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Discussion Starter · #1 ·
THAT is the question.


lol


Seriously, I just installed my new suspension last weekend and the car will be ready next weekend (it has to since I'm autoxing on the 20th).

I am running new spring rates (10K front and 8K rear).

I've read multiple posts about having a rear sway bar or not but I'm still not sure what difference it does exacly. I plan to do some testing on my first race weekend since I will autox for fun this year but I would like to hear from you guys before. Whether you are more into autox, lapping or time attack doesn't matter to me for now.

Btw, this year I will autox for fun since all my effort and money is going toward the Time Attack championship.
 

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In theory a sway bar is no different than a spring of the same rate, except the obvious differences in pure dive.

In practice, my cars always felt better without a swaybar at the drive axle (given equivalent wheel rates) and this seems to be the case for the majority of people no matter what car they drive.

Why this is I don't know. I don't believe in the theory that a sway bar mechanically "lifts" the inside tire off the ground or how there can be different amounts of load transfer given the same wheel rate. My theory is the better grip comes from a more independent suspension as each wheel is allowed to articulate on its own since there is no link between them (think live axle vs. independent suspension as an extreme example).
 

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My experience agrees with Roc, on both my 91 mr2 and my new 03. Swayless feels much better and is easier to drive imo, its very consistent.

If your not going to change your rates, I'd go with a larger front bar (~22mm che bar) and no rear bar. If you go swayless you need very high spring rates in order to compensate.
 

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Discussion Starter · #4 ·
Does having an LSD helps or changes anything? (swaybar wise)
 

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<------ You mean like this?

I don't believe in the theory that a sway bar mechanically "lifts" the inside tire off the ground or how there can be different amounts of load transfer given the same wheel rate. My theory is the better grip comes from a more independent suspension as each wheel is allowed to articulate on its own since there is no link between them (think live axle vs. independent suspension as an extreme example).
 

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Discussion Starter · #6 ·
Ha ha! I love that picture!
 

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I've been meaning to ask you to post the full sized picture. Can you post the full sized picture? ^_^

I lift tires without using any sways at all. But NOTHING like that. I've only ever seen it lift an inch or less on the inside front tire.
 

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<------ You mean like this?
The real question is would you get the same amount of wheel lift with the same front wheel rate using only springs. To get more wheel lift with a swaybar with the same wheel rates would indicate more load transfer and i dont think thats true

Plus the tire is equally as useless 1 inch or 1 foot off the ground :)
 

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I think the sway bar really prevents droop. I am not sure I have ever seen the wheel get lifted when jacking up a side. But I have seen the wheel prevented from dropping. Sway bars make it easier to change tires because you don't have to lift the car as much to get it off the ground. So I would say with the same spring wheel rate without the bar you would not get as much "lift" or limited droop. Now whether it is not touching the ground, I would think wheel spin coming out of a corner without a rear bar says that it is possible to unload a tire with just springs alone.
 

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I've been really, extremely happy with my front and rear Addco swaybars. I think that some owners think that installing a front or rear swaybar is too much trouble, so they advocate not having them. Then, they justify their decision by saying "you don't need them."

Ignore them.

When you beef up your front and rear sways and endlinks, the car feels seriously more planted and stable with virtually no roll or lean, and if either set of tires loses grip, recovery is MUCH more predictable and controllable.

After doing the front and rear swaybar install, when I hit Turn One in my housing area, it was a real OMG moment. That's when I realized that the stock setup was basically a lumbering, wallowing fat cow. The sways and endlinks just plant the car down solid and give you oh-so-much more control. Run, don't walk, to do this mod.
 

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I would think the sways are way easier to install than different springs. Although I can now change both front springs in 30 mins and both rear in 45 mins. The sways are at best a suspension band-aid fix to allow you to run soft springs and have a nice cushy ride without getting a lot of roll. They are a compromise. Stiffer sways should make your car feel faster than stock, but it does not mean it would be faster than a stiffer spring setup. Hopefully you can swap cars with someone else in your area and experience the difference at an autocross. You can have another OMG moment.
 

