brake squeal

so i reciently replaced my brake pads and had my rotors turned. both front and back. flushed through some new brakefluid

my brakes squeal like crazy really loud.. almost all the time. ear piercing loud. i've done alot of brakes on cars and never had this problem. the pads were duralast gold. i used the grease on the back of them, installed the new disk brake hardware. cleaned everything as i was reinstalling it all

what am i missing?

Did you do a bed-in procedure after installing the pads? I used the same pads on my wife's Toyota and usually no noise.

See if your e-brake is sticking, or if the pistons in the rear are in all the way and in the right orientation. IIRC, there is a slot in the pad that slides into a pin on the piston.

What composition are the Duralast Gold made out of.?
Certain types of pads on a turned rotor will squeal real bad.

And you don't use brake grease behind the pads. That is for lubricating the other moving parts.
If needed, use an Anti-Squeal product on the back side of the outboard pad only, not the piston side.
Clean all the grease off and wipe with acetone or something to clean the back of pads and leave no residue.
Apply the Anti-Squeal stuff and let dry/cure somewhat before re-installing the pads. It provides a rubbery coating to the back of the pad that will absorb the harmonics which cause squeal.

If after a proper bed in and putting the anti- squeal stuff on the back of the pad, you still have squeal, I would recommend new, not turned rotors.

Rick is right about the grease. I read that you greased te back of the pads and wanted to reach through the monitor and slap you . ONLY Anti-squeal should be applied to the backings of the pads. Also, putting grease on the backings could potentially cause a rattle when going over bumps, or a slight "knocking" sound at initial braking. I can pretty much guarantee that squeal is from that grease.

No disrespect intended, but imo greasing the backs is fine - if it's high-temp brake lube. I do it anywhere the pad touches another metal part (ie. caliper or piston). I never use the anti squeal goop, because I've never needed to. Installed the right way with proper bed-in, pads won't squeal unless they are super abrasive (race/track compounds). Even those can made to quiet down with proper technique.

Most of the time, squeal is the result of metal/metal contact between the rotor & pad. Freshly turned rotors are pure iron, and I believe Duralast Gold pads are semi-metallic (metal flakes). Bed-in creates the deposit boundary layer between rotor and pad surfaces that quiets things down. If you don't bed-in, it takes longer for that boundary layer to form, or it might not form at all.

Give her 10 hard stops from 60-20 mph, make some smoke. This can also help to fully cure the compound on the pad. Rotors should have a light grey satin haze after bed-in is complete. Another sign bed-in is complete: squeal goes away!

If that doesn't cure it, you have another problem to deal with, such as a stuck guide pin or caliper piston.

It's been going on for a couple of months and I've had a few 60-20 braking situations. Sorry I missworded my post, it wasn't grease. No need to splap me. It was the Anti-Squeal stuff.

AA, you're wrong. Never should you grease the back of the pads. And no, squeal is not caused by pad-to-rotor vibrations most of the time. The squeal is caused by the vibration between the pad and the caliper, which is why they make ANTI SQUEAL to put there.

walkin wrote:

It's been going on for a couple of months and I've had a few 60-20 braking situations. Sorry I missworded my post, it wasn't grease. No need to splap me. It was the Anti-Squeal stuff.

Did you replace the Anti-rattle clips?

i didn't at first. i had never replaced them on any other brakes i've worked on. after it kept squealing i went and bought them and put them on.

i'll take a look at the rear calipers to make sure they are lined up with the pads correctly.

if i do end up putting new rotors on, is it best to replace the pads again? i'm probably not going to have the car much longer, its just driving me crazy.

walkin wrote:

i didn't at first. i had never replaced them on any other brakes i've worked on. after it kept squealing i went and bought them and put them on.

i'll take a look at the rear calipers to make sure they are lined up with the pads correctly.

if i do end up putting new rotors on, is it best to replace the pads again? i'm probably not going to have the car much longer, its just driving me crazy.

How do you know the rotors were not turned too thin?

Albertj

i dont know. i took it to a checkers auto parts. i've seen people in there before getting them done but i've never had much confidence in that store.

Eh, try to find out exactly where the squeal is coming from. I doubt it's from the front. Possible, but unlikely.

No, you don't necessarily need to repalce the pads if you replace the rotors. Just make sure that the pads are worn evenly end-to-end. You'll just have to do a few more 40-0mph stops in a row to burnish the pads to the new rotors.

A thin rotor won't cause a squeal either. All that will do is cause the rotor to warp easily.

Abaddon wrote:

Eh, try to find out exactly where the squeal is coming from. I doubt it's from the front. Possible, but unlikely.

