas that receive a lot of rainfall. That’s because the drilled holes give the water a place to escape, preventing it from staying on the rotor surface for too long. 

Since the water escapes that the rotor is more dry, this provides an improved brake bite.

They’re not recommended for racing cars, though. That’s because drilled rotors don’t really withstand continuous heat and cool cycles all that well, something that’s unavoidable on a performance vehicle. 

This can cause them to fail sooner. They remain a great option for street cars.

Slotted holes

As the name suggests, slotted rotors have grooves that are cut along the face of the rotor, the part that comes in contact with the brake pad. 

During repeated heavy braking, the brake system’s temperature increases and a layer of gas and dust is formed between the pad and rotor because of the material transfer caused by the friction. 

The slots on the rotor allow these gases to escape. This improves the brake bite and maintains stopping power. Slotted rotors are widely used on heavy trucks, off road vehicles, SUVs, and performance vehicles.

How to prevent brake rotor warping

There are a few precautions that you can take to prevent brake rotors from warping. Once new brake rotors and pads have been installed, you should probably break them in. This is done to ensure that the pads properly clean the rotor and apply the right amount of friction. Not breaking in these parts initially could prevent the pad from properly cleaning the rotor in the future.

The braking system tends to generate a lot of heat and if heated metal is cooled down too quickly, it can cause the metal to warp. So while driving over puddles of water might seem cool, the temperature difference between the water and the braking system will be significant. It will cool off the pads and rotor too quickly and this can end up distorting the metal.

Merely changing your driving style can go a long way in maintaining the health of your brake rotors for longer than you might imagine. 

If you’re someone who tends to break hard even when the car can be easily brought to a stop with gentle breaking, you’re putting way too much stress on the pads and rotors than necessary. 

Be a little light with the foot on the brake pedal and your braking system is going to reward you for it.

Another simple method to prevent rotors from warping is to ensure that the lug nuts are evenly tightened once they have been removed. They should be tightened in either the star or the cross pattern so as to prevent uneven clamping between the rotor, hub and wheel.

Cryogenic treatment can prevent rotors from warping

Brake rotors are made of metal and cryogenic treatment is a proven way of increasing abrasion resistance and help reduce warping under rapid temperature changes for metal components. A lot of stress can actually build up inside the metal once during the casting process. These residual stresses can lead to physical deformation, warping, during rapid temperature changes. Cryogenic treatment relieves these residual stresses before they have a chance to warp rotors that are under hard uses conditions.

This treatment is routinely used for brake rotors to not only increase their lifecycle but also improve performance. Many professional racing teams rely on the cryogenic treatment of their brake rotors for this express purpose. 

The same treatment is also applied to engines of racing cars that experience an immense amount of stress and heat during races.

Deep cryogenic treating/stress relieving

Deep cryogenic processing is the most effective way to increase the dimensional stability of metals. This highly precise process requires the temperature of the metals to be first brought down, slowly, to below -300⁰F.

The metal is then left in the cryogenic cooler for up to 24 hours or more, depending on the metal and the application, so that the intended effect can be achieved.

This is done to alter the crystalline structure of the metal in order to relieve stresses that may be present in the metal after going through the manufacturing process. The changes brought on by the cryogenic process are permanent and are effected throughout the volume of the material.

How we do it at CTP

Controlled Thermal Processing Cryogenics is a leader in the cryogenic processing of metals and plastics with decades of experience in this field. We have had both treated and untreated brake rotors tested by laboratories according to the SAE 2707 JUL 2004 METHOD B. 

The results from these independent testing labs confirmed that brake rotors last significantly longer after they have been cryogenically treated with no change in braking effectively. 

We have also seen in some cases that cryogenically treated brakes have had a lifespan of up to 300% compared to their untreated counterparts.

Take it from us, we know a thing or two about increasing the durability of brake rotors, after all we were founded by Jim Birks, a race car driver who was later joined by Rick Diekman, an engineer who has worked with prestigious car manufacturers like General Motors and Ford.

Improved performance and lifespan isn’t just the only benefit. Many worn out rotors end up in landfills and pollute the environment. Even the recycling process contributes to the pollution as it requires energy to transport them, melt them, and then recast them. 

Cryogenic treatment is a greener method of significantly extending the life of brake rotors so that the same set can be used for far longer, thereby reducing the number of rotors that end up in landfills.

Our team at CTP Cryogenics has almost four decades of experience in this industry. We use state-of-the-art cryogenic equipment to enable consumers and businesses to improve the quality and lifespan of everything from brake rotors to engines. 

We provide our services from three locations across the United States, so that customers on both coasts and everywhere in between can take advantage of our cryogenic processing and consulting services.

Interested in learning more about how cryogenic treatments for brake rotors can help you save money in the long run? Reach out to CTP Cryogenics today for a consultant and a free no-obligation quote.