How to Tell if Rotor Is Bad (15 Bad Rotor Symptoms)

A warped brake rotor is one of those wear-and-tear car problems that would be folly to ignore. Not only does fixing it become pricier the more it gets delayed, but it is also one of the worst issues to have, given the level of risk it puts a driver in when on the road. Some of its symptoms start rather quietly and may not be noticeable to the untrained eye – which is why learning how to tell if a brake rotor is bad is extremely important.

There are several ways to spot bad rotor symptoms. By feel, sound, or visual inspection, you should be able to ascertain if indicators such as pulsation/vibration, wobbling, grooves/scoring, blue marks, and screeching or grinding noises point to defective rotors or some other brake component.

Here are 15 common signs of a bad rotor you should be aware of:

  1. Vibration in the steering wheel
  2. Pulsating brake pedal
  3. Intermittent brake noises
  4. Grinding when hitting brakes
  5. Screeching after brake pad installation
  6. Out-of-round rotors
  7. Deep grooves or score marks
  8. Cracked rotors
  9. Blue discoloration
  10. Corrosion
  11. Strong chemical fumes
  12. Wobbling or rotor runout
  13. Lopsided, inconsistent braking
  14. Oversensitive/insensitive brakes
  15. Longer stopping distances

Determining what causes rotors to go bad quickly is not exactly a piece of cake, even for long-time vehicle owners. But with more repair experience and a little help from this guide, you will be well on your way.

Rusty Disk Brakes

Signs of a Bad Rotor

1. Vibration in the Steering Wheel

When hitting the brakes, your brake pads press against the smooth, flat surface of the rotors to halt or slow down your vehicle. This friction causes the brake rotors to become extremely hot (not to mention receive significant amounts of pressure), resulting in the rotors becoming bent, uneven, or warped over time.

Structurally, rotors and calipers are attached to the same spindle where the wheels are connected. So, if the rotors lose their smoothness, the feeling of unevenness or vibration transmits through the spindle and eventually reaches the steering wheel. Consequently, steering will not feel as smooth as it used to be with rotors and brake pads in good condition.

2. Pulsating Brake Pedal

The cause of this symptom is similar to the first item in this list – warped, bent, or uneven brake rotors. But instead of the steering wheel, the pulsation is mostly felt in the brake pedal. This feeling may be completely isolated in that area or possibly detected in other parts of the vehicle. Another reason for the pulsation is that your rotors may be nearing runout.

One way to help prevent premature warping of your brake rotors is to ensure your brake components are capable of proper heat dissipation. Since the brake system creates friction-based heat to put your vehicle to a halt, brake parts mustn’t overheat more than they should. Otherwise, the excessive heat can cause the brake rotors to buckle, plus other components to be prone to failure or damage.

Skimping on rotor replacement is also not advisable. Cheaper, lightweight brake components do not contain sufficient material to dissipate heat and may just be added salt to injury. Ceramic, stainless-steel, or cross-drilled slotted brake rotors are always the best replacements due to their higher tolerance for heat and effectiveness for heat dissipation.

3. Intermittent Brake Noises

Persistent brake noises are often interpreted as a guaranteed bad rotor sound. However, this may not always be the case. It takes keen listening skills to tell the difference between noise coming from a warped rotor and the odd sound from a vehicle left overnight in the open accumulating moisture. This latter type of sound is actually normal and goes away after driving for a while. It is also easy to prevent by keeping your car indoors when the weather is snowy, rainy, or humid.

What you should look out for is squealing, which indicates brake wear or severely worn-out brake pads. After all, squealing or squeaking occurs when the brake pad wear indicator hits the brake rotor. This noise could also be from a very dirty vehicle or a buildup of brake dust.

Service your brakes and immediately change the brake pads when this happens, as continuing to use worn pads poses a huge safety risk while on the road. Not to mention that it can overheat other brake components and cause excessive brake material buildup on the rotors. Scraping is another thing to be wary of, as it is a sure sign of worn rotors and pads. In most cases, scraping noises lead to rotors that have already developed deep grooves or edges.

4. Grinding When Hitting Brakes

Grinding noises emitted from your vehicle during braking is another means of how to tell if a brake rotor is bad. This noise comes from brake pads that have already worn down to the brake system’s metal backing plate. In this scenario, the latter grinds into the brake rotor’s surface, thus creating the sound. Either that or you have a pebble or some other type of debris stuck inside your brakes.

Whether the grinding noise is debris-related or not, it is an indication that your brake rotors are already beyond repair and would have to be immediately replaced with new ones. Seek a professional’s evaluation if you suspect foreign material inside your brakes is causing the grinding sound. Also, it is best to change your brake pads while you are at it to ensure the contact area between the rotors and brake pads is even on all fours of your vehicle.