No, you don't necessarily need to repalce the pads if you replace the rotors. Just make sure that the pads are worn evenly end-to-end. You'll just have to do a few more 40-0mph stops in a row to burnish the pads to the new rotors.

A thin rotor won't cause a squeal either. All that will do is cause the rotor to warp easily.

I stand corrected.

Albertj

Quote :

if i do end up putting new rotors on, is it best to replace the pads again?

You can reuse the pads.

Abaddon brings up a good point - always replace the spring clip hardware. It's only $20 or so for a complete set.

But I still don't agree on the squeal and ant-seize issue...

Abaddon wrote:

And no, squeal is not caused by pad-to-rotor vibrations most of the time. The squeal is caused by the vibration between the pad and the caliper, which is why they make ANTI SQUEAL to put there.

This may be the case with older asbestos and newer organic (cheap) pads, but semi-metallic pads like the Duralast can and do squeal because of the metal fibers in the pad composition. It's a fact that metallic pads are noisier than ceramic. They need to be bed-in to run quiet.

Anti Squeal is a band-aid. I have never needed it with proper bed-in. I use HP+ compound - notorious for squeal, but they are silent most of the time. When they act up, I give them another bed-in. If the pads don't come with anti-squeal (mine didn't), I won't use it. If the pads come with a grease pack (mine did) I do use it, exactly as the manufacturer recommends:

From Hawk Performance:

GearHead Grease Pak
• High Temperature Brake Parts Lubricant
• Helps Eliminate Brake Noise
• Protects Moving Parts

To Silence Brake Noise:

"Apply 1-2 grams on the backside of the brake
pad and evenly spread across the surface making sure to cover any
areas where the pad contacts the caliper or piston."


If you try the GearHead Grease, it's nothing like the heavy paste that is anti-seize. It's a thin, slippery, high-temp grease. I've used Permatex blue brake caliper grease with identical results.

AA, I'm not trying to argue with you, but now you're talkin about HP brake pads. Those are a whole different story. I hear Corvettes with squealing brakes ALL THE TIME. Yes, they are made from different, harder compounds, and yes, they will squeal. You even admitted above that they are silent "most of the time". For walkin's sake, we are talking about normal replacement brake pads. I've done hundreds of brake jobs, at least one a day (I do it for a living). I've yet to have a brake job come back for a squealing problem. Only In rare instances will a hard spot in the rotor, or an over-abundance of "metallic" in a pad cause the squeal. In my experience as a mechanic, and from what GM Training at the Tech Center has taught me, is that a squeal 99% of the time is a metal-to-metal vibration either where the pad contacts the caliper bracket, or between the pad and the caliper. On a different note, why do the more expensive brake pads have a thicker, softer Anti-Squeal plate on the back of them? They're also usually riveted, not glued like the "cheap" pads.

FYI, Anti-Squeal doesn't come with any brake pad set (that I've seen), they only come with grease. Anti-Squeal is designed to help absorb the vibration that causes the squeal, not band-aid it. Nobody is required to apply the stuff. It's purely discretionary, and good practice IMO. I wouldn't argue with you about Industrial Designing because of an experience I had, so please don't contradict what I know, and what I've been practicing for years. If I were to do the brakes on your car, your hubs would get cleaned and sprayed with Zinc-X, the rattle clips would get cleaned/lubed (if they didn't need replacement), and the pads would get a healthy coating of Anti-Squeal.....blue if I have Permatex, or red if I have the Napa stuff.

I always know ahead of time when I'm going to do a brake job or at least a pad replacement. So that gives me the time to apply the proper product to the back sides of the pads and I try to apply it only where it will contact other metal.
On the outside pad, that can be a considerable amount of area and on the inboard side it is only the circumference of the piston.
But I do it and have been doing it for years on not only my cars but back when I worked in the industry we ALL did it to customers cars and allowed some time for the stuff to set-up before installing the pads and then taking it out on the highway for a bed in procedure.
Just as replacement and/or lubrication of the hardware and anti-rattle clips is important, we/I put the same emphasis on the anti-squeal compound and using the correct brake pad and disc for the standard car.
I currently run something other than standard, but for a customer who is buying standard they don't want to know what it is I'm doing to make the car squeal free.
But someone who is installing "standard" brakes they need to know what to do to make them squeal free, and that is what has been mentioned by Abaddon and somewhat by myself previously.
To the OP, I have had problem squealers that would not go away without replacing the rotors.
Unfortunately the vast majority of rotors made today do not have enough hardened metal on the surface for them to withstand a cuttting of that surface and can cause a squeal with a new pad, even after all the other protections are taken.
But, before replacing anything, take it all apart again and apply the proper coating and pay attention to the moving parts and make sure there is no corrosion or resistance of any kind in the parts that need to slide.
I guess I am reiterating what Abaddon (Scott) has said.

