Question about brake noise while driving.

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  #1  
Old 03-10-09, 11:56 PM
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Question about brake noise while driving.

I'm hoping to confirm what a person told me is causing a brake related noise before doing the repair, and I'll try to keep this short as possible. I have an '06 GMC Sierra extended cab, 1/2 ton, 2 wheel drive,with only 13,000 miles on it. And I'm a contractor, and a couple weeks ago, I was coming back from a job that was a ways up a mountain road, and coming back down this road is not the best on brakes, especially when a truck as high geared as mine isn't easy to slow down by downshifting. Anyway, I've been on roads like this here and there, so I'm sure my brakes have been getting glazed over time. I get to the bottom of this hill and I'm getting a high pitched squealing noise that I know is glazed brakes. That wasn't a big concern, but I noticed when I got on flat ground I was getting a "chirp" that was keeping with the revolution of the wheels while driving, no braked being applied. I confirmed it's coming from the left front wheel. It's the same pitch as the glazed brake sound, but like a said, more of a "chirp". I get home and figure I'll see what happens the next day. In the morning, it won't do it all.....all the way up to this job.....no unusual noise, but I'm also not braking nearly the same way. Anyway, coming home, same thing......squealing brakes, and the chirp is back on flat ground. To fast forward, I end uo going to my mechanic, and ask him what the chirping when I'm driving is coming from. He says it could be a lot of things, but he'll check it out if I want. He takes the front brakes apart, scuffs the rotors, scuffs the pads(which were glazed good), makes sure everythiing is as it should be, adjusts the back brakes, and puts it all back together.He even commented that the pads looked like they had got pretty darn hot, and the rotors had a nice mirror like finish. My squealing brakes are gone, but after I drive a bit and apply the brakes a few times, and not necessarily going downhill, the chirp is still there. I had to go to another out of town job the other day, and go over a different mountain with not nearly the downhill slope, but you still have to brake a fair amount. Anyway at the bottom, I turn onto a highway, and taking off from a stop, there is the chirp, and it speeds up as the truck speeds up, but I noticed it goes away if you keep driving, and don't apply the brakes. Further experimentation proves that this happens after you have braked at least few times, so it is definitely related to the brakes/rotors warming up, and does go away if allowed to cool off a bit before braking. Now, my mechanic says the next step would be to turn the rotors and put new pads on, and that maybe the rotor is just not perfectly true, and is just barely getting touched by the pad as the wheel turns. Let me also add that there is no pulsating brake pedal, indicating a warped rotor, so that isn't it. Anyway, his estimate to turn the 2 rotors and put new pads on was a little pricey, and I'm considering doing it myself, so when I called to get a price on the pads and started to describe the problem just like I did here, the guy kind of stopped me and said(with confidence) that what was happening is that I have hard spots on the rotors from them getting hot(which they have), and that those hard spots will "bulge" out, if you will when the rotor gets warm/hot from braking, and can just barely come in contact with the pads while driving, and make this high pitched "chirp". This makes a lot of sense, and he told me this like he's seen this before, and it also explians why if you drive a bit without braking, or let the truck sit, the chirp is gone......until you brake a few times or so. So my question is; does this sound like the cause of the chirping noise to anyone? He also said you could probably turn the rotors, but the hard spots are still there and the noise could come back, or not. It's a hit and miss. Sorry for the long story, but I wanted to be thorough, and if you made it this far, thanks for reading, and really appreciate any feedback. Thanks in advance!
 
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  #2  
Old 03-11-09, 08:05 AM
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turn the roters nput some pads on it solve your probs.[doing this 4 20years] your roter has a worped spot from getting hot and thats what your hearing is that spot hiting the pads thats a given bet money on it!
[also make sure the dust cover behind the roter didnt get bent and is now hiting the roter but like i said turn the roters n some new pads should b good 2go [simpel fix] 100 bill should get you roling again. and dont let that other guy do it he should have known better not that complicated.
 
