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Discussion Starter #1
OK, what is a swaybar and what does it do?

When you ask most tweakers this question, the answer you get is "It reduces body roll." When you follow on and ask, why is this good, the answer you get is "It reduces weight transfer by keeping the body level."

While the first answer is completely correct, the second answer is totally wrong.

Let's talk about weight transfer. Only one factor determines the % weight transfer in a curve. That is the angle from the center of gravity to the outside wheel. Therefore, there are only three ways to reduce lateral weight transfer.

1) Move the center of gravity further away from the outside wheel. -- This works great on oval tracks. Kind of useless for the street as you get closer to the other wheel when you do this.

2) Lower the center of gravity - usually by dropping the ride height, but racers do all kinds of things to lower their CG.

3) Widen the track - fender flares (think 1985 BMW M3), etc.

I'll avoid a lenghty discussion of how weight transfer effects tire grip. Let's just say for now that the more heavily loaded a tire is, the less effecient it is in carrying its appointed lateral (turning) load.

So, if body roll is not a factor in weight transfer, why do you worry about it? The answer is that it is a secondary issue, not nearly as important as weight transfer. Body roll can have three effects:

1) Annoy the driver
2) Lessen tire performance through camber changes
--NOTE: Double wishbone suspensions compensate for this effect very effectively and only experience issues at extreme body roll angles - this is why Honda is so commited to this suspension geometry across its line (as much as possible)
3) Make left-to-right transitions slower

I'm sure you are saying at this point:
Enough already - tell me about swaybars. :sleep:
The reason swaybars are important is that they do have an important effect on weight transfer.

A swaybar is just a spring that couples one side of the suspension to the other with a given spring constant. (A coil spring is just a tortion spring wound into a helix, actually.) It carries the force of the weight transfer as opposed to having that force transmitted through the coil spring to the frame to the other three coils.

The reason the swaybar is important is that it transfers the weight to only one other coil, not the other three. Therefore, you can use swaybars to tune the amount of weight that is transferred to the front or rear axle because of the LATERAL weight transfer.

It is desirable for stock FWD cars to understeer, that is have the front wheels loose lateral grip before the back ones. The reason is that if a FWD car OVERSTEERS, the best way to get out of the skid is to floor the accelerator. As you can imagine, this could cause serious trouble for soccer moms. (Read lawsuit, or perhaps a book titled Unsafe at Any Speed.)

A favorite techinque to make sure that you get a car that understeers happily in emergency maneuvers is to have the weight transfer preferentially on the front axle. This means putting a big swaybar up front and little or no swaybar in the back. This puts lots of load on the front, outside tire, and it slips accordingly. This is also a major reason that front tires wear so much faster on FWD cars. (You can guess the other reason.)

Note: the weight transfer to the front happens because the stock-configured car will stick its butt waaaay up in the air when cornering hard while the nose will dive

Well, we aren't soccer moms (or if we are, we don't drive like our peers). We know that there is better handling to be had if we neither understeer or oversteer, but handle neutrally when under full throttle.

Therefore, the quickest, cheapest, easiest way to rememdy the situation is to match the front swaybar with a slightly smaller rear swaybar. This will even up the weight transfer so that near equal weight is on the two outside tires, as opposed to only one of them.

We still want a little understeer on the street, as snap oversteer is BAD, not to mention scary. I thank God that it has only happened to me on an autocross course.

Note: Snap oversteer is where the car oversteers suddenly and without much warning. It is very hard to recover from without VERY quick wrists, espically on a FWD car.

That's the story of swaybars - the real empasis on a double-wishbone equipped car is really to balance the weight transfer between the front and rear axles. The advantage of using a swaybar without changing springs is that you retain your stock ride quality.

I love my swaybar. It have me 5mph in corners on the stock doughnuts. On a Cvic, keeping the revs up in those corners is worth many, many horsepower. The result is even better on the Si Rims. I was a little surprised at the sensation that the tail just tucks in now and doesn't rise. Now I'm just spoiled. Beyond upgrading my shocks for ride quality reasons (the Si rims threw off the suspension tuning, much to my surprise), I plan to make no additional suspension modifications. I am, believe it or not, happy.

Please feel free to post any additional questions.
 

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shorthand said:

So, if body roll is not a factor in weight transfer, why do you worry about it? The answer is that it is a secondary issue, not nearly as important as weight transfer. Body roll can have three effects:

1) Annoy the driver
2) Lessen tire performance through camber changes
--NOTE: Double wishbone suspensions compensate for this effect very effectively and only experience issues at extreme body roll angles - this is why Honda is so commited to this suspension geometry across its line (as much as possible)
3) Make left-to-right transitions slower

Please feel free to post any additional questions.
Hmm, I think its also important to note that the reduction in body roll frees up additional suspension travel that would otherwise be taken up. It also gives a crisper turn-in.