Quote :

On a different note, why do the more expensive brake pads have a thicker, softer Anti-Squeal plate on the back of them? They're also usually riveted, not glued like the "cheap" pads.

It's a safer alternative to using anti-seize, and it doubles as a heat barrier, improving stopping and preventing fade.

EBC (a world leader in brake rotor and pad development) has this to say about anti-seize:

"Anti Seize compounds and noise reduction pastes or silicones have been tried but EBC does not recommend these as: A) it is possible to get such compounds on the pad surface which is HIGHLY DANGEROUS, and also B) they only last a short while, sometimes not even the pad bed in period."

Unless you have tried and compared organic, ceramic, semi-metallic, and ferro carbon pads with solid, slotted, drilled, and dimpled rotors, and used OEM vs. F-body calipers - ALL on the same Riviera, you can't know what I do about how brakes function on this car. I've spent a lot of time and money testing products on this car, and have learned a few things in the process. I've shared this info with other members, helping them achieve very solid, reliable braking on this heavy car.

I have a problem trusting mechanics sometimes, because their policies are aimed at business profit first, customer satisfaction second. Also, their expertise usually has general application, not specific to any one vehicle. For this reason, I only let certain specialized mechanics work on my car (INTENSE racing, for example, and even they have been wrong). And no one but me touches the brakes, mainly because I don't trust most brake mechanics. Their priority is to get the car in and out as fast as possible, spending as little as possible. Also, much of their industry knowledge applies to brake pad technology of 20-30 years ago (asbestos days). Pad compounds have changed since then, and so has much of the theory. For example, it used to be thought that brake judder was caused by warped rotors - thanks to companies like StopTech, we now know the truth about uneven compound deposition. However, there are mechanics in shops all over the country who will still tell you your rotors are "warped" if vibration is reported.

The Hawk HP pad example is legitimate for a couple reasons:

1) Even though they tend to be noisier than the average pad, I run HP pads all year without anti-seize and very little noise. How can I do that? Proper bed-in and pad selection that matches my driving style, combined with knowledge gained from experience with brakes on the Riviera. They were noisy as hell until I bed them in.

2) Hawks are a type of semi-metallic, not so different from the Duralast Gold, except the Hawks contain carbon which helps with heat. Because of this, the Hawks are actually a bit quieter, at least the HP-S are. Anyone who knows brake compounds can tell you semi-metallics are the noisiest type of pad on the market.

Why are the Duralast Gold made semi-metallic? The name says it all - Duralast comes with a lifetime warranty, and that means they must use the hardest, longest-lasting compound available - semi-metallic. It's as simple as that. I've used the Duralast Gold pads, and they were noisy for a while until properly bed-in.

An expert named Austin C. Davis wrote a book on how mechanics are not always right, and here are some of his opinions on brakes:

"A certain amount of high-pitched brake noise is considered "normal" these days because of the harder semi-metallic brake pads that are used on cars now. Semi-metallic brakes are made of bits of metal shavings in place of the asbestos material that has been banned by the U.S. government. These semi-metallic brakes have great stopping power and have a long wear life, but can cause a high-pitched squeal that drives car owners crazy and frustrates mechanics who can't get it to go away to please their customers.

Some brands of semi-metallic pads are inherently noisier than others because of the ingredients used in the manufacture of the friction material. Think of it this way, the longer life pads or pads that claim to have more stopping power usually contain more metallic material. Yes, they will last longer and could enhance braking but the chance of causing a squeal noise is very high. The squealing noise that might be caused from use of these pads does not affect braking performance and does not indicate a brake problem.

The brake rotor is the round metal object that the brake pads squeeze together like the white part of an Oreo cookie. The rotor is metal and has a smooth slick finish, and the brake pads are made of metal shavings and also have a smooth somewhat slick finish. The more metallic material found in the pad the greater the chance for noise, and vise-versa.

The other type of brake pad is called organic. There is no metallic material used in this kind of brake pad. Organic style brake pads can only be used on vehicles that are specifically designed to use them. Improper use of organic pads on a vehicle designed to use semi-metallic can severely reduce stopping ability. Organic pads are softer than semi metallic and usually do not have a squeal problem. Unfortunately due to shorter life expectancy, inability to stop larger vehicles, and the addition of substances like asbestos in their construction, they are not very widely used."



I'm not saying you can't add that goop to the backs of the pads. It might help, but personally I'd rather stop the squeal at the source. Good cleaning, fresh clip hardware, grease lube, and a thorough bed-in was all I needed to quiet mine. There may come a point where a ceramic pad is the better option, if low noise is your primary concern.