  #3  
Old 03-11-09, 09:44 AM
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Originally Posted by geno1613 View Post
turn the roters nput some pads on it solve your probs.[doing this 4 20years] your roter has a worped spot from getting hot and thats what your hearing is that spot hiting the pads thats a given bet money on it!
[also make sure the dust cover behind the roter didnt get bent and is now hiting the roter but like i said turn the roters n some new pads should b good 2go [simpel fix] 100 bill should get you roling again. and dont let that other guy do it he should have known better not that complicated.
I've had a warped rotor before on my '90 Chevy truck and I had pulsation in the brake pedal when braking and never had a noise while driving, plus like I said, this only does it after braking a few times and the brakes getting warmed up. I'm not getting any pulsation in the brake pedal right now.
 

Last edited by acillatem; 03-11-09 at 10:07 AM.
  #4  
Old 03-12-09, 05:29 AM
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im sure turning the rotors and new pads would fix the noise your hearing atleast for awhile, unfortuanatly there is really no way of knowing if the same problem will reoccur down the road, your vehicle only has 13k on it so im sure theres still alot some life left in the pads but they are generally replaced to solve noise problems.
if the noise is loud and annoying you will want to have it fixed but if its not very noticable and your brakes are still in good condition and your not having any braking problems and you can live with it for awhile, I wouldnt be to concerned having it repaired right now.
 
  #5  
Old 03-12-09, 10:37 AM
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Originally Posted by bejay View Post
im sure turning the rotors and new pads would fix the noise your hearing atleast for awhile, unfortuanatly there is really no way of knowing if the same problem will reoccur down the road, your vehicle only has 13k on it so im sure theres still alot some life left in the pads but they are generally replaced to solve noise problems.
if the noise is loud and annoying you will want to have it fixed but if its not very noticable and your brakes are still in good condition and your not having any braking problems and you can live with it for awhile, I wouldnt be to concerned having it repaired right now.
Yeah, that's what I'm thinking.......right now it's just a little annoying. The further I drive and brake more, the louder it gets, so I'm going to play it by ear. What I was most curious about is if the guy's theory is correct in that the hard spots on the rotors sort of "bulge" out when they warm up a little, and that is why I only get this chirping after I've used the brakes a little, and also why it goes away when it cools off. He also said that you can turn the rotors with hard spots, but that the same hard spots may bulge out agin with the new pads and cause noise again. He said I might be better off replacing the rotors. If that's the case, I'll do the job myself, because the shop I went to wants $274 to replace the pads and turn the rotors, which is a little pricey. If he starts turning the rotors and says there are hard spots and I should replace them, I'm out another $200. I can do the whole job myself with brand new premium rotors and premium brake pads for just under $300. That's why I'm asking if the guys theory about the hard spots is accurate.
 
  #6  
Old 03-12-09, 10:45 AM
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Hmm...even $300 seems a lot of parts..a quick (admittedly) search showed all the parts would be about $210 or so....don't remember the brand. Raybestos? Dunno...

Something you may want to check as well, make sure all your lugs are torqued to spec, using a torgue wrench, not an air gun. And using the correct procedure...1/2 spec then full tight or whatever it may be.
 
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Old 03-12-09, 11:01 AM
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Originally Posted by Gunguy45 View Post
Hmm...even $300 seems a lot of parts..a quick (admittedly) search showed all the parts would be about $210 or so....don't remember the brand. Raybestos? Dunno...

Something you may want to check as well, make sure all your lugs are torqued to spec, using a torgue wrench, not an air gun. And using the correct procedure...1/2 spec then full tight or whatever it may be.
Yeah,the $300 was based on my local parts store for premium ceramic pads and premium rotors. I'm not sure who has good quality parts online......that is the one thing I haven't actually bought online.
 
  #8  
Old 03-12-09, 11:08 AM
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One thing to do is see what you can find online, then ask for a price match. Kinda funny that the same thing sold (ordered in) from the store is $10-20 more than buying from the chains website. Most of the time they have free shipping over a certain amount. Or sometimes its ship to store and you pickup.

I'd rather have the store get the sale if I can of course, but $90 is $90, right?

No one ever carries parts for mine, so I almost always have to order anyway.
 
