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Brake discs, also called Brake rotors, are one of the most essential components of a car. If they are lipped and have grooves or cracks, it would directly impact your braking and driving experience.
I have defined brake disc (rotors) lipping and have also explained what causes it, how it impacts braking, and what to do if your discs are lipped.
Meaning of “Brake Discs Are Lipped”?
If your brake discs (rotors) are worn out, they are most likely to have a lip on the edges. This lip can be felt when you trace the disc (rotor) to its outermost edge. New discs are perfectly flat, but the brake pads do not contact the entire surface of the disc, and when the pads wear the disc down, they leave a lip on the perimeter.
Issues caused by lipped Discs (Rotors)
As mentioned before, lipped discs can cause several issues impacting your driving experience and braking performance. Below, I have mentioned some of the most common ones.
Keep in mind a lot of the problems are not directly caused by the lip that is developed on the edges but instead by other defects such as disc grooves. For example, If your discs are lipped, they are worn out and most probably have uneven wear.
Wobbling and Vibrations:The most common issue that you are going to face is wobbling and vibrations while braking at high speed. The car feels like it’s shaking, and the steering wheel wobbles until the pedal is released.
Reduced Braking Performance: These brake discs can even cause longer braking distance, which is quite unsafe.
What causes lipped Discs (Rotors)? And how to avoid it?
As mentioned before, new discs are perfectly flat, but the brake pads do not contact the entire surface of the disc, and when the pads wear the disc down, they leave a lip on the perimeter.
So, it’s evident that most discs will have a lip once they are worn out. But the way I apply brake matters a lot. I personally drive fast and slightly aggressively, so it’s obvious I brake hard, too; due to this, my brake discs developed a noticeable lip at only about 4970 miles (8000 km), and I had them replaced along with new pads (it’s highly recommended to use new pads with new discs).
So, for a better disc life span, be a little gentle on the brake pedal and avoid driving aggressively so you only brake when it’s required.
What to do if you have lipped Discs (Rotors)?
Resurface: Brake discs can be resurfaced on a lathe machine, but it is more complex than it sounds. Resurfacing reduces the thickness of the discs, so you would need an expert who can make sure only a minor layer is removed. Most manufacturers provide a minimum thickness of a rotor mentioned on the rotor. For example, if a rotor has to be a minimum 1.5 mm thick, ‘Min.TH=1.5’ will be mentioned on it.
Replace: Replacing the rotors is easy but can be expensive.
I prefer replacing instead of resurfacing, but it’s totally up to your preference.
When is the right time to replace brake Discs (Rotors)
Brake discs are one of the most critical components and should not be neglected. It’s important to know when to replace them.
Replacing brake discs depends on the condition of the discs and the manufacturer’s recommendations, too. Below, I’ve outlined specific scenarios that necessitate disc replacement.
1) Thickness: As mentioned before, most manufacturers provide a minimum thickness of a rotor mentioned on the rotor. For example, if a rotor has to be a minimum 1.5 mm thick, ‘Min.TH=1.5’ will be mentioned on it. You can measure the thickness with a micrometer or take it to a mechanic who can measure it.
2) Scoring or Grooving: Scoring or grooving that can be felt using the bare fingers can be evident that your discs need to be replaced. Grooving often causes the car to wobble while braking, which is not a pleasant experience at all.
3) Cracks: This is one of the most apparent signs that your discs need to be replaced. Excessive heat weakens the discs, and they end up cracking. They should not be neglected for obvious reasons.
4) Warping: The discs can be warped due to excessive heat caused by heavy braking or cheap brake pads. Disc warping is not as common as lipping or grooving, but if yours are warped, immediately replace them because, apart from vibrations or pulsations when braking, warped discs can fail catastrophically. Also, warped rotors increase the stopping distance, which could cause an accident.
5) Manufacturer Recommendations: There should be a minimum thickness mentioned on the disc itself. If there is not, go through the owner’s manual to figure out what it is. If your owner’s manual does not have this information, you should visit the official service center.
6) Rust and Corrosion: Minor rust on discs is normal, especially if your car is parked for a while or right after rain; that thin layer of rust goes away as you drive the car for a bit and engage the brakes. However, excessive rust is not normal and can stay even after you have driven the car and applied brakes; it clearly indicates that you need new discs.
Other things to keep an eye on
If you notice reduced braking performance, such as longer stopping distances, squeaking sound while braking, etc make sure you have the brakes inspected by a professional.
What to do if you cannot inspect your brakes on your own?
If you are a rookie who has no idea what to do. It’s better to take the vehicle to someone who can do it for you. I prefer taking my car only to the authorized service center, especially if it’s new (due to warranty).
Are brake Discs (Rotors) covered under warranty?
No, most manufacturers do not cover discs under warranty because it’s a wear and tear part, just like the clutch plates. But if your car is brand new, some companies may cover the cost under warranty or discount you either because of a manufacturing fault or as a goodwill gesture.