B7 RS4 rear subframe assembly/uprights etc. for wide arch A4 Avant 2.0 tfsi build

[efy2bjg]

Hi All,


I'm almost finished with the body and brakes chapter of my wide body A4 Avant project (pics soon!). I was due to pick it up this week but the shop aren't happy with my initial plan of fitting the rs4 rear brakes with modified carriers and a spacer behind the disc.

Currently the car is running 25mm rear spacers and the rs4 wheels fit perfectly flush with the OEM RS4 rear flares. The current plan is to take off the A4 uprights/knuckles and machine these back to get the right offset on the discs/calipers. This is doable and the shop is happy to proceed.

The plan is to get a donor a4 subframe and assembly and build this/ powder coat etc. in advance and then swap it out all in one go to save getting it on the ramps for ages. These A4 assemblies are pretty cheap 2nd hand here in the UK.

This has me thinking though, could I get an rs4 rear assembly instead? And use all of this or a combination to do away with the machining plan and current wheel spacers?


Questions: Any input greatly appreciated.

- Is the B7 Rs4 diff the same ratio as a B7 2.0 tfsi quattro? and would it bolt up to the a4 propshaft? ****Update*** :-( No, I believe ratios are different, A4 35/9 https://www.jimellisaudiparts.com/pr...1R500044A.html, RS4 37/9 https://www.jimellisaudiparts.com/pr...AR500043T.html)

- Are the body mounting points the same on the rs4 rear frame/cradle as the A4? I think the rear sub frame part numbers might be the same? ****Update*** part numbers for A4 and RS4 rear subframe are the same ( 8E0505235BT https://www.jimellisaudiparts.com/pr...0505235BT.html

- If no, would the RS4 shafts bolt up to the A4 diff? The flanges look the same, not sure on width? Would the A4 diff bolt up to the RS4 frame/cradle? ***Update*** Rs4 rear 8E0501203P shafts appear to fit A4 8E0501203K https://www.jimellisaudiparts.com/pr...E0501203K.html)

- Are the RS4 shafts longer/shorter than the A4 ones? Are the splines on the hub end the same a4 and RS4? *** Update***as above RS4 shafts fit A4 diff and hubs https://www.jimellisaudiparts.com/pr...E0501203K.html

- Or in the extreme, would an RS4 gearbox/clutch fit on the 2.0 tfsi engine! etc.! **** no need for this then!!


I'm basically looking for any combination of using more RS4 rear parts that would save machining the a4 uprights/knuckles, the current use of spacers, and importantly allow me to use my perfectly reconditioned and matching (with front) powder coated RS4 rear brakes!!

As above any input greatly appreciated.

Many thanks in advance
Ben

[efy2bjg]

Some updates in the above.

So the plan is:

- Swap in RS4 rear subframe with arms, hubs etc.
- Retain A4 rear diff, mounted to (same part no.) RS4 rear subframe
- Use (assume stronger) RS4 rear driveshafts
- Fit RS4 rear brakes
- Machine wheel spacers to 10mm from 25mm

Jobs a good'un.... until I'm wrong and it doesn't fit... :-0