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Update 11/9/2013

After a good bit of driving, the noise reoccurred. I took it back to the mechanic and we decided it must be the brake pads. They're pretty worn out, and like I said before, they're worn unevenly. Since the problem is intermittent, perhaps the pads are making an awkward angle with the rotor sometimes, leading to the grinding/groaning noise.

I ordered new EBC Red Stuff (ceramic) pads and EBC USR (slotted) rotors. I had the shop install them today. So far so good - no noise - but we'll have to see what happens in a thousand or so miles once the pads are fully broken in.

I know I can answer my own question, BTW, but I'm going to wait until the pads are broken in before I conclude the answer to the problem.

Update 11/2/2013

I went to a well reviewed independent auto repair shop in my area. The first thing the mechanic brought up was that my rear brakes (the drums) needed to be adjusted. The mechanic showed me how my left drum was completely stuck, whereas my right drum was too loose. After he adjusted the drums, he told me to drive around for another couple hundred miles and see if the noise comes back.

Additionally, the mechanic mentioned that the drums could be the reason behind the uneven wear on my front pads. He also mentioned that the groove on my front rotor, although far from desired, is unlikely to be the cause of the problem.

Let's see what happens this week!


The Story

I have a 2012 Honda Civic LX. It's my first car, and I must say I drive it rather hard. After about 20k miles, my brakes started to feel wavy - I would hold the brake pedal, and the car would slow down in an inconsistent, wavy manner.

I figured that my rotors were warped (or, according to StopTech, pad material was transferred unevenly), and I wanted to learn more about my car's brakes, so I decided to replace my rotors and pads.

I bought new EBC rotors (OEM replacements) and pads (Ultimax2, OEM replacements), and I replaced the originals. I made sure I installed the EBC parts exactly the way the OEM parts were installed, and I was sure to check the brake fluid level and re-grease the caliper pins and pad brackets.

After I installed the EBC parts, the brakes felt orgasmic. With that said, I tried my best to avoid using them too roughly in order to follow EBC's break-in procedure (see EBC's FAQ, item #9). I followed the break-in procedure for about 500 miles or so before I slowly transitioned back into my previous driving style. Still, the brakes felt great.

The Problem

After a few months, my brakes started to emit a terrible grinding/groaning noise when I braked sometimes. This part is important - my brakes do not create the noise consistently - only sometimes. When I don't hear (or feel) the noise, my brakes seem as amazing as they were after I installed them.

The Details

  • I was able to capture a recording of the sound after driving around for about 2 hours one night. I've uploaded the sound here.

    Make sure you turn up your speakers so that you can hear it well. Every time you hear the noise, I was coming to a slow stop.

  • The noise does not appear at high speed stops or during throttle braking. It only appears at low speed stops.

    With that said, it still only happens sometimes during low speed stops - other times, I'm able to come to a low speed stop with perfectly smooth, silent brakes.

  • The noise has never happened after a cold start (i.e. when I drive to work in the morning).

    The noise seems to only happen after I drive around for a while. It seems to happen more often after I drive around for a while, then stop the car for a little bit. For example:

    • Cold start
    • Drive to XYZ
    • Park for 15-30 mins
    • Drive away

    There's a good chance that the noise will occur during step 4, but no guarantee.

    With that said, the noise does occur sometimes after driving around for a while without stopping at all.

  • The noise can come and go. For example, I could drive around for a while, start hearing the noise, then the noise might go away, and then it might start happening a couple of stops later.

    This rules out surface rust, which would go away after the first couple of times of braking.

  • Sometimes, especially after the noise happens or before it's about to happen, I can hear a faint screeching/squeeling sound when I brake. I can only hear it when I roll my window down and practically stick my head out the window. This sound is very, very different from the grinding/groaning noise.

  • I do not notice any loss of performance in the brakes, even while the noise is occurring. The car slows down correctly.

The Investigation

The other weekend, I took apart my brakes to see if I could pinpoint any obvious problems. I also cleaned and re-greased all of the appropriate parts, although that did not help. Here are my observations when I took apart the brakes:

  • The pads are worn unevenly. The tops of the pads are visibly thinner than the bottoms of the pads.

  • The outer side of my driver's side rotor has an apparent groove on it:

    Rotor groove

    The corresponding brake pad has a matching groove:

    Pad groove

    However, if this groove was the cause of the noise, wouldn't the noise happen every time I brake?

  • I tried to bed in the pads using the 60-10 x5 procedure (slow down from 60 MPH to 10 MPH several times with short cooling periods in between, also described on EBC's FAQ).

    This did not help - the noise happened again the next day.

    With that said, I'm not entirely sure if I performed the procedure correctly - perhaps I did not slow down quickly enough.

