Robofc

Just bought an RS America with h&r red springs. Took it to an autocross and it understeered like a pig. On its 11 year old PS2 tires the grip is poor and even undrsteeree badly in tight Marin corners.

My shop put on a 24mm adjustable rear sway bar in place of the 20mm stock mo30 rear with 22mm bar up front.

It eliminated most of the low speed understeer but is now too harsh for the back roads.

Why does the euro RS have bigger front 24mm swaybar with smaller 18mm adjustable rear. That would induce much more understeer than even stock RS America, all things being equal. But they are not equal as the Euro RS has much (double) stiffer rear spring rates. Is this why it doesn't have more understeer.

Anyway: if 22mm front with 24mm rear Swaybars feels great in tight corners (very neutral), can I create the same undesteer/oversteer balance with stock 20mm bar by increasing front camber (only -1.2 now) and putting 224/45/17 on the front vs stock 205s?

sml

fix your 11yr old tyres first.
then test.
then get back to us.

KaiB

Agreed, without tires and a somewhat fresher suspension, one would have no way of knowing how steady-state handling really is.

Remember, yer anti-roll bars influence steady-state handling more than they do transitional handling - a function of springs/dampers and tires.

Vandit

11yo tires, wow. That's a safety hazard! Get some Hankook RS3s and yea, upsize the front to 225/45.

Robofc

The old tires just allow me to feel how on the limit handling feels at a lower limit. It should not effect the understeer/oversteer balance, which is my question.

Why is the RS bar 18mm and the RS America bar 20mm? Is it because the double spring rates for the euro RS make the rear suspension harder and thus have more oversteer? Which is the best sway bar for neutral handling?

carnumber6

in a quick answer yes the euro RS has way different spring rates than either the M030 or the HR red springs. somewhere online is a chart showing the difference in spring rates for all the different springs available for the 964. try newer tires with the larger front tires and you will see a big difference. also check all of your suspension bushings, mine were shot and badly in need of replacement.

sml

understand your point but disagree.

i think the difference in the grip levels are sufficiently significant such that it is not a valid reference point .. maybe a mini-reference point, but i wouldn't be spending money or time based on the results .. i would say 'that's interesting' and move on.

kinda like setting-up Kai's Claudia's on an ice-skating rink .. dont think it would work very well .. an extreme example, but i'm sure you get my point.

boxsey911

I think if you took a Euro RS to an autocross you would see pretty much the same thing regarding bad understeer in tight turns. The RS is more at home on full race circuits. It only comes alive when it's travelling very quickly. What I'm saying is that for autocross a softer car is probably a better tool than a stiff car. Therefore moving to an adjustable suspension set up (KWV3 or PSS10) that you tune to suit your autocross might be a better way to go.

Oh! and agree that grippy tyres will still be needed.

anto1150

I completely disagree.
The more the grip, the more travel and deformation the suspen (and tyres).
Hence, if you have no grip but run aggressive geometry, you'll result in no grip at all...! And because our engine is in the "wrong" position, you'll get hips of understeer!
You'll experience a tremendous change in car's behaviour as you'll fit new tyres...

bgiere

why not get some even older tires to really test it out?

Vandit

He may be onto something.

Chris Harris drives AMG C63 on spare tires
http://youtu.be/HPh90yNX-mY


As far as setups, the RS and the RSA are such different cars, so many variables at play here to simplify any comparison of components used on each respective car.*

There's also the whole subjectivity of handling, one person's perspective of neutral is another's understeering plow and another's tail happy monster.

Best bet would be to get some bars (and other components) that have adjustability and mess w/ the settings until you find something that suits your needs and preference.

Robofc

The car is now almost neutral in 40 mph corners, with a hint of understeer to telegraph the limit.

Dwane

Yeah....That's the ticket.

Robofc

As to the question at hand?

Steve Weiner-Rennsport Systems

Two things:

First, the motion ratios between the front & rear swaybars are totally different so comparing sizes and making hard predictions about balance isn't valid.

Second, the RS had MUCH firmer spring rates than the RSA which balanced the car toward neutral. Most American drivers would find the Euro RS to be slightly "loose".

Swaybars should be used in matched sets for the reason mentioned above. This ensures predictable handling as you adjust them to your skills and preferences.

Camber doesn't directly affect balance in the same way that ARB's do. Camber settings are only to keep the tire patch flat on the ground during hard cornering and optimized with tire temps. 225's up front will give more grip, all things being equal, as long as you use the appropriate camber settings for the tires you use.