Sway Bars vs. Strut Bars

[SOHCmyDOHC]

Im looking at a purchase between strut bars or sway bars, or both if possible?  Whats the differnece and which is best?  Can both be applied at the same time:eh:

Thanks,

-Ln.

[HaLo]

In Order:
1. Both are best.
2. Sways
3. STBs.

[LanceS13]

The difference...
A sway/anti-roll/anti-sway bar (it's all the same thing) acts as an extension of your springs, connected left suspension components to the right ones, and reducing body roll.  Get both front and rear ones...just a rear one will likely make the car fairly tail happy; just a front one may make it push.  Get both and  fine tune with adjustable struts.
A strut tower bar is a chassis brace that connects the top of the left strut tower to the top of the right strut tower.  These reduce chassis flex, making the car more stable under hard cornering.  Get front and back...you can never have too stiff of  a chassis.
They're both good upgrades.  The sway bars may make a bigger difference, but the stb's are cheaper, so bang-for-the-buck is about the same.

[tnord]

i could be wrong about this but........won't a front sway with no rear make the car oversteer because the rear of the car has more lean than the front, thus messing with the suspension geometry, and removing some of the contact patch. while conversely, a rear bar with no front will cause the car to push because the back of the car holds better than the front.

[LanceS13]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (tnord @ Mar. 27 2002,12:28)</td></tr><tr><td id="QUOTE">i could be wrong about this but........won't a front sway with no rear make the car oversteer because the rear of the car has more lean than the front, thus messing with the suspension geometry, and removing some of the contact patch. while conversely, a rear bar with no front will cause the car to push because the back of the car holds better than the front.</td></tr></table><span id='postcolor'>
not really
Consider a rear-bar-only case: &nbsp;during a steady state turn the front will allow more body roll, while the rear limits it. &nbsp;As the front rotates while keeping both tires on the pavement, the rear has to follow, but the inside tire will start to lift...thus, decreasing rear contact patch and causing oversteer. &nbsp;The opposite is true for a front bar...however, in this case, initial turn in is better, but the car will begin to push at steady state. &nbsp;It's best to get both. &nbsp;Getting just one compromises overall contact patch and maximum grip. &nbsp;Fine tune to neutrality with spring rates or shock/strut stiffness.

[tnord]

the inside rear doesn't always have to lift though. i'm somewhat confident that it only happens when the rear bars are too stiff in the presence of lots of body roll. &nbsp;their mere existance doesn't necessitate the loss of traction. inside rear tires typically lift on fwd cars (especially the old GTI's). this happens obviously because there is too much body roll and not enough weight transferred to the rear of the car. and of course those fwd guys always need as much weight on the front as they can get, so they don't mash the throttle into the apex like us rwd guys do. basically, it'd be quite the trick to get our inside rears to lift if you ask me. &nbsp;pretty much every older vw and civic i see at the track lifts the inside rear, does this mean they are operating at less than optimal traction? most definitely not. while there are clearly improvements to be made, the fastest way through a corner is on 3 wheels for some cars.

[tnord]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (LanceS13 @ Mar. 27 2002,12:43)</td></tr><tr><td id="QUOTE"></span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (tnord @ Mar. 27 2002,12:28)</td></tr><tr><td id="QUOTE">i could be wrong about this but........won't a front sway with no rear make the car oversteer because the rear of the car has more lean than the front, thus messing with the suspension geometry, and removing some of the contact patch. while conversely, a rear bar with no front will cause the car to push because the back of the car holds better than the front.</td></tr></table><span id='postcolor'>
not really
Consider a rear-bar-only case: during a steady state turn the front will allow more body roll, while the rear limits it. As the front rotates while keeping both tires on the pavement, the rear has to follow, but the inside tire will start to lift...thus, decreasing rear contact patch and causing oversteer. The opposite is true for a front bar...however, in this case, initial turn in is better, but the car will begin to push at steady state. It's best to get both. Getting just one compromises overall contact patch and maximum grip. Fine tune to neutrality with spring rates or shock/strut stiffness.</td></tr></table><span id='postcolor'>
after re-reading my post i realized i kinda rambled and didn't really answer much so i'll try again.

