Audii-Dudii

I'm coming from an '02 S4 and have had my '04 3.0 USP for about a month now. Lately, I'm starting to find its handling a little bit annoying in some respects. Specifically, when hitting one-wheel bumps (say, running over a manhole cover or an expansion joint), I find the back end has a tendency to kick sideways ever-so-slightly as the wheel moves up and down, something neither my B5 A4 or S4 have ever done. I also find that when driving in a spirited manner, it has a tendency to shimmy or wiggle a bit upon entering a corner before it takes a set, again something neither my B5 A4 or S4 have ever done.

A search of the archives for bumpsteer issues turned up only a single post in the B6 S4 forum that (sort of) touches on this: "Both the S4 and RS4 are plagued by an odd oscillation, gyration (call it what you want) but it is a tendency for the rear end to become light, swing around slightly, then settle. It is a non linear, three step process rather than the smooth break away of the BMW rear end under the same conditions. Otherwise the Audi holds its course with much more confidence than the rear drive BMW."

I've read that the B6 chassis' rear suspension geometry is much improved over the B5 but based upon what I'm experiencing, I'm not so convinced. (And for the record, it behaves exactly the same way whether it's the right or left rear wheel, so I've ruled out alignment issues because it's highly unlikely a misalignment would ever be symmetrical from side-to-side. Also, as the car is completely stock and has only 45k on it, I don't think this is due to worn-out parts, either, although I suppose the shocks could be approaching that point...)

Given that this is my daily-driver, I don't necessarily want to go to the trouble of plotting bumpsteer curves or computer modeling the suspension to figure out what's going on, but ignoring it is becoming increasingly more difficult for me and if somebody has already figured out an easy fix for it, I'd rather not reinvent the wheel.

Any thoughts on this or am I the only one who is experiencing and/or annoyed by it?<ul><li><a href="https://forums.audiworld.com/s4b6/msgs/396841.phtml">The B6 S4 forum post I referred to above...</a></li></ul>

bhvrdr

has been talked about by press in this respect. I noted it on the S4 much more then the A4. A cheap swaybar should rid this. YOu could even try an OEM RS4 bar for about $120.

tuneda4

when are you selling the s and getting back into an a4?

MikTip

<center><img src="http://www.hotchkis.net/images/PRODUCT/large/712.jpg"></center><p>
-<ul><li><a href="http://www.hotchkis.net">http://www.hotchkis.net</a</li></ul>

Tomasz@Startup

What you describe sounds like too stiff of a rear sway bar. So I am completely perplexed why the two recommendations below suggest you get even a stiffer one.

My guess is that the OEM sways on these cars are pretty stiff, especially with Sport Package and that is what you are feeling.

I installed our GT coilovers on the B7, and I did not experience this behavior. I am guessing, GUESSING, that the stiffer valving and stiffer rear springs actually work better with the OEM sway bar.

Link to more information about the coilovers and spring rates I was running.

P.S. Good to see you back AW.<ul><li><a href="http://startupracing.com/B6ProductsSuspension.htm">More information on coilovers</a></li></ul>

MikTip

What about the front bar? Tires? Tire pressures?

diagnosticator1

in the clamp on the wheel bearing housing/upright casting. The bump steer curve as set OE, is not optimum when the front or rear roll bar stiffness is changed from OE, without a recalibration of the bump steer setting.
Because the roll bar actively transfers compression and rebound forces/motions from one side to the other, the stiffer the roll bar is, the higher the coupling between the otherwise independent opposite sides will be. Imagine that one side is suddenly compressed, this will also tend to lift the opposite wheel off the pavement. As the chassis settles in response, the reverse behavior occurs on rebound, tending to lift the car up. Depending on the balance in the roll bar stiffness and the spring rate of the suspension springs, the combined effects can momentarily upset the directional stability of the chassis under certain situations and conditions.

derleicaman

I have noticed this on my car as well. It really came to my attention when I was riding as a passenger in my car. The tail seems to side step a fraction after going over an uneven surface, say a bump in the road only on one side or the other. I have the H-Sport S4 bars.

I never noticed this when I had the Eibach/FSD setup and the rear bar on soft setting, but only after I switched to the Vogtland CO's and set the rear bar to stiff setting. The fact that I notice this when an uneven surface or bump is encountered convinces me that this side step action is due to the sway bar.

MikTip

<center><img src="http://pictureposter.audiworld.com/6607/suspen.jpg"></center><p>...

Merkin

damn that design looks complicated, hope nothing breaks in the long run