Sway Bars?

[240sxHitman]

I was just wondering are Suspension Technique sway bars good? I have a 91 240 hatch. and if there are others that are good let me know.

[Exar-Kun]

Depends on what you're looking for. Bang for buck the ST bars can't be beat. It's what I'm running right now. You also don't want a sway bar thats stiffer than your springs, but that's another issue.

Whitelines are nice and offer adjsutability, the Cusco peices are similar in dimensions to the ST and cost a lot more, but ma be a bit more rigid.Largus makes some h-u-g-e ones, 'drift spec' or whatnot...

to be honest, No one should be using sway bars that large, IMO...

-Chet

[240marcuSX]

chet, could you provde more information on that? or give me a link? or just shout, "CHECK THE FAQ" at me? kthx. i think that may be the problem im having.

[Exar-Kun]

check the sus faq for dimensions.-chet

[240marcuSX]

Suspension TechniquesFront 27mm Rear 20.6mm

thats what i have, but i also have eibach pro-kit springsm, could this be the reason for my understeer? what issue would having swaybars stiffer than your springs cause?

thats the question that i should have asked in the first place, lol.

[Exar-Kun]

There coudl be a lot of reasons for underteer...not knowing what true unedersteer is, first off....

no offense meant directly to you, but the sheer ammount of peole who whip out "my car undetsteers" is unbelievable now....it's like the token excuse for not having any driving ability or something...

/end rant temporarily

onto your point.

Air pressure, alignment, shock and spring and sway bar settings (as well as weight distribution, tire tread different F/R etc) can all affect the handling of a car related to under/oversteer.

First you gotta understand that, and it's rarely just "oh is X causing it?"YOu have to take the car and tune it one thing at a time to determine if what you're doing is having any positive effect...

it's why I don't reccomened changing a suspension setting or part on more than one level

(IE, dont put on sway bars, srpings, and heim joints all at once to 'fix' a problem)

because you wont know what did what, and where you have to go from there.

Anyways, eibach suppsoively does dial out a bit of understeer in their spring settings, but it's still geared toward (the more controllable on the street) understeer.

as far as the bars go, the realative increase in stiffness

is 16-20% front and 30-40% rear (just doing diameter calculations, the stiffness is actually much more due to the urethane bushings and other things), which would in theory) mean more neutral handling, with less body roll across the board. make sense?Also, something to think about, is you WANT more grip in the bakc of the car, relatively, because that's where power is applied, and a tire can only recieve so much traction stress whether lateral(cornering) or longitudinal (power) ...so any power applied eats out of your tires grip in the rear...

making sense?

I would screw around with tire pressure and alignment settings one at a time until you find settings you like (or bring you closer to what you want)

then goto adjusting things or changing out parts....its cheaper, and you'll learn a lot about how the car functions as a unit, and one things always has a ripple effect.

-Chet

[Veriest1]

no offense meant directly to you, but the sheer ammount of peole who whip out "my car undetsteers" is unbelievable now....it's like the token excuse for not having any driving ability or something...

/end rant temporarily

onto your point.

it's why I don't reccomened changing a suspension setting or part on more than one level

-Chet

I couldn't agree more, even though I'm relativly new to "precision driving." Most people who experience understeer for the first time don't come back just saying "Oh my car understeers." Nope, normally they've soiled their pants if understeer really happened to them. I personally thought I was going to die the first time I had it happen in the Bimmer. The first time anyway. It's still not fun after that but... techically understeer is less dangerous than oversteer because of the natural response to hit the brakes.

My point: Understeer is going to be caused by to high of an entry speed (Read: driver mistake) and really isn't the cars fault... usually.

I'm not looking forward to tuning the 240's suspension. Everything seems like it was messed up and needed replacing and that combined with changing the geometry via coilovers = headache. Any recomendations on how to go about this and save myself sometime by not making stupid mistakes? The car is in my sig.

Sorry if this is to close to thread jacking but uh... I hope everyone had a good Christmas.