5. Screeching After Brake Pad Installation

Although new brake pads take some time to settle in after installation, loud screeching sounds should not be regarded as normal. This high-pitched noise indicates that your rotors are glazed or the edges are burnt due to excessive heat. Upon inspection, you may also see a dark ring or blue marks (discussed further in a later part of this guide) on the rotor surface. If you have not had your new brake pads for long yet, taking it easy on the brakes when at high speeds may eradicate or reduce the occurrence of screeching. Otherwise, it may be time to replace those rotors.

6. Out-Of-Round Rotors

Apart from unusual vehicular sounds, visually inspecting brake components is another effective way to identify bad rotor symptoms. By performing regular inspections, drivers can tell a good rotor vs bad rotor. Usually, they discover a lip around the edge of the brake rotor or thinning of the rotor surface, especially in older vehicles with severely used brake systems. However, if you want to determine whether your rotors are out-of-rounds or require resurfacing, you will need proper measurement devices to measure the roundness and thickness of each rotor face. Or you can have it done in an auto shop.

7. Deep Grooves or Score Marks

This is, perhaps, the most obvious reply to the question, “What does a bad rotor look like?” A healthy brake rotor typically has a flat surface that is smooth both to the eyes and touch. The smoothness of the rotor face helps ensure its good contact with the brake pads, preventing the latter from wearing too deep into the rotor.

A brake rotor that looks like the opposite of this description is guaranteed to have bad contact with the brake pads — hence, damaged brake rotors lead to impaired brake performance. Although these surface imperfections accumulate over time, they sometimes manifest due to driving habits or braking system abuse. Grooves/scoring on the rotor face is always a sign for immediate brake rotor/pad replacement and must never be delayed or disregarded.

8. Cracked Rotors

Cracks or gouges can develop in brake rotors after being subject to extremely high temperatures. The excessive heat then causes the brake rotor to form dents on its surface. These cracks do not impede the function of the brake rotors, provided they are only on the surface level. However, deeper cracks pose greater risks and may even be early signs of a brake rotor snapping in half.

Unlike with tires (where you would only need replacement once you have reached the tire tread limit), it is unwise to maximize the use of a brake rotor to the point of runout. Even before you reach that stage, you have most likely already experienced major inconveniences in halting your vehicle. To continue driving your car with a broken rotor would be nonsensical, not to mention dangerous.

9. Blue Discoloration

Blue marks on the surface of your brake rotors usually precede worse part issues such as rotor cracks, faulty calipers and brake shoes, and uneven wear on the brake pads. The discoloration is from excessive heat attributed to riding the brakes, incorrectly aligned brake calipers, or insufficient heat dissipation by stock brake components. In some cases, it is due to unexplained pressure being applied to the brake pads even if the brake system is not engaged.

Seeing blue rotors should prompt you to perform a brake inspection on your car. It will be in your best interests to find out right away which of the components mentioned above are defective or in need of replacement — so that you do not run the risk of getting into more serious braking system issues. Veterans recommend replacing discolored rotors with cross-drilled slotted rotors and the brake pads with ceramic ones to improve heat dissipation.

10. Corrosion

Momentary rust formation is expected during winter or the rainy season due to moisture buildup in the vehicle (and in its brake system components), especially when left outdoors. But it is a different story for a car that is well-maintained and stored inside the garage. Should you notice rust forming around the outer edge of your brake rotors, then make sure to replace them sooner than later.

When not attended to, slight corrosion on the rotor surface can lead to grinding noises and rough braking. There would also be rust pitting in the brake pads, contact area, or vanes. Worst-case scenario, the brake rotors can get stuck due to excessive rust brought about by oxidation, making it extremely difficult for either the vehicle owner or a professional mechanic to remove and replace.

Rusty Brake Rotor on Wheel with Brake Caliper

11. Strong Chemical Fumes

Chemical odors coming from your vehicle can signify overheated brakes or malfunctioning calipers (one that is locked in place), potentially leading to brake failure. Faulty brake calipers, in particular, can put too much stress on a brake rotor, causing it to be warped or become off-balanced. Sometimes, smoke comes from the affected wheel. Meanwhile, brake rotors give off the sharp, unpleasant smell due to being overheated but have no smoke accompaniment.

Should you experience either one of these scenarios, make sure to pull over a roadside and let your brakes cool down first. After a period of rest, proceed with driving but use your braking system in moderation. Once you are in a safe location, attend to immediate repairs (or replacement) of your calipers, brake pads, and rotors.

12. Wobbling or Rotor Runout

Contrary to popular belief, wobbling is not only an early sign of wheel runout but also of damaged wheel bearings (or bearings with excessive play). The latter does not only occur when driving over 70 mph, leading to warped rotors and uneven brake pad wear. Wheel runout still needs to be examined since it negatively impacts how a brake rotor functions. However, ensuring wheel bearings are torqued to spec and in good condition is crucial, too.

13. Lopsided, Inconsistent Braking

Incidents of vehicles pulling only to one side when engaging the brakes have a variety of probable causes – among them a bad brake hose or a caliper issue. It may be difficult to pinpoint this problem at first. But once you do, determining whether the front or rear brakes are defective becomes easier.