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I think the sway bar really prevents droop. I am not sure I have ever seen the wheel get lifted when jacking up a side. But I have seen the wheel prevented from dropping. Sway bars make it easier to change tires because you don't have to lift the car as much to get it off the ground. So I would say with the same spring wheel rate without the bar you would not get as much "lift" or limited droop. Now whether it is not touching the ground, I would think wheel spin coming out of a corner without a rear bar says that it is possible to unload a tire with just springs alone.
This is correct. However it will also depend on the length/travel of the struts. Short struts with little travel will also limit droop. An inverted BC coilover has 2 inches of travel on the rear. It won't droop much. So even without sway bars you can lift a wheel.

On my car the swaybar prevents full droop on the front. On the rear my swaybar endlink bracket and the endllink is adjustable so droop is not an issue.
 

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I've been really, extremely happy with my front and rear Addco swaybars. I think that some owners think that installing a front or rear swaybar is too much trouble, so they advocate not having them. Then, they justify their decision by saying "you don't need them."

Ignore them.

When you beef up your front and rear sways and endlinks, the car feels seriously more planted and stable with virtually no roll or lean, and if either set of tires loses grip, recovery is MUCH more predictable and controllable.

After doing the front and rear swaybar install, when I hit Turn One in my housing area, it was a real OMG moment. That's when I realized that the stock setup was basically a lumbering, wallowing fat cow. The sways and endlinks just plant the car down solid and give you oh-so-much more control. Run, don't walk, to do this mod.
SE, I don't just not run stiffer anti-roll bars, I took the stock bars off the car and run none at all. Your car will do better than mine in a drag race, and in street comfort, but nowhere else. For me, the real reason to not run bars is to eliminate a source of variability in the way the car handles as conditions change. On top of that, my car is more responsive and faster than yours and it is partly because I don't run anti-roll bars. Part of the problem here is that what feels fast and what is fast aren't always the same thing. A "no swaybar" setup isn't for everyone, but when the goal is a faster car, if anyone's advice warrants ignoring, it is the people who don't validate their conclusions with timing/race results :p

To the OP, without an LSD, no bar on the drive axle ftw. With LSD, setup compromised for street comfort, try matching the bar rate bias ratio to that of the springs to minimize handing variation with venue/conditions (if you can tolerate the ride quality of a higher front than rear natural frequency). Otherwise, 10% stiffer or so rear springs than front, a huge front bar, and a tiny or no rear bar. Personally, I find that the reduced torsional/ cowl shake motion from no bars a bigger ride benefit than the downside of the extra spring stiffness anyway...
 

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A roll bar should be used as a tuning device rather than an initial design item. This means that it should be used to obtain the optimal handling given certain circumstances, only after the rest of the suspension (in this instance especially the spring rates) were optimised. Typically, sway bars are used as tuning devices when one use a single suspension set up (same dampers and spring rates) for all tracks, and then use the roll bars to tune the suspension. However, I believe one should first adjust the dampers before you adjust the sway bar.

Typical Situation where above applies, would be when you will race on a bumpy track. First soften the damping, and then fine tune with sway bars. The sway bars will mainly assist with balancing of the car front to rear but on a bumpy track will often be contra productive, as it will unload a wheel where you do not want it to. But generally it should provide more good than bad, as you should simply reduce sway bar leverage on a bumpy track. In saying this, it probably is clear that I believe adding a non adjustable sway bar, is no good at all. It should be adjustable for height (used when doing corner weights) and should be adjustable to provide more or less leverage to increase or decrease load.

Now having said that, it may appear that I am saying one must add sway bars all round, which is not always true. I have seen GT cars without sway bars front or rear, and although I do not understand it, reckon those guys must know what they are doing. I pressume it is because the setup is already perfect and they are able to adjust damping and spring rates to the optimum. The Ultima also has no sway bars, and upon discussing it with them, Ultima reckons it is not required due to the stiffness of the suspension. It makes sense to a certain degree. A sway bar is used to assist with weight transfer management (especially roll of the vehicle) and if the spring rates are very hard, there should be minimal roll already.