[240marcuSX]

no offense taken, but dont mistake me for some kid that went out and raced once and came to some conclusion,

ive tested multiple combinations of tire pressures and damper settings, with the same tires and approximately the same weight dist. and swaybar settings (mine arent adjustable) ive found a big empty parking lot where i test these things, after the apex of turns, my front tires squeel from pushing so much, and my rear wheels have just enough grip to my liking.

onto the bottom line, i replaced my stock swaybars to reduce body roll etc. but i also made the mistake of buying pro-kit springs, a combination that i suspect could cause too much understeer (to my liking). and i was just trying to find out if this combination could cause this.

variest - it isnt my entry speeds that need work, its my cars ability to increase exit speeds that needs work. (not to blame the car, but that IS what the problem is)

[Q45tech]

The main problem with very stiff sway bars is the shocks don't have the rebound control to control them in rapid left right transistions when they oscillate like the springs they are.Good rule of thumb is to have the rear sway bars no more than 50% of springs wheel rate.Most oem rear springs have a 100-120 lb/in WHEEL rate so a 50-60 lb/in sway bar wheel rate is a good upper limit.

On 240-300-Q45 etc the bar mounts/couples at the ~~ center of lower rear arm so the bar is ~~4x stiffer than what actually gets to the wheel.

A ~~20 mm rear bar in standard oem configuration [convolutions plus right angle arms] yields a 35-40-50 lb/in at the wheels depending on bushings and end links.

I use an oem 20mm rear bar [from a Q45a] on my Q with 123 x 0.9= 110 pound inch wheel rated springs ~~ 40 pound inch extra or 36% stiffer than no bar.

Self protective against oversteer except in cold rain [tires change].

Sway bars really are not much good for reducing sway, just for tuning the front rear roll couple stiffness towards more neutral steering [less understeer].

On most cars the front sway bar is way too stiff to induce understeer in turns...........many times a softer [-10-15%] front bar will help tire over load and wash out.......just like adding 5-7% stiffer bar to rear when you soften the front........the ratio of stiffness is what counts.

My Q has a softer front bar from a Q45t 28 vs. 29 mm [13%] so this adds to the rear 36% ratio to ~~=42% stifffer rear ratio than stock.Much more nimble but not oversteering.

Higher load index [than oem] front tires can reduce the understeer by reducing tire slip angles under the same corning load plus increase tire life signifficantly..........the strongest [load index always goes on the heaviest end].

[Exar-Kun]

you face two problems with the prokits, their progressive rates make it hard to determine their stiffnes at any point in time....

IE, if the front is 80% compressed and rear is only 50%, what's their rate at those compressions, etc?

Try running equal tire pressures F/R and stiffening the rear dampers a bit and see how you like it from there.

No, I didn't confuse you with some kid You got a good ammount of posts under your belt.

Also, Thanks Dennis for more extapolation on sway bar v. spring rate! Always an interesting read....

You live in ALT right?

-Chet

[Q45tech]

I didn't want to confuse by adding in the progressive rear springs that go from 100 lb/in to 200 lb/in with the linear fronts ~~ 146 x 1.15 =167 lb/in.

the rear stiffness might be 140, 150, 160, 170,........240 with bar and pro springs...........over just a 2.5" compression

This is a nightmare to model except that the [very very stiff] front sway bar engages progressively [on the Q] also so mostly you are not in oversteer in dry weather.

Those that have the front sway bar end links attached to the front struts have much less progression so aburpt oversteer is more possible with progressive rear springs.

Shock temperature Winter vs Summer is another variable in slowing/speeding up body roll weight transfer.

On a old Z, I30, Maxima, or 240 careful with progressive rear springs with or without sway bar changes..........mostly soft sidewall tires will take up the slack.........sometimes.

[Bronze MFP]

Good stuff, i was about to run a pretty stiff setup for my stabilizers, but I have to rethink the gameplan now, thanks q-tech!

[240sxHitman]

Depends on what you're looking for. Bang for buck the ST bars can't be beat. It's what I'm running right now. You also don't want a sway bar thats stiffer than your springs, but that's another issue-Chet

Well I have S tech/Agx on my car now, stiff but not bad until you meet the streets of ny . but i like it. Do you know how it would be if i added St bars?

