Squealing Brakes..(Pads)

Arnold · August 07, 2013, 04:07:34 PM

My 94 1 Ton GM Van had new brakes put on it when I bought it.

A few years later it started the "wear sensor" noise. The noise was somewhat odd as it started and progressed to a "scream" really fast.SOOo..I bought new pads and set out to change them.

Upon pulling it apart.the pads were not even close to half worn

My neighbour was having the exact same problem..on about an 05
GM 4x4 3/4 ton. His garage did his. They said his pads were about 30-40% worn. He said it was the combination of the way the pads were manufactured and they way they wore. Pads getting "wear hardened".

Last week..after another few years of service on those brakes.
I go through the above again

Pads look great..maybe 25% wear.

This is not your normal 'wear sensor" noise..you will do the brakes when you get time. This is a do not drive the truck type of screaming.

All else is well there..(calipers,slider pins and bushings),all stilll lubed up.moving freely.put new pads on noise gone.

Anyone else ever heard of this?

enjenjo · August 07, 2013, 05:40:45 PM

Do you put antisqueal compound on the back of the pads when they are installed?

Scuffing the rotors with a Scotchbrite pad will stop it for a while.

Arnold · August 07, 2013, 06:25:08 PM

Quote from: "enjenjo"Do you put antisqueal compound on the back of the pads when they are installed?

Scuffing the rotors with a Scotchbrite pad will stop it for a while.

Thanks..I had thought about the antisqueal compound..but it was on there for the first set and it ended up doing it anyway. I did not put in on for the second or third set. My neighbour put it on his and his did it.

Not really a problem..IF I order the pads..they cost me about $50. Incl. shipping. If I need them within a day..as in now..the local auto parts places want about $150-$230 for the only kind they stock.
Guess I am ok for another 2 years of front brakes at $50

I notice a really big difference in improved brake feel and cold performance when the pads are new.

Someone said it might be if it has original GM rotors on..as they are ridiculously hard and can be really hard on pads when they are hot.

phat46 · August 07, 2013, 09:31:35 PM

Have you tried doing a couple hard stops? Not exactly panic stops but close, I like to get up to about 45 and stop fairly hard. This has cured squealing brakes for me several times. It seems that the light braking I do in normal driving seems to glaze the pads and a couple hard stops must clear the glazing off for a while at least.

wayne petty · August 07, 2013, 10:49:45 PM

brake pad squeal..

is the wear surface of the brake rotor SMOOTH?

or is there a RIDGE around the outside and sometimes the inside???

is the surface between flat or does it look like a 78 RPM record.`^^^^^^`

a 12 inch rotor with 2 inches of wear surface width.. is about what you have..

so the outside diameter of the wear surface is just shy of 12 inches..

the inside diameter of the wear surface is about 8 inches..

the outside goes about 37 inches as it goes around..

the inside of the wear surface.. goes around 26 inches around.. with variations between them as it gets larger..

what happens is brake pad grips and slips at different positions on the rotor face... when the inside grips.. the pad rotates one direction.. as that releases the outside grips and the pad rocks the other way.. its constantly rocking back and forth..

when you have grooves or wear marks in the rotor.. it becomes like a record and starts playing the screechy squealy brake song..

anti squeak stuff does two things.. it either grips the pads tight to the caliper or it allows them to slip so they don't squeak...

sometimes.. there are little metal tabs that hold the brake pad tight in the bracket.. if these get worn.. they can allow the pads to shift until the people on the sidewalk give you dirty looks...

there is another issue with worn rotors.. because of thickness variation .. being usually thinner out near the edge.. this can reduce your braking application force..

what happens is when you depress the brake.. the calipers that are parallel.. squeeze the brake pads that are parallel.. to contact the inner part of the rotor wear face... then something has to give.. usually the caliper and the piston can flex slightly but this takes extra brake pedal.. so you get slightly lower brake pedal that does not seem to stop the truck anywhere near as fast as it used to..

i know that this does not answer your questions.. but i bet it explains some of the answers you need..

Arnold · August 09, 2013, 01:17:49 PM

Phat46..Yes..I have tried that..I think a bit too late though

I think you are right in them being glazed up. Takes 2 years..and then bang..screaming. I don't think that 2 years of driving..glazing..perhaps heating too..is gonna get fixed by trying to get the glaze off these. No big deal..I just change the pads and the screaming goes away for another 2 years

Wayne..the very first time I had this apart..rotors,pads like new.Drove it for 2 years until the screaming started. Yes..there were shims/antisqueal on the pads..rotors like new.The second time I had it apart..same deal..screaming..there was a tiny ridge on the inside of one of the rotors.Not really enough to bother turning them. Rotors were still like new.I put the shims back on but no antisqueal.3rd time apart..same screaming..the ridge on one rotor is a bit bigger now..not enough for me to bother turning it yet. Still look almost like new.No they are not thin..to get the new pads on the piston has to be pushed all the way in still.

Thanks again guys..another 2 years and they will start screaming again and I will just change the pads again

Crosley.In.AZ · August 09, 2013, 01:29:56 PM

yep, scuff the rotors. Sand paper, roll-loc fiber disc , something. Not need to be perfect, just scuff them

had a Ford F-150 truck , rear disc would kinda rumble - squeal at light stops... scuff them a every few months.

That Ford ate front pads. A good set would last 26-28 k miles. Glen told me this was normal

phat46 · August 09, 2013, 05:40:23 PM

Quote from: "Arnold"Phat46..Yes..I have tried that..I think a bit too late though I think you are right in them being glazed up. Takes 2 years..and then bang..screaming. I don't think that 2 years of driving..glazing..perhaps heating too..is gonna get fixed by trying to get the glaze off these. No big deal..I just change the pads and the screaming goes away for another 2 years
Wayne..the very first time I had this apart..rotors,pads like new.Drove it for 2 years until the screaming started. Yes..there were shims/antisqueal on the pads..rotors like new.The second time I had it apart..same deal..screaming..there was a tiny ridge on the inside of one of the rotors.Not really enough to bother turning them. Rotors were still like new.I put the shims back on but no antisqueal.3rd time apart..same screaming..the ridge on one rotor is a bit bigger now..not enough for me to bother turning it yet. Still look almost like new.No they are not thin..to get the new pads on the piston has to be pushed all the way in still.

Thanks again guys..another 2 years and they will start screaming again and I will just change the pads again

Yeah they can go past the point of no return, last year my neighbor in his mid eighties asked me to look at his Ford Windstar brakes. It seems his son in law had replaced his front brakes and used ceramic pads and didn't,t break them in. The pads were very glazed as were the rotors, the van was very hard to stop in a hurry and I was worried the old guy might not be able to stop in a panic situation. I replaced the front pads with some o.e.m. Type pads, had the rotors turned and took it out and did 4-5 firm stops and it was like a new vehicle. No problems since, but the way the old guys drives I think even o.e.m. Pads will glaze eventually.