When you press on the brake pedal, you expect a smooth and consistent stop. So when you instead feel a pulsating sensation, it’s an unsettling feeling that makes you wonder what’s wrong with your brakes. Fortunately, there’s a simple solution.
In this blog post, we’ll take an in-depth look at what causes brake pedal pulsation and what you have to do to fix it. We also provide a few helpful tips to prevent it from happening again.
Let’s get started.
What Does Pulsating Brakes Feel Like?
When you press the brake pedal and experience a strong regular rhythm in the pedal instead of smooth depressing, that means you have brake pedal pulsation. This means there is an uneven contact between the rotor and pads as you hit the brakes.
Now, you don’t always feel the pulsating while you first leave the driveway. But once the brakes warm up, that’s when you’re most likely going to feel the brake pulsation.
So let’s take a look at what’s causing the pulsating.
What Causes Brake Pedal Pulsation?
If your brake pedal pulsates, there is usually only one cause – a warped brake rotor/disc. However, some people may mistake the abnormal feeling in the pedal for pulsating when ABS engages during emergency braking or if a sensor breaks, causing it to activate. But there are often simple ways to tell.
With that said, ABS usually isn’t considered a cause for brake pulsation. However, I will briefly touch on the topic for you. But let’s start with the rotor issue.
When the time has come for you to experience a pulsating brake pedal, the attention should be on the rotors. A warped rotor means it, at some point, became too hot or damaged. Now, there are different scenarios where this could’ve happened.
First, there could be an underlying issue with your car’s brakes, such as sticking brake components or a faulty master cylinder. But it could also be because of an aggressive driver that does a lot of hard braking and fast stops. Or maybe because you’re riding the brakes in a steep downhill, causing them to overheat.
Other times, the brake pads simply wear down the surface of the rotor until the thickness variation is enough to be felt through the pedal as pulsation.
However, no matter the reason, when the rotors warp, they will no longer trace a flat planar path as they rotate. And while it sometimes can feel like your whole car is shaking, the deviation, called run-out, is often very small but enough.
The uneven surface of the rotor causes an uneven motion that carries through the braking system, which leads to the feeling of rhythmically jerky braking motion when you hit the brakes.
This can be felt more or less at high speeds or when slowing down, and you can often feel the steering wheel shaking as you brake.
Finally, a wobbling or shaking feeling together with uneven brake pad wear, is a clear sign that you’re breaks need immediately attention.
Engaging ABS (Anti-lock Braking System)
In situations where you have to slam the brakes, the ABS (Anti-Lock Braking System) can activate to avoid locking the wheels. It does this by rapidly increasing and decreasing brake fluid pressure to individual calipers, which is why some may confuse this with actual brake pulsation.
However, the “pulsating” or strange feeling in the brake pedal from the ABS is simply a safety feature of the braking assist system performing as intended. This is why many mechanics refer to this as a “brake pulsation myth.”
However, there are times when you should raise your eyebrows. Such a situation would be if the ABS engages and the pedal “pulsates” during normal brakes, often accompanied by a significantly grinding or growling noise and the ABS and Traction control, or ESP BAS light popping up on the dashboard.
If so, you may have an issue with an ABS sensor or wiring between it and the vehicle computer.
How do You Diagnose a Pulsating Brake Pedal?
Suppose there are no warning lights nor excessive grinding noise when braking; it’s safe to say it’s an out-of-balance rotor at fault. Since most of the braking power is distributed to the front, that’s the most common place you’ll have a pulsation problem, but how do you tell?
Well, in the perfect world, it would be best to take your car to a shop where they can remove the brake rotors and individually measure the lateral run-out (LRO) with a dial indicator. But your car has four rotors, which could make it an expensive process.
So how can you determine this yourself? Well, there are no certain ways. But as a rule of thumb, when replacing the rotors on one side, you should also replace the other side, preferably the pads too. This means you only need to determine whether the rotor is bad at the front or rear.
The best way is to play it safe by doing a few simple tests:
1. Perform a Brake Test
Find a smooth open area where you can go in a straight line with ease and accelerate up to 15 to 20 mph. While doing so, keep going in a straight line while you GENTLY apply the brakes. A regular pulsating rhythm under your foot as the wheels rotate is a strong indication of a warped rotor.
Also, if there’s any vibration or shaking in the steering wheel when braking, then more than likely, the pulsation is coming from the front rotors.
If you feel shaking or vibration throughout the vehicle or even in the seat, it’s more likely it comes from the rear rotors.
2. Jack Up the Vehicle, Listen and Observe
Now, this is not a guaranteed way of telling which wheel is to blame. But jacking up one wheel at a time and trying to spin it while listening and observing could give you a hint about which one it is.
If three of four wheels spin smoothly, with no noticeable difference, but the fourth wheel makes a slight grinding noise or seems to brake slightly in sync with the wheel’s rotation, you may have found the bad rotor you’re looking for.
