While most people know what the brakes on their car areresponsible for, a lot of them don’t realize how many different componentsthere are to the braking system, and how those parts can get damaged or wornout. Brake rotors are one of those components, and through use, they can becomewarped and ineffective.
So what causes brake rotors to warp? The main cause ofbrake rotors warping is excessive braking at high speeds, which causes therotors the heat up. When the rotors become too hot, the metal they arecomprised of becomes soft and begins to warp, causing the rotors to malfunction.
Warped brake rotors can cause excessive wear of your brakepads and in severe cases, can even impact a car’s ability to brake. Keepreading to find out more about the function of rotors in a car’s braking systemand how warped rotors become a problem.
Table of Contents
What Are Brake Rotors?
Before we can do into the causes of brake rotors warping,you’re going to need to know a little bit about brake rotors, what they aremade of, and how they work.
Brake rotors (also commonly known as brake discs) are largemetal discs that are located directly behind the wheels of a vehicle. If youwalk alongside a car and inspect the wheels, you can typically see a visiblebrake rotor.
There are two standard categories of brake rotors:
- Drilled brake rotors: Drilled brake rotorsfeature a circular series of drilled holes that help gas, water, and heat todissipate from the brake rotor quickly, as well as give the calipers extra grippingpower in wet conditions.
The downside of drilled brake rotors is that the drilled areas can cause thestructural integrity of the brake rotors to be weaker than if they were solid,which can lead to degradation or even cracking under harsh driving conditionssuch as high-speed braking.
- Slotted brake rotors: Rather than havingholes all the way through them, slotted brake rotors feature indentations onthe front surface of the rotor that help to dissipate water, air, and heat formaximum stopping performance.
Slotted brake rotors are popular on performance vehicles such as race cars butare not typically practical for everyday use because they tend to wear downbrake pads very quickly.
The way brake rotors work is that when a car is braking, thecar’s brake calipers clamp down on the rotor, and the rotor stops the wheelfrom spinning. Because they must absorb a ton of friction, brake rotors must beconstructed to withstand very high levels of heat.
The heat generated by brake rotors also has to be designedto dissipate quickly because the brakes are used so frequently while driving.
How Do Brake Rotors Work?
Brake rotors work as part of an integrated system along withthe calipers and brake pads. When the operator of a vehicle presses down on thebrake pedal, this causes the calipers to clamp the brake pads down on the brakerotors. The brake pads push against the moving wheels to slow them.
What Are Brake Rotors Made Of?
The majority of brake rotors available on the market areconstructed from gray cast iron. This is because gray cast iron disperses heatwell, which is the single most important aspect of brake rotor construction.
While most brake rotors are made of iron, there are alsoceramic rotors used that have the following advantages over metallic ones:
- They are lighter to handle
- They are more stable than metallic rotors at highspeeds
- They are more stable than metallic rotors athigh temperatures
There are many benefits to using ceramic brake rotors overmetallic brake rotors, but ceramic rotors tend to be much more expensive than metallicrotors.
Metallic rotors might be less expensive but wear morequickly and produce more brake dust. A good compromise can be semi-metallicrotors, which fall between metallic and ceramic rotors in price and offer someof the advantages of ceramic rotors at a lower cost point.
Another option for rotors is a rust-proof coating, whichincreases the durability of the rotor as well as maintains its shine for addedcosmetic value.
What Causes Brake Rotors to Warp?
When a brake rotor becomes warped, the surface of the rotorbecomes rough and uneven. The primary cause of brake rotor warping is excessiveamounts of heat build-up when braking. Excessive heat can affect the brakerotors negatively in two ways:
- It can cause the brake pads to break down andglaze the brake rotors with gripping material, reducing their effectiveness
- Excessive heat allows the brake pad to wear downthe rotor surface, which leads to rougher patches on the rotor where thedensity of the metal is uneven
In either case, the rotors are damaged by excessive heat,and this damage, in turn, affects the stopping performance of the vehicle.
Does Hard Braking Cause Brake Rotors to Warp?
Hard braking alone does not cause brake rotors to warp, aslong as braking is done when the car is already driving at a lower speed.However, repeatedly braking from high speeds, such as the maneuvers performedon a racetrack, causes heat to build-up faster in the braking system.
