Wheel/Suspension Setup

[ZeroK66]

Hi Guys,

Having been driving a new RS4 the last few days, it has become shockingly apparent at just how appauling my S4 handles... bump steer, fighting steering under braking etc

Current setup:

Bilstein PSS9s Coilovers (Shocks set to stiffness 6 out of 9)
H&R "fatboy" ARB's set to stiff both front and rear
BBS CH 19" 8" et50 w/ 15mm spacers = et35 with eagle F1 tyres all round at approx 36psi front and rear

On a bumpy B-Road even slowly the car is a handful, energency braking on an en-even road surface is just a nightmare. I am probably exaggerating what it is like, but having driven such a crisp and sorted car like the B7 RS4 I realise what I am missing. I know the S4 would never be as good... but I am sure I am missing something!! Surely this cant be acceptable?

Since fitting the PSS9s replacing my H&R coilover kit that had burst shocks the handling has obviously been massively improved, but I still am suffering with poor A/B road performance. Even acceleration has not exactly been in a straight line.

The PSS9s feel as though they are set a little too soft and I feel like the car floats about a little too much. The obvious thought is to set the shocks firmer... which most with the PSS9 kit have done, but then I can only imagine performance on bumpy roads being even worse.

The point of all of this is:

A: Anyone fancy letting me drive their "sorted" S4 to see how it handles a bumpy b-road?
B: Anyone know of any suspension/handling companies that would take your car in and work on the setup to get the best out of it?
C: Any suggestions on what to try?

Anyone heard of corner weighting a car with coilovers?

Going to do a post in the RS4 B7 forum about my thoughts of the car. My dream come true would be a B7 chassis with a 2.7T - I am going to start investigating this... then again if the new B8?? S4 is going to be a 3.0 TFSI twin turbo... maybe I should be patient?

[S4]

its hard to say, some might agree... some not. .. I would like to bet the 18" rims and 40 series tyres make it much better. going up 2 sizes can do that, and having it sit really low on 19"s.

I know you have most prob had 18" on before, worth a try.

I agree with B big time, setting it up proper is not easy. people have 4 wheel alignment and don’t know how to get the best out of it.... look at some of the tyre places.


Darren

[ZeroK66]

Certainly the first few things I am going to try is

A: Soften the ARB's
B: Raise the suspension
C: Change the wheels and tyres...

I just wish I could do this in a controlled environment at the same time -mix and match so I could find the best balance rather than trying different things weeks apart. Does anyone know of a company that may be able to help with the setup?

My alignment was done by Auto PS who work on these regularly and the results came back wtih everything just about spot on... so I am confient it is setup pretty well. Would love to chat to guys who have changed their setup outside of factory settings and find out what their setups are now...

[mikeyquattro]

I'd look at softening your dampers too

[ZeroK66]

Anyone had corner weighting done? I want to have this done at the same time as raising the suspension...

[tdiquattro]

Didn't Viper give some figures for corner weights in another post?, I would like to get mine done too. I have been reading up on suspension settings as well, this is quite interesting but more race specific, still gives some good theory...

http://www.optimumg.com/techtips_techtips.htm

In my other thread the HRs are listed as 450lbs fr / 450 rear, not sure if that is accurate info.

[Doug_S2]

I drove your car before on the shot H&Rs and it was really bad. I have not driven it fast on the new setup. I cannot complain about my setup and i have driven the B7 RS4 on the A361 (past your brothers house) and my car is a lot better handling (and a lot faster!) We can drive each other back to back if you want.

[ZeroK66]

That would be good... I should get my car back pretty soon. Something deffo not right. I remember when you took me for a spin in yours it felt so well planted and "safe"... I always assumed the new suspension would sort that. It was a vast improvement, but now I have something to compare against I know my car is not right. I will give you a shout at some point and arrange something for when I next come up. I need the exhaust silenced a little too... so if we fitted it all in that would be good. You know anyone that can do corner weighting?

[MCB]

I always assumed the new suspension would sort that.

Is that just the spring and dampers or did you fit control arms or new bushes? Could you have worn bushes?

Sounds like the car maybe suffering from bump steer?

[ZeroK66]

I have got the whole lot done...

Doug replaced the suspension arms, bushes, anything related I believe was changed. Deffo suffer with bump steer very badly on slow bumpy roads.

I think the ARB's are set too stiff for the suspension setup. I could probably do wtih having both set to medium.

Thing is I feel the car leans too much as it is - like the shocks are too soft... so its all very complex to find that right balance!! Lord help me!

[Prawn]

Sorry only just seen this as I dont frequent here very often these days.

To be honest I do not have any records left from the car so will be commenting from memory.
I always found the damping on the Bilstein stuff to be pretty poor especially when stiffened up, it did not give any progression to the damping and always felt 'crashy' over bumpes and 'vague' over undulations IMO.
If you run too low at the front you will get bump steer I seem to remember it was 25.5" wheelarch to floor (will be on one of my old posts), you cannot get away from this as its inherant in the Audis geometry, unless you shim the steering rack, or bend the steering arms.
I ended up junking the PS9 kit and going to Stasis and this did cure all of the issues but was an expensive option.
You could play around with spring rates but you would need to adjust the valving of the PS9's to make it work, on my Stasis setup I was running 650Fr/750R springs and it was spot on butthats with very good valving in the dampers.
For the ARB's I ran soft front and stiff rear - I think, changing these does have a fair effect on the overall handling.

So overall, probably not much help - sorry.

Thank god I have only got the radical to set up now, much simpler.

[DavidT]

I've no experience of PS9's or the Stasis stuff but I agree that running the car too low will have a big effect on the handling. As prawn says, there are lots of posts about how low to run, the S4 is 30mm below standard from memory.

I would say set the front ARB to soft (both ARB's only have 2 settings) and that will make a big difference to the way the front end 'sits' on b roads. I'm in the minority but found my car (with the H&R coilovers & their big ARB's) undriveable on b roads, too bouncy & severe understeer on tracks.

The big wheels won't help, its a good idea to try some 18's if you can on 40 series rubber.

Good luck, let us know how you get on.

[Matt_H]

B: Anyone know of any suspension/handling companies that would take your car in and work on the setup to get the best out of it?

The guy that runs this:

http://www.wheels-inmotion.co.uk/

knows his stuff, he did a 4 wheel alignment on my car but I think his main bag is setting road cars up for the track. Try having a look at his forum, its virtually entirely dedicated to suspension chit chat so you may be able to get some more technical advice from there. Its probably too far from you, he's relocating to Amersham in Bucks, but it may be of help, you never know

Matt

[ZeroK66]

Thanks Matt, thanks David...

David, do you remember your suspension height? I seem to recall a million years ago seeing a post you made with height at the front and rear?

As I have the larger rear ARB would it not be wise to set this to the softer setting? This would probably = the stiff setting on the smaller H&R ARB.

I have had the car back about 2-3 weeks now and I find the bump steer is only particularly bad at low speeds. The car is really bumpy on rough bits of road - to the point where you end up causing the car to kangaroo because you cant keep your right foot still and end up tapping the throttle... very funny.

When I am next up to see Doug I shall deffo get a few things changed as suggested here. I will keep you posted.

[S4TAN]

Kept scraping my link pipes on speedbumps causing the exhaust to leak, so just had my car raised by 4mm all round on the coilovers - 4mm may not sound much but has made a big difference to the ride (believe it or not) - less "crashy", more comfortable, and no more exhaust scraping!