in your post you state that a rear bar limits body roll. this is true. you also say that a car with a rear bar but no/smaller front through a turn will result in the front "rotating." i don't think this is accurate. because the front has no bar it will have more body roll, resulting in a loss of traction to the front wheels. because the rear has a sway bar, it will be more stable, keeping it's tires on the road........not sliding around. if the front of the car has more traction than the rear, it will obviously oversteer. if the rear has more traction, the car will push (understeer).

this is why front bars are thicker than rears. operating the rear tires at a higher slip angle than the fronts will allow the car to be pointed (done with trail braking iirc) in the desired direction, followed by the application of the throttle to give back traction to the rear of the car when it is already correctly aimed. basically it is a controllable mild slide.

[LanceS13]

ok...trust me. &nbsp;I currently have just a rear bar and I have to run my rear shocks full soft and fronts full stiff to keep from chasing my tail at track days and autocrosses. &nbsp;I may not be able to give a super extensive lecture on the physics of it, but I can tell you from experience.
By "rotating" I meant rolling...poor word choice on my part. &nbsp;Body roll doesn't have as much of an affect on maximum steady state cornering power as it does on how a car can handle transitions. &nbsp;And I didn't mean lift completely off the ground...but contact patch will start to decrease. &nbsp;Some cars lift the inside rear wheel in steady state cornering b/c the stiffer rear suspension allows more time to be shaved from quicker transitions than could be saved from keeping all four tires down under steady state cornering.
With stiffer rear bar...
At steady state turning, the car body tends to roll to the outside. &nbsp;The front can roll more while keeping more contact on the inside tire. &nbsp;The rear will follow the front, rolling to the outside, but the stiffer suspension doesn't allow the inside tire to retain the original contact patch size. &nbsp;The increase in traction on the outside tire isn't enough to compensate, and the car oversteers. &nbsp;
In transition cornering, the front can't keep up with the rear. &nbsp;I've found that this can cause push or oversteer depending on the attitude of the car at each turn in...but oversteer most of the time. &nbsp;I guess the rear just has better "turn in" than the front.

[DSC]

And for this one I'll do my patented link to turn fast <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>

Anti-roll bars (sway bars) (http://www.turnfast.com/tech_handling/handling_antiroll.lasso)

Strut tower bars (http://www.turnfast.com/tech_handling/handling_chassis.lasso)

Also, tnord, I'm with lance on this one. I tried different combos on mine and with just a rear bar it was extremely tail happy...with just a front bar it would push through turns with the back feeling like it was just "flopping around"

Edit: haveing both sways and a front stb, I think money vs performance the sway bar wins big time. &nbsp;The strut tower brace just made the car feel more solid, I think the sway bars would actually reduce lap times.

[tnord]

The rear will follow the front, rolling to the outside, but the stiffer suspension doesn't allow the inside tire to retain the original contact patch size.

i think this is pretty much the only thing we disagree on. i think it's cool that we both know the other has track experience so this discussion hasn't turned into insults and shouting like other topics.......but anyway......

i'm not trying to call you a liar by any means. seeing as how you have some experience with this setup and i've just read books.
here's what i'm stuggling to accept;
the addition of a rear sway bar is there to reduce body roll and maintain optimum "suspesion geometry" between the tire and the road. i have a hard time understanding why or how the inside wheel loses traction because of this.

note: i would think that softening your rear shocks and stiffening your front ones would create oversteer. i mean, under normal circumstances you would install stiffer shocks to enhance handling. say you had a completely stock car and put in a set of tokico's, that would be good right?

also: i know there's a good possibility that my logic is flawed, i'm just putting in my thoughts so maybe someone will correct me where i'm wrong..........looks like it's time to read through the books again.

