A6 Avant Le Mans vibes

[Scott Thomson]

Hi folks,
I have a 2009 Le Mans 3.0 Tdi Automatic that likes to shake its self silly above 50mph. There is no real noise as it happens, just the vibration that covers the whole car, not only the steering wheel. Long journeys are a sickener.
The problem has been there for over a year now, new wheels/ balancing etc. not fixed the issue. The odd thing is if I overinflate the tyres slightly, it seems to help a little. If I have passengers in the car, it is murderous. Any ideas?

 

[B5NUT]

Manual or auto?

 

[Scott Thomson]

Sorry, Auto

 

[KrisKrk]

Engine mounts bushes could've give way and passing all vibrations onto the chassis.

Higher speed = higher revs and harder engine work. Hence vibrations would be stronger

 

[Steveredman]

Could also be a CV joint problem, I had similar symptoms with my B6 A4, new CV joints and driveshafts cleared the vibration completely.


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[Scott Thomson]

Thanks folks, last night i tried knocking the car into neutral at speeds high enough for the vibration to be noticeable. Even revving the engine hard did not make any difference to the level of vibration so I feel that the engine mounts are not the issue. Any advice on how to pinpoint the CV joint, other than blind replacement?

 

[Steveredman]

Thanks folks, last night i tried knocking the car into neutral at speeds high enough for the vibration to be noticeable. Even revving the engine hard did not make any difference to the level of vibration so I feel that the engine mounts are not the issue. Any advice on how to pinpoint the CV joint, other than blind replacement?

Unfortunately I haven't got anything, I'd had several garages take a look and they had all pointed at the gearbox. It was the gearbox specialist who pointed at the CV joints, at least 2 were knackered (on a car that had 4, I would assume your car has 8 (4WD?)).

In the end I replaced both driveshafts and all 4 joints, saying goodbye to the perpetual vibration made it worth every penny!


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[Scott Thomson]

Thanks Steve, yes mine will have 8. I am very wary of just chucking money at the car in blind hope. Reading now that rear diff mounts can cause it, it seems to only be noticeable in 6th gear but shifting down doesn't clear it. Tyres are new and matched. It is also not uniform. Last night it was terrible but on the same road this morning, much less.
Wife wants rid. I do not but can't justify keeping it if it keeps up with the teeth rattling

 

[D T]

What tyres are you running (Pirelli by any chance?) and did the problem first show up after they were replaced (I note you say they are relatively new)?