S3 Suspension and Set-up Guide
After spending an horrendous amount of money and time on my S3, I thought I'd best share what I found out before I forget it all. Personal opinions and a little experience. There's an emerging trend for cars with more show than go, if that's your thing so be it. However, if you're into big wheels and slammed suspension, then this thread isn't for you. Go wind down your tinted windows, turn up the bass, and cruise on by.
Ess_Three's testing threads and advice have been the basis for the way I set my car up (as it should for most of you). However, they are good for his style of driving, not ideal for mine. I'll also try and cover a few things his testing threads haven't.
As the cost of an S3 has lowered significantly over the last couple of years they have become more available to a wider market, and as such there's been an increase in the available tuning accessories, fashions, and styles. Whatever the latest product, the basics remain the same if you want an S3 to go round corners quickly, safely, and with predictable handling characteristics.
So, where to begin....
Shocks and Springs
This comes up on the forum quite a lot. Do I go for shocks and springs, coilovers, lowering springs on there own, etc. Most people have there own opinions and recommend what they know. Afterall, its not easy or cheap to have experience of different set-ups on the same car.
Shock absorber comression and rebound is always going to be compromised/designed to the surface your driving on. Stiffer shocks work well on nice smooth tarmac, whereas softer ones can work much better over bumps and uneven surfaces. This means you should consider the roads you drive on most when choosing your set-up. As the S3 is in its element on British backroads, something between the two extremes is needed.
Coilovers, in general, are track orientated and have firm rebound rates. Great on smooth tracks, but they let the tyres skip over bumps leading to less grip and more understeer. The 'bells and whistles' fully adjustable ones still give a tooth rattling ride, and once they're adjusted and on the car will you really be changing them again??? I can't think of anyone that does for road use. Its an expensive way of getting a car that won't handle as well as a standard suspension kit under everyday conditions. However, if you intend on doing a lot of track days, they're brilliant.
Can't afford a suspension kit and just want lowering springs? Don't! Chances are that your old suspension is knackered and not up to much. The shocks will be operating half compressed and outwith their normal tollerences. You'll end up with an ill-handling bouncey beast.
The best option then, is the shocks and springs kits. And the best of those seems to be the billy and H&R combo. The Koni FSDs are also very good once you're used to them.
Another question I see on here quite a lot is how low to drop it. Personally I'd say there isn't really a right answer but 25-35mm is the acceptable norm. Going any lower will limit the range of travel in your shocks, and even if they're designed to go lower, the ride won't be good. And you're more likely to have tyre rubbing problems.
Anti-Roll Bars (ARBs)
If you don't know what they are, I'll quote Ess_Three
"Now anyone who knows how ARBs affect a cars set up will confirm that normally, the larger the front bar, the more the understeer. And, the smaller the rear bar, the more the understeer."
So to remove cornering roll from the car without unduly affecting under/oversteer, you need a proportion increase in ARB size. Again, as we drive on UK roads, a little compliance is still needed. Putting the biggest bars you can find on there can reduce your grip levels.
Of the options I know of, Eibach have a 21mm front ARB, Neuspeed's is 22mm, and the R32 OEM ARB is 23mm. Neuspeed also have a 25mm ARB if you like hedgerows and fields. Similarly, there's options for the back aswell. Personally I'd recommend 21mm front and 19mm rear.
Uprated ARBs and standard shocks? Again, bad idea. The cornering forces build up in the bar and distribute it across both shocks. A sudden loading or unloading on an old shock is not a good thing.
There's always some sort of debate over wheel size onthis forum, and there's always going to be someone that thinks biggest is best. What you actually need out of a wheel is a combination of low weight, minimal gyroscopic effect, and spoke rigidity (you don't want the wheel to flex).
Whatever wheel size you want, you should be trying to maintain the same rolling radius - i.e. the sidewall is reduced to maintain the same overall circumference when the tyre is on.
A 17" wheel has too much tyre sidewall for a good crisp turn-in and its more likely to roll under in a high speed corner, although the small wheel diameter reduces the gyroscopic effect. The problem here is more to do with the tyre size. If the S3 wore 205/40/17s it'd be perfect.
19's are the opposite. Minimal sidewall and increased turn in, but its too much. The lack of sidewall removes any complaince from the tyre, and the increased gyroscopic effect makes it worse to turn-in than a similar weighted 17" wheel. The net effect is a tyre that wants to turn-in but a wheel that doesn't.
Obviously then 18" wheels are the ones to go for on an S3. They don't look too big, they handle well, and they're have the largest choice of tyre fitments.
Again, everyone has an opinion. Here's mine:
Wet weather specific: avoid them, this is about performance
General, all round: Goodyear Eagle F1s
General, summer use: Yokohama Parada Spec 2
Summer/track: Toyo R888 - unbelievable grip
Ignore the manual, I've tried alot and this is what I've found:
17" wheels - front 30psi, rear 32psi
18" wheels - front 32psi, rear 34psi
19" wheels - front 34psi, rear 36psi
That's all unloaded pressures. I don't let passengers in my car :)