Not talking about street cars here, I’m talking about a very stiff sprung race car.

With the near infinite selection of spring rates, and the ease of swapping them (I got it down to under an hour now), do we really need anti-sway bars? Why not balance the car with springs only and drop the sway bars all together? Also the anti-sway bars are not light, and ditching them will save weight.

I admit the ability to fine tune with an adjustable sway bar is nice. After they are “tuned in” to the liking of the driver, however he/she often will not adjust them again. In this case why not just get the spring rates “tuned” without anti-sway bars. Please school me

 

Anti-dive and anti-squat.

When you hit the brakes the springs affect antidive, the sway bar does not. Similar with anti-squat. You can tune in less antidive with springs and and bar and still have the same wheel rate in roll, if that's what you want.

Also when it starts raining, one of the quick suspension tune things we used to do was quickly disconnect the sway bar. Don't know if that applies to a FWD car.


Modified by Grumpy at 9:03 PM 8/2/2004

 

I've been wondering about this very subject recently.

Grumpy makes a good point about the anti-dive that I didn't even consider. I'd like to hear what others have to say on this as well.

My CRX's suspension is based on high spring rates (500f/600r, not exactly "high"), with minimal OEM sway bars. I did upgrade the front to a DA Integra bar to stabilize it a bit, though I am having some trouble putting power down now (open diff). What benefit would getting a larger rear bar have for me, if any? I don't want to make the car any twitchier, so I am assuming that I should just leave it alone.

If I sound confused or am getting too far away from the subject, please excuse me.

 

i have so much to learn.

 

been pondering the same thing lately if stiff spring virtually eliminate body roll (or sway), then doesnt that reduce or eliminate the effects of a swaybar?

 

ha wht are you running now. I'm still on wussie 450 springs.

 

No the sway bar adds to the effect.

Its like your holding a 500 lb weight and someone tosses you 5 more pounds. Now you got 505.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Grumpy &raquo;</TD></TR><TR><TD CLASS="quote">No the sway bar adds to the effect.

Its like your holding a 500 lb weight and someone tosses you 5 more pounds. Now you got 505.</TD></TR></TABLE>
Is it really as simple as it sounds? I guess I just always thought there was more to sway bars than there really is.

 

Sway bars philosophy is more complicated that that, BUT the cumulative effect is sway bars add the force preventing roll.

 

While springs of course affect dive under braking and squat under acceleration, the terms anti-dive and anti-squat are traditionally used to describe properties of the suspension geometry and not related to spring rate. Anti-dive and anti-squat are varied by changing the location of the suspension pick up points and not by varying spring rate. A suspension can be set up for no dive whatsoever under braking irrespective of the spring rate, just by angling the suspension wishbones such that they intersect at the center of gravity, and then all the braking load is taken by the rigid suspension points instead of being reacted by the springs. Just a question of definitions. These are explained in many suspension books such as those by Carroll Smith, Alan Staniforth and Paul Van Valkenburgh.

Sway bars are used to increase the roll rate or stiffness during cornering and to allow more fine tuning of the oversteer/understeer balance than is possible with springs. This is done with first selecting the main bar rate via its diameter and then adjusting the end links to fine tune the balance. There is however one dis-advantage in using too stiff a sway bar, and that is in one wheel bumps, where the sway bar rate adds to the spring rate and may be too high to be properly damped if the damper is set for the spring only. Then the tire may not stay on the track and thus lose grip. I have very rarely seen any race cars without any bars at all, and they usually all use both a front and rear roll bar. Next time you go to a race, have a look. It is possible to dispense with the front bar on a FWD car, but not everyone thinks that is the fastest way around the track. One of the purposes of running without a bar at the power end of the car is to increase traction under acceleration by more equally loading the tires when coming off a corner.

 

dont need them on drag cars

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Sway bars are used to increase the roll rate or stiffness during cornering and to allow more fine tuning of the oversteer/understeer balance than is possible with springs.</TD></TR></TABLE>

Tue, but with springs coming in 10lbs/inch increments you can get down to some fine tuning there as well and reach the same roll resistance you had with the sway bars.

 

A swaybar adds rate in a nonlinear fasion unlike a spring (linear force per deflection). The effective moment arm is proportional to the cosine of the rotation angle (nonlinear); it gets smaller as the angle increases from zero, thus the torsion on the swaybar is less so it deflects less. This is a positive in my eyes, since the swaybar adds more rate when the springs are deflected more, which will better keep you off your bumpstops and reduce roll/pitch under higher g-loads. Though the effect is smaller on a stiffer race car where stiff springs don't deflect much and thus the bar doesn't rotate a whole lot.


Modified by GSpeedR at 11:13 AM 8/3/2004

 

So the consensus is that the stiffer the springs, the less effective swaybars are. But what about other characteristics of the car? Ive heard people tell me if you remove the front bar, the car "feels loose", and doesn't "react as fast". How can we put these impressions into more technical terms?

