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When Should You Resurface Rotors? (And When To Replace Them)

June 15, 2021

It looks like there’s something wrong with your brake rotors.

Should you replace or resurface them

In this article, we’ll look at these two rotor fixes to help you decide when you need to resurface rotors and when you need to replace them. We’ll also throw in some rotor FAQs at the end, highlighting an easy solution to any rotor issue.

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Let’s get started. 

What’s Brake Rotor Resurfacing?

Rotor resurfacing involves removing a tiny fraction of the rotor’s surface using a brake lathe. 

Resurfacing rotors help eliminate corrosion and brake pad deposits, which smooths out surface irregularities that may cause braking vibrations. It’s a brake service procedure that typically accompanies a brake pad replacement to create a ‘new’ surface for maximum brake pad friction.

Can resurfacing fix all rotor surface imperfections?

No. 

Rotors resurfacing won’t resolve hard spots that come in the cast rotor, as these usually extend well below the rotor surface. Shaving can help remove these hard spots and allow the rotor to run true, but they will eventually return. 

In this case, the best solution is a new brake rotor.

So, when is resurfacing viable?

When Can I Resurface Rotors?

The first consideration is the rotor thickness. 

A resurfaced rotor must meet the minimum thickness specification defined by the rotor manufacturer. If a rotor can’t meet the minimum thickness, you shouldn’t resurface it as it’ll become too thin, unsafe, and warp easily.

Next, the rotor mustn’t be warped or cracked

Always get a new rotor for this type of damage.

While rotors don’t always need resurfacing when you install new brake pads, resurfacing ensures the new brake pads have a good surface to grip. 

Now, let’s see when you should absolutely replace rotors instead of resurfacing them.

When Should I Replace Rotors?

The brake rotor is generally designed to last up to 70,000 miles, but its actual lifespan depends on several factors — like driving style or brake pad type. 

You should get a brake rotor replacement if you have a worn rotor that’s too thin, cracked, or warped. You’ll also need a new rotor if resurfacing the current rotor thins it beyond the manufacturer’s safe minimum thickness

Rotor wear is typically the same on the left and right disc brakes, so brake rotors are usually replaced in pairs. 

However, even if one rotor is still good, they should be changed together to maintain even braking. A significant rotor thickness difference in either can cause the brakes to pull to one side.

So how do you decide which option to go for?

Should I Replace Or Resurface Rotors?

While rotor resurfacing is an easier brake job, replacing rotors is now more affordable than it used to be. 

Most original equipment rotors were designed with enough thickness for at least two brake pad replacements, but newer cars tend towards thinner rotors to save weight. 

As a result, replacing might be the better option, as you won’t have to worry about the rotor wearing down before the new brake pads do.   

Additionally, some rotors are meant to wear down together with the brake pads, so resurfacing might not be an option at all.

Whatever you choose, make sure to get the opinion of a reliable mechanic as the rotor is an essential brake system component, and you need it functioning at optimum capacity. 

Next, let’s go over some FAQs to give you a better view of the brake rotor.

10 Brake Rotor FAQs

Here are a couple of brake rotor FAQs and their answers. 

1. What Is A Brake Rotor And How Does It Work?

The rotor, brake pads, and caliper are the main brake components in a disc brake system. 

The brake rotor (also called the brake disc) is a heavy metal disc connecting the vehicle wheel to the wheel hub. When the wheel rotates, the brake rotor spins with it.  

How do disc brakes work?

The brake caliper is suspended over a section of the rotor. 

During braking, brake fluid transfers pressure from the brake pedal, engaging the brake caliper. The brake caliper then clamps the brake pads onto the brake rotor, generating friction to slow the wheel to a stop.

Note: The brake rotor and brake pad are only used in disc brakes. In a drum brake, friction is created by pushing a brake shoe against a brake drum instead.

2. How Do I Know I Have A Rotor Problem?

You might have a rotor problem if you notice vibrations in the steering wheel or brake pedal when braking. Sometimes there could even be strange metallic noises when you apply the brakes. 

3. What Causes Rotor Vibrations?

Rotor vibrations while braking are typically caused by:

4. Why Do Brake Rotors Wear Down?

When the brakes are applied, the brake rotor thickness reduces a little bit each time. 

How fast the rotor wears down depends on a few factors:

5. What’s Rotor Runout?

Rotor runout defines how much the brake rotor deviates from side to side when viewed from its front edge. It’s also called lateral runout or axial runout, and creates a wobble during tire rotation.

Excessive runout can cause the rotor to wear unevenly, producing vibrations during braking.  

Some reasons for excessive runout are:

6. How Is Excessive Rotor Runout Corrected?

A few options to clear excessive runout are:

1. Installing tapered shims between the brake rotor and hub.  

2. Resurfacing the rotor with a brake lathe also helps correct the runout. This is easier to do with an on-car lathe than a conventional bench or machine lathe. 

3. Using a torque wrench (instead of an impact wrench) to give a final tightening to each lug nut prevents distortion in the hat section, inhibiting rotor disc wobbling.

4. Cleaning the inside of the rotor hat and the face of the hub using a drill-powered brush before installation will remove dirt and corrosion.

7. Can I Change My Rotor Type?

If your vehicle was initially equipped with composite rotors (with a separate hub and disc section), they could usually be replaced with cast iron rotors. 

There are a few things to note, though:

Cast iron rotors are less expensive and more rigid than composite rotors, and they’re also typically heavier. The hat section is thicker, and this can affect the steering and handling of some vehicles.

Always refer to manufacturer recommendations or get your mechanic’s advice before switching.

8. How Does Heat Affect Rotors?

Heat impacts both rotor wear and performance. 

Remember, braking friction generates a lot of heat. The disc section of the rotor absorbs the heat and dissipates it via cooling fins (or vents) between the faces of the disc. A rotor that can’t dissipate heat well is more prone to brake fade and warping, leading to uneven wear.

Vented rotors are almost always used in front disc brakes where there’s more braking load, while rear rotors can be non-vented.  

9. What Are Premium Aftermarket Rotors?

Premium aftermarket rotors typically have the same casting configuration as original equipment rotors. This results in the same style and number of cooling vents between the disc faces — which is important for heat dissipation and managing brake noise. 

Economy rotors usually have a standard cooling vent configuration to simplify the casting process. 

If a replacement rotor has a different design than originally installed, cooling or noise problems can crop up. So, if you need a new brake rotor, it’s advisable to install premium aftermarket rotors to circumvent braking problems.

10. What’s An Easy Solution To Rotor Problems?

If you’re unsure whether your pedal vibrations are from a worn rotor or something else, your best (and easiest) move is to get a mechanic to look at it.

An even better option is to rope in the services of a mobile mechanic like RepairSmith

This way, you won’t have to drive a possibly unreliable vehicle to a workshop.  

But what is RepairSmith?

RepairSmith is a convenient mobile vehicle repair and maintenance solution. 

Here are the benefits they offer:

Fill this online form for an accurate cost estimate of your brake rotor replacement and repairs.

Wrapping Up

Resurfacing rotors may sound like it’s becoming a thing of the past as newer rotors continue to grow more affordable. However, there will still be situations where resurfacing makes more sense. 

Whatever the situation, you can always rely on RepairSmith to help you out. Just contact them, and their ASE-certified technicians will be at your doorway in no time!