If a driver has to perform an emergency stop and a hardbrake with their vehicle at a low speed, such as twenty or thirty miles anhour, this should cause no damage to the braking system.
However, if a driver is repeatedly slamming to a stop fromhigher speeds such as forty miles per hour or above, this is eventually goingto cause the brake rotors to warp.
Why is It Important to Replace Warped Rotors?
There are several reasons it’s important to repair orreplace warped rotors when they occur, and some of these include the following:
- Increased wear in the braking system: Awarped brake rotor not only causes brake pads to wear more quickly thannecessary, but it can also cause damage to the brake calipers, which can be avery expensive mechanical repair.
- Decreased ability to brake: The mostdangerous reason it’s important to replace warped rotors is that allowing thisdamage to continue can eventually lead to your brakes failing, which can, inturn, lead to a serious car accident.
- Increased liability: It is dangerous forthe driver of a car with bad brakes in the case of an accident but driving acar with a faulty brake system also makes the driver responsible for any otherdamage they might cause in a wreck related to the brakes failing. If a personis badly injured or killed as a result of vehicular neglect, civil and criminalcharges can even be pressed.
It is sometimes easy to skimp on maintenance for vehicles,especially for those drivers on a tight budget, but the brake system is not asystem you want to try and limp along.
If you have issues with your brake rotors, it is a serioussafety hazard, and the vehicle should not be driven until the rotors arerepaired or replaced.
How to Inspect Brake Rotors for Warping
It can be difficult to tell the condition of a brake rotorjust by looking at it on the vehicle. While brake pads have sensors and visibleindicators that they are becoming worn, brake rotors are not that obvious intheir presentation during an inspection.
Here are a few warning signs to look for when visuallyinspecting your brake rotor:
- Visible cracks
- Grooves on the rotor
- A lip on the edge of the rotor
- Heat spots
- Rust (surface and corrosive)
Can Warped Brake Rotors Be Repaired?
In some cases, a warped brake rotor can be resurfaced ratherthan being replaced. When a car mechanic resurfaces a brake rotor, they returnit to a smooth finish that provides the correct friction for proper braking.
Brake rotors that are resurfaced are not considered warpedany longer because their surface is even again, but resurfacing a rotor doesmake the rotor thinner overall each time it is performed and decreases itsremaining service life.
Brake rotors are commonly resurfaced any time the brake padsare replaced on a vehicle because putting new brake pads on an uneven brakerotor can drastically reduce the overall durability and life of the brake pad.
Once a brake rotor has been resurfaced several times in thecourse of changing brake pads, a mechanic will typically recommend to thedriver that the rotors be replaced.
What Does it Cost to Have Warped Brake Rotors Replaced?
The cost of having warped brake rotors replaced can varybased on some of the following factors:
- State taxes
- Labor rates at individual shops
- Waste disposal fees
- Brake rotor material type
- Brake rotor condition
Brake rotors that are not too badly damaged can often justbe resurfaced or repaired, which can be significantly cheaper than having therotors replaced entirely.
On the flip side of that, brake rotors that have beenallowed to be badly damaged due to continued neglect are more likely to havecaused ancillary damage to the brake calipers and brake pads, which will driveup the cost of the overall brake repair job.
On average, the cost of replacing warped brake rotors rangesbetween $406 and $559, including the cost of mechanical labor.
Can You Replace Warped Brake Rotors Yourself?
Many repairs on a car can be undertaken by the car’soperator as long as they have some fundamental knowledge about how the car’ssystems work and what parts/tools are needed for the job.
However, because the brake system is a serious safetyconcern when it comes to a car’s operation, the repair of the brakes should notbe undertaken unless the driver is very experienced with car repairs. If adriver has never changed their oil before, they certainly shouldn’t be tryingto replace their brake rotors off a YouTube video or something similar.
This is because failure to reintegrate the braking systemcorrectly can lead to the brakes failing, and on the road this can have deadlylasting consequences or at the very least, wreck your car.
