Squealing brakes

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  #1  
Old 07-21-18, 09:40 AM
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Squealing brakes

Ok, it really got on my last nerve.
Have 2005 RAM. Don't think it's relevant, as rotors and pads are completely replaced with AM ones. Around 3 000 miles back. So they are, basically, new.
Truck brakes fine for the first about 20 minutes of driving. Then, it start squealing horrendously, literally like metal on metal, at slow speed braking, light pedal touch. Press harder - noise goes away.
Worse, there is no pattern to it. It may not do it at all, may do it for hour.
Everything was checked, cleaned, re greased several times. Everything is lubricated where it needs to, calipers slide on guides, I even ground off cemented rotors layer in the front.
Truck squeals. Not uncommon on the road, big rigs and large trucks do it all the time.

Again, it literally sounds like metal on metal. Pads are semi mats. Not the cheapest ones, I buy 2nd from the bottom.
What am I missing?
 
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Old 07-21-18, 10:10 AM
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Sometimes it is the brake pads themselves. I have had to go to different pads before to stop noise. This is after many years as a brake mechanic. did you put some high temp lube on back of pads and use new hardware?
 
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Old 07-21-18, 11:00 AM
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pads are completely replaced with AM ones
Not sure what AM is but as an ex GM brake engineer I can tell you with absolute confidence that OEM brake pads are the best!

We spend months developing the formulations for the pads for each specific vehicle, aftermarket pads, nope, generic!
 
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Old 07-21-18, 01:58 PM
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AM likely means "after market"
 
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Old 07-21-18, 04:19 PM
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Pads

Since you have addressed all the usual suspects, it's your pads. Low end pads can have too much metal in them and that squeals.


The OEM's were semi metallic, so its not the compound you have used per se. Go for the OEM pads, the Mopar brand made by Magneti Marelli and you will probably be back to normal sounding brakes.


For greater certainty, I would double check that your anti rattle retaining clips are on properly, not bent or broken. Might replace with a new clip kit. Also, make sure you don't have brake fluid leaking on the pads, that can cause squeal, make sure everything is dry and the caliper piston is not leaking.
 
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Old 07-21-18, 09:47 PM
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As flat noticed - all usual suspects are in check.
Yes, AM is after market.
I'll re inspect tomorrow rear end. It was supposed to be property hauler that ended going on 1 hr 20 min commute one way twice a week. hence I didn't really shoot for expensive parts.
Yeah, I agree - it's likely metal in pads.
btw, yes, all clips were new with pads. All clips were also lubricated. i grease everything on brakes, short of rotor and brake mating surfaces.
I'll circle back with update. That squeal - and it's a good word - is absolutely annoying.
 
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Old 07-22-18, 04:03 PM
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Did you put grease between the backing plate of the pads and the pistons on the calipers?
 
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Old 07-23-18, 05:34 AM
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Have you checked the emergency brakes (EB) on the rear wheels. Perfect places for mechanical hangups (including cables to EB lever in cab).
 
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Old 07-23-18, 11:55 AM
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Oh yeah.
Did I grease - TWICE - everything!
There is no mechanical hangup. Wheels spin fine. Well, as fine as rear diff and driveshaft will allow.
Also, squeal - that was not there when I bought the truck - shows only when brakes are lightly pressed right before the final slow down. And, after about 20 or so minutes of driving. I figure, rotors warm up enough to cause something.

Well, it's in limbo as of now. I got MOpar pads ordered for the rear end. Should have them around Thursday, will swap them out Saturday, will update.
Two things to mention.
I had ALL of my cars ever on AM pads and rotors. I never had squeal.
And, as balm on my tormented soul, I was exiting garage at work this am - BMW pulls in towards parking card reader and, as it slows down - same squeal hit me coming from it. Made me feel better.
 
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Old 07-23-18, 03:51 PM
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BMW are notorious for brake noise. We only would use dealer parts for them.
 
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Old 07-23-18, 05:40 PM
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BMW are notorious for brake noise.
BMW use high metallic pads, that is why their wheels are always black.

99% of vehicles use NAO pads, a high organic mix, good braking with, hopefully, low noise.
 
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Old 07-26-18, 10:45 AM
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OK, got my Mopar pads.
Will have them installed Saturday, as promised to esteemed colleagues here but..
(those who watch Game of Thrones, remember what The Haund said - everything spoken before "but" is bs)
This is what I learned from internet:
good brake pads should be:
1. have angled edges and gas removal channel in the middle
2. be uniform in appearance and have no embedded particles
3. leave no residue on skin, when finger slides on top of braking pad material
4. smell like fish.