[jmauld]

after the apex of turns, my front tires squeel from pushing so much, and my rear wheels have just enough grip to my liking.

but i also made the mistake of buying pro-kit springs, a combination that i suspect could cause too much understeer (to my liking).

With the above comments and those parts, I'd guess you're hitting the bumpstops and sending your front spring rate through the roof..

[Ceptos]

ok i didnt read through all the posts, not enough time atm, so hopefully im not repeating anything. but, i wanted to say that when buying sway bars you should always look for adjustability, at least imo. just getting rid of body roll isnt going to dramatically increase your handling (especially if you're already running stiff springs), but it will improve feel and response. the adjustability allows you to tune oversteer and understeer to a point, and to me, this is the main function of sway bars, their adjustability. i dont know how much of this is true, but ive also been told the majority of body roll should be taken care of with the springs. plus you get to feel cool when you soften them up for running in the rain, heh =)

ive always had my eyes on the whitelines. again, this is the way i look at it, they may not suit your application.

[j-z]

with what all you suspension gurus are saying about the relation to stiff sway bars and spring rates really makes sense. i just recently put on ST sways on my s14 and they are damn well worth every cent. my car really needed them cause now everything ties in together and complements each other so well. after adding the bars, my tires grab the road so hard i get flung in sideways motions to where its ridiculous while occupying the cockpit. as of now im running d2s with 7/5 spring rate dampened moderatly, 225/45/16 yoko avs es 100s, -1.5 degrees of camber all around, a bit of toe in on the front and pretty much 0 on the rear cause thats as far as i could get with stock adjustments, tie bars front and rear, and the battery in the back. my car is near perfect in response and handling. she has a very neautral attitude. i just started auto-xing my car as of lately and i did pretty decent without the bars. i can not wait till the next one so i can really test the limits of my driving and my cars capabillities with the addition of the ST sway bars. woot woot!!!!

[Exar-Kun]

ok i didnt read through all the posts, not enough time atm, so hopefully im not repeating anything. but, i wanted to say that when buying sway bars you should always look for adjustability, at least imo. just getting rid of body roll isnt going to dramatically increase your handling (especially if you're already running stiff springs), but it will improve feel and response. the adjustability allows you to tune oversteer and understeer to a point, and to me, this is the main function of sway bars, their adjustability. i dont know how much of this is true, but ive also been told the majority of body roll should be taken care of with the springs. plus you get to feel cool when you soften them up for running in the rain, heh =)

ive always had my eyes on the whitelines. again, this is the way i look at it, they may not suit your application.

adjustability is great, but a [propperly selected sway bar diametere, etc would leave you dealing with other more impactfull (and benificial) things to adjust far before sway bars should ever come into consideration such as tire pressure, alignment settings, spring rates/heights, damper settings...

the list goes on and on. Plus, I know nary a person who HAS adjsutable sway bars that should be messing with them in the first place... considering most people are confused as to what under/oversteer really is, etc....

but that's another matter.

If you think you'll USE the adjsutability, and you've explored other options for tuing the car to your liking, be my guest....but the majority of suspension work should be tuned where it occurs-the actual suspension springs, dampers and linkages.-chet

[Ceptos]

understood, but i was mainly commenting on the sway bars by themselves (i basically meant to say that the use of sway bars was tuning balance instead of just reducing roll, not that you should tune balance with sway bars). i also like to cover my bases so i only buy a part once instead of outgrowing it so to speak. they are pretty far down on my list as well, i have a set of coilovers with a few sets of springs i can change in and out im fooling with now, and i still have to get through all of the control arms, ouch my wallet.

[Bronze MFP]

Quick question, if you're not supposed to have a stabilizer stiffer than your springs, why does the s14 Nismo front stabilizer have a 10kg/mm rate when the front spring rate on their r-tune coilovers is only 8kg.mm? was that a bad move on nismos part or do you think they know what they are doing?