This is a term that is thrown around in the industry and between enthusiasts quite a bit, but an explanation rarely follows. You’d be forgiven in thinking it involved a fancy dinner and a bottle of wine back at your place, but the correct answer is a little less romantic than that. OK, a lot less romantic, but it’s an important process to familiarize yourself with, especially if you plan on doing any sort of track or performance driving.
If you’re not familiar with the process or why it’s done, but basically: when you buy a set of brake pads, especially higher performance pads, they will come with instructions on or in the box on their specific bed-in procedures. This is a process to “mate” your pads to your rotors with gradually increased heat cycles to create a thin, even film of brake pad material on the surface of your rotor.
These cycles are like Goldilocks and the three bears: temperatures need to be just right to prevent scarring of the brake pad and rotor surfaces, or uneven pad transfer. So first let’s get into the procedure itself, and then afterwards I’ll talk a bit more about why it’s important.
How to bed-in your brakes:
First of all, I always recommend going by the pad manufacturer’s specific instructions on how they prefer the procedure to be done, but here is my general recommendation (for most pads):
- Find an open and preferably empty stretch of road that will allow you to repeatedly go through this procedure (the process might seem a little odd to onlookers)
- Accelerate to 35 mph and apply moderate brake pressure to reduce your speed to 5-10 MPH
- Repeat this process 3-4 times to get some heat into the brake pads
- Now turn up the heat even more by increasing your speed to 45 mph and braking down to 10 mph
- Repeat this process 3-4 times
- Coast as much as possible for 5-10 minutes
- Now park the car and allow the brakes to fully cool for an hour.
Pro-tip: It’s important to avoid coming to a complete stop during final bed-in stages if at all possible. It’s possible to literally melt your pads against the hot rotors and imprint pad material in one spot on the rotor. Of course it goes without saying to still use common sense and stay safe, and brake in an emergency situation. Use your noodle. Oh, and it’s perfectly normal for your brakes to smell pretty strongly as you go through this process. That’s normal.
No seriously, check with your pad manufacturer!
Again, I really want to stress that it’s important to check your own brake pad manufacturers recommended procedure. For instance, EBC puts a special bed-in coating on their pads, and for something like their GreenStuff pads in street use, they basically just tell you to get out and drive. It’s a little more involved if you’re running higher performance pads, like the YellowStuff and are going to be doing track days, but that just reaffirms my point of checking with the manufacturer.
What happens if I don’t bed my brakes?
That really comes down to how you drive, the specific pads you use, and a little bit of luck. It’s no surprise that the average driver out there has most likely never even heard of bedding in brakes, and most mechanic shops don’t bother with the procedure either. This is because average daily driving usually doesn’t bring enough heat into the pads and rotors for there to be a huge issue — but that opens you up to a problem the second you do start working the brakes hard to whatever reason.
Like I mentioned up top, where this really becomes important is in higher performance driving, or in any application where the brakes will be worked hard, such as towing. Bedding your brakes properly will help to keep them quiet, prevent “warping” of the rotors, and help with even wear of the pads and rotors.
“Warped” rotors and that judder you feel:
If your rotors have not been properly bedded in, or they lost that bedding by being overworked, you can end up with uneven pad deposits on the surface of the rotor. At first, this can just mean uneven amounts grip across the surface, causing the pads to grip, then slip, then grip, then slip, etc, and that’s the judder you’re feeling as you brake. At the extremes, however, if this is not corrected, it can result in uneven rotor wear, and a “warped” rotor. I use quotes there, as the term is a bit of a misnomer, though that is a topic for another time.
Brakes are squeaking and squealing:
This one is particularly annoying to me, because not only are you bothering everyone around you, but usually squealing brakes means they need to be replaced. There out that quickly? Nope! This confusion comes from the fact that most brake pads have a built in metal tab that ride on the rotor once the pads wear down to a certain level.
However if your pads aren’t worn out and are making this noise, it’s actually your rotor that is “singing.” What’s going on here is that the conditions are just right for the brake disc to vibrate as it passes between your clamping pads, through a mechanism that is actually pretty similar to a bow being dragged across the strings of a violin — the difference being your brakes aren’t exactly conducting a symphony as you pull up to a stop light.
Properly bedding your brakes can solve the issue in some cases, but there are a few other small things that can make this happen. For one, if there was some dirt or a small layer of rust on the surface of the hub when you put the rotors on, that could give the disc some play to vibrate as it turns. Another possibility would be a tiny amount of play in your brake pads. This can be solved with brake shims or some sort of lubricant between the pad and the caliper. Auto parts stores will try to sell you this stuff for a premium, but a little bit of anti-seize will work just as well.