tbb2

I pulled the ABS, #48, 60 Amp fuse, from the under hood fuse box.

The dragging noise is much worse with the ABS disabled.
But the gravelly (chattering) noise expected of the ABS is gone.

I am suspecting that the front right caliper is not closing tightly or evenly onto the rotor, and is activating the ABS.
Based on work done
- the front caliper compresses easily enough with a C-clamp
- and resets holding the rotor firmly.
I am thinking air in the brake line ... but the lines have not been opened since they were bled Aug of 2015.

Do I recall correctly there is a mechanism that pushes the pad off the rotor when the brake is released?
This really may not apply since the noise is when I apply the brakes and only now am I noticing some drag at low speed when the brake is released.

If the noise was not pointing so distinctly at the front right I would investigate the other wheels.

canucklehead

For the single piston caliper to work it needs to float, but also, the outer brake pad closest to the piston also needs to slide in its clamps. It it is binding that can cause dragging. The caliper retracts by way of the seal getting twisted a bit as the piston is forced out, and the action of it going back to shape draws the piston back a bit.
I bought a brand new AC Delco set of factory brake pads for my 2013 and the pads were so tight in the little stainless clips that there is no way it would float. Its the first time I have ever had to grind a brake pad down a bit to fit properly in the caliper.
check your pads and see if they are snug but not super tight in the clips. Also, make sure the wear is even top to bottom and inner and outer pad is roughly the same.

tbb2

mountainmanjoe

a bit of uneven wear is pretty common.

Any store that carries brake parts will have brake lube.

StanVan

Here's another thing to consider. The rubber line that goes between the steel line and the caliper has a hold down bracket in the middle of the hose. This bracket can rust and constrict the rubber hose. making it not fully release. I just had this issue on my Equinox. The weird thing is that it doesn't look rusty, but I haven't pried it open to look closely.

I just looked up my Express, and the front lines have a bracket, but the rear ones don't seem to.

tbb2

There is always more on first time jobs for me ...

RIGHT FRONT WHEEL - the source of the noise
- I removed and disassembled the caliper to lubricate the slides since that was all I could suspect was causing a pad to bind and drag.
-- It struck me as odd that, after a few days of sitting, the surface of the pads were covered with flicks of rust while the rotor had a very few.
-- I pulled the slides - cleaned, rubbed w/ 0000 steel wool, brass brushed, sanded w/ 600 grit paper (could not get down to all shine), cleaned and lubricated w/ CRC Silaramic brake lubricant.
--- The bottom slide had some corrosion on the inboard end.
--- An oddity is that the bottom of the inboard pad was worn about 1/16" more than the other three points.
-- The pads are not worn out (remember for later), the wear bars that would touch the rotor are not close.
-- After cleaning and lubrication the pads slide easily, by hand, on the slides.
-- The caliper pins slide freely, by hand.
-- There is no noticeable brake fluid.
- I reassembled and road tested.

HERE IS THE RUB
- Windows up I hear little to nothing when stopping. I think I am hearing something only because I am listening for something.
- Window down, now I hear something! ... Maybe initially when I was listening with the widows down in the city, the environment was just too loud.
-- With the ABC fuse still pulled I am hearing, through the window now, the grinding shudder as I come to a stop. So I was wrong, the gravelly noise is possibly or not all related to the ABS.
-- Road test notes:
--- At speeds above 30 I hear nothing when applying the brake
--- From 20 mph down I hear increasing dragging and at the last 10 or so feet hear the gravelly/grinding sound.
---- I have had two people with some familiarity with cars ride with me and they both think the gravelly sound is the sound of metal on metal of a worn out pad on the rotor. The pads are not worn out.
--- During a deceleration over a long distance using very little brake pressure there is very little if any noise.
-- Something NEW - now I can hear a light rotation drag at slow speed driving, with the window down, ... whoosh whoosh whoosh. This stops when I tap on the brake once or a couple times.
--- This is similar, in my mind, to a seized caliper I had in another vehicle. When I stopped the caliper grabbed the rotor and when I started to drive the dragging started and would stop when I tapped the brakes several times.

WHAT NEXT
- My mind is telling me the bottom caliper piston is not retracting as much as the top.
-- BUT then the corrosion on the slide was on the inboard end not close to the rotor.
--- Can a rotor be out of alignment? As far as I can understand the wheel would move as a unit around bad bearings and it would not impact the rotor. There is no bearing noise.
- I can pull the drivers side wheel and check the feel of the caliper compression to see if it is noticeably different.
- I can pull the passenger side wheel and put a wood block over each piston one at a time and test to see if there is a noticeable difference in resistance.
- How would I test piston retraction?

THOUGHTS, COMMENTS, QUESTIONS, FUNNY STORIES?

canucklehead

How old are your rotors and when were they last turned? Ceramic brake pads can shudder and groan if they are fading out because of hot shiney surfaces. Rear brakes do the same when they get wet, like when a rear wheel cylinder or axle seal is leaking.
Rotation drag and other noises can also come from worn wheel bearings. They don't last nearly as long as the bearings that were pressed into the rotor/hub assembly. My 2013 has 165000 kms on it and the front bearings went bad. I also have had to put new front and rear rotors on as the surface was not even and looked like they were not giving the pads a consistent contact surface.
When you had yours apart, did you press the caliper pistons back as if you were installing new pads?

tbb2

See the dashed inserts above for answers.
Thanks for the feedback.

canucklehead

No problem.
I would say maybe its time for a new set of rotors and pads. If you remove your rotors, and the surface on the inside does not match the outside, replace them. I wouldnt machine them. Mine looked ok from the outside, but can't see the inside surface very much at all unless you remove the rotor. One I did the inner surface was lousy.
New pads will require you to push the piston way back, testing your thought about them being seized. It will also put the caliper into a different position further away from the rotor and on a different part of the slide pins.
On a side note, when my front bearings went they made a whirring road noise kind of sound. No grinding, and there was zero detectable movement.

Let us know what you find once you get it all apart.

StanVan

Or the rubber hoses. I didn't believe it either. I replaced the caliper and disc- no joy. I replaced the hose and no more noise.