New Front Pads & Rotors - Metallic Noise on Light Braking

discgolf01 · February 8

Hey guys, so ended up replacing both front rotors and pads to fix a pulsation issue. Took it out and did the sequential 40mph to 10mph hard brake 4 times to set the pads to the rotors.

2015 Sierra 1500 crew cab, 5.3L, 60k miles. New pads and rotors were both AC Delco gold.

Within the next day or so, started hearing a very high pitch obviously metallic noise coming from the left front.

How it started:

-Very light braking, only at very beginning of the brake pedal travel

-Only under 10 mph

-Almost instaneous, a very quick "chirp" then it would be gone

-Harder braking and this noise would not happen

What it is now, approx 150 miles later

-Happens at braking at 40mph

-Noise usually lasts all the way down to 25 mph

-Approx first 25% of brake pedal travel

-Harder braking makes the noise go away

-Occiasionally the noise can be heard all the way down to full stop. Interesting to note that when it does happen at very slow speeds (under 5mph), and therefore slow rotor RPMs, the noise is cylical, meaning on/off/on/off, not consistent. This seems to me it would indicate something on the rotor, but is only heard when that part of the rotor touches the pads.

My first thought with the high pitch metallic noise was the pad clips, but I doubled checked all of them during replacement (new clips) to make sure they were in the proper position and full installed to the bracket, maybe one came loose/moved?

Was hoping to get thoughts from others on this before I dive back into them, as my next step was going to swap pads left to right and see if the noise follows the pads or stays with the left rotor.

Thanks in advance!

Edited February 8 by discgolf01

mikeyk101 · February 8

Did you put any grease or disc brake quiet to the back side of the brake pads?

CamGTP · February 8

What brand of parts did you use, just curious.

discgolf01 · February 8

...

Edited February 8 by discgolf01

discgolf01 · February 8

12 hours ago, CamGTP said:

What brand of parts did you use, just curious.

I knew I forgot something. Both pads and rotors were AC Delco gold. Updated the original post with the info, thanks.

discgolf01 · February 8

13 hours ago, mikeyk101 said:

Did you put any grease or disc brake quiet to the back side of the brake pads?

The pads were AC Delco gold and had something I've never seen on pads before: they had a blue plastic film on their backs that said remove before installing and under the film was a sticky substance on the back of the pad. Because of this, I did not grease the back of the pads because I was thinking they wanted the pad to stick to the caliper piston when they retract from the rotor? Every pad replace I've done on my cars over the years have never had any sticky substance on the back and I've added grease between them and the pistons.

The sticky substance was definitely intentional and covered all of the back of the pads (both inners and outers).

Interestingly, I replaced the rear pads a few months ago, also with AC Delco gold parts, but the rear pads did not have this sticky substance on their backs.

discgolf01 · February 13

Bumping, and adding that this noise only seems to happen after the brakes have warmed up, zero noise at any speed when cold (outside air = 55F) and in the first 5 or so miles.

discgolf01 · February 16

Update: Pulled everything back off, cleaned the slider pins, pad clips, removed the adhesive that Delco put on the back of the pads, cleaned up the residual adhesive on the caliper, greased everything back up, including the backs of the pads, and swapped pads from left to right.

Did some agressive downhill stops to get everything warmed up and the same noise returned. Happening at different speed then before, but still there.

So I guess next step for me is to ditch the AC Delco pads and go aftermarket. Was thinking the PowerStop Evolution Plus ceramics - anyone have any recommendations? No trailering, definietley not a sport truck, don't care too much about brake dust, just looking for good stopping and zero noise.

Thanks!

discgolf01 · February 24

Update: Replaced the AC Delco pads with Powerstop ceramics https://a.co/d/hq4FdEv

Redid the same run with multiple points of aggresive downhill breaking and so far so good, no noise.

Long story short: I don't recommend the AC Delco Gold front pads due to noise when hot.

mikeyk101 · February 24

Good to know. Thanks for posting this update.

asilverblazer · February 26

I did front brakes on my truck, I used:

ACDelco Gold Performance discs 18A2804SD

ACDelco Gold Ceramic Disc pads 17D1411CHF1

I didn't grease the pad clips or the back of the pads. The clips because I don't like the idea of the grease mixing with dirt and brake dust and drying out into a hard block that does more harm than good. I didn't grease the back of the pads because, messy.

Well it squeals something awful in drive throughs. Thats it though and I'm not going to tear it all down to try and fix it.

Anyone use a dry graphite type spray on the pad clips? Lubrication without the mess.