What are your thoughts about that?
 

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Very informative post! As we've stated in another thread, we really cant suggest on what sway bars to buy. It's really what the driver needs/wants.
 

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Discussion Starter #5
Crisper turn in is essentially the left-to-right transition bit, just half of it. God knows its true, the feel is much crisper. My EX stock you turned the wheel and waited a bit. You got used to it, but it was annoying and definitly brought it negative marks in the auto mags. Now it turns quite crisply. You can actually feel the sidewalls roll in.

I guess it frees up some suspension travel, but I'd say its only a big difference when you hit a bump while cornering hard. You still need stiffer springs to drop a car b/c of straight line bumps.

My point, at the end of the day, is that you generally want to match your front and rear swaybars (assuming the same spring rates on all four corners).

A swaybar is just a hunk of spring steel with bushings and mounting points. Brand matters little. That's why there's no need to replace the stock front swaybar. If you want to, you might replace the rubber bushings with polyurethane to remove some of the play in the setup, but that's it.

That's also why the suspension techniques bars are good and cheap. It has a 1st class mounting kit that will resist tear out pretty well on weak subframes, and besides that it is a hunk of spring steel (just an unwound coil spring). Aluminum might be lighter but it doesn't have the same elastic properties.

If you have a front bar, you're usually best just buying a rear to match. There is little need to replace the front bar with something nearly identical. If you're running a stock class, you actually might want to consider getting a smaller front bar to even things up. (Solo stock classes can't touch the rear swaybar, but can modify the front.)
 

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shorthand said:
Crisper turn in is essentially the left-to-right transition bit, just half of it. God knows its true, the feel is much crisper. My EX stock you turned the wheel and waited a bit. You got used to it, but it was annoying and definitly brought it negative marks in the auto mags. Now it turns quite crisply. You can actually feel the sidewalls roll in.

I guess it frees up some suspension travel, but I'd say its only a big difference when you hit a bump while cornering hard. You still need stiffer springs to drop a car b/c of straight line bumps.

My point, at the end of the day, is that you generally want to match your front and rear swaybars (assuming the same spring rates on all four corners).

A swaybar is just a hunk of spring steel with bushings and mounting points. Brand matters little. That's why there's no need to replace the stock front swaybar. If you want to, you might replace the rubber bushings with polyurethane to remove some of the play in the setup, but that's it.

That's also why the suspension techniques bars are good and cheap. It has a 1st class mounting kit that will resist tear out pretty well on weak subframes, and besides that it is a hunk of spring steel (just an unwound coil spring). Aluminum might be lighter but it doesn't have the same elastic properties.

If you have a front bar, you're usually best just buying a rear to match. There is little need to replace the front bar with something nearly identical. If you're running a stock class, you actually might want to consider getting a smaller front bar to even things up. (Solo stock classes can't touch the rear swaybar, but can modify the front.)
I agree for the most part, but i think that upgrading the front sway bar could be needed if a LARGE rear bar is being added. For someone like myself, i currently have a 22mm aftermarket rear sway bar with the oem front. The setup is nice, but i have too much front body roll, which is causing the car to get upset and lift the inside rear tire quite easily. Killling some of that with a larger front sway bar will match the car better, but then to offset the added understeer, im also moving up to a 25.4mm rear sway bar.
 

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does anyone make sway bars for a 95 accord ex sedan? anyone have a 95 accord set up and really liek it? thanks.
 

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Discussion Starter #8
PseudoRealityX said:


I agree for the most part, but i think that upgrading the front sway bar could be needed if a LARGE rear bar is being added.
I agree completely - the first thing you must do with swaybars is balance them front and rear. If you're putting one in the rear that is sitffer (larger) than the front, you'll probably have to upgrade the front also. However, before you go that far, I'd recommend you seriously start factoring in your coil spring rates (and therefore shocks also).
 

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You know guys, just because they look the same size on the outside doesn't mean that they are the same on the inside. I bought a front and rear sway bar kit from Suspension Techniques and what a difference it made to the handling of the car.

Do you think the bars are different if the aftermarket one weighs about 10 times more? Hell yea! A lot of stock sway bars are hollow inside!!!
 

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95AccordWagonLX said:
You know guys, just because they look the same size on the outside doesn't mean that they are the same on the inside. I bought a front and rear sway bar kit from Suspension Techniques and what a difference it made to the handling of the car.

Do you think the bars are different if the aftermarket one weighs about 10 times more? Hell yea! A lot of stock sway bars are hollow inside!!!
Very true, and there are easy calculations to figure out what the hollow equivalent would be, but of course, i forget them right now.
 

