S6 brake fitment issue

[Kaclaytor]

I recently bought an 08 s6 with 183k miles. Car was not drivable when I bought it. The front brakes are locked up, but not in a normal way. The brand new rotors from fcp euro are dragging on the caliper brackets. I have tried different rotors, and different caliper brackets. No changes. I currently have the brackets modified so I could take the car for a test drive, but would really like to get the issue resolved. Has anybody else ran into a similar issue? I’m not sure if the hubs were replaced at some point or the knuckles. But those are the only other parts that I can see causing brake rotor offset issues. This was an unplanned purchase, I recently sold my single turbo c5 allroad, and found this car being parted out so I made an offer on the entire car.

[10Banger]

Firstly, congrats on the car!
Why were they parting it? Maybe the PO tried his hand at wheel bearings when doing the brakes and didnt get them seated entirely? Take a look and see if any of the splines on your CVs are visible inside the hubs. Maybe a photo or two would help us understand a little more.

[Kaclaytor]

Thank you. I am not sure the actual reason the car was being parted out. I was told the head gasket was suspected to be blown. Hood latch cable was broken and I was not able to open the hood at the time of purchase so I couldn’t confirm anything about the engine other than it ran and sounded good. Brakes were dragging so bad the car would almost not move, he said the e-brake was locked up. I had no reason to believe otherwise as a new one was included ( I think he was under the impression that was true). So I didn’t think much of the issue. After getting it home and on the lift things are not adding up, engine is healthy with no signs of any issues. Front suspension is all new, and I think the brake caliper issue was what caused him to want to part the car out. I am guessing the owner was a little out of his elements with the car. The wheel hubs are seated tight to the knuckle. I have tried confirming hub part numbers, but Audi wasn’t much help in confirming if my part number was correct. Doesn’t match the new part number from Audi but that doesn’t mean it wasn’t the correct part number 15 years ago.

[Kaclaytor]

Can anybody confirm this knuckle part number.

[audis6]

What i find in local shop, same part with number 4F0 257 is same as 4F0407241J 4F0407253H and it fit on

Check your disc size

[audis6]

Any findings where is problem?

[Kaclaytor]

Not a positive diagnosis, but I am leaning toward hub assemblies. I am trying to find somebody doing a part out who will sell me complete hub assemblies.

[RRussell]

08 s6

Drivers

Passengers

[Kaclaytor]

Issue is resolved. Wheel hub was from an a6. I’m not sure how this setup was working in the past unless the car has a6 front brakes as well.

[desertrock]

Definitely pretty interesting, but glad that you solved it. You mentioned the rotors were new, so maybe they took the old hubs&rotors from an a6?

[Kaclaytor]

Im guessing that the car had a6 brakes on it and the previous owner swapped to proper s6 brakes and didn’t realize the hubs were different and couldn’t figure out what was wrong.

[desertrock]

This made me think. On my S6 the left rear wheel sticks out further than on the right by about a centimeter, causing an issue with wheel fitment. There’s also no obvious culprit, and it’s more of a cosmetic annoyance than an actual problem.

But.

Could it be that some part has been replaced in the past with an A6 part in my case too? It’s also possible that the fender has been worked on.

[RRussell]

I would just check part numbers, sounds almost like incorrect axle length. Maybe from a similar model with different differential.

[Kaclaytor]

Possibly, but I actually think that is an s6 thing. My car is the same way, which i didn’t notice until a put spacers on.

[Dlugi11]

More likely the subframe is not centered, but shifted to the side where the wheel is further out.

[desertrock]

Good tip. Need to check that out. Seems more than likely it’s the subframe.

[audis6]

Copy Paste from From;
How to align rear subframe

Sub frame Alignment NotesWith the exception of springs and shocks, the A6 suspension components are wholly attached/contained by the sub frame. The rear suspension allows for camber and toe to be set. As shown in the sub frame drawing, the bolt holes in the sub frame bushings are oblong. The drawing also shows the dimensions along with clearances. Thus a bolt centered in the bushing hole will have 4.5mm clearance on each side and 3mm clearance front and back.

Alignment Discussion
Lateral axis movement sets the rear end tracking left or right in relation to the body. This affects “crabbing”, i.e., where the rear end track is offset from the front end. In the 2009 A6, the lateral offset can range from +/- 4.5mm.

Longitudinal axis movement sets the rear end placement forward or backward in relation to the body. This is less impactful to the overall alignment, affecting driveshaft strain and to a lesser degree, wheelbase. In the 2009 A6, the longitudinal offset can range from +/- 3mm.

Rotational movement affects tracking as well as the amount of adjustment needed to achieve the desired toe spec. A clockwise rotation will require higher inputs on the driver side and lower inputs on the passenger side to achieve a given toe-out. A counter-clockwise rotation will be the opposite

How to align front subframe

[10Banger]

In case you need more parts, I still have the entire rear end of my S6.

[Kaclaytor]

I think I am down to cosmetic things for now. I will let you know if I end up needing anything else. Waiting on a replacement front wheel bearing currently. One was shot, and for some reason a replacement is a month out.