Hello
I am looking for a little info on my problem. My '98 a4 quattro manual v6 (125,000 km.)has a vibration-surging under an acceleration load equivelant to an 8% grade, it is not affected by turning. This occurs downhill, flat or uphill as long as the load is on the drivetrain. This occursafter about 6 km. of driving(warmed up).It feels like it shakes the rear of the car but may be just showing up there. I havedisassembled almost every piece from the rear to the front of the drivetrain. The outer cv's have no play andare smooth through their motion.All cv's Ihave disassembled have just had a light polishing on the contact sufaces.I switched both front and rear shafts side to side. I rebuilt the propshaft with a runout of 0.003. No change. The final drive has been inspected and is fine. No Audi techs I have talked to have been able to give me any direction after I have given them my info. My friend who services the audis here put his laptop on the car while we drove and reproduced the problem. There was no problem with the engine(misfires etc.). I am now at the transaxle and clutch which are out and so far I see no problem although I still have to take these parts to a tech to be inspected. This problem is severe enough to breakdown the oil film in the centre dif. and destroy it (expensive). Oil levels were all fine. I think I have mentioned everything. A few beers for one who can solve this one. Thanks, Brian.

Finally a solution. I had to drink by myself. A previous owner (moron) had replaced the final drive sometime in the past and I was the one who had the problem surface. They replaced the final drive with a DAK (37/9-4.11 ratio)when the car required a DAJ (35/9-3.89 ratio) to be compatible with the front dif.(3.89 ratio)This spun the torsen which it is not designed for and wore it out prematurely. I happened to discover the discrepency while looking (for anything as I was at my wits end) through the Bentley manual. The DAK belongs with the automatics. I found a used final drive, replaced it and voila, the car seems to be okay. Why the old final drive was vibrating I do not know yet as the oil was coming out clean, twice. But at this point I do not care , my car is back, so I think I will have another one. Enjoy, B.