What Causes Brake Shuddering Shaking and Pulsing on My Car or Truck

Wooh. Ooh. Had a little brake pulsation there. Guess we're gonna have to check that out.

Hey, friends, it's Len here from 1A Auto. Let's say you're driving in your vehicle, you've been on a nice, long road trip, and you step on the brake and you happen to notice a little shake. You're trying to figure out what it is. It's called a brake pulsation. I wanna talk about it.

So a brake pulsation's something that generally happens after you've been driving for a short period of time. Maybe you've warmed up those brakes a little bit. Once the brakes are warm, that's when you're actually more than likely gonna be feeling a brake pulsation. So if you first leave your driveway, you step on the brake, maybe you're not gonna feel anything. Go for a ride down the road, probably still not feeling much of anything. You go for a longer drive, once those brakes heat up, that's where the discrepancies in the rotor are gonna come up, and you're gonna notice you have a brake pulsation.

Now, in this video, we're not necessarily going over how to diagnose where your brake pulsation's coming from, but I will kinda touch on it a little bit for you. Once your brakes are hot, you step on the brake, if you feel your steering wheel shake around a little bit, more than likely the pulsation's coming from the front brake rotors. If you feel it throughout your whole vehicle or even in the seat, more than likely it's coming from the rear of the vehicle.

Now, the most common place for you to have a brake pulsation is gonna be from the front brakes. The reason for that is because your vehicle's gonna put the majority of the braking power to your front. With that said, the front rotors need to be much thicker than the rear rotors. As you can tell, your front rotors are gonna be thick, and they're also gonna have cooling fins in them. The reason for that is because, like I said, they get the majority of the braking coming from the fronts, so they need to be able to dissipate the heat properly. If there's gonna be an issue with the front rotors, whether it's on the braking surface or the cooling fins, it's obviously gonna cause an issue.

The rear rotors are gonna be much thinner than the front rotors, as you can tell. The reason for that is because your rear brakes are actually mostly for stabilizing your vehicle when you're braking. They still need to brake a little bit because, of course, you don't wanna just be braking with your fronts, because then your vehicle's gonna do a nosedive every time you step on the brakes.

Now, I want you to keep in mind that that little rotor that's super thin like that is only basically for small passenger-size vehicles. Overall, if you have an SUV or even a pickup truck, something with some sort of larger towing capacity, you're gonna need a larger braking surface. So in the rear of those type of vehicles, you're probably gonna find a rotor that looks much like the front rotor. It's just as thick, and it also has cooling fins.

Brake pulsations are usually caused by unbalanced or warped rotors. The main cause of warped rotors is generally because of overheating. The reason why your brakes might overheat is generally because either your cooling fins are rotted on the inside and they're not function they way they need to to be able to dissipate the heat, or maybe you have a sticking brake condition where your pads are just continuously applying brake pressure to the rotor, creating heat in excess of what the rotor can actually dissipate. Could also be because you're driving in traffic, a lot of stop and go, and you're applying a lot of heat to those brakes, or even you're driving down a long steep hill and you're riding those brakes.

So we talked about overheating. Now we need to talk about brake surfaces. The surface of your rotor is super important to how your brakes are gonna function. When you apply your brake, your brake pads are supposed to press up against that brake rotor, apply friction, and create heat, of course, but it's also gonna stop the vehicle. If your rotor braking surface looks like this, you can just imagine, if I was to squeeze something against it and this was trying to spin, what it's gonna do. You're gonna, of course, feel a brake pulsation. It's gonna go like this on the pad, which of course is gonna send the pulsation up and through your vehicle.

A warped rotor might not always be the most apparent thing to look at, though. You might actually need something such as a dial indicator to check the runout. The runout is the amount of movement from your brake rotor surface going side to side. Most manufacturers recommend less than two thousandths of runout on your brake rotor. After that, you're probably gonna notice some sort of brake pulsation.

Something that's important to remember is that the rotor that's showing the issue might not actually be the cause of the issue. There's a whole bunch of things that could cause an overheating condition. Some things that I would think about if I had an overheating condition would be checking those brake calipers. I don't mean just pushing back the piston. That is of course important, because if the piston is not functioning as it should, it's not gonna be able to release the pads from the rotor, and of course you're gonna have an overheat condition. You also need to check those sliders. That's the part where the caliper connects onto the bracket. They need to be able to move in and out easily. If they're not lubricated or they're seizing up inside, that's gonna cause an issue.

You might also notice that your brake pads are frozen inside your caliper brackets. The reason why that might happen is because there's rust buildup in between the caliper bracket and the pad themselves, and it's making it so the pads can't actually go against the rotor and then release from the rotor. So they're just kinda squishing up against the rotor with the force of the caliper, but they're not able to release, which is causing constant pressure on those rotors, creating friction and of course heat. If you have a problem with either your front brakes or your rear brakes, obviously it's gonna put extra pressure on the brakes that are functioning. So if you have an issue in the rear where those calipers are either frozen or the sliders have an issue, obviously it's gonna put way more pressure on the front brakes because they're going to be doing all the work. More work means more heat overall, which of course would lead to an issue.

Some rear calipers are gonna have an emergency brake that connects right into them. That's called, like, an e-brake integrated caliper. What's important to think about that, though, is if you have an issue with the emergency brake, whether it's the cable or even the lever up front, and it's applying constant pressure to that caliper, of course it's gonna overheat. You also want to think about those flex hoses. If you have a restriction in your flex hose, it's gonna cause an issue where you're not gonna be able to have brake fluid flowing the way it should, which of course could continue putting pressure on those brake pads.

