Brake Noise - only when pads are warmed up

[The Critic]

What causes brake pads to become noisy, but only once warmed up?

I road tested a vehicle yesterday and noticed the rear brakes emitted a nasty grinding sound upon coming to a complete stop. However, the brakes have to be moderately warm in order for the noise to be duplicated.

The pads appear to be Wagner Quick Stop. They are also paired with uncoated white box rotors. Overall, a very low-end set of parts. The pads are near-new and the rotor surface condition is perfect.

 

[dubber09]

Take pads off, clean bracket under 'hardware' and lube between bracket and 'hardware'. Check how tight pads are when in bracket, file ears a bit if needed so they slide easily. Check and lube pins.

 

[Audiman]

Take pads off, clean bracket under 'hardware' and lube between bracket and 'hardware'. Check how tight pads are when in bracket, file ears a bit if needed so they slide easily. Check and lube pins.

If pad ears need filing throw them In the scrap pile and buy something that fits.

 

[dubber09]

Sometimes pads need to be 'fitted' a bit, not a reason to throw them away. It doesn't happen often but still does. A year or so ago I was changing pads on a RAV4 and one pad had to have one ear filed a bit.

 

[D60]

Sometimes pads need to be 'fitted' a bit, not a reason to throw them away. It doesn't happen often but still does. A year or so ago I was changing pads on a RAV4 and one pad had to have one ear filed a bit.

Completely agree, although it's a time suck for the professional.

A couple thou is the difference between a slip fit and a press fit.....

 

[Hall]

A couple thou is the difference between a slip fit and a press fit.....

Sometimes it's nothing more than a metal burr on the backing plate too

 

[The Critic]

I wasn't the one who did this brake job....and since the vehicle is getting sold, I'm not messing with it.

Was really just curious...

 

[930.engineering]

If pad ears need filing throw them In the scrap pile and buy something that fits.

It shouldn't happen, but it happens sometimes, even with reputable brands like Ferodo, Textar etc..
Probably it doesn't require a workshop 'file', quite often these are appropriate, just to trim back a bit of paint from the pad's ears:

 

[edyvw]

What causes brake pads to become noisy, but only once warmed up?

I road tested a vehicle yesterday and noticed the rear brakes emitted a nasty grinding sound upon coming to a complete stop. However, the brakes have to be moderately warm in order for the noise to be duplicated.

The pads appear to be Wagner Quick Stop. They are also paired with uncoated white box rotors. Overall, a very low-end set of parts. The pads are near-new and the rotor surface condition is perfect.

It could be just a compound. Noise is very common in track/racing pads. I currently have HAWK HP+ in front for track purposes, but, how to explain, everyone in the neighborhood knows when I come back home.
In cheap applications that happens, bcs. well, cheap.

 

[Oliveoil2]

Sounds like they weren’t bedded in properly.

 

[The Critic]

Sounds like they weren’t bedded in properly.

They are very well-bedded in after 15K. The material transfer onto the rotor surface is visually uniform.

 

[dubber09]

Hawk - same exp on Audi TT - had to replace to another brand/model. Too noisy.

 

[Oliveoil2]

They are very well-bedded in after 15K. The material transfer onto the rotor surface is visually uniform.

They are glazed

 

[edyvw]

Hawk - same exp on Audi TT - had to replace to another brand/model. Too noisy.

These are HP+, I just put them when doing track. After that, I replace them with normal pads.

 

[Audiman]

Must be just me, as a professional mechanic, that hasn’t had the need in all the pads I’ve fitted ,of decent quality, to file any of them down. This is a cheap pad problem or a rusted pad carrier problem. Are all those that are filing down pads re applying the powder coat to stop the metal from rusting? Thus locking the pad into the carrier. If your in an area that spreads salt this will be a guaranteed problem.

 

[The Critic]

Are all those that are filing down pads re applying the powder coat to stop the metal from rusting?

Extremely rare. If you’re lucky the average flat rate mechanic in the US may apply some brake grease.

 

[Audiman]

What happened to pride in your work, I wouldn’t do to a customers car what I wouldn’t do to my own.

 

[The Critic]

What happened to pride in your work, I wouldn’t do to a customers car what I wouldn’t do to my own.

Welcome to flat rate, where cutting as many corners as possible on gravy work makes up for poor paying warranty work.

 

[researcher]

They are glazed

Exactly! I had this happen before, took some garnet sandpaper (not aluminum, can create cementite onto rotor) and sanded down the pads and the rotor surface.. It worked for awhile but those cheap pads did it again in like a year..

 

[JHZR2]

Welcome to flat rate, where cutting as many corners as possible on gravy work makes up for poor paying warranty work.

How do we know it’s any different in Europe?