Thumping noise when I'm hitting the brake


#1

I have a 2005 Mitsubishi endeavor. When I try to slow down my vehicle by slowly pressing the brake pad, I hear this thumping noise. almost rhythmic.

Brought it to my mechanic, he looked at my rotors and told me the rotors are rusted which is normal he said (??). He said the brake pads are still good. No point in changing the rotors now. Advised me to change the rotors LATER when I replace the brake pads.

Basically he said, the sound is normal, nothing to be alarmed about.

Here’s a video of the thumping noise

Just wanted to get a second opinion on this.

Thanks!


#2

Your video is unavailable. Did you accidentally set it private?


#3

I did. sorry. Should be available now


#4

Other than a second opinion why not find an empty parking lot and make 6 or seven stops a lot quicker than you normally do and see if that clears off some rust and reduces the thumping.


#5

I don’t know much about cars. I will give this a try later today. Thanks. Just wanted to get on a second opinion about the sound.


#6

I’m not sure what the sound is but it doesn’t sound normal.


#7

Do you feel anything in the brake pedal when this happens? Do you feel anything through the steering wheel or the seat? And, how fast were you going when you made the video?


#8

SLIGHT vibration. VERY VERY slight. Almost none.

Steering wheel is good. Seat is good.

Very slow… 10 mph or less. It doesn’t make any noise when I don’t hit the brake. It only makes the sound when I press the brake slowly. Like when you see the light turns red from 100 feet away and you’re slowing down. That’s when you hear the sound


#9

…and I have to wonder if the OP has considered the tires to be part of the problem.


#10

I have not. Since the vehicle doesn’t make any sound when I don’t hit the brake.


#11

I believe the mechanic. Can’t make out the sound very good, but sounds more like wheel bearing and not tire or brakes. Can you tell whether it comes from the rear or front?


#12

It’s not normal to hear a thumping sound when you hit the brakes. so you do have some kind of problem there. Whether it is serious enough to need do anything about now, hard to say. It sounds like your shop tech has told you “no need to do anything now”, so if you trust your shop, follow that advice.

If you’re curious what’s causing it, there’s several possibilities

  • Rust just on some sections of the rotor, as your shop suggests. This seems unlikely if your drive your car every day. Removing the wheels followed by a visual inspection of the rotors and brake components is the first step.
  • Warped rotors. Caused by heat build up during heavy braking (like long downhills), discs have worn thin beyond their specs, or wheels were installed improperly at some point. The amount of warping is fairly easy for a shop to measure using a run-out gauge.
  • Tires damaged, uneven tread wear patterns, or out of round. You might only notice this during braking b/c during braking the car’s weight distribution front to back and angles on the suspension parts change.

#13

I wanna say from the front.


#14

I just checked my wheels… the left front and the right rear wheel are missing one lugnut each. I will buy lugnuts tomorrow. I wonder if this might be the culprit


#15

Are the remaining lugs tight? If they are loose you would get much more vibration. My guess, based on the sound, is that you have a small spot or rust ridge on the rotor. Probably the back side. I don’t why this seems to happen on the back of the rotor more often than on the front. If you are really concerned, and somewhat handy, it is not hard to do a brake inspection on each wheel. Until you start to feel the brake pedal start to pulse more noticeably it is likely not a big issue but , big disclaimer, all possible brake issues should be treated as VERY serious.


#16

3 of the mechanic from that shop including the owner have driven the car.

The pedal is not pulsating really… just SLIGHTLY… barely can feel it… it’s the sound that concerns me. especially like you said brake issues should be treated very serious


#17

Your mechanic checked the brakes and did not notice 2 missing lugnuts?. Or did they forget to reinstall them?


#18

It’s hard to say while listening to an audio clip on the internet but it sure sounds like a small spot on one of the rotors that has rusted or chipped. I’ve had it happen and it is usually not a major issue BUT it usually gets worse pretty quickly, especially if you drive a lot like I do. When it worsens it will get louder and the pedal will start to pulse more noticeably. You may even notice some unevenness in the braking. Then you will have a safety issue.


#19

I bought the car about 2 months ago. The car was inspected by another mechanic in NY. It passed the inspection including brake. I brought the car to my mechanic about 2 weeks later for other issues. I mentioned the brake vibration/sound. They lifted the car and I guess they just looked at the brakes from the outside? Without really dismantling the whole thing?


#20

Yeah, I think I’ll just change the rotors just to be safe. Im planning on doing a long road trip