If you use the car for gymkhana or autocross, I presume you may want a softer suspension if compared to track racing. You especially want the rear to provide best traction, which could mean that you need the front sway, but the rear is less important (general rule is stiffer front sway provides better traction on the rear, and vice versa). The front sway can then be used to provide more (increase the sway leverage) or less (decrease leverage) traction at the back and could in that way assist with overall balance.

Be it as it may, a sway bar is sometimes used as crutch to correct other issues with the suspension, and one should not fall into this trap. It could be that a car with no sway bar works better than one with two, as the rest of the setup is already very good. You will however then loose this as tuning device given different circumstances.

Another reason why you may find a car to handle better without sway bar, is that the sway bar is installed incorrectly. When doing wheel corner balancing, the sway bar must be disconnected at one side, and then be connected without causing load on either side at standard ride height. A sway bar may be connected causing load to one side, which will make handling unpredictable and the car may feel that it handles better without, but for the wrong reason.

In my view, adding a sway bar correctly, should assist under most conditions. I would propose that a sway bar is added at least at the non-drive end (with the spyder will be front end with drive at the back). But the sway bar should be the last adjustment being made to tune the suspension. A lot of guys reckon that adding a stiffer sway bar always makes the car handle better - I disagree. It depends on the rest of the suspension set up.

Apologies for the long post!
 

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This explains it better than I could near the bottom of the page "Springs vs Bars"
http://farnorthracing.com/autocross_secrets24.html

One of the real world problems with going to stiffer swaybars is they are supposed to be a "tuning" device and not the source of the majority of your anti roll resistance. However, with any swaybar stiffer than stock and normal coilover spring rates, roughly half of your body roll is being controlled by your swaybars. So its really not a fine tuning device at that point but in fact the opposite.
 

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A roll bar should be used as a tuning device rather than an initial design item. This means that it should be used to obtain the optimal handling given certain circumstances, only after the rest of the suspension (in this instance especially the spring rates) were optimised. Typically, sway bars are used as tuning devices when one use a single suspension set up (same dampers and spring rates) for all tracks, and then use the roll bars to tune the suspension. However, I believe one should first adjust the dampers before you adjust the sway bar.

Typical Situation where above applies, would be when you will race on a bumpy track. First soften the damping, and then fine tune with sway bars. The sway bars will mainly assist with balancing of the car front to rear but on a bumpy track will often be contra productive, as it will unload a wheel where you do not want it to. But generally it should provide more good than bad, as you should simply reduce sway bar leverage on a bumpy track. In saying this, it probably is clear that I believe adding a non adjustable sway bar, is no good at all. It should be adjustable for height (used when doing corner weights) and should be adjustable to provide more or less leverage to increase or decrease load.

Now having said that, it may appear that I am saying one must add sway bars all round, which is not always true. I have seen GT cars without sway bars front or rear, and although I do not understand it, reckon those guys must know what they are doing. I pressume it is because the setup is already perfect and they are able to adjust damping and spring rates to the optimum. The Ultima also has no sway bars, and upon discussing it with them, Ultima reckons it is not required due to the stiffness of the suspension. It makes sense to a certain degree. A sway bar is used to assist with weight transfer management (especially roll of the vehicle) and if the spring rates are very hard, there should be minimal roll already.

If you use the car for gymkhana or autocross, I presume you may want a softer suspension if compared to track racing. You especially want the rear to provide best traction, which could mean that you need the front sway, but the rear is less important (general rule is stiffer front sway provides better traction on the rear, and vice versa). The front sway can then be used to provide more (increase the sway leverage) or less (decrease leverage) traction at the back and could in that way assist with overall balance.

Be it as it may, a sway bar is sometimes used as crutch to correct other issues with the suspension, and one should not fall into this trap. It could be that a car with no sway bar works better than one with two, as the rest of the setup is already very good. You will however then loose this as tuning device given different circumstances.

