Brake rotors are a vital part of your vehicle’s disc brakes. However, they degrade over time, especially if you hit the brakes hard and often. As a result, their ability to stop your vehicle eventually deteriorates.
When it’s time to replace worn-out brake rotors, you sometimes have a choice between buying replacement parts or resurfacing the old rotors. Both options have their strengths and weaknesses, which we’ll discuss to determine which is better for your situation.
What is Brake Rotor Resurfacing?
It’s a machining process that smoothens the surface of the brake rotor. Resurfacing eliminates any distortion created by friction, heat, and physical contact between the rotor and the brake pad over years of use.
Resurfacing evens out the thickness of the rotor’s surface. It corrects the uneven thickness resulting from abrasion and heat deformation. This eliminates problems such as noise and vibration from the brake pad encountering an uneven surface.
Resurfacing also applies a new finish on the brake rotor’s surface. The restored surface finish helps the brake pad get a good grip on the rotor, increasing the amount of friction produced and improving braking power.
A machine tool called a brake lathe is essential for brake rotor resurfacing. There is also a special lathe that lets the mechanic repair the rotor without removing the rotor first.
Advantages of Brake Rotor Resurfacing
Brake rotor resurfacing can restore much of the braking performance of aging brake rotors, making it safer to drive on the road again. It can also make the rotor last longer.
Resurfacing also saves you the hassle of looking for a new brake rotor and the cost of buying and installing the replacement.
When Should Rotors be Resurfaced?
Generally, the brake rotors need resurfacing once they show symptoms of degradation.
Two common warning signs are pulsations in the brake pedal as you slowly halt your vehicle and your car moving unevenly while slowing down. The pulses and erratic movement come from the brake pad moving across rough rotor surfaces caused by uneven wear and pad friction material.
Whenever you replace your car’s brake pads, it’s a good idea to also resurface the brake rotors. The old pads have likely scored the rotor, making the surface uneven. By giving the replacement brake pads a smooth surface finish, both the pads and the rotors will work better together. In short, they will deliver better braking performance and last much longer.
Brake Rotor Thickness
Not all brake rotors are suitable for resurfacing. That’s because resurfacing makes them thinner, and rotors need to have a certain level of thickness to operate effectively.
Most manufacturers put the brake rotor’s minimum thickness where you can see them easily. If the rotor doesn’t have a visible mark, you can try to look for the specifications in a repair manual or repair database.
There are two ways to determine the thickness variation of the brake rotor. One is to use a micrometer to measure the brake rotor’s thickness at different locations on the rotor. The other method requires a dial indicator, which can spot changes in the brake rotor.
A good rule of thumb is to look out for surface variations of 0.001 inch or more. Remember the pulsations and uneven movement mentioned above? Even a seemingly minor chance of 0.001 inch can trigger those problems.
Can You Resurface Drilled and Slotted Brake Rotors?
Some high-performance cars have drilled and slotted rotors. Drilled brake rotors have holes carefully bored through them as well as venting between the opposite rotor surfaces. Meanwhile, slotted brake rotors have shallow grooves cut into their rotor surface.
These rotors offer superior braking performance because they quickly get rid of dust, heat, and moisture that can affect the brakes. Slotted brake rotors also remove the glazed layer of material on the surface of brake pads, which improves the pads’ ability to grip the rotor surface.
Resurfacing drilled and slotted brake rotors is possible. However, it’s recommended to have an experienced professional do this task.
This is because the brake lathe can get damaged while resurfacing a drilled or slotted brake rotor. Whenever the rotor holes or slots go beneath the lathe’s point, the cutting tool will come in contact with an intermittent cut that can break it.
Some auto service shops won’t resurface drilled and slotted brake rotors because of the risk to their tools. You should call your shop ahead of time and ask them if they perform this repair job.
Brake Rotor Resurfacing vs. Brake Rotor Replacement
Your brake rotors are causing the brake pedal to pulse, and you have a choice between resurfacing the old rotors and getting new ones. What should you do?
In most cases, getting new brake rotors is ideal. Some brake rotor designs are thin by design and will stop working properly if they get resurfaced.
Some car manufacturers also recommend replacing the brake rotors instead of resurfacing them. If you bring your car to the dealership for repairs, ask them if they allow resurfacing rotors.
Need to get back on the road as soon as possible? Then, it’s best to replace the worn-out brake rotors. It takes more time and effort to resurface the rotor rather than replace it. Resurfacing the rotor and checking its evenness add more time to the repair job.
Furthermore, a resurfaced brake rotor can perform differently from its factory-fresh condition. Car parts like brake rotors are designed and manufactured to specific standards. Resurfacing a rotor will change the part’s characteristics and potentially alter its performance.
Another difference is warranty coverage. Many rotor products come with a separate warranty for additional reassurance.
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