Some vehicles are gonna have a ride height sensor generally located somewhere in the rear. The reason why they have that is so when you step on the brake and the vehicle starts to tilt a little bit, it's gonna sense that the rear of the vehicle is lifting up a little bit, and it's gonna divert more of the fluid to the front rather than the rear, that way there you don't have a slipping or out of control situation.

And now that leads us to talking about suspension issues. If you have weak shocks or struts, obviously your vehicle's gonna handle much differently. You step on the brake, it's gonna wanna dip, like I had mentioned. If it dips too far, of course it's gonna divert the amount of pressure going from one brake to the other. And, of course, it could cause braking issues overall. If you have weak suspension, your braking's gonna go from a short distance to a much longer distance due to the fact that the suspension's kinda doing what it wants instead of what it should. And, of course, don't just stop at checking those shocks and struts. You also wanna check to make sure the rest of your front suspension or steering components are good as well. If you have a tie rod end that's loose or anything like that and your tire can move, as you step on the brake, that tire's gonna be moving, and you might think you have a pulsation, but really it's another issue.

So now we need to talk about something that nobody really likes to talk about. That's called driving habits. Maybe you just learned a certain way of driving or maybe you just kinda picked it up over time. Some people take a lot of time driving on the highway. They just cruise along. They're hardly using their brakes until, of course, they get to that exit, they start using the brakes real quick as they're turning. That's gonna put a lot of pressure, especially on those outward brakes, which is gonna heat up those brakes and potentially cause a pulsation over time. Or maybe you're driving through the city. City's a lot of stop and go. You've got stop signs, you've got red lights, you've got pedestrians, you've got all these different things that are gonna make you have to go and then stop. If you're the type of person that likes to race to each stop sign, you're gonna be putting a lot of pressure on those brakes and of course bringing up a lot of heat.

If you're doing a lot of city driving or a lot of stop and go driving, it's best to just go with a drilled and slotted rotor like this, which we sell at 1aauto.com. And this is gonna work especially well for dissipating that heat overall, and you'll have less chances of warping your rotors.

So let's just try to sum this up a little bit. Overall, a brake pulsation's more than likely gonna come due to overheating the brake rotors. Sometimes it could also be because of the brake rotor surfaces maybe being pitted or rusted or rotted due to the fact that the calipers or the slider pins aren't functioning as they should. Generally speaking, the pulsation's gonna come due to a discrepancy in the rotor braking surface, one way or another, whether the rotor's a little bit warped or, of course, like I said, it's pitted or rotted.

So are brake pulsations considered a safety issue? Well, I'm gonna leave that up to you. We'll call it your prerogative. The thing for me is if I step on the brake and the pulsation's minor in my steering wheel or minor in the seat, I'm really not super worried about. Sometimes you'll have a brake pulsation that's just out of control. You step on the brake and it [vocalization] like that. Obviously, that's not gonna be a very good thing. It's gonna be a safety issue overall, especially if it's slippery road conditions. The reason for that is because the reason why you're pulsating is that brake's grabbing, not grabbing, grabbing, not grabbing, grabbing, not grabbing, and of course that could cause a slipping or sliding predicament.

Once you've determined what the issue is, you need to, of course, correct that issue. If you find that the issue's just that you have warped rotors, whether it be in the front or the rear, you need to make sure that you replace the rotors with the pads. It doesn't matter what condition those pads are in, even if they're brand new. The reason for that is because the surface on the pad needs to wear into the surface of the rotor. If, of course, you decided to try to save some money and only do the rotors and not the pads, you're gonna end up with brake noises and more than likely a pulsation as well.

One thing that I want to mention to you is you can't actually cut your braking rotors anymore. Back a long time ago, people used to do it, and it used to kinda work out fine. They had plenty of meat on those rotors, you can cut them down a little bit and they're still good. The problem is that nowadays the rotors are made with much thinner material. They kinda just try to keep it right at the minimum specs, that way there it keeps the vehicle lighter, and it's more fuel efficient overall. Obviously, if your brake rotor looks like this and I was to try to cut this down so it's thinner and I can get a nice smooth braking surface, it's gonna have an issue, because by the time I get into where the metal's actually still good in there, this is gonna be very thin. That wouldn't be good. If you have very thin brake rotors, they're not gonna be able to dissipate the heat overall, and of course the brakes aren't gonna be able to function as they should.

Something that I also like to mention is I don't want you to confuse a brake pulsation with your ABS unit activating or anti-lock brake system. The anti-lock brake system on your vehicle is supposed to be able to create a controlled stop in case of an emergency, instead of coming to a sliding, skidding stop. In which case, of course, you could slide past where you wanted to actually stop. When your ABS activates, it's gonna cause a pulsation in the brake pedal, and it might be confused with a brake pulsation, but it's actually just the computer of the vehicle doing its job.

Okay, friends, we tried to make you a nice, educational video about brake pulsations. We wanna make sure that you understand that it might not necessarily only be your brake rotor that's an issue. You have to pay attention to your whole braking system and make a determination on what needs to be fixed. Like I said, if you have to replace your rotors for any reason, you need to replace those pads no matter what, and vice versa. Nobody should be replacing just the pads without the rotors or just the rotors without the pads. Obviously, if you have a caliper issue, that's gonna need to be addressed as well.

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