Here's Mopars that I received, Magneti Marelli as mentioned.

They do smell. That's for sure. Otherwise, they left heck of residue on finger (cermaics? Leaving residue?) and appear to have ton of particles. No gas removal channel.

Just an observation. Came from Dodge Dealer.
 
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Old 07-28-18, 06:01 PM
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No gas slit

Yes, that is what the OEM pads look like, they have no "split" in the middle like many pads do. The original pads were semi metallic, I presume they still are so you would see grains in there. Semi metallic means still heavy on organic material for good cold braking properties. They will probably dust more than aftermarket pads, especially ceramics, but the braking will be better. Given how different the OEM design is from many pads out there, I suspect they are that way for good reason. Will be interested to hear if this solves things for you.
 
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Old 07-28-18, 06:37 PM
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Interested myself. I had them replaced around 4 hrs back and took for 30 min spin.
Son took truck out to pick up a dresser, I'll ask him. he'll be on it for over an hour, it should show itself.
I also, as another preventative measure, ground off outer rotors cemented layer.
Flat, That channel in the pad center actually is useful. Peculiarly, picture on the box depicts pads WITH slot. I know, I know "generic picture". So they SHOW better pads, include worse.
So typical.

Not to start an argument... But definition of good pad is - it does NOT leave residue on finger. It does not specify semi this or that. Simply - no residue.

https://www.youtube.com/watch?v=-OrPURjLjog

Look at #1. That's quality pad.

While on it..
Found two ways of removing pads noise.
1. temper pads edge at 45 degrees. All around.
2. spray pads backing with Liqui Molly copper spray.
Which apparently is not available in the US.
 

Last edited by ukrbyk; 07-28-18 at 06:59 PM.
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Old 07-29-18, 03:04 PM
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OK, I drove truck today for over 20 miles, in 2 12 mile trips. So far so good. I'll have final result Tuesday, after commute to Seattle, 31 m one way.
Just keep in mind 3 points:
1. new pads
2. resurfaced DIY rotors, as in - glazed cemented outer layer on rotor ground off to bare metal
3. old pad had a very rusted contact area between brake pad outer shim and caliper. Also, caliper piston contact surface was rusted, so it's all greased now.
So there are 3 variables that changed, not just new pads. Old pads didn't squeal right away either, took them forgotten amount of time to get there. "old" pads had maybe 6 000 miles on them and were not worn out. Glazed and shiny surface - that indeed. Plus, that rust. I am not totally sure what exactly was the cause then.
 
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Old 07-30-18, 05:26 PM
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Pads

The slots in the pad are there to change the resonant frequency of the pad, which also depends on the thickness of the backing plate. These are both done for noise control. I don't think gas control enters the mix, as many pads do not have the slot. It is not a sign of a quality pad.

Chamfering on each end can also help reduce noise, and flex of the pad on initial contact, especially for long pads.

But many pads have no slot, and no chamfering. It depends on the brake system design, backing plate, friction material, etc.

Most of the OEM focus is on good consistent cold bite, fade resistance under typical use and low/no noise. Also a reasonable wear level service life on the disc.

High performance pads are focused on fade resistance, full stop. Noise and grab when cold are not on the menu. These pads typically are worse performers for most people. Only racers, maybe heavy tow vehicles in mountain areas, would benefit from the tradeoff against the OEM option.

Although you changed a few variables, which could well have been the cause of the squeal, the OEM pads are no doubt the proper design for your vehicles system. I guess we will only know if you change back to the old pads with the newly cleaned up rotors and lubed components!
 
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Old 07-31-18, 01:56 PM
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So far so good.
Over 40 miles today, FWY and city stop and go.
Slot is slot. It removes debris, or is intended to. More important, it permits for pad material expansion, when it gets hot. Just like they have in concrete pavements and bridges. I am not brake pad engineer, but the word is that gas is produced during braking and slotted rotors and pads do allow better escape for them.
Ah, and yet another one. Underlayer. Pads supposed to be mounted on underlayer that permits pad movement during its temperature change. Sort of like a bitumen layer.
 
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Old 07-31-18, 02:31 PM
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word is that gas is produced during braking and slotted rotors and pads do allow better escape for them

In high performance driving/braking there is a benefit, for daily driving, zip.

It;s the formulation of the material in the pads that makes all the difference, chamfers, grooves have a very minimal contribution!
 
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