[tnord]

ok......looks like it was my misunderstanding of how sway bars work that led to my false conclusion. Here is what it says in my book "secrets of solo racing"

"setting a bar more stiffly means that it will transfer some of the weight at this end that was previously being transferred at the other end of the car. this is done by resisting the roll of the car on the tightened end, before as much weight is transferred on the other end, where the sway bar is set more loosely. all of this happens because of the stiffness of the entire car. if the car does not resist tisting along its long axis, none of this works.
the advantage is this: transferring weight decreases the cornering power of that end of the car, as the extra grip of the heavily weighted tire is less that the grip lost on the lightly weighted tire. so, for example, tightening the front bars will make the front end stick less well, but, since less weight is being transferred at the rear of the car, it will make the rear stick better."

now it makes sense.......and yes lance i know you stated something similar to this......but for some reason it didn't click with me.
i wasn't making the connection between body roll and weight transfer.

[LanceS13]

The shocks work on the same principle as the sways...just with finer adjustments.
It's all about balance. &nbsp;Stiffer suspension does allow better handling, but you have to balance the stiffness of the front and back to make it work for you. &nbsp;If it's not balanced properly, then handling is likely being hurt more than helped.
Look, I drew a picture (http://www.eframes.com/ef-cgi/l/lc240sx_netdoor_com/6832suspension_geometry.jpg). <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'> &nbsp;The top two diagrams are front and back a of stock front/stiff rear setup; the bottom two are front and back of a stiff front/stiff rear setup...all at a steady state corner to the left. &nbsp;Of course, there a few other factors, but it's the basic idea. &nbsp;Does this make sense?

[LanceS13]

oh...sorry...looks like you figured out yourself.
I'm better with situations/pictures than words/explanations. &nbsp;<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'>

[Ballistic-Mobile.com]

Wow, now i am confused. &nbsp;Lance in your drawing the top two diagrams, to me, should be reversed. &nbsp;If the stock sway bar is in the front and the stiffer sway bar is in the rear, then the front should have more body roll than the rear, therefore the outside front tire should be recieving the most weight out of all four tires...Correct? &nbsp;In this case the car should have understeer. WAIT, i just reread some of the posts and I can see were you are right. &nbsp;But your drawing should be drawn i think to the following specs. &nbsp;stock FR should recieve the greatest load, stiff rear should recieve 2nd strongest load, followed by stock LF, and finally stiff LR

[silviaks]

I am thinking of getting some sway bars too...which ones yall think is better? WHITELINE or SUSPENSION TECHNIQUES???

[Grant]

either one is fine, if you want stifness adjustability, go with whiteline

[leadfoot_240sx]

Greddy makes a good front strut tower bar &nbsp;<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/thumbs-up.gif" border="0" valign="absmiddle" alt=':thumbsup:'>

[LanceS13]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Ballistic-Mobile.com @ Mar. 29 2002,9:41)</td></tr><tr><td id="QUOTE">WAIT, i just reread some of the posts and I can see were you are right. But your drawing should be drawn i think to the following specs. stock FR should recieve the greatest load, stiff rear should recieve 2nd strongest load, followed by stock LF, and finally stiff LR</td></tr></table><span id='postcolor'>
You're right...it was a very quick, rough and, conseqently, only fairly accurate sketch.

[Ballistic-Mobile.com]

Lance,
I didn't mean to call you out or anything agressive, just wanted to mak sure my understanding of physics was right <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'> . &nbsp;Thanks for clearing it up for me. &nbsp;What would you recommend (size) for the front and wear sway bars of an s13. &nbsp;I want to have a perfectly handling car much more than a very powerful car. &nbsp;There is a much reduced risk of death if your car handles beautifully and is a beast than just a beast.
thanks

[LanceS13]

I couldn't tell you that, b/c I only have a rear bar right now. &nbsp;(you don't want to go this route unless you like chasing your tail). &nbsp;Besides, my ideal setup may be different than your depending on driving styles. &nbsp;Popular sizes are 20-22mm rear and 27-29mm front. &nbsp;I suggest getting an adjustable bar like Whiteline so you can fine tune it to your liking.