Thought I would post something considering the enormous amount of research and effort I had to do to repair my front differential. I have a 2014 VW Touareg V6 3.0, I started to hear a grinding sound coming from from drivetrain, considering I've had my car serviced by the VW dealership since new I took back to them with the problem in hope they had a resolution. Turns out they are pretty clueless to these types of situations and quoted me a new diff for $11k. I acknowledged their incompetence and proceeded with option two: rebuild my own diff.
My friend has a workshop with all the tools and equipment I could ask for so we raised the car on the 2 post hoist and lowered the subframe to remove the diff, simple task, just need to be remove the bolts that secure the steering arm pipes when lowering as it puts strain on this. Also check out some of the YouTube clips for removing, it's well documented.
We had the diff out within a few hours and drained the oil. The oil was full of metal shavings which had us concerned about the condition. Once we removed the bolts we were careful to ensure the shims and outer bearings were still in the case, the shims were very important as they needed to go back in the same side.
The carrier bearings looked in good condition, same with the needle bearing on the shaft output. We proceeded with removing the shaft input nut (which was extremely difficult to remove with lock tight on, we had to put a small amount of heat to soften the lock tight while turning). We removed the two pinion bearings which are deep groove ball bearings, the back pinion bearing if I could describe it had delaminated bearings and the outer race was pitted on one edge. I suspect it was low on oil after the VW dealership did this service 2 years ago.
Buying parts for this rebuild was also difficult, VW don't sell internal parts as it's a ZF differential, seems impossible to get information so please take this as information only from my aspect it's better to understand what your in for than hearing the price tag on a new diff.
Diff part # OBM409505T(ratio 3.27)
Part numbers below:
Carrier bearings x 2 - KOYO LM300811
Carrier seals x 2 - ZF 0734 319 681
Pinion/input shaft seal x 1 - ZF 0734 300 235 or 0AA409189B
Oil deflector 0AA409375E
Front pinion bearing ***- F-563575.SKL-H92 or 0735 300 584
Back pinion bearing *** - F-236120.03.SKL-H92 or 0735 300 530
Putting it back together was surprisingly easier than expected. Managed to get some engineers blue to ensure the diff was central, this diff had only done 140k so the markings were spot on.
We reused the crush sleeve and added a small shim to get the preload back within spec. We also changed out all bearings and seals as a precaution including the needle bearing.
I hope this helps!