The more I read about sway bars the more I think they are unneccessary

[SlowJim]

Hey all,

I think, like most others, I fell victim to the marketing of sway bars and thought they "increased grip by reducing body roll". They were my first mod on my 350Z, before I even did coilovers. When I read explanations like this and this, I am starting to realize if you have the right spring rates you will see zero benefit by upgrading sway bars, even during road course conditions using fat R-comp tires.

Am I wrong here? Everything I am reading says a stiffer sway bar reduces grip. If one is to select stiff enough spring rates, have their car corner balanced, use non-staggered tire sizes, etc. - can sway bars potentially do more harm than good?

 

[Vorshlag-Fair]

You are oversimplifying the benefits of larger and adjustable anti-sway bars. These exist even on F1 cars (and don't even get me started on FRIC, which is essentially a front-to-rear hydraulic swaybar system used in F1 - until it was banned), and they do have their place on all modern sports cars when used in competition. Yes, many people go to big swaybars FIRST and they often get used as a CRUTCH for proper spring rates. That is very very true. But even when you have increased spring rates DRAMATICALLY firmer than stock, with appropriate dampers to match, you will likely still benefit from larger than OEM bars.

Don't take every damned thing you read on the interweb at face value - even what racers or suspension designers or vendors (like me) write. The only way to REALLY know what works is to TEST IT. I have 27 years of competition experience so I have built my own set of "theories" but I always question the "common way of thinking", even when it is my own. When we had tripled the front spring rates on our Mustang (above) with AST dampers we did a timed autocross test. Using BIG adjustable Whiteline swaybars at both ends we did a full sweep on each bar, from softest to firmest settings, and we let THE CLOCKS DECIDE what was faster. Guess what? Full stiff on each bar produced the lowest lap times. I would NOT have guessed that.

We eventually took the tripled spring rates and DOUBLED them again, and now we need LESS bar, but we still dial in what the clocks say is faster. Even with 800 #/in springs we still get some serious body roll without some swaybar in there to control things...

 

[csamsh]

Are swaybars on some cars unnecessary for controlling body roll? Maybe?....because the body roll could be controlled in other ways. It's all wheel rate

e.g., look at this Porsche 962...the little tube right in front of that heat exchanger. I suspect this may be present more for tuning out some sort of frequencies than actually controlling roll

 

[jayel579]

Sway bars are a tuning piece within the entire suspension system. Everything has to work in balance with each other (Tires, Shocks, Springs, Bars, etc). There isn't a magic bullet that cures handling and even if there was, your magic bullet may not work for me. I read a lot here of what guys run and question in my mind why they do that because that doesn't work for me and my car but I never say they are wrong unless it is an obvious basic rule breaking idea.

 

[sheizasosay]

Adj swaybars are a very good investment.

 

[Eel Mit]

Sway bars allow you to use a softer coil spring for better street manners.

They are essentially an unwound spring similar in action to a torsion bar, except they are not under constant tension. They only spring into action when the car leans hard to one side, adding the spring rate of the suspension.

 

[JAJ]

The McLaren MP4-12C road car doesn't have sway bars and it handles pretty well.

 

[GrabberBlue5.0]

The McLaren MP4-12C road car doesn't have sway bars and it handles pretty well.

A $300000 car is an exception to the rule. It has been engineered without them and likely already has a very stiff carbon fiber chassis

 

[Whiskey11]

A $300000 car is an exception to the rule. It has been engineered without them and likely already has a very stiff carbon fiber chassis

I'm pretty sure the McLaren also has active suspension components that fight roll through other means.

 

[GrabberBlue5.0]

I'm pretty sure the McLaren also has active suspension components that fight roll through other means.

You're probably right, I don't know much about that car, but I think it's a dumb comparison to a mustang lol, that's all I was really getting at.

 

[DILYSI Dave]

Sway bars are a good "Phase 1" type mod on a dual purpose car because they increase the wheel rate in turns without increasing it on straights. This means that the car does corner flatter with better camber control, etc., without the harshness that comes full time with stiffer springs.

That said, no - that doesn't make them irrelevant in a world of infinite springs. I have tuned a car on this theory, and it was good. Then in an effort to prove that I was right to a friend, I started playing with swaybars and to my dismay, the car got better. What I discovered was that even with sufficient spring to support the car, control roll, control the contact patch, etc. - swaybars added the ability to dynamically shift the corner weights in the car. In my Civic, a bigass rear swaybar had the effect of allowing me to roll into the throttle sooner and harder without generating wheelspin, because the swaybar's moment upon the chassis ended up pushing the inside front wheel into the ground. In the same way, a bigass front bar in the Mustang helps it put power down.

Now in my civic, I did run with no front bar. This was because the rear wheels in a FWD pretty much just keep the bumper from dragging. I could get all of the rear wheel control I wanted without the dynamics of a front swaybar.