The Question

What's causing this terrible grinding/groaning noise when I use the brakes sometimes?

share|improve this question
3  
One of the best written questions I've seen in a long time! Do the sliders on the calipers all slide freely? –  Nick C Oct 28 '13 at 10:44
2  
@NickC If you're referring to the caliper pin slider assembly, then yes, the caliper slides freely on the pins. They are not sticky and there are no obstructions. –  Agop Oct 28 '13 at 16:21
    
does your car have abs? –  vlsd Nov 1 '13 at 18:14
    
Yes, the car is equipped with ABS. I've felt it engage when I've had to prevent an accident a couple of times. I feel like it's not related to this problem because this problem occurs during low speed stops. –  Agop Nov 2 '13 at 0:49
    
I'm curious, did the mechanic explain why the problems with the rear brakes result in uneven wear on the front pads? –  vlsd Nov 5 '13 at 2:40

6 Answers 6

You have new brakes it takes time to them loose the original coating/surface. My have the same problem for a time but not lasted for this long.

The grove is does noot sounds good. If they are not too deep you could go to a shop and they could make resurface it.

Sometimes your disc soo thin that they could 'bend' because of the heat. Is this sound 'still' or it variable 'pitch'? Do you feel anything in your brake pedal?

If yes, replace it right now.

http://www.dba.com.au/easy-way-to-tell-when-you-need-a-disc-brake-change/

http://answers.yahoo.com/question/index?qid=20090329193351AAmido1

Grooves are not normal they are the result of either wear or the previous pads not being changed soon enough and the rivets or steel backing plates cutting into the rotors. The brakes may appear to be working normally but the grooves prevent the new pads from being in full contact with the rotors. It is taking a longer distance to stop because of the grooves. In an emergency situation a few feet might be the distance between an accident or no accident, or a minor fender bender and serious injury.

Have the rotors resurfaced or replaced in the near future. You might have to replace the pads again as well.

share|improve this answer
    
I don't feel anything obvious in the brake pedal when the noise occurs. However, I can feel a faint vibration that corresponds directly to the noise (perhaps the noise is literally causing the vibration). –  Agop Oct 29 '13 at 1:14

The groove could simply be a bit of dirt stuck there and I doubt it would generate the noise you describe (although getting rid of it is ideal). Based on the fact that the pads are thinner at the top than at the bottom and that the noise comes and goes seemingly at random my guess is that the corresponding calipers are getting stuck on their grooves for some reason. Check again that the pads themselves can slide back and forth easily on their grooves (especially the one responsible for the uneven wear) and that the metal clips are clean, greased and intact (they bend easily, so I would look for that too).

If you have ABS this could also be an ABS issue, but I know next to nothing about that.

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1  
The disc does not appear to be thinner anywhere. It's the pads that are thinner towards the top than towards the bottom. The pads do appear to be able to slide correctly. And, yes, the car does have ABS. –  Agop Nov 2 '13 at 0:42
    
oh ok. if the pads are thinner at the top this still means that at some point they're not parallel to the rotor. either the rotor has some wobble (would be more noticeable at the top) or the pads have too much play in their guides... –  vlsd Nov 2 '13 at 1:06

Yes It looks like dynamic groan. This can be solved by chamfering top or side of the disc pad. Rotor surface micro undulation may cause this. Grind the discu surface.

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I have the same grinding noise on my Pontiac Bonneville.

My brake pads and rotors were installed not long ago. I think in my case its my ceramic brake pads heating up the rotors creating a grinding noise. Once the rotors cool down they work fine, but if I brake hard at a high speed the grinding noise returns and will continue until they cool down. The noise however does not effect the car from stopping true, it just sounds real bad.

I bet if I changed my brake pads from ceramic to semi metallic the noise will go away. I think the heat of the rotors against the ceramic are making the noise. Maybe slotted rotors would dissipate the heat and stop the noise.

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up vote 0 down vote accepted

Well, the new rotors and pads were the answer. I'm surprised that the EBC OEM replacements gave me so much trouble, but the new EBC Red Stuff (ceramic) pads and slotted rotors have been wonderful. Even with my typical hard braking, no noise, and better performance, too.

(Apologies for the delayed answer. I became sidetracked and completely forgot about this question, but now that I'm back on StackExchange, I noticed I never answered it.)

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I don't know much about fixing cars, but I had a similar problem with my 2009 Accord. The brakes would grind / gurgle on the first couple stops, but after a few minutes I could slam the brakes with no noise, and they didn't feel squishy or anything. It turned out to be bad calipers on the front brakes, according to my mechanic.

share|improve this answer
    
Unfortunately, the problem I'm having appears rather different. The noise never occurs during the first couple of stops (i.e. after a cold start), and it reoccurs arbitrarily (i.e. it doesn't go away after braking a few times). –  Agop Oct 29 '13 at 1:13

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