3. Visually Inspect the Brakes
Again, this is not a guaranteed solution. It just gives you a better overview of the brakes’ condition. But if you’re lucky, you can sometimes tell if a brake rotor has been too hot. Check if any brakes are in significantly worse condition than the others. If so, chances are that’s where the problem lies.
How do You Fix a Pulsating Brake Pedal?
The only way to fix the problem of a pulsating brake pedal is to replace the warped rotor. While doing so, it is recommended to replace the brakes on both sides to avoid uneven braking. It’s also smart to change the brake pads while at it since they usually are the cheapest part of the brake assembly.
Some people or mechanics may recommend that you can resurface the rotors to save you some money, which might work if the warping is mild. However, my experience is that this method is outdated, and you usually have to return for rotor replacement within six months.
When replacing your rotors, it’s important to ensure you get one compatible with your vehicle. If you’re unsure of what type of rotor you need for your car, consult your owner’s manual or speak with an experienced mechanic who can recommend the right part for your vehicle.
Once you have the correct replacement part, you’ll need to remove the old rotor from your car and install the new one. This process can be tricky and time-consuming, so it’s best left to a professional if possible.
If you do decide to attempt this job yourself, ensure you follow replacement instructions carefully and have all of the necessary tools on hand before beginning.
Once the new rotor is installed, test out your brakes by driving around at low speeds and gradually increasing them until they feel normal again. If everything feels okay, then congratulations! You’ve successfully fixed your pulsating brake pedal!
Note: Do not forget to check the brake calipers to ensure the piston is functioning as it should, otherwise it will not be able to properly release the brake pads. But also check that the slide pins move in and out easily and lubricate if needed.
Here’s a Youtube video from 1A Auto explaining the issue of brake pulsation:
Is It Safe to Drive With Pulsating Brakes?
A pulsating brake pedal may be nothing more than a nuisance at low speeds but can become a danger at higher speeds, especially if it affects the steering wheel. It’s, therefore, not recommended, but whether it is safe to drive with a pulsating brake depends on how fast you go and how severe you think the pulsation is.
However, even a mild pulsating brake pedal can have a negative impact on the ABS performance and braking distance.
How do You Prevent Brake Pedal Pulsation?
Mechanics and car enthusiasts often speak of the importance of taking care of your car and, nonetheless, your brakes. For many car owners, it can sometimes get a tedious hearing about it. But they are not wrong. Here are the main factors to prevent brake pedal pulsation:
Regular inspection and maintenance are key
If you want to prevent brake pedal pulsation, staying on top of your car’s brake maintenance is key to a safe and smooth drive. Regularly inspecting your brakes can help you recognize problems quickly. Plus, it’s a great way to ensure your car is always in tip-top shape. So, make sure to get your brakes inspected annually for optimal performance.
If you sense something off in your car’s handling, don’t delay—take it in for a brake inspection as soon as possible. That way, you can nip any issues in the bud and keep your car running optimally. After all, your safety is paramount!
Driving responsibly and smartly puts less strain on your car
When you’re behind the wheel, it’s important to drive responsibly. If you often come to a fast stop by braking too hard and too quickly, it not only causes extra strain and wears on your brakes and other parts of the car but can cause the brakes to become too hot.
To protect your brakes and reduce the likelihood of this issue, try to slow down gradually instead of suddenly coming to a halt. Doing so will extend the life of your brakes and keep them functioning at their best.
Frequently Asked Questions
Why Do My Brakes Feel Like ABS Is Kicking In?
If your brakes feel like ABS is kicking in, it means the system is detecting a potential loss of traction and is intervening to help you stop. This could be happening due to slippery conditions, or it could be because of a fault or malfunction in the system. If you notice this happening, it is important to get your brakes checked as soon as possible.
Can ABS Cause Brake Pedal Pulsation?
Yes, ABS can cause brake pedal pulsation. When ABS is activated, it rapidly releases and engages the braking to prevent wheel lock-up. This rapid motion can sometimes be felt as a pulsation in the brake pedal and may also cause a vibration in the brake pedal.
Why Does It Feel Bumpy When I Brake Hard?
Your brakes may feel bumpy when you stop because of a few different issues. But the most common reason is warped brake rotors that cause an uneven braking surface when the brakes are applied. To fix this, you should have your brakes inspected, and rotors replaced if necessary.
Is Brake Pulsation Dangerous?
Mild brake pulsation is not typically dangerous, but it can be a sign of an underlying issue that needs to be addressed. If you notice pulsation in your brakes, it is important to have them inspected as soon as possible. Ignoring brake pulsation can lead to further issues down the road, such as worn-out brake pads.
Warped rotors can be both inconvenient and potentially dangerous, so it’s important to identify this issue before it becomes a bigger problem for yourself and others on the road with you at any given time! With proper inspection and maintenance, you should have no issues when dealing with this issue.
I hope you found this blog post helpful.