When in doubt, it’s always better to let a professionalmechanic handle any repairs on your car that involve systems that involvepassenger and road safety. Everyone has to start somewhere, but warped rotorsmight lead to other problems in the braking system that a novice mechanic maynot recognize.
How to Tell if Your Brake Rotors Are Warped
There are several symptoms a driver might notice if theirbrake rotors are beginning to warp. Drivers should watch out for the followingsigns of warping brake rotors while driving:
- Noticeable vibration in the brake pedal (alsoknown as brake judder)
- Noticeable vibration in the steering wheel
- Noises while braking such as thumping, groaning,and squealing
- Noted loss of performance in braking/stoppingpower
- Temporary loss of brakes
Because there is usually significant damage done to thebraking system by the time some of these symptoms are noticed, it is importantto have vehicles inspected regularly so that any wear and tear in these systemscan be noted and addressed before it becomes a performance issue.
Not only is this the safest way to ensure that a carcontinues to brake correctly, it can also save in costly repairs to othercomponents of the braking system down the line.
How Warped Brake Rotors Affect Your Driving
The most noticeable difference in the way warped brakerotors affect driving is that they increase the amount of time it takes for thebrakes to stop a vehicle. This lack of stopping power can come on gradually orall at once, depending on how the rotors are warped.
In practical scenarios, this can lead to a driver misjudgingthe amount of space needed to brake at a light (causing them to plow into thevehicle stopped in front of them),
Warped brake rotors can also lead to the brakes failingentirely, especially during an emergency stop. This can lead to collisions orworse if the brakes fail while a driver is trying to avoid a street-crossingpedestrian.
How to Prevent Brake Rotors from Warping
The main thing a driver can do to prevent brake rotorwarping is to not brake at excessive speeds or directly after accelerating.
Instead, a driver should take their foot off the gas pedaland allow the car to decelerate naturally before braking with an even, a smoothpush of the brake pedal rather than stomping it to the floor.
By braking smoothly and coasting to a slower speed beforeapplying the brakes, you can not only prevent warping of your brake rotors, butyou can also increase the durability of your brake pads. A few simple changesto the way someone drives can greatly increase the life of their brakes.
Should All Brake Rotors Be Replaced at Once?
If it turns out that a car needs brake rotor replacement, itcan often be an expensive investment. Brake rotors rarely need to be replaced(only above every third or fourth brake pad change, which means rotors usuallyonly need to be replaced roughly every 200,000 miles).
That means if brake rotors do need replacing, therehas usually already been some kind of damage done to the pads and calipers.Replacing the pads, rotors, and calipers on a car can range upwards of athousand dollars.
Because front braking action is typically more importantthan rear braking action, for those on a limited budget, it is possible toreplace the front brake rotors first and then get the rear brake rotorsreplaced at a later date.
‘This will increase the safety and stopping ability of thevehicle but will still give the driver a break on the expense involved.
Replace Brake Pads Regularly to Avoid Replacing Rotors
One of the most important ways to prevent premature brakerotor failure is to replace your brake pads regularly. This should be performedapproximately every 50,000 miles, but some high-performance brake pads aredesigned to go as long as 70,000 miles.
Along with regularly inspecting your brake pads for signs ofwear, you should also have your vehicle inspected on schedule by a mechanic,whether it needs repairs or not. An optimal time to do this is during a routineoil change at the repair garage.
Many car mechanics offer “trip checks” and other generalinspections that will check out the systems on a car that may be needingmaintenance attention, but you can also ask your mechanic to inspect the brakesspecifically if you feel like your brake pads are starting to wear.
Unlike rotors, brake pads are often designed with a built-in“squealer” that causes the brakes to start squealing when they are within athousand miles of seriously needing replacement. This gives a driver time toarrange for a stop at the garage.
Careful Driving Leads to Long-Lasting Brakes
Replacing warped brake rotors can be a hassle since it iscostly and can be a repair that takes several hours, but this problem with thebraking system of a car can be easily avoided with regular maintenance and carefuldriving. By allowing a car to glide at a slower speedbefore braking and being gentle when pressing the brake pedal rather thanslamming the brakes or braking at excessive speeds, drivers can do their partto make sure brake rotors last as long as possible.
