All,

ok so whats the deal?

Can I get lower (softer, not physically smaller) rating springs and upgrade my swaybars for the same affect?

Any downside to do this? If not then why don't more people set their cars up like this?

Please discuss and post opinions.

Cheers
D.

 

Springs do not substitute for swaybars, and vice versa. They are complimentary mods and a typical car will benefit from both in some sort of balance. Swaybars and springs function in different ways; most notably, a swaybar has no effect when both wheels on the same axle encounter a bump at the same time. This makes swaybars a great tool for tuning roll resistance, it will theoretically allow you to run lower spring rates while maintaining the ability to reduce body roll in corners. Too much swaybar can reduce the "independentness" of the suspension, and a noticeable example of this is the car's increased tendency to lift the inside rear tire in a hard corner with a stiffer rear swaybar. Swaybars also have little to no effect on straight line performance (in most cases), and therefore ride quality, and so that makes them a good, simple, early suspension modification to improve handling but not sacrifice ride quality, as is the result when spring rates are increased.

Springs should be the main modification and swaybars should be used as a tuning tool.

 

well I want to reduce my street bumpiness but decrease body roll on the track.

so presumably softer springs + heavier swaybars should do the trick?

 

As long as you can deal with the dive and squat characteristics...

Light springs and heavy swaybars also mean that your damper sees a big difference between straight line effective spring rate and and effective rate in a turn. It makes front-to-rear vs side-to-side dynamics not balance out.

 

In general terms, soft springs and stiffer bars can work to to improve track worthiness. The OEM springs are actually pretty low as far as kg/mm rates. With the OEM sway bars you have a significant under steer problem. For me, desired vehicle balance is different for the street, autocross and the track. As mentioned above , a softly sprung car with big bars will have some degradation in street ride versus the OEM setup. For track days this and a proper alignment could be a very worthwhile compromise. About 6 months ago Grassroots Motor Sports had an article wherein they dramatically improved the handling of a Subaru wagon. IIRC, bigger, stickier tires, alignment, and sway bars were the biggest bang for the buck. Incidentally, after market springs showed no improvement.

The global suspension tuning problems here are quite complex. There are excellent discussions in the competition forum. You have ride height and suspension geometry issues. You soft spring and weight transfer issues especially when braking and turning. You can throw in progressive spring versus linear spring issues. All dual purpose (street/track) will be compromised. Ultimately, most people choose to favor one venue over the other and set their car up to that preference. The alternative dual purpose suspension will unavoidably have weaknesses in both applications. Simply put, luxury cars and sports cars have different suspension design goals and one will be able to dramatically out perform the other under certain circumstances.

 

I have the exact combo you are talking about.....

Its soft on the street and capable on the track but you do have to tollerate some additional roll and brake dive.

Because I am used to a very stiff car with no roll I think this combo FEELS too soft for the serious track **** (especially with sticky tires) but that doesn't mean it doesn't perform well. It just not a crisp as I would like it to be. It feels like it rolls a tad, sets up, then holds position. If you don't mind a balanced shift then it probably what you want. I'm hoping it grows on me a little more than it has thus far.

 

I'm going with the ever popular 'Vishnu' setup that Warralton and Kekek run on their competition winning coilovers, that is, 12k/16k spring rates on stock sway bars.

I'm waiting on my dampers to come back from bilstein, so I have no real comment yet on the feel, but I know that it is a common and proven setup.

 

I would be wearly to compare the evo suspension to the WRX. The WRX has a very poor factory susension setup especially when it comes to sway bars. Which is why so many suby owners get bigger bars. I would not use that to compare to the evo which i feel has very adequate bars for the stock and most slightly stiffer springs (switfts, hotchkis, ect..).

 

Jeff..that is exactly how the sl softer spring/ bigger bar setup feels like to me too. You CAN tune out a little of the initial roll by going to really hard bushings but it'll still do it a little bit. There is also a dive issue under braking and more weight transfer than you really want. < but that makes for fun in trail braking >

I agree for the street it is more than adequate

Milburn

 

^ I see you are from Atlanta.... my race crew is planning a road trip to Road Atlanta this summer. The Blisteins will be nice for the 13 hours trek.

 

thanks guys, so is it mainly springs or dampers that transfer bumps in the road into the cabin?

 

Your springs are plenty soft allready. The dampening is very strong which makes your car feel tight and responsive. Just find a used set of Bilsteins from a MR. The factory provided us with the best street suspension compromise. A experienced SCCA champion friend of mine bought a Evo and wanted to take it to Lime Rock for a run in stock form. On his first lap going through big bend he said "the car needs a suspension, it needs everything". What felt fantastic on the street was completely inadequate on the track. Very soft springs with very hard dampening.

 

Springs but its the combo that gets it right. Soft springs and over dampening gives you a harsher ride. Stiff springs and under dampening gives you "crashing" and a bouncy ride

For the road you want a combo of slighter stiffer springs and MR bilsteins. It does appear to be true that the Bilsteins over damp the factory springs a bit( Chronohunter- Paul Gerrard ) The ride is actually better than stock if you go to ~300 lg springs. It will be taut with just a bit of suppleness. Not recommended for rougher roads, though.

If you have to travel on less than good roads, look into getting some high quality rally dampers and keep the spring rates to ~300 lbs.

For road racing you want much stiffer springs and you'll have to up rate your dampers to handle them. 10-12kg ( 500/550 front 600 rear)

My personal opinion and choice is the combo I have, along with the Whiteline bumpsteer and a good alignment. I also chose a 25mm adjustable rear bar that on stiffer settings with the combo above allows me to hang the tail out on mountain roads, bringing it back with a quick countersteer and throttle. On softer settings the car is neutral on the road, but less challenging and less fun. Its my daily driver though so civility and ride are important

I do not recommend tracking the combo exclusively as it is a compromise. Not enough spring and at higher rates of speed you will definitely want to stabilize the rear. Stock bar would be enough. IMHO :-)

Milburn

 

Thanks guys!

Don't forget that AUDM spec has harder springs, say 300/250 lb's.

I guess if I get adjustables I can dial the damper down for the road and up for the track.

 

Careful - no amount of adjustable damping is going to turn your ride from cadillac to caterham. The key is to be honest with yourself, know how much ride quality you're willing to sacrifice for performance, and choose your spring rates appropriately. Do not rely on adjustable damping to "tune out" ride harshness.