 

[jayel579]

Sway bars are a good "Phase 1" type mod on a dual purpose car

I think I would have to disagree with you here and say better shocks would be the better step one modification.

 

[SlowJim]

Thanks to all for the well-thought out responses. I love how this site basically gives me a direct line to the top S197 handling experts in the country. Most of the other Mustang forums I've been on seem more about big power garage queens.

I think I'll start out with a front sway bar only and go from there, since the Eibach pro-kit on my car has a fairly high rear rate.

 

[csamsh]

Thanks to all for the well-thought out responses. I love how this site basically gives me a direct line to the top S197 handling experts in the country. Most of the other Mustang forums I've been on seem more about big power garage queens.

I think I'll start out with a front sway bar only and go from there, since the Eibach pro-kit on my car has a fairly high rear rate.

Just make sure it's adjustable, whatever it is!

 

[Dubstep Shep]

As many have said, there are vehicles that do not have sway bars.

That said, it's a bit idealistic to say that would be the best setup on our vehicles.

The height of the CG vs the width of the car really effects the roll, so those lower, wider cars have an inherent advantage over a taller skinnier one. Their mass produces less roll, and the wider wheels mean a lower spring rate can counter more roll.

Could you run enough spring on our cars to not need a sway bar? Maybe. But the spring rate would be so high it would handle like crap.

 

[DPE]

I'm not in the realm of expert by any means, but I've done a lot of chassis tuning on a number of different platforms over the years. As has been made clear, it's the combination of parts and what you want the car to do that dictates what you should do about swaybars.

If you have the budget to make spring/damper/camber-correction/swaybar changes, in my mind swaybars on the S197 are the last thing to buy. The shocks are really, really bad on these cars IMO, and are the first thing to remedy. With shocks, springs and camber correction, you then see where you're at and can use swaybars to fine-tune balance or increase/decrease roll stiffness at one or both ends if you think you need to.

Of note, Strano's adjustable rear bar in its softest setting is actually notably softer than the OEM 2011+ GT rear bar. And I happen to agree with him that in stock form this car feels like it has too much rear bar (especially compared to my 2010 GT, which had a roughly 50% softer rear bar than my 2014 Brembo GT does). So while it's typical to get swaybars to increase overall roll control (and that is of course the correct route in many applications), in some situations 'less is more'.

 

[BMR Tech]

I hope they need sway bars - or we just wasted over a year of our time, on the new bars we are about to release in a few weeks. Doh! lol

Sway bars are always an interesting topic. The bars we recently designed, are stiff. Real stiff, actually.

The fronts, we went real big on. The rears, we went right below the rate of a Boss LS....and up substantially higher than anyone offers. Few reasons behind that, including the ability for a corner carver, a standing mile racer, a drag racer, and a daily driver - to be able to utilize one of the 4 options of adjustment.

Most of our customers are "soft spring, big bar" kinda people. We felt that was the best arena to cater to.

 

[cbass]

I had this conversation with a friend about 10 years ago. He said sway bars are a bandaid for improper springrates. I countered that shocks are a bandaid for a flawed spring design.

He still pulled them. Everybody was faster than him.

 

[sheizasosay]

I had this conversation with a friend about 10 years ago. He said sway bars are a bandaid for improper springrates. I countered that shocks are a bandaid for a flawed spring design.

He still pulled them. Everybody was faster than him.

Fred Puhn says they are the bang for buck champ.

 

[rextang]

Sway bars are a good "Phase 1" type mod on a dual purpose car because they increase the wheel rate in turns without increasing it on straights. This means that the car does corner flatter with better camber control, etc., without the harshness that comes full time with stiffer springs.

That said, no - that doesn't make them irrelevant in a world of infinite springs. I have tuned a car on this theory, and it was good. Then in an effort to prove that I was right to a friend, I started playing with swaybars and to my dismay, the car got better. What I discovered was that even with sufficient spring to support the car, control roll, control the contact patch, etc. - swaybars added the ability to dynamically shift the corner weights in the car. In my Civic, a bigass rear swaybar had the effect of allowing me to roll into the throttle sooner and harder without generating wheelspin, because the swaybar's moment upon the chassis ended up pushing the inside front wheel into the ground. In the same way, a bigass front bar in the Mustang helps it put power down.

Now in my civic, I did run with no front bar. This was because the rear wheels in a FWD pretty much just keep the bumper from dragging. I could get all of the rear wheel control I wanted without the dynamics of a front swaybar.

Dave, I used your advice to great benefit years ago on my CRX. I ran HDPE events experimenting with and without the front bar and with the rear adjustable on max stiff. Thank you very much for that tip. From there, I learned that playing with bar stiffness (and tire pressure) has differing effects at different speeds. In other words, after making a change one should test the resulting handling characteristics at both low speed and high speed in a controlled environment. What felt like neutral handling at low speed, was actually oversteer at higher cornering speeds. Anyway, glad to see you here.