Another reason why you may find a car to handle better without sway bar, is that the sway bar is installed incorrectly. When doing wheel corner balancing, the sway bar must be disconnected at one side, and then be connected without causing load on either side at standard ride height. A sway bar may be connected causing load to one side, which will make handling unpredictable and the car may feel that it handles better without, but for the wrong reason.

In my view, adding a sway bar correctly, should assist under most conditions. I would propose that a sway bar is added at least at the non-drive end (with the spyder will be front end with drive at the back). But the sway bar should be the last adjustment being made to tune the suspension. A lot of guys reckon that adding a stiffer sway bar always makes the car handle better - I disagree. It depends on the rest of the suspension set up.

Apologies for the long post!
Wow! We really disagree on most points. Interesting! I got started down the road towards no anti-roll bars based on someone else's advice, but I ended up with this setup because of my own testing. The number one benefit I see to no bars is that I don't need to change the setup for changing conditions. All permutations of setup that I had with bars I was constantly fiddling with for different venues, or weather, etc. I guess you'll have to trust (or not) that I know how to install suspension components correctly and didn't get to this conclusion erroneously.

Philosophically, I change springs (bars would be included in that if I had any) as a first line of change. I then change tire pressures and dampers as needed to go along with the spring change, not to adjust bias. I do not tune handling with dampers. I do not tune handling with tire pressures. Dampers and tire pressures have an ideal setting that go with the setup. In my view, anything else is giving up grip to get balance. So I setup balance with springs, where most of the lost grip at one end gets found at the other end. I acknowledge that a comfortable driver with a car that is performing under its theoretical best can be faster than a theoretically faster car that makes the driver uncomfortable. I'm just not willing to compromise on either side of this.

I don't reduce damping on bumpy surfaces. I don't increase it on smooth surfaces. Maybe I'm giving up some performance there, but I don't actually think so. At least not very much. I was surprised to find that my autocross specific setup worked otherworldly well on a road course, thought I do acknowledge that it is a fact that the fastest setup for autocross is going to be different from the fastest setup for a much higher speed, larger minimum corner radius track.

I agree that bars generally have no place on the driven axle of a properly setup race car.

If you use the car for gymkhana or autocross, I presume you may want a softer suspension if compared to track racing. You especially want the rear to provide best traction, which could mean that you need the front sway, but the rear is less important (general rule is stiffer front sway provides better traction on the rear, and vice versa). The front sway can then be used to provide more (increase the sway leverage) or less (decrease leverage) traction at the back and could in that way assist with overall balance.
As someone with a bit of experience on road courses and at autocross (much more so at autocross), I'll say your presumption doesn't make a lot of sense to me. For one thing, my biggest worry taking my car to road courses was that my setup favored steady state oversteer, which I felt wouldn't be exactly optimal on a road course. For another example, most serious track racers who don't have a ton of aero place some emphasis on ride natural frequencies. My ride natural frequencies break all the rules towards the stiff direction, axle pair ratios backwards, etc, and my car is substantially faster than it was with softer rates, for autocross.
 

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I should have said why on some of that....

You'll want more rear stiffness for lower speed events than for higher speed events because the direction changes are much more frequent, so we bias in favor of quick transitions and reducing corner exit understeer, where at higher speeds you want the stability to corner at the highest possible near-constant speed for seconds at a time, and there is more room for error in exit understeer and relatively less torque (after the smaller gear reduction of the higher gear) to create it.

You'll want more stiffness at lower speed because the bump input is less unsettling as a downside, and the benefit in quicker transitions is more important as an upside.
 

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Rocwandrer - you say that we disagree on lots of areas. I do not see the difference on many areas regarding sway bars, unless if I am not reading properly.
 

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Rocwandrer - you say that we disagree on lots of areas. I do not see the difference on many areas regarding sway bars, unless if I am not reading properly.
It seems hard to separate overall tuning philosophy from anti-roll bar tuning philosophy, but I guess if we limit the bar to a small portion of the roll control, then we don't disagree much on the bar part of the setup.
 
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