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jesse, springs!!!!!!!! aren't you running on the factory springs still??? if so i would highly recommend upgrading the springs. doing that will help keep the rear tire planted and reduce your camber loss, increasing the amount of grip at the front of the car. keep in mind as well that suspension geometry has a big affect on how effective sway bars and springs are. and sway-bars are only half of the equation, springs are the other half. after all, the only thing the sway bar has to push against is the inside spring.
solo-x
 

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if i put larger sway bars (front & back), would it be too stiff to tear-off the body mountings?

let's say i'll put type-R sway bars on my SiR civic ( if it fits)
 

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solo-x said:
jesse, springs!!!!!!!! aren't you running on the factory springs still??? if so i would highly recommend upgrading the springs. doing that will help keep the rear tire planted and reduce your camber loss, increasing the amount of grip at the front of the car. keep in mind as well that suspension geometry has a big affect on how effective sway bars and springs are. and sway-bars are only half of the equation, springs are the other half. after all, the only thing the sway bar has to push against is the inside spring.
solo-x
Nope, im currently running Suspension Techniques Sport Springs. Im unsure of the rates, but they lower around 1". Plus, im saving up for some GCs that ill have custom rates put in. The hot setup seems to be about 325front and 250 rear for my car.
 

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Discussion Starter #14
Alien - the whole point of the article is that bigger is not better with swaybars. Just match the front and rear up and then concentrate on your coil springs and shocks.

Body roll is no big deal for those of us with double wishbones on all four corners (that includes all 92-00 civics & integras, and almost every other Honda - Honda has made a huge commitment to the double-wishbone suspension geometry, and only abandoned it on the Civic out of necessity IMO.)

I don't know how big the TypeR rear bar is, but the rule of thumb is 19mm's won't tend to tear out, but 21's and 22's will. The steel you're drilling through is darned near sheet metal.

The brackets make a huge difference. Make sure its not held on to the subframe with just bolts and washers. There must be a solid backplate that transmits the force from the bolts to the subframe.
 

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shorthand said:
Alien - the whole point of the article is that bigger is not better with swaybars. Just match the front and rear up and then concentrate on your coil springs and shocks.

Body roll is no big deal for those of us with double wishbones on all four corners (that includes all 92-00 civics & integras, and almost every other Honda - Honda has made a huge commitment to the double-wishbone suspension geometry, and only abandoned it on the Civic out of necessity IMO.)

I don't know how big the TypeR rear bar is, but the rule of thumb is 19mm's won't tend to tear out, but 21's and 22's will. The steel you're drilling through is darned near sheet metal.

The brackets make a huge difference. Make sure its not held on to the subframe with just bolts and washers. There must be a solid backplate that transmits the force from the bolts to the subframe.
Correct, and honestly, you should tune understeer/oversteer with the spring rates first, and then worry about sway bars.
 

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shorthand said:
Only one factor determines the % weight transfer in a curve. That is the angle from the center of gravity to the outside wheel. Therefore, there are only three ways to reduce lateral weight transfer.

1) Move the center of gravity further away from the outside wheel. -- This works great on oval tracks. Kind of useless for the street as you get closer to the other wheel when you do this.

2) Lower the center of gravity - usually by dropping the ride height, but racers do all kinds of things to lower their CG.

3) Widen the track - fender flares (think 1985 BMW M3), etc.

There are 3 factors that determine the amount of lateral weight transfer in a corner.
1. The height of the car's center of gravity
2. The amount of centrifugal force acting on the CG
3. The track width of the car
You can calculate the amount of weight transfer with this formula: (Centrifugal force * CG height)/Track width - centrifugal force is in pounds, CG height and Track width in inches.

So the only ways to reduce the total amount of lateral weight transfer are:
1. Increase the track width of the car
2. Lower the height of the CG
3. Reduce the car's weight

In a turn, the centrifugal force on the CG of the car creates a torque around the roll axis (because the roll axis is below the CG on all conventional cars). This torque is called the total roll couple, and leads to body roll.

The total roll couple rotates the body of the car around the roll axis, which is the movement that the suspension's roll stiffness is resisting. You cannot change the total amount of force acting on the roll axis except by one of the three ways listed earlier...however, you can change how that weight is distributed. The force acting on the roll axis is resisted by both the front and rear roll stiffness of the car, and the percent of the total lateral weight transfer each end of the car gets is simple to find out. You just take the roll stiffness of the front and divide by the total roll stiffness of the suspension (same for the rear)...this gives you what percent of the weight transfer is loaded onto each end of the car in a turn.