AA wrote:

Unless you have tried and compared organic, ceramic, semi-metallic, and ferro carbon pads with solid, slotted, drilled, and dimpled rotors, and used OEM vs. F-body calipers - ALL on the same Riviera, you can't know what I do about how brakes function on this car.

Gee, in the years of being a mechanic, I must've been installing the exact same rotor and pad combo the entire time! Thanks for straightening me out AA!
I'm done arguing with you. You're right, you're ALWAYS right. Don't EVER trust a real mechanic, especially over the internet, because he's out for your money......gimme a break. Quit "learning" from what you Google for once and realize that there are ppl out here in this world that have far more hands-on experience than you when it comes to cars.

Nobody is using Anti-Seize btw.....

No need to get bent out of shape. I'm not always right, just sharing my points of view, which didn't come from Googled facts, they come from installing and testing a half dozen pad/rotor combinations on a Riviera, and from installing first hand the very same Duralast Gold pads mentioned by the OP. Don't have as much professional experience as you, but enough time under the car that I know the brakes inside/out.

The difference between you and I is, you can do brakes just as easily on most any car out there - I am only familiar with the Riv and a handful of other cars.

I apologize; didn't mean to offend you re: your profession. I also don't think you are not knowledgeable or a crook. But as a professional, you have to respect that a competent DIYer could learn quite a bit in practice. Why not learn from what I know to better yourself as a mechanic? You can surely understand how an owner who truly loves his car would not trust most repair work to the average mechanic. Nothing personal, but we've all been burnt at some point by trusting a professional who should know better than us.

Walkin, I was thinking......If they squeal constantly, even when not on the brakes, check the rattle clips to make sure they aren't contacting the rotor (bent or shifted). Also, check the backing plates for contact with the rotor. The small piece that hangs down over the lower ball joint has a tendency to move and contact the rotor, which could cause a horrible screech, especially when turning.

I suppose working at a Buick dealer doesn't qualify me as experienced either......

And yes, I understand you may have been "burnt" by a mechanic before, but the half dozen times you've "experimented" with your brakes does not compare to sometimes 6 a day that I do. They all get done the same way, test driven, and delivered. I'm not going to suggest using something just so you have to go spend money at the parts store. You using or not using Anti-Squeal effects me in no way shape or form, I'm merely suggesting what I know works.
I have ppl like you come in all the time. They leave happy, and usually return. I have to please customers so they come back, and they refer friends. I get my paycheck from consumers, not from my boss.....my pay comes directly from the bill you pay. I take extreme pride in the work I do, as I'm sure you do. Yes, there are WAAYYY too many hacking, cheating mechanics out there, and I've worked with them. Not all of us are "out to get you". Yes, I take those comments personal.....

Fair enough. I respect what you do, Scott, and the pride you take in your work. I've also seen how fast mechanics can do a job, and that's impressive. I could not compare in speed/efficiency, as I'm pretty slow in doing the work. If it matters, my job as an industrial designer involves finding and solving problems for people/companies who need an 'outside perspective' with regard to their products or services. I do analysis, data recording, and results comparison in order to offer a 'better way' of doing things for people who already know. They pay us for fresh perspectives, if that makes sense. I get paid to tell professionals what they are doing wrong, based on only a few weeks of research. Hope you can understand why I would challenge your position - I challenge everything, it's the nature of what I do.

I completely agree on the clip hardware. Pick up a new set, lube, and reinstall. There are also anti-noise shims available in place of anti-squeal. I know I'm using the Google here, but if you search "Duralast Gold Squeal", you can read thousands of reports in forums of people who've just installed these pads and have squeal issues. If you read further, you'll see in many of these cases the noise went away after a thousand miles or so.

Aaron does have a tendency to challenge things which gets people riled up sometimes, his intentions are good though, as he says thats what he does for a living. You guys are both assetts to the site. I hope you don't feel less inclined to share your insight and experience with us, it is interesting and welcomed.

...the OP could also consider cleaning the pad faces and the rotor faces with CRC Brakleen (or equiv) then spraying the rotor faces with a light coat of Disc Brake Quiet - it is an aluminum powder spray CRC makes. Because it is sprayed on the rotor friction faces one MUST MUST follow label directions scrupulously.

That said, if nothing else has worked, that probably will. I have used it on stubborn problems but did not mention it before b/c I did not realize how stubborn teh squealing problem was going to be.

Only other thing I can think of is to be sure to let the squirrels out from under the hood out for a smoke break, and leave 'em by the curb before they take their last drags and make it back in...

Albertj