Hi all, 

I'm new here and hope thet I've posted this in the right place. I've got an A5 S line Cabriolet 2.0 tdi B8 2010. Recently, once the engine is warm, the car starts vibrating at over 50mph. I thought it might be a tyre or balancing problem. I replaced one of the front tyres as it had a ridge in it and got all of the wheels balanced. I thought the problem had gone, but have now realised thet it only does this once the engine is up to temperature. Its quite a severe vibration and under braking too, as I said this only happens at over 45-50mph. Has anyone experienced this before or does anyone have any idea of what it is likely to be? 

 

Welcome Josh,

If everything with the steering and wheel balance is correct, consider engine mountings. 
Having said that, the …’ under braking too…’ may point to sticking calipers or other brake issues. 
Kind regards,

Gareth. 
p.s. should have asked:- does this issue also occur when the the car is stationary and the engine revs. held steady above idling? 

Hi Gareth,

Thanks for your suggestion, I'm gonna have to get it booked in and looked at. To answer your question, everything is fine at idle, sits at about 900rpm quite smoothly. Would engine mounts only happen once the engine is warm though? 

Thanks Josh,

Wasn’t really talking about it being stationary at idle revs., but if you get the car up to its operating temperature and then rev it to say around 2.5K revs. while stationary, does it vibrate under those conditions? 

Ah, good suggestion, I'll see if I have time over the weekend to try it out, got a busy one, friends kids birthdays and all that 🙄 I'll let you know what happens when I get round to it.