If you’ve ever seen the recent movie Gran Turismo, you may recall a scene where Jann plows through a corner and crashes because his brakes were glazed. Upon closer inspection, the mechanic confirmed the young driver was correct, which explained the reason he overcooked the corner.
Simply put, glazed brake pads are brake pads that have overheated and no longer work correctly. The surface of the brake pad becomes smooth and cannot bite into the rotor the way it is supposed to.
Glazed brakes can greatly increase your stopping distance, making them fairly dangerous to drive on (particularly if you are trying to set a fast lap time on the track).
Are you worried you may have glazed your brake pads? Here are some symptoms that suggest your brakes are glazed, and how you can actually fix them yourself.
Symptoms of Glazed Brake Pads
Most of the symptoms of glazed brake pads involved greatly reduced braking performance. Here are some specific examples to look for.
1) Increased Stopping Distance
One of the easiest ways to tell you’ve glazed your brakes is if your stopping distances are greatly increased. This is obviously pretty dangerous, as you expect your car to stop in a certain distance with a certain amount of pressure.
2) Can’t Engage ABS or Lock Brakes
If your brakes are glazed, you may not have enough stopping power to lock the tires or engage ABS. This means your vehicle is no longer able to fully utilize its braking potential.
3) New Braking Noise
Glazed brakes sometimes sound different than the brakes you’re used to hearing. This is because the surface of the brake pad has changed. If you notice a change in the way the brakes sound, it would be worth taking a closer look to see if something is wrong.
4) Brakes Don’t Bite
When you first hit the brakes, you should feel the initial bite of the brake pad into the rotor that immediately slows the vehicle down. If you have to press the brake pedal hard before you get the vehicle to slow down at all, your brake pads may be glazed.
5) Excessively Smooth and Shiny Brake Pads or Rotors
When you glaze your brakes, your brake pads will look very smooth and shiny. Typically, brake pads look black like new asphalt. Brake pads have a bit of texture if you look closely.
Brake rotors should also have a texture and not be completely smooth. New brake rotors have a cross-hatched pattern that looks like a lattice machined into the surface.
As you use the brakes, the cross-hatch pattern is replaced by a ring of pad material that is typically dark blue in color. If your rotors are really shiny without any of this bluing from the brake pad material, you might’ve glazed your brakes.
Causes of Glazed Brakes
1) Too Much Braking (Without Cooldown)
The number one cause of glazed brakes is simply using your brakes too much, or using them improperly without letting them adequately cool down between braking events.
Your brakes heat up when you use them and they need time to cool down between braking events. If you ride your brakes or brake aggressively often, you may find yourself with overheated brakes.
You can easily overheat your brakes by riding them. Riding the brakes is applying gentle braking over a long period of time, like some people do while driving down a mountain pass. Brakes can never cool down while you are applying them, even if you’re braking gently.
A better strategy for braking downhill is to apply the brakes a bit more than you need to, then coast downhill for a while until you start going too fast, then apply the brakes again. This momentary rest in braking will allow the brakes to cool as you coast.
If you drive down a very steep hill such as descending Pike’s Peak, you will want to engage a lower gear. The transmission will help slow down the vehicle and prevent excessive braking. Some steep hills may even require first gear for this.
2) Stuck Caliper Piston
If one of your brake calipers gets stuck, you may experience glazing on a single corner of the vehicle. A stuck caliper is often accompanied with other symptoms. One corner might be smoking, and you’re likely to smell brakes next to the stuck caliper.
That rotor will also be very hot. If you have an infrared thermometer, you can see that the temperature of the rotor under the stuck caliper is significantly higher than the other three.
3) Stuck Caliper Pin
Caliper pins allow a floating caliper to slide back and forth as you apply and release the brakes. A stuck pin could cause one side of the brake pad to remain in constant contact with the rotor, which is likely to give you glazed brakes on one corner of the vehicle.
A stuck caliper pin may have similar symptoms to that of a stuck caliper piston. When one pin is stuck, it’s common for one pad or one side of one pad to be excessively worn, while the other pad looks relatively good.
How to Fix Glazed Brake Pads
1) Resolve the Underlying Issue
The first thing you’ll want to do is figure out how you’ve glazed your brakes in the first place. Otherwise, if you do any work to the brakes, you are likely to end up glazing them again.
If it’s a simple matter of braking too much, try to adjust your driving style to give the brakes more time to cool down. If you have a mechanical issue such as a stuck caliper, replace the failing component(s) before you try to service the pads and rotors.
2) Sand the Brake Rotors and Pads
Sanding the brake pads and rotors is an easy way to remove the surface glazing without fully replacing the brakes. This is especially good to try if your brake pads and rotors are relatively new.
A good rule of thumb is to replace the brake pads once they are less than the thickness of the backing plate (ignoring any shims that may be present).
If you go to sand the pads and notice they’re a little thin, please just replace them. There’s no need to stretch the life of braking components and risk an accident. Brake pads are pretty cheap.
3) Re-Bed the Brakes
After sanding or replacing the brake pads and rotors, you’ll want to bed the brakes to make sure there’s a nice, even layer of pad material around the brake rotors. Follow the brake pad manufacturer’s instructions for bedding the brakes properly.
4) Replace the Brake Pads and Rotors
Sometimes your brakes will still be messed up even after sanding. If you still notice poor braking performance after trying to remove the glazing yourself, replace the brake pads and rotors.
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