ajg617

At the point of wear on the inside of the rim, there is a chamfer where it sits immediately outside of the raised part of the raised hub surrounding the axle bolt. There are no wear marks on the rotor inside of the lug holes and I can't see any wear marks on the raised hub - but then again, it's steel not aluminum. That's what is so darn confusing. If the wheel is bolted firmly to the hub and securely sandwiching the rotor, the area of wear on the rim can't be rubbing against any other part since they all turn as one unit when properly bolted together. And it is now happening on rim number 2 having already worn down rim number 1 to a point that the metal-to-metal noise I was getting went away. I added a picture of the area where the shards are coming from - inside the red circle.

SloopJohnB@mac.com

and not on the hub of the wheel where it mounts to the axle.

Try this: Get some Prussian blue machinist's marker dye (Dykem, marking blue, layout dye) or a marker pen. You can also use PVC prep solvent…it's basically dye in a PVC etcher.

Degrease/clean the areas on the wheel hub and the car axle hub where the shavings come from and you think the axle is rubbing.

Use the dye or marker (Sharpy also works well) pen on those areas, let it dry for a few minutes and then put everything back together. Go for a SHORT drive and disassemble and examine the areas you hit with the Prussian blue or the sharpy.

It should show you exactly where it's wearing on the aluminum hub and the axle.

CRuby

This location of the wheel is supposed to seat on the wheel hub, & sandwich the rotor axially between the wheel & the hub.
If you see wear marks on that center portion of your wheel, then obviously there is unintended motion between 2 parts.

Starting at t=4:30 of link shows the mating hub surface. This is the other half of that wear surface.

You mentioned about your brake pads: "noticed that it was much more worn towards the outer portion of the rotor - so much so that the pad surface closest to the hub was making contact and the outer was about 1/16 away from the rotor surface. You could see the angular wear."

Sounds as though your caliper &/or rotor are not seated properly to the hub.
I suggest removing rotor & double checking all this surface.

N_Jay

Are you using factory lugs?

Could your lugs be bottoming, leaving the wheel just a tad loose?

Just Me

Whaaaat? That doesn't move relative to ANYTHING that can touch it. Its flush aginst the hub face (or rotor i guess).

Kris Hansen

Shoot some photos.. What you describe is not making sense.

ajg617

Yup, it sure doesn't. Two photos below from today. Keep in mind that this shot is from the former rear rim which Audi switched to the LF yesterday morning. On the rim taken off LF (now on LR), the entire beveled edge where I've circled some rotational scrapes was bright shiny aluminum with rotational gouges the entire circumference. So this has only been on one day and 100 miles. The circle inside of the rim near the back of the center cap were aluminum shards. The bigger 'vertical' marks on the bottom are likely from rubbing during mounting.

The second picture is of the LF hub. When I took the original wheel off last weekend, there were bright aluminum shards everywhere, both inside and outside of the raised area of the hub surrounding the axle bolt - those around the axle bolt were stuck to axle grease. There are still some shards which I've circled, but most have either fallen off or were cleaned off by the Audi tech yesterday.

Regarding my perception of brake pad wear being uneven, the tech reminded me that the edges of the pads are beveled and that's what I was seeing - not uneven wear.

Just two other notes - the rubbing noise gets much worse when the brakes are hot, whether driving on highway or stop and go. Also there is no noise at all when driving in wet conditions.

And yes, this whole thing makes no sense at all. What is happening, should be able to happen unless the lugs are loose which they haven't been.

ajg617

Original factory wheels and lugs.

Kris Hansen

The second shot is odd looking - can you get a shot a bit zoomed out? In that photo, is the brake rotor not sitting on the hub correctly for real? I can not think of a single reason for anything to be rubbing there, none of the pieces in that area shoudl be able to move against each other if things are tight. Check the axle bolt, make sure the brake rotor sits correctly on the hub..

ajg617

Wow, I just noticed what you were talking about! These pics were taken at the same time this morning at Tire Warehouse (nail in the LF tire). I'm not sure if it is the angle at which I took the picture or if the rotor moved out a bit when the guy was changing the tire (shouldn't have with the caliper holding it on) but it sure seems like the rotor is not set right on the hub. But this definitely doesn't look right. Wheel coming off again tomorrow! Maybe that would explain the brake pulsation too....I can't believe I would miss that. Factory Audi rotor.