Brake squeak

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Dec 27, 2019
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#1
Make
Gmc
Model
Acadia
Year
2015
Miles
55000
Engine
4.3
Left front squeak. When cold, squeak starts when braking and turning left. After warm squeak whenever apply brake. Sounds metallic scraping. Replaced pads, rotors, clips with ACDelco OE (ceramic). Well lubed all moving parts, disc quiet applied back of pads. Before replacement the squeak was a grind sound. Pads were about 50% before replacement. Even wear. I think the grind was rust build up on circumference of rotor. Plenty of clearance everywhere. Thought it might be the clips so tried it without the clips and did not help. Is constant squeak whenever brake applied. No witness marks anywhere. Buffed pads with sandpaper, did not help. I might try next to swap left and right. I’m stumped...Any ideas?
 

billr

wrench
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#2
Wheel bearing? Are these simple spindles with separate inner-outer bearings, or 4WD with a bearing "unit" that the axle drives through?

Have you checked the rear brakes at all? Noises are notoriously hard to locate, they often sound like they are coming from a completely different place then they actually are.
 
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#3
Yep it was rear brakes. Had to recruit a helper on side of street to listen as I drove by. So I figure this was two issues. Rust on rotor edge made grinding sound on front. I changed those and about same time a squeak appeared. So I naturally figured it was still the front had issues as that was the only thing that changed recently. Ugg. Thanks for the help!
 

nickb2

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#5
One thing I use "now" to help resurfacing old rotors is this nifty gadget. It is called a flex hone, much same principle as a cylinder honing tool.

I have been using one for the six past months, half down on tool degradation. I estimate that next month, will need a new one. Yet, I must remind you guys, this is my day job. So a tool like this for the guy who only does family and friends, awesome tool to save money and do a good finish. Here is a link. I have just started using them, got sold. That is it. Just sold. ;) It really works. Low speed good downforce is better, high speed tools degrade it quicker and creates a more smother finish than I want. Again, wink wink.

I do alot of high end cars, they often have drilled rotors, this things works great for those also.

http://blog.brushresearch.com/resurfacing-slotted-brake-rotors-with-flex-hone-tools
 

nickb2

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#6
Next on list to do, slotting and beveling cheap pads to reduce squeal and chirps.

Using brake quiet is often not enough. Slotting the actual pads themselves is more beneficial, but using brake quiet is always a must, just helps the pieces to be sticky and reduce vibration. This is number one cause of al brake noise.

The slotting of the pads can be seen in high end pads, but a low end pad may have same ceramic, semi metallic branding, but just sold cheaper to reduce labor cost. SO before putting in new or used pads, make sure they are slotted in the middle to help brake gasses escape. #1 noise reducer is this, and a bevel on each end on pad at disk contact point.
 
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#7
80's and 90's Ford brakes were always squeaking until you used them several times, every morning. GM motorhome wasn't that bad, but squeaked like crazy after sitting still all winter long.

Problem was made a lot worse with rotors made in China.
 

nickb2

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#8
And I second jack, good catch bill, sometimes clients think it is coming from somewhere else, they do not realize a car/truck, when it comes to resonance.
 
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#9
Reason? Sound travels through metal seven times faster than air. When it gets at the end, switches back to air and that is where you hear it from.
 

nickb2

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#11
Hi, I think my car is falling aprt in the front. every time I hit a bump, something goes BANG.

Yup, that is your spare tire, did some one try to fix the brakes on this, in a non professional mannor. At this point, pleading the 5th, and as a canadian, I have no 2nd

Well gosh, no, no body touched the car. Really. I guess it is the lap dog that unscrewed all this, and put the lugnuts backwards. Must have one heck of a bbq to get to that point.


Will it cost much?> Nope, just bring right back to the guy who fixed it in the first place.

My cat, is called door knob for a reason.