corporeal

I've recently bought an A8 4.2 tdi (2006). At both town and motorway speeds, when the car goes over a pot hole or uneven ground, I am sensing a degree of rear wheel steer. It feels like there is some amount of give (horizontally) in the sideways direction.
Just wondering if anyone else has experienced this and how did you fix it. I know the suspension has a complex set of links and bushes, so my guess is one or more of these need replacing. It would be good to know (may be on a diagram) which bits need to be replaced.

mishar

Start with the four wheel alignment. If the rear wheels have extensive toe angle wheels are pushing to the opposite sides and the moment one loose traction a bit the other pushes the rear end sideways. That will also ware your tires prematurely.

corporeal

Thanks Mishar, I hadn't consider a four wheel alignment might be a fix. But from your explanation it sounds like a good place to start.

The all the tyres need replacing soon, so can the wheel alignment be done now or is it better to do the wheel alignment after the new tyres are on?

mishar

It wont hurt if you do it right now. It should be definitely done when the new tires are on.

krazzz

Even if the alignment doesn't fix it a good shop would notice other problems with your suspension and may be able to pinpoint it for you.

snapdragon

Mine does this too, but it's on my job list below front lower arms.
At the back there are tiny anti-roll bar links, track control arms, a large forged control arms.
There are also 2 bushes on each 'wishbone' and 4 big bushes on the rear subframe.

MP4.2+6.0

As Mishar says, start w/ alignment. But then you note it needs tires too, and to me I could think of either as likely contributors to your issues. Add to it some of the posts noting the alignment shop should also take a close look for wear items. As many of us know, the front upper control arms are a "when" not "if" to replace, and you won't want to spend money on an alignment where a worn part is throwing it off all by itself.

corporeal

Thanks for the feedback from all.

I'm in greater Manchester (UK), and I wanted to know if anyone knows of a good local independent Audi specialist and 4 wheel alignment kit. I don't really want to take it to a main dealer, unless they can provide a competitive quote.

03_AR_CO

By all means find an independent alignment specialist that has some experience with Audi suspensions. I took mine to the dealer, local to me, and they advised that the toe on my rear wheels was way out and the eccentric bolts were frozen and could not be adjusted. Went on to say I needed $800.00 worth of rear suspension parts replaced. 2 weeks later I stopped at a local alignment shop and never mentioned a word about frozen parts,and patiently waited for them to say something. The alignment mechanic test drove the car before and after, and when he parked the car for me after completing the alignment, he got out of the drivers seat smiling and said "that's the nicest car that has been in this shop in very long time". I got a before and after read out, and he had been able to get everything right without replacing $800.00 in additional parts.

corporeal

Thought I would post a concluding comment.

I have replaced the tyres and then took it for a 4 wheel geometric alignment. It wasn't a surprise when the garage told me the rear alignment was way out.

On the same day I was travelling from Manchester to Portsmouth, a distance of around 250 miles. Whilst, the rear ends 'skip' feeling over pot holes had disappeared, the car had developed a new bad trait in its handling at motorway speeds - the car needed continuous inputs to keep it heading in a straigh line. Obviously at this point, I was cursing Audi's decision to design in a complex suspension into this high end car.

But gradually the car got better, after about 200 miles, the suspension seemed to settle down. I put this down to garage having to make such a large adjustment. So this must have moved the suspension into a position that had never been used. So the bushes and tie ends needed some time to bed in. Hopefully this means it will get even better with more miles.

Thanks to all you folks for the helpful advice.

Ps, in the Manchester area there is a small chain of accident repair shops called Northern Accident, they are able to do 4 wheel geometric alignment checks.