Hi guys,

I have a strange vibration with my '99 A6 4.2. It seems to happen between 60-75mph and when under load (i.e. accellerating or slowing down in gear) You can feel the body of the car vibrating from side to side but it doesn't vibrate through the steering wheel.

First thing I did was have the wheels balanced which made no difference, so then I took it to Audi who looked at it for a day told me a wheel was buckled. I put the spare on each corner and it made no difference so I took it back to Audi who had it for nearly 2 weeks, they said they regreased a UJ on the prop as it was tight, regreased the prop center bearings and rebuilt the rear diff as it had a problem. Their report said the vibration was 90% solved and for further action I would need a new rear diff and rear driveshafts (which cost a fortune).

I soon realised that the vibration was exactly the same as normal and all my money at Audi hadn't made any difference. I also still think (as I told Audi) that the vibration seems to be coming from the front more than the rear and so I am not confident that changing the rear diff will make any difference and will just be wasting more money. I have done a search on here but not found any similar problems so I was wondering if anyone has experienced something similar and what resolved the problem?

My guess is a front driveshaft CV joint or maybe transfer box but it is hard to test these things!

your guess is closest C/V joint/ wheel bearing/ drive shaft, C/V joint makes a crunching noise when on full lock at slow speed each way - bearing makes an annoying hum at speed - drive shaft inner C/V joint gives your symptoms

Hi Dave,

Thanks for the reply. Is there any way of telling if the inner CV joint is gone without just randomly swapping shafts? Are there any specialists in the UK that can diagnose these 4wd problems accurately?

Am presuming you checked all tires for wear? I had a similar issue, but with much greater humming noise. Turns out 3 of the 4 tires were causing the trouble, although the local 'stealership' originally proclaimed it to be a front hub. I have a fantastic alignment shop (they do nothing else) and those guys didn't try to get me in for the alignment -- instead gave good advice and my recent ebay purchase of 4 Kumho tires should be arriving shortly.

Good luck!

-=K=-