If one brake is noticeably working harder than the other (resulting in the car pulling only to one direction when halting), chances are your front brakes are at fault. Plus, the side the vehicle pulls toward is where the working brake is. But if the lopsidedness of the brakes is close to negligible, it is probably the rear brakes needing inspection and rear calipers that are not functioning properly.

14. Oversensitive/Insensitive Brakes

For vehicles with hydraulically-operated brake discs, catching this braking system behavior early on makes a world of difference in how much an owner will end up spending for repairs and replacement parts. There are two sides to this issue — one is you barely touch the brake pedal, but braking still engages. The other is having to depress the pedal near the point of being snapped off the bushing just to get it to work.

If you find yourself in either situation when pressing the brakes, it could mean low brake fluid, air in the brake lines, overly thin brake pads, or a bigger problem involving your vehicle’s hydraulic system. While these do not directly impact your brake rotors, they would eventually — if not properly diagnosed and resolved.

15. Longer Stopping Distances

In the absence of telltale signs involving one’s sense of smell or touch, this is probably the most obvious sign to tell if a brake rotor is bad. Experienced drivers can easily recognize something has gone awry with the braking system through its performance. For example, warped/damaged brake rotors would naturally compromise a vehicle’s overall braking system functionality. This may manifest in that car’s inability to stop at an acceptable distance — a.k.a. braking system fade or brake fade.

Brake fade usually happens during high-performance driving or going down steep descents. It is likewise a result of contaminants on the brake rotors, causing the brake pads to lose grip and slide over the rotor surface. However, it can also be a gradual outcome of repeated/sustained brake use, especially when driving a vehicle under heavy load or in high-speed situations. Decrepit rotors eventually incur chips and uneven surfaces — imperfections that reduce brake efficiency since the pads get less braking surface on the rotors.

How Long Do Brake Rotors Last?

On average, one brake rotor will last 2-3 sets of brake pads before nearing its runout. But if you need a guide, brake rotors are stamped with a minimum thickness specification. Vehicles used for high-speed racing or hauling will surely have rotors with less-than-average life cycles. It does matter whether a brake rotor is old, brand-new, or resurfaced. Its make and material should also be considered.

In mileage, rotors given proper brake inspections, timely brake pad changes, and even wear can last from 15,000 to 100,000 miles before warranting replacement. However, these figures can change depending on driving habits, riding conditions, and frequency of upkeep or servicing. The health of other brake system components also largely affects the longevity of your rotor. Hence, it is best to account for these factors before pushing the limits of your braking system.

When Should I Get Them Replaced?

Ultimately, the response to this question depends on the severity of damage your brake rotor has sustained. Minor scratches on the rotor surface can still be remedied by machining the discs. But if the rotor is too warped or damaged, then a replacement would be more suitable. Better side with caution and replace the rotors before they are completely worn out, instead of risking meeting a catastrophe on the road.

In some instances, a different brake component may need a replacement to prevent (further) damage to your brake rotors. While in others, you will have to automatically get new brake pads with them. You should be able to decide whether to tarry or immediately proceed with replacement after following these simple steps:

How Do I Check My Rotors?

  1. Lift your car off the ground with a jack stand and remove the lug nuts from the wheels.
  2. Take off the tires and wheels to expose the brake rotors.
  3. Loosen the bolts on your brake calipers to remove them.
  4. Remove the brake pads and rotors from your vehicle for inspection.
  5. Thoroughly examine the rotor faces and outer/inner edges for any grooves, scoring, or unevenness.
  6. Do the same for the brake pads and ensure they have not yet reached their minimum thickness requirement.
  7. Clean all brake components, including the mounting surface for your brake rotor.

At this stage, you should see any deformities to the brake rotor or damage to individual brake system components. Your findings should point you toward your next course of action.

Conclusion – How to Tell if Rotor Is Bad

Rusty Brake Rotor

To review, here are 15 common signs of a bad rotor:

  1. Vibration in the steering wheel
  2. Pulsating brake pedal
  3. Intermittent brake noises
  4. Grinding when hitting brakes
  5. Screeching after brake pad installation
  6. Out-of-round rotors
  7. Deep grooves or score marks
  8. Cracked rotors
  9. Blue discoloration
  10. Corrosion
  11. Strong chemical fumes
  12. Wobbling or rotor runout
  13. Lopsided, inconsistent braking
  14. Oversensitive/insensitive brakes
  15. Longer stopping distances

Remember, driving around with a bad rotor or repeated occurrences of any of these symptoms is a definite no-no. For this reason, you should opt to immediately replace warped rotors or have a professional mechanic deal with the issue if it becomes too complicated. Inevitably, even the best-quality brake rotors are bound to decline. But with good driving habits, regular vehicle inspection, and strict adherence to scheduled maintenance, you should be able to prevent pricey repairs and further brake system damage.

Kris Peter

Adventure seeker and off-road enthusiast. I love the thrill of going off-road and taking on the elements.

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