  #9  
Old 03-12-09, 11:48 AM
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Originally Posted by Gunguy45 View Post
One thing to do is see what you can find online, then ask for a price match. Kinda funny that the same thing sold (ordered in) from the store is $10-20 more than buying from the chains website. Most of the time they have free shipping over a certain amount. Or sometimes its ship to store and you pickup.

I'd rather have the store get the sale if I can of course, but $90 is $90, right?

No one ever carries parts for mine, so I almost always have to order anyway.
Yep, I like to stay local if I can, but in this economy, I'll save anywhere I can If it's substantial. Like I said, my local sho wants $275 to turn the rotors and replace the pads with some good ceramic pads, but If the rotors have hard spots that are just going to cause the noise to come back when they warm up, then I can take the same $275 and replace the pads AND rotors, and won't have to think twice about the hard spots bulging out and making noise. That's where I'm on the fence...........don't know enough about it know what the odds are of those hard spots giving me a problem if I just turn the old rotors.
 
  #10  
Old 03-12-09, 11:52 AM
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Well, no matter what you do...$275 to remove and turn + new pads seems like a lot, I agree. Esp when they have lifts and impact tools, what maybe 1 hr? They gotta make a living, but not off one job, right?
 
  #11  
Old 03-12-09, 12:21 PM
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Originally Posted by Gunguy45 View Post
Well, no matter what you do...$275 to remove and turn + new pads seems like a lot, I agree. Esp when they have lifts and impact tools, what maybe 1 hr? They gotta make a living, but not off one job, right?
I know.......I'm a painting contractor, and I make decent money, but not like that. I don't mind paying someone for quaity work, and this guy has a reputation of being honest and doing good work, but it is pricey. Like you said, they will do this job in an hour, and they will turn the rotors right there. He has $134.99 for the pads on the estimate. I called the same napa auto parts store that he would get them from and I can get the same pads for $87.99. I know they mark up parts, but between the markup on the parts and the $128 labor charge he has, he'll make a clean $100+ after paying his employee to do the job. Let's face it, that brake job isn't that hard. If he starts turning the rotors and decides that they should be replaced, I'm out another $200.
 
  #12  
Old 03-12-09, 01:13 PM
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new rotors will not be any better than the ones that came on your truck from the factory the brake pads may be better quality though depending on what you buy.
the only reason they are going to turn the rotors is mainly to give a good machined surface for the pads to break in to, this is common to solve brake noise problems if they are warped they are not warped enough for you to notice them while braking, and warped rotors alone doesnt usually cause brake noise.
you can probably do the work yourself and save some, many parts stores or machine shops can usually turn your rotors if you take them off and they usually dont charge much to do it.
his labor rate may be a little on the high side but suspect it will take more a little more than an hour depending on what type of turning lathe he has unfortuanatly labor rates vary so much it may not be out of line for your area.
 
  #13  
Old 03-12-09, 02:27 PM
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Originally Posted by bejay View Post
new rotors will not be any better than the ones that came on your truck from the factory the brake pads may be better quality though depending on what you buy.
the only reason they are going to turn the rotors is mainly to give a good machined surface for the pads to break in to, this is common to solve brake noise problems if they are warped they are not warped enough for you to notice them while braking, and warped rotors alone doesnt usually cause brake noise.
you can probably do the work yourself and save some, many parts stores or machine shops can usually turn your rotors if you take them off and they usually dont charge much to do it.
his labor rate may be a little on the high side but suspect it will take more a little more than an hour depending on what type of turning lathe he has unfortuanatly labor rates vary so much it may not be out of line for your area.
O.k. I know why they would turn the rotors, and the noise I'm bothered by isn't braking noise........it is the chirping noise I get with the revolution of the left front wheel after the brakes/rotors have warmed up a bit. The shop has already taken the front brakes apart and scuffed the rotors and the pads, and he said the pads looked like they had got pretty hot. When he put it all back together, it had gotten rid of the squealing when I brake, just as I knew it would......I knew they were glazed. The chirping noise I am getting is the same high pitched tone as a regular brake squeal, it's just sounds like a bird chirping as the wheel turns, and it won't do it when I first start out, or when it's cooled off. If I go across town, and do some normal braking for a bit, the chirp shows up. As soon as it cools off, and I don't touch the brakes for awhile, it goes away. The guy at my local parts store said what is happening is that the rotors have hards spots on them from getting hot, and when they get warmed up(from braking) that they bulge out just a bit, or swell, if you will, and that those spots are just barely making contact with the pads when the wheel turns, hence the chirping noise. As soon as they cool down a bit, they don't stick out,and the noise goes away. That's what he saqid, and it sounds very logical. He also said that if I turn them, they may be just fine, but there is a chance that those sam,e hard spots could still bulge out a bit,and the noise could come back quickly, that's why he suggested possibly replacing the rotors......to eliminate the chance of the noise coming back, which is the entire reason I would be doing this.........it is very annoying. The part I put in bold is the part I'm curious as to the accuracy of, and that's why I posted the question. It makes sense to me, but posted here to see if anyone agrees.
 
