C5 RS6 01E 6-Speed Vibration/Axle Questions

[LarsMA]

Hello,

I have a 2003 C5 RS6 with a manual swap 01E. Currently at 100k miles, swap was done by previous owner about 5k miles ago. Started to notice vibration under load typically between 2-3k RPM usually in higher gears like 4th, 5th, 6th. Never noticeable in lower gears at any speed or RPM. Saw another post where people seemed to indicate it's common for front axle inner CVs to cause this issue. We already replaced rear diff bushing, checked transmission and motor mounts, replaced center bearing and bushing and it didn't help.

We pulled the axles recently and can't seem to locate ones that match the flange. Seems to me someone may have modified the flange on the axles that are currently installed.

Any help with what the correct axles are here? What the part numbers are and where to source?
Any other advice on diagnostics would be appreciated too.

Cheers,
Lars

[Shoppinit]

Could also be a fuelling or coil pack problem causing a misfire under load. Who knows what’s been done to the ecu so you might not get any codes. You could check for loose plugs.

Just as likely it’s an inner cv joint, as you say. So your problem is identifying the part number for it given you don’t know what the donor car was?

[rs4wagon]

what colour is it?avus or the wrapped purple one?Avus used 2.5 tdi as i supplied clutch and flywheel,as far i remeber its dqt box.I used 2.5 inner and 1.8t outer

[asgor]

For what is worth, I was able to correct a pesky vibration in the steering wheel between 40-50mph by replacing the upper control arms. Had new tires installed, road-force balanced twice and the vibration still persisted. I was due for new control arms because they were making horrible noises and to my surprise the vibration was gone after replacing them.