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Brake pads grinding on rotor..

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Old 04-01-2011, 03:16 PM   #1
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Brake pads grinding on rotor..

For the past week I've been hearing this constant grinding/squeaking noise coming from my front driver side. But, it stops when I put my foot on the brake. I'm taking a look at it now and it looks the pad is snuggled right on the rotor. The pads aren't too bad but I plan on getting new rotors and brakes soon. Any ideas why its making this noise? Is the brake pad supposed to be rubbing right on the rotor like this? Any help is appreciated.
Old 04-01-2011, 05:17 PM   #2
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Re: Brake pads grinding on rotor..

Disc pads usually have "squealers" built onto them.(a small springlike curved finger)
They will touch the rotor at rest, but when you step on the brake, the pad will shift or flatten slightly onto the rotor and the squealer will then lift slightly and not contact the rotor.
Get ceramic pads for replacement. They keep your wheel cleaner.
Old 04-01-2011, 11:28 PM   #3
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Re: Brake pads grinding on rotor..

Quote: Originally Posted by lmleck
Disc pads usually have "squealers" built onto them.(a small springlike curved finger)
They will touch the rotor at rest, but when you step on the brake, the pad will shift or flatten slightly onto the rotor and the squealer will then lift slightly and not contact the rotor.
Get ceramic pads for replacement. They keep your wheel cleaner.
You are entirely incorrect in your instruction on how a brake pad works. Yes a pad has a "squealer" but it is there to act as a pad wear indicator. It will only touch the rotor if the pad is 1/8" thick or less. When that happens it will squeal all the time to let you know...."hey Im getting close to being metal to metal, change me now!" A brake pad itself does not have any flex or spring to it. All noise is vibrations, and that is why when you step on the brake it either stops or quiets the squeal, because you are dampening the vibration against the rotor. Much like if you ring a bell and then grab it, the ringing stops.

To the OP: Even a new pad will ride against the rotor at all times. Depending on how much pad you actually have, it could very well be that your wear indicator is touching down. Could just be dirty pads and need to be cleaned and the edges beveled if there is plenty of pad left. Also check to see how your wheel bearings are doing. A worn or loose bearing can also cause a rough, humming, or grinding noise.
Old 04-03-2011, 01:28 AM   #4
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Re: Brake pads grinding on rotor..

I was just going through this on my 97...A PO had pad slapped the truck without doing anything to the rotors. The rotors had a heavy glaze set to them. This led to squealing on light brake application. The noise would go away with heavier application. I swapped my set of winter tires/wheels a couple of weeks ago and roughed up the rotors with a scotch-brite pad. Just a light scuffing with a non-directional pattern to bust up the glazing. That quieted down the noise for a couple of days.

Fast forward to yesterday and the Pro-cut brake lathe rep was in to upgrade and service our on-vehicle brake lathe at the shop. He needed vehicle to try it out on after he was done so I threw him the keys to my S10. 30 minutes later the rotors are cut with a nice smooth non-directional finish. I roughed up the pads (almost new thickness) with some 80 grit on the bench and popped them back in.

No more noise. Smooth stops. Getting back to the original post, calipers can drag due to dry slide pins or a piston that won't retract fully. I'd say that your plan for pads/rotors is a good one. When you do it, look over the calipers and grease the slide pins fully. If you do go with fresh rotors be sure to clean all the goo off of the new rotors to keep the pads from getting contaminated. Then, take the truck out on a low traffic road and burnish the pads in to the rotors with 4-5 good solid stops from 25 mph with a little cool time between stops. The stops should be firm (not locked up) but not light braking either.
Old 04-03-2011, 03:28 AM   #5
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Re: Brake pads grinding on rotor..

Quote: Originally Posted by lmleck
Disc pads usually have "squealers" built onto them.(a small springlike curved finger)
They will touch the rotor at rest, but when you step on the brake, the pad will shift or flatten slightly onto the rotor and the squealer will then lift slightly and not contact the rotor.
Get ceramic pads for replacement. They keep your wheel cleaner.
wow. lol
Old 02-18-2013, 01:53 PM   #6
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Re: Brake pads grinding on rotor..

I will revive this old thread. Someone may find it helpful.

I had a squeaking on both front brakes after I installed new pads. I checked the pins, replaced the O-rings and lubed them with no change. It sounded just like the pad wear indicators were rubbing the rotors on my new pads.

I replaced the rotors and pads with Raybestos ceramic pads and rotors and the noise was gone. I do not think the brand or type of rotors and pads makes any difference in this case.

The problem was that the previous Bendix ceramic pads were 1/4" wider than the AC Delco pads that were on the vehicle. The Bendix pads were braking on 1/4" portion of the unused surfaces of the AC Delco rotors.

Finding:
Make sure new pads match the width of the wear pattern on the old rotors. It would be best to replace your old rotors with new rotors or at least have your old rotors resurfaced every time you replace the pads. Obviously, the run out of the rotors should be checked, but also, the contact pattern on the new pads and old rotors should be checked and the pattern must match.
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