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Old 03-12-09, 02:46 PM
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I didn't comment before..I'm no professional mechanic or metallurgist. I have heard of this, but I have a hard time getting my brain around it. Heres why....

1st half of my brain...
If a rotor gets hot..it gets hot equally, right? The wheels are spinning and the caliper is applying equal force around the circumference of the rotor (assuming non-warped rotors). And since the rotor is made of one big homogeneous piece of machined metal..why would one portion get a "hard spot".

And here's the other half of my brain...
When you stop..the pads make one portion of the rotor retain more heat at the stopped position. Therefore it could be somehow hardened more than the rest.

And the 3rd half of my brain...lol
The above would only apply if you braked hard and long enough to get the rotors almost glowing..and then stopped dead and let it sit long enough to cool off.


And JMO, I disagree with stock rotors being as good as premium quality aftermarket. Stock rotors on my wifes SUV needed replacing after only about 18k(?) miles (warranty was 12k of course). Replacements lasted 90k with tons of hilly, stop and go driving.

Why do many manufacturers only warrant stock brakes for 12k miles? That may have changed, haven't shopped for cars in a while.
 
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Old 03-12-09, 03:07 PM
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Originally Posted by Gunguy45 View Post
I didn't comment before..I'm no professional mechanic or metallurgist. I have heard of this, but I have a hard time getting my brain around it. Heres why....

1st half of my brain...
If a rotor gets hot..it gets hot equally, right? The wheels are spinning and the caliper is applying equal force around the circumference of the rotor (assuming non-warped rotors). And since the rotor is made of one big homogeneous piece of machined metal..why would one portion get a "hard spot".

And here's the other half of my brain...
When you stop..the pads make one portion of the rotor retain more heat at the stopped position. Therefore it could be somehow hardened more than the rest.

And the 3rd half of my brain...lol
The above would only apply if you braked hard and long enough to get the rotors almost glowing..and then stopped dead and let it sit long enough to cool off.


And JMO, I disagree with stock rotors being as good as premium quality aftermarket. Stock rotors on my wifes SUV needed replacing after only about 18k(?) miles (warranty was 12k of course). Replacements lasted 90k with tons of hilly, stop and go driving.

Why do many manufacturers only warrant stock brakes for 12k miles? That may have changed, haven't shopped for cars in a while.
What the 3 halves of your brain(lol) are telling you also makes sense, but there is no other explanation, that I can think of anyway, that causes this chirping noise only when the brakes warm up a bit after a little braking. The only other theory I can come up with is that the rotor may be slightly warped, but not enough to feel it in the pedal,and that when it warms up a little, it expands, because metal does that, and that ever so slight expansion is enough to make it just barely have contact with the pads.......but that is probably a longshot. The thing that shoots that theory down, for me anyway, is the fact that my '90 Chevy truck had a warped rotor that you could easily feel through the pedal, but I never had this chirping noise while driving.....even after braking downhill for a while on some of the mountain roads around me, which takes me back to the theory of the guy at the parts store LOL! I also agree with you on the aftermarket rotors......GM and everyone else will cut corners anywhere they can, and they probably put a sufficient rotor on, but definitely not a premium rotor.
 
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