Matched spring rates vs Matched swaybar stiffness - What's the difference?

[wpmarky]

Scenario for general discussion for those that have gone through various suspension setups.

 

How does a set up of matched spring rates w/ staggered sway bar stiffness compare to match swaybar stiffness & staggered spring rates?

 

For example:

 

8k springs @ all 4 corners w/ 22mm front sway bar & 25mm rear sway bar

 

vs

 

6k/8k springs (F/R) with matched front & rear sway bars (25mm front & rear).

 

Can anyone shed some light on what the difference would be between the 2?

 

Here's what I'm currently thinking, differing opinions welcome.

 

Sway: In order of most sway to least sway

Staggered spring rates w/ 22m F&R sway bars

Matched springs & 22/25 F/R sways

Staggered spring rates w/ 25mm F&R sway bars

Matched spring rates w/ 25mm sway bars

 

Understeer/oversteer:

Matched springs w/staggered sways- minor understeer w/ throttle oversteer.

6k/8k springs w/ matched sways: close to neutral w/ minor oversteer

 

Dive/squat: less dive/squat with stiffer matched springs during straight line hard braking & acceleration

 

Weight balance:

More even with matched springs during initial turn in.

More even with staggered spring rates while on the throttle during turn exits.

 

Overall Daily driving handling: I would prefer 6k/8k for NVH comfort and turnability at DD speeds.

Spirited mountain roads handling: 6k/8k with matched sway bars

Auto-x handling: I think I would prefer 8k/10k springs with 22mm/25mm adjustable sway bars for quick tight turns

HPDE Road course handling: Matched spring rates with 22/25 mm f/r sway bars to carry more speed & throttle sooner through the high speed turns.

 

After going through stock spec.b springs/bilsteins, rallitek/bilsteins, pinks/bilsteins, and now BC BR Coilovers 6k/8k, as well as the 20mm AVO RSB, 22mm Perrin, and 25mm Perrin sway bars, I'm still curious how other setups feel.

[Th3Franz]

The easiest way is to do a percentage based stiffness comparison.

 

The one important piece that's missing..

what tires are you running and will you always be running street tires?

 

Here's a link to a handy table

http://www.oakos.com/wrx/swaybarchart.htm

 

Also, you should take into account the mechanical advantage of the multi-link rear suspension that causes the effective rear spring rate to be lower.

 

A lot is driver preference, but I am running a softer version of this and would recommend it.

6k/8k springs with 23mm front bar, 21 mm rear bar

 

If you want the car to be more twitchy, some rear toe out will do it.

[dmanaenk]

Subscribed, since I want to get some springs or coilovers.

 

That chart always confuses me. Do 22mm adjustable and non-adjustable bars have same or different stiffness (adj in max setting)?

[Saul_Good]

WPmarky: not sure if this will answer your question, but I have gone from

staggered springs (MR 6k/8k, Bilsten Pinks 4/6, stock) and staggered sways (23F, 21R) to matched springs (RCE T1 9k/9k) still with same staggered sways, and like the feeling better. It's actually almost neutral in that the car doesn't feel like it'll come around on me when i have lift oversteer. Also the 6k fronts were still too soft for the track and I still had lots of dive when breaking. With the 9k i get almost no dive.

 

The only real difference would be my FLSD would aid in me keeping a tighter line since im able to get on the gas sooner and not have as drastic a track-out condition as i did pre-FLSD.

 

Anyways, hope that helps somewhat.

[whitetiger]

just want to mention that hollow and solid bars have different stiffness even though they may be the same thickness.

 

the bottom line is the best way to control weight transfer is with properly stiff struts and springs. swaybars make the suspension less independant so they only meant as a final tewak in handling behavior. people with soft springs and stiff bars have therefor sacrificed grip for handling behavior. also sways dont help with squat or dive so they are a poor solution to control weight transfer. this is why i tell everyone who asks me, get a stiffer matched spring/strut combo, or coilovers and see how you like the car before you go for sways.

 

I autoxed my car for a whole season just on coilovers tien flex(8k/9k)with stock sways just to learn who the car behaves before is stated adding sways and other more minor parts. It reall help me get a better sense of what i need to focus on to make the car behave the way i wanted it to. And as saul_good said, a FLSD doesnt hurt either;)

[wpmarky]

Good stuff, thanks for the responses so far.

 

I too have read tha the reason for 6k/8k is because of the multilink design, but during turns I can feel the weight leaning forward. I have yet to put in the matching 25mm front, so this may change afterwards.

 

Saul, how did your car feel with 23/21 sways before the front LSD?

[Saul_Good]

I can only tell you how was when I had bilstein/pinks because they have always been on after that.

 

I got less lean in turns and a better turn-in from just the bilstein/pinks. It's obviously way better now. But thats what i remember coming from that combo.

[Th3Franz]

Good stuff, thanks for the responses so far.

 

I too have read tha the reason for 6k/8k is because of the multilink design, but during turns I can feel the weight leaning forward. I have yet to put in the matching 25mm front, so this may change afterwards.

 

Saul, how did your car feel with 23/21 sways before the front LSD?

 

I'm running Bilsteins and pinks with 23/21 sways with the open diff. With a proper alignment, the car turns in hard and is very neutral while staying relatively flat around turns. Coming out of very tight turns, the car wants to push while on-throttle but for medium to high-speed turns I can floor it before the apex and the car tracks out great.

 

I think the added caster from the LCA's helps quite a bit for the faster turns. I was able to hold 75 mph around the carousel before apexing at Road America on street tires, and there was still some speed left in it.

 

With the new brake setup, my car does dive a lot. I love the suspension setup for an all-around street car that sees the track on our crappy roads, though

[shaneomac1602]

currently running Tein H-tech springs on stock shocks, and plan on running a Perrin 25mm rsb.

 

here are a few questions i have:

 

what are the spring rates of the h-techs?

 

i hate, let me repeat, i hate understeer. i would prefer neutral to oversteer as those are much more controllable. would i be better running a 22mm or 25mm fsb? i was planning on running a 25mm to try for neutral steering, but i was thinking about buying a 22mm fsb so i would have the ability to kick out the rear end if need be for quick cornering.

 

i dd my car, but do plan on taking it to the track for a few road races if i can find the time or entry spot to get in somewheres close. what would be the best setup you guys could suggest for me? im not scared of some NVH as i like the ability to "feel" what my car is doing.

 

i would appreciate any and all advice you guys could give me

[Th3Franz]

you hate understeer? Get better struts, period.