 

This is a very complicated topic and one not simply solved, there are soooo many variables. One thing not mentioned is the CG-to-roll center distance which makes a big difference on how effective sway bars are. If the roll center is placed at the CG, sway bars have no effect since the car doesn't roll. A good thing you say? Well, no, because now the car can't be tuned. OTOH, putting the roll center low prevents jacking, a good thing, but then the car leans more, so bars work well in this case. Of course having sway bars isn't great because it make independant suspension less independent. They're heavy too. The biggest fault of them is that they work by the following principle: Sway bars tune the suspension by decreasing grip at that end of the car. Yes, you're making the tires stick less by using sway bars. This cannot be good. Yet it works because it allows the car as a whole to be faster even though traction has been compromised at one end. In a perfect world the suspension would be designed from the start so no bars are needed... but that's hard to do.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote"> Sway bars tune the suspension by decreasing grip at that end of the car [i]and increasing grip at the other end.[i] </TD></TR></TABLE>

fixed it for ya!

nate

 

I think it "relatively improves" the other end, but I'm not sure that's in an absolute sense.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 577HondaPrelude &raquo;</TD></TR><TR><TD CLASS="quote">With the near infinite selection of spring rates, and the ease of swapping them (I got it down to under an hour now), do we really need anti-sway bars? Why not balance the car with springs only and drop the sway bars all together? Also the anti-sway bars are not light, and ditching them will save weight.</TD></TR></TABLE>

This right here is actually refered to as "Old School German Suspension Tuning". Do everything with springs.

My car uses a rear bar but no front bar and not only am I able to achieve a very nice amount of oversteer in my ITA crx but I can power out of the corners pretty well even without an LSD.

A good person to chime into this thread would be CRX Lee.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote">I think it "relatively improves" the other end, but I'm not sure that's in an absolute sense.</TD></TR></TABLE>

nope, it's pretty absolute as far as weight transfer distribution is concerned. there are instances were increased roll stiffness on one end of the car actually improves grip on the same end, but that's more a function of terminal roll angle vs. static camber and dynamic camber gain.

nate

 

I agree with Grumpy on this. Sway bars add roll stiffness and not compression stiffness. From the things I have experienced and come acrossed, there are basically two opinions when it comes to suspension tuning.

1. stiff springs and stock or no bars.

2. soft springs, big bars and custom valved shocks.

I personally go by idea # 2, for the following reasons. When picking spring rates I consider stability and cornering power. Stiffer springs inprove stability, but reduce corner power and soft springs reduce stability, but improves cornering power.

Also one of the major reasons for stiffer springs is to reduce roll/sway. But because we can reduce roll by utilizing anti-sway bars, the springs don't need to be as stiff. Which would result in a set up that is compliant over bumps and berms, but would have enough roll stiffness to be stable in the corners. For an example of this, look at the circle track guys. They have come full circle from super stiff spring rates to soft springs (around 175lb rear); just stiff enough to prevent bottoming. Now they tune with bars and shocks.

If you read one of the best books on handling, Fred Puhn's "How to make your car handle" he states the same philosophy. Do all your tuning with shocks and bars, then use a spring that is just stiff enough to prevent the car from bottoming out.

just my $.02

 

Very interesting thread

I know Lee Noble hates sway bars, which is why the M12 GTO is designed not to use them.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DTMotorsports &raquo;</TD></TR><TR><TD CLASS="quote">....use a spring that is just stiff enough to prevent the car from bottoming out.
</TD></TR></TABLE>

Uh-huh. At what ride height?

Scott, who wonders why we aren't all putting lift kits on our kaa's...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">But because we can reduce roll by utilizing anti-sway bars, the springs don't need to be as stiff. Which would result in a set up that is compliant over bumps and berms, but would have enough roll stiffness to be stable in the corners.</TD></TR></TABLE>

A stiff sway bar is NOT compliant over berms or curbing when just the inside 2 tires are on them, in that case sway bars make the car stiffer. The ONLY time the sway bar is NOT adding to the spring rate of the compressing side is when both sides are compressing the same amount at the same time (ie over a lateral bump that both tires hit at the same time). You also state that soft stings and stiff shocks make for a very compliant suspension over bumps. I don't think this it true because the stiff shocks will be very harsh over a bumps especially at race speed.

If you can get the car tuned in with just srpings and shocks (I don't see why you could not), I fail to see the use of thick heavy sway bars. However, I can see the use of small diameter adustable sway bars (20ish mm) on both ends for real fine tunning.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 577HondaPrelude &raquo;</TD></TR><TR><TD CLASS="quote">
The ONLY time the sway bar is NOT adding to the spring rate of the compressing side is when both sides are compressing the same amount at the same time (ie over a lateral bump that both tires hit at the same time).</TD></TR></TABLE>

You're right, don't know what I was thinking when I typed berm. I meant when both sides were compressed at the same time.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 577HondaPrelude &raquo;</TD></TR><TR><TD CLASS="quote">
You also state that soft stings and stiff shocks make for a very compliant suspension over bumps. I don't think this it true because the stiff shocks will be very harsh over a bumps especially at race speed.
</TD></TR></TABLE>

When I mentioned custom valved shocks I was referring to rebound valving versus compression. I should of been more specific. Ultimately I meant to say that controlling the amount and rate of roll was more important than actual stiffness. But like with everything else there is always that middle point, just depends what side you are on, when tuning.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rice_classic &raquo;</TD></TR><TR><TD CLASS="quote">This right here is actually refered to as "Old School German Suspension Tuning". Do everything with springs.</TD></TR></TABLE>
I buy into this method, not so much because I believe it is better than the sway bar method, but because I've seen people tearing rear subframes from the chassis when using large bars in conjunction with soft springs. I fear putting too much stress on the rear subframe of my weakened rust bucket.

Although this problem may be limited to street stunnas who "tackle the mountain passes" with cut stock springs, blown shocks, and sway bars bigger than anyone in their right mind would dare to put on an actual race car . . . has anyone here had any problems with sway bars tearing rear subframes in their EF race cars? Is there anything I could do to help prevent such a thing from happening?

Sorry if I am going too far OT.