Rear subframe replacement

[Davemca8]

Good evening, I have just joined this forum after owning my a6 avant for 8 years. 

At the beginning of the year my MOT reviled that my rear subframe was heavily corroded so I took it upon myself to rub it down and give it a coat of paint. In doing this I knocked a fairly large hole in the right supporting arm of the subframe. Rather than give up on this car and rush to we by any car I have decided to replace the rear subframe. 
 

I found a replacement on eBay that appears to be in reasonable condition and I’d like to order replacement parts such as drop links, control arms if required and all the fasteners required. I am having difficulty finding part numbers especially for the fasteners. Are there any diagrams with part numbers available? I have found American ones but not exactly what I need. 
 

Has anyone tackled this job before ? I have a fair amount of experience working on cars but haven’t tackled anything like this. I’m worried about alignment of the subframe and haven’t worked out exactly where to start. I’d like to remove the entire subframe with all the arms, hubs, brakes etc then swap everything over on the drive before refitting. Any help would be greatly appreciated! 
 

2012 A6 avant C7 2.0tdi FWD 

[spartacus 68]

Don’t under-estimate the task at hand. Luckily this is a 2WD version, but you’re looking at 13 year old car, and everything will be seized on. Hat off to you for attempting.
 

Look at parts here: https://www.lllparts.co.uk/catalogs/audi/RDW/A6/717/5

If it were me, then absolute minimum tools would be air compressor with air hammer, axle stands, full socket set with 1/2” extension breaker bar, heat (blow-torch), plus gas penetrating fluid, impact driver, battery or power torque wrench, ceramic anti seize grease, coil spring compressors, scissor jack, 2-tonne jack, wire brush, preferable on drill attachment for exposed bolt threads. Put money on rear coil spring rubber seats. being corroded.

Given the work you’re going to, this had better not be your daily driver. Allow yourself a few days, ideally under cover. Brake lines, then flexible hoses, clamp where possible, you’ll need to bleed brakes afterwards. Suspension parts, Meyle HD or Lemforder, and only torque with full vehicle laden weight.

Prior to dropping subframe, mark position. At the end, you’re still going to need to do alignment. Also use new subframe bolts from Audi.

You will likely need VCDS for rear electro mechanical brake, or chance it just leaving handbrake off and refit pads. Put the car battery on trickle charge, during refit.

Given you’re going to hassle of replacing, then swap out rear bearings too. F.A.G., nothing else. Once done, spray everything with Lanoguard every year.

Edited 15 hours ago by spartacus 68