HIGHLY SPRUNG OR ANTI ROLL?

[Torquemonster]

Here's a question for the road racers out there - cause what I thought I knew, I'm no longer sure...

...of course we all know what Thought thought. He thought he had a car, but he only had a horn.

Anyway... There have ever been 2 schools of thought - one school = stiff spring rates and shocks and modest sway bars for best handling. These cars handle flat and good at high speed, but are bone jarring on the road, cause long term rattles etc, and do not handle well on bumpy roads - they skip and judder.

The second school uses softer spring rates and big sway bars - for acceptable ride, good tire contact over lower speed bumps, and keeps the car very flat.

I've always been of the opinion that a good road car that also sees some track duty must have a compliant suspension.... as in progressive spring rates for maximum compliance over slow dips and bumps etc, and progressively stiffer as suspension is forced to work harder at speed AND stiff anti-sway bars. The reason was that stiff anti-roll bars allow a good basic ride and plenty of suspension compliance to keep the wheel on the road while controlling roll - keeping the car nice and flat.... (as a side they work well in drag cars too and guys who take them off are nuts - we used them to run 6 seconds!).

The new SRT10 has gone for stiff spring rates that obviously work very well on a track or smooth road - who can argue with over 1g - that is better than the Euro supercars manage. However, it will limit the car over secondary paved roads and bumpy race tracks.

So which is better - progressive rates and strong anti-sway for maximum suspension compliance OR stiff rates and maximum grip at speed on smooth surfaces and the trade off they make a low speeds and comfort?

 

[GTS Dean]

Moderate to stiff springs, with well-tailored shock valving. Your shocks should allow you to easily adjust between compliant action for the wet and/or undulating surfaces and very firm for dry, smooth pavement handling.

 

[Mike H]

Well here is my 2 cents......There is no one majic setup, as every track is different, as well as ones driving style. Softer setups are usually more compliant and stiff setups require very precise steering input. If you are very smooth in the corners stiff may be good.
We run different setups depending on the track. At a Sebring track, where it is flat I like a stiffer setup. At a Mid Ohio, with lots of off camber turns and such I like a softer setup.
You need to look at each track different and see how the car handles the track. We work on high speed corners first, looking at how the car handles into the corner first, then how it handles out of the corner. I like a very nuetral car that turns in fast and is smooth out of the corner so we get maximum speed down the straights.

 

[jrkermode]

I agree with the above, only I would add chassis stiffness to the list.

It's all about wheel rate. In a single wheel deflection, the stiff spring / soft sway bar could have an identical wheel rate to the soft spring / stiff sway bar. A flexible chassis also acts as a spring, often differently on each corner. The wheel rate is also affected by the mechanical advantage of the suspension, so the rates of the springs are kind of irrelevant.

I realize you probably meant wheel rate, but I thought I would mention it specifically to be clear.

It's hard to generalize specific set-ups. The only general statements I'm aware of are:
Softer grips better than harder
Springs (individual wheel, Z & sway bars) are for static loads.
Shocks are for dynamic loads.

It's also critically important to keep in mind what Mike H mentioned. The best set-up is the one the driver can go fastest with. That may not be the same as the set-up which is theoretically "optimum".

 

[Torquemonster]

Thanks guys for your input. It seems adjustability is the key from what you are all saying. I think my preference for the roads however would remain softer progressive springs (soft being a relative term) with adjustable shocks and adjustible but large anti-sway bars. I like my cars to corner flat, but I also like suspension compliance to absord ripples and bumps without bouncing the tire off the pavement - causing a slide. I'm a good line, smooth type driver - not just because thats faster but because I don't have the balls to drive sideways truth be told.... at least I'm being honest. I love a good slide for fun, but feel too mortal to try it at speed deliberately. I respect those guys who can do it - maybe one day I'll do one of those courses so I can steer a Viper around a corner on the throttle... I've always marvelled at the guys who can do that with total control... my attempts in the past have swung between exhiliration and total "oh $#@*!" then coming out of it with a heart rate near death experience. Also, coming off the home straight at the redline in 4th gear backwards put a damner on things too... that was some serious speed to be flying around in circles! That was in a track prepped race Mustang on old slicks that did not have any feel at all and I over braked locking the rears....