Metal on metal scraping noise

[andrew96]

Hey fellow Audiziners,

So recently I've started to hear a loud metal on metal scraping noise coming from my passenger side rear wheel. I looked it up in my Haynes manual and it said brake pads. Well I just replaced the brake pads and my rotors look fine, no scoring what so ever. At first I thought it may have been the dust shield rubbing on the rotor but after pulling it apart I found it wasn't that. So I replaced brake pads. Still getting the same noise. It happens if I go above 3 or 4 mph and has no correlation with braking, accelerating and turning. So I'm thinking of two different things... Either a warped rotor or a bad cv axle. My rotor at a glance looks fine.. But how can I make sure it's not warped? My cv axle also seems fine.. No play or torn boots. I took off the boot and there's plenty of grease and no dirt or anything inside that shouldn't be... I'm at a cross road. Any advice would be great before I drop more money! Thanks!

[redline380]

Sure it isn't the shield? Stick your fingers through the wheel and cram it in farther.

[Let it snow]

Did you jack up the car and give the wheel a spin? Also check for play in the wheel bearing.

[CyberPMG]

Jack the rear of the car up and see if you can move the rear wheel back and forth from side to side (do not loosen the bolts). If the wheel wiggles, then the wheel bearing is in need of replacement.

Spin the rear wheel to see if you can hear the noise. You can check the rear brake dust shield to make sure it's not in contact with anything. Also check to make sure the emergency brake is fully release and not binding (usually cable is sticking and won't fully release).

[andrew96]

Definitely not the shield. Spent a lot of time with the shield making sure it wasn't scraping. I did spin the wheel and could hear the scraping. Looked under while a friend spun it and couldn't see anything scraping. How do I check for play in the whee bearing ?

[redline380]

How do I check for play in the whee bearing ?

Jack the car up and grab the wheel on the top and bottom. Shake. If they is play it is the bearing. If there is side to side play, if is a tie rod.

[ECS Tuning-Audi]

With new pads its very possible to hear some slight scraping until the pads bed in. Doesn't sound like you have performed a bed-in process so I would attempt that first. On a road with low traffic get up to speed and give 3 hard stop from about 60-5 in a row. Drive for 1-2 minutes after that and allow the brake temps to stabilize. Repeat this once more. Do not come to a complete stop until the brakes have cooled a bit. See if you still notice the noise.

Jason

[MacFady]

+1 to above, do a proper bed in on your old rotors and see what happens after. If there is an uneven distribution of pad material on your rotor now then you might hear scraping. Is the scraping rhythmic with your speed or is it constant? When you spun the wheel by hand was the sound rhythmic? Just a note if you haven't bed in brakes before that there will be a smell and likely some smoke, just don't come to a complete stop until things have cooled down after the bed in. I usually increase the top speed between each consecutive near stop.

[andrew96]

I'll try bedding them in later. What confuses me is that I had the same noise with my old pads. I had driven them to the end of their life and had that sound towards the last 30 miles or so. once I replaced the pads it was the same noise. I haven't really driven it on the new pads yet because I didn't want to mess anything up too bad until i had a good idea of whats going on... I'll work on bedding them in. the sound is consistent. no correlation between accelerating, turning or braking. As soon as the car is moving I can hear it but it ONLY comes from the right rear, not both sides. Considering its only the right side, you think the pads could still be the culprit? thanks for all the input!!

[ECS Tuning-Audi]

Could be possible. But there's only so many areas that could produce a constant sound. Pads on rotors, Dust shield scraping rotor, or possibly a wheel bearing.

Jason

[MacFady]

In regards to the wheel bearing, more diagnostic (in my experience anyway) than the rocking of the wheel by hand is to find a parking lot or stretch of road where you can safely do road slalom test, just swerve the car back and forth in long sweeps and see if the sound changes when there is increased load on the rear right, when turning left in your case.

I don't think the pads are the culprit, the fact it was there before and after changing them sort of rules that out IMO, but it doesn't mean it's not an issue with some other part of the brake system/hardware.

[andrew96]

Sounds like I got a few things to check. I've never had any wheel bearing issues but I always thought it was more of a rumble sound. I'll check though.

What are the all the components that could be making this noise? Warped/scored rotors, pads, cv axle, wheel bearings, center diff bearing, dust shield? Anything else I'm missing that I should check?

[imnuts]

Could you have a seized caliper, causing the pad to constantly rub?

Sent from my DROID Turbo 2

[Let it snow]

Also make sure your exhaust is not making contact with your center driveshaft.

[andrew96]

I've got an interesting update.. I jacked the car up today and checked both left and right side rear. Remember that my right side is having the problem. So with the wheels on....on the left I can spin the wheel easily but right side it's real tough. With the wheels off... I can rotate the left side rotor easily and the hub and cv axle rotates with it. Brake caliper seems fine since it spun freely. On the right side... I can spin the rotor but the cv axle and hub will not spin with it. Brake caliper seems fine since the rotor will spin. I can not hear the noise while spinning only the rotor but can hear it when spinning the whole assembly with the wheel on. The cv axle has no up and down play so the joint seems fine but I can move it about 1/8th of an inch in and out. From my understanding that's normal. Both left and right side cv axle does this. I checked for wheel bearing play and couldn't get any so that seems fine... With all this being said it would make sense to me that the wheel bearing is totally shot... Maybe some of the ball bearings inside it busted out causing the sound... But then again there's no play in the bearing.

[ECS Tuning-Audi]

If you can't spin the whole wheel/axle assembly with the wheel on on one side or it's tough you definitely have an issue with a wheel bearing. Both sides should spin freely.

Jason

[MacFady]

S... I always thought it was more of a rumble sound

I've had bad wheel bearings make a variety of sounds, from rumbling like you say, to a loud howling sound, to a high pitched squealing sound.

I'll note that from your latest description, with the wheel off you shouldn't be able to freely spin your rotor on your hub, there is a screw that usually partially connects the disc to the hub. With the wheel on I don't see how it would matter though.

[andrew96]

I'll note that from your latest description, with the wheel off you shouldn't be able to freely spin your rotor on your hub, there is a screw that usually partially connects the disc to the hub. With the wheel on I don't see how it would matter though.[/QUOTE]

I bought the car used and for some reason it never had those screws. I have noticed the hole in the rotor for said screw. Seems like I need new bearings at least. I'll order them tomorrow. Thanks for all the input!!