Adding a larger rear anti-roll bar does three things: it increases the roll stiffness of the rear, and it increases the total roll stiffness (assuming the front bar, and the springs are not changed), and because the total roll stiffness has been increased it reduces the degrees of body roll experienced in a turn. This will increase the percent of weight transfer that the rear of the car will get in a turn. But you were talking about why this is good...well, shorthand said that body roll can disrupt the driver, which is a major consideration, so reducing the total amount of body roll can be really beneficial. Also, it reduces the amount of weight placed on the outside front tire, which is the tire doing most of the work in a turn. Since that outside front tire is doing a few jobs already (turning and accelerating at the same time for example) we want to reduce the amount of weight transfered onto it so that it can grip better because we won't be using any of its available traction for a third purpose. So this helps the front tires grip better, increases the amount of lateral weight transfer handled by the rear of the car, and with the combination of the two it reduces the amount of understeer you experience.


This is by no means a complete discussion, that would be way too long, but hopefully it helps you understand anti-roll bars a little better along with Shorthand's post. I think I may have gotten a little too technical, so if there is something that isn't clear, just let me know, and I'll try and explain it a different way.
 

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PseudoRealityX said:


Nope, im currently running Suspension Techniques Sport Springs. Im unsure of the rates, but they lower around 1". Plus, im saving up for some GCs that ill have custom rates put in. The hot setup seems to be about 325front and 250 rear for my car.
After talking with a few guys, im fairly certain that the new rates will be 250 lbs front and 200 in the rear. I know that doesnt sound like much to you honda folk:), but its on the edge of streetability in my car.
 

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that will make a huge difference. my roommates golf III had h&r sport springs which are virtually the same as the st sport springs and switched to shine racing springs (225#fr 120#rr) night and day difference with the turn-in and reduction in body roll. mac strut suspensions due have one flaw, and that is that they love to pull up the inside front tire. shine racing does the vw's with no front bar and a large rear bar. i'll let you guys know how the golf performs, i'm betting its going to be hella fast.

honda doesn't actually get all that spring rate to the tires. wheel rate on my car is about what you're planning on going to. i'm guesstimating because i can't find any literature anywhere that tells me the spring rates that i have right now. maybe next season will find some nice koni double adjustable coil-overs on my car. :)
 

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Discussion Starter #19
Re: Re: Swaybar Physics

Bampf said:

You can calculate the amount of weight transfer with this formula: (Centrifugal force * CG height)/Track width - centrifugal force is in pounds, CG height and Track width in inches.
That's why I phrased my whole discussion in terms of % weight transfer, not net pounds. In other words, we're both right. However, perhaps net pounds is a better way to model the nonlinear terms in tire friction. I'm not sure - there's a great autocross physics site from someone who has a higher degree than I in the subject. Of course, with all those equations, I'm not sure that those without a bachelors in physics can really read it.


In a turn, the centrifugal force on the CG of the car creates a torque around the roll axis (because the roll axis is below the CG on all conventional cars). This torque is called the total roll couple, and leads to body roll.
Never before has one of these anti-roll discussions gotten deep enough that I wanted to discuss heave, but I think its time. There is one more thing that will cause higher weight transfer in a turn - that's heave. Heave occurs when the lateral force lifts the car's center of gravity some. Its been forever since I studied suspension, but I believe that it occurs when the CG is above the roll axis. Roll axis is determined completely by suspension geometry.

I know that in many situations, this is a more dominant effect than body roll itself in terms of grip, again espically in double-wishbone suspensions. I also remember that while raising the roll height will reduce roll, it will increase heave, which might well be worse in some cases. Dropping a car will reduce roll height, as I remember. If it reduces roll height quicker than CG, you might actually increase % heave, though this is greatly outweighed by the benefit of simply dropping the CG.
 

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solo-x said:
that will make a huge difference. my roommates golf III had h&r sport springs which are virtually the same as the st sport springs and switched to shine racing springs (225#fr 120#rr) night and day difference with the turn-in and reduction in body roll. mac strut suspensions due have one flaw, and that is that they love to pull up the inside front tire. shine racing does the vw's with no front bar and a large rear bar. i'll let you guys know how the golf performs, i'm betting its going to be hella fast.

honda doesn't actually get all that spring rate to the tires. wheel rate on my car is about what you're planning on going to. i'm guesstimating because i can't find any literature anywhere that tells me the spring rates that i have right now. maybe next season will find some nice koni double adjustable coil-overs on my car. :)
Yup, i have a buddy building a first gen Scirocco for SM. His suspension setup sounds assbackwards, but its seen success with other drivers, so hes going to use it.

And yeah, i understand wheel rates, but since the VAST majority of hondas use the Double wishbone, i threw that in there so someone didnt try to tell me to use like 500# rear springs.
 
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