Odd sound after brake install

Define the odd sound you are hearing? Zeeee noise is puzzling.
Maybe a audio recording from your phone might
help our owners with their suggestions about this issue?

Since the install was done by a former GM master tech- I doubt there was an install issue.
It might be a parts defect- but the GM guy would have noticed it.
New brakes & pads need a bedding in process. It might go away- then again maybe not.
Imo- you can never go wrong with new stopping power for your ride.
I was never a fan of crossed drilled rotors- but that's just me.

One of our owners will chime in with some clues to help you out.
I would ask the GM guy who installed them- what he thinks this sound is.

Luck with it.

LAC

Slotted rotors are mostly bling today and drilled can be a negative, but people still do it mostly for looks while pretending they are doing it for performance. You can actually get cracking starting at the drilled holes, so I tend to avoid them unless they are OEM as they are on one of my cars.

Having said all that, I don't recall the drillings causing any particular noise and have a hard time figuring out how that could happen unless there is something touching something else that it shouldn't, all things being normal. I'd be tempted to take it either to the guy that did it or to someone else and ask them to diagnose the noise (they can do things like apply an on car wheel balancer that spins a wheel up, and then watch/listen as the brake is lightly applied.

Frankly, I think you are right to be bugged by this - bits making sound is often caused by bits not supposed to be in contact which on a braking system can be bad news.

BTW, I have zero noise associated with the car that has drilled discs nor with another one that has slotted rotors.

A little bit of an update. I haven't driven the car in a few days since I'm off work. But I will have a video on Monday that will have the sound. He took it on an extensive test drive on the highway and city streets. He noted that he does hear the sound, but sometimes it sounds almost off-beat. When i hear it, it was a constant zeeeeee noise. However he noted a pulsing sound. The sound comes in, dies off and comes back. But happening about 5 times a second, zee.... zeee... zee... etc he said that he noticed it on the orignal install and it didn't seem to be something to be concerned of but did say hat he had seen slotted rotors make a hiss sound during rotation in the past. So this was a possibility. I will note that i had the rear diff fluid done by the same guy. He took it on a test drive after that and noted that there we're no odd noises coming from the rear diff, specifically noting nothing during slow tight turns. This was echoed after the most recent test drive stating that he doesn't believe it's anything diff related. I just worry about it since I've heard many people here with rear diff issues. Dad who also works along side this tech suspects it could be something drivetrain related but is unsure otherwise and doesn't think it has anything to do with the brakes. Tech said if it got worse we would happily dig deeper but that it doesn't appear to be anything to be concerned off since it's very unnoticeable. But I will upload a video Monday and hopefully I can get to the bottom of this

Well it is good that you had the installer look it over- take it for a test drive for his evaluation in different scenarios to ascertain what it might be- to this noise.
Off beat... he noted a "pulsing" noise.
He noticed it before- but was not concerned about it. Slotted rotors making a "hissing" noise.

It is not drivetrain related. That's a good thing. Not the brakes. It is very unnoticeable to him but not to you, cause you hear it all the time if I interrupt this description correctly?
It the noise- hisses and pulses.
If it gets worse- a deeper dive into the world of hissing & pulsing.
Sounds like something from Hollywood if ask me.

I've been known to make hissing and pulsing noises during the love making process but.. that is another story.

Brake booster? Proportioning valve?
We've all heard a power steering pump whine when low on fluid.
There is no vibration from the new rotors. There is no brake fade.
Is it enough time- for the new pads to be bedding in to the new rotors?

Maybe the video on Monday will tell us more about this problem.

LAC

It is noticeable to me, and to him. But you have to listen for it. Radio at normal volume and you can't hear it. The sound is noticeable at all speeds above 20mph, when off the brakes. He believes it could be drivetrain related, but is confident it's not the rear diff. Possibly a brake hub rubing? They both believe its nothing to be concerned about, i would just hate for it to be an actual problem down the line. It's present in the rear of the car only and on both sides. I also noticed this substance. The picture makes it look blue but it's actually white. Not sure that that coul be or if its related.

I do hear the humming sound- very slight but noticeable.
What it is- I'm not sure, so the GM guy might just be right
in his opinion that it is air flowing-through the drilled holes in the rotors.

Since there is no other odd sounds related to this new brake set up,
grinding or rubbing noises, no fade to the pedal, no pulsing of fluid,
no warning lights flashing in the DIC- I think you might be ok here.

IF it were something else besides the new brakes- you would know it.
The hub bolts should be checked- for torque specs on occasion.
Brake shield backing plates attachments points should be tightened.

Look for signs of any new wear, or shinning metal rubbing the new parts.
Brake fluid level checked often, hoses/fitments, caliper squeal, any pulling
to one side or the other, when applying the brakes.

After they have been bedding in some maybe a good old fashion panic stop-
just to see how they do stop the car under different conditions.
If you don't run into any new issues- you should be ok I think.
Then again- if do you notice something abnormal in the future
with their performance level or lack thereof- have the GM guy look them over again.

If your brakes don't stop you- while you're out & about something else will.
The neighbor's car, his trash bins, his wife's new flower garden, the odd
tree, concrete barrier, cement truck- you know normal obstacles.

LAC

* Not really an edit on my part- just an additional thought of mine.
The only time I've heard this humming type noise or read about it here on
the forum was that for some of our owners- is from the rubber seal, above
the plastic cowl to our windshield. If yours has a gap between the glass or
the cowl itself- this could be a source for this humming sound- maybe.
Just my 2 cents worth.