Stillen Sway Bar Charts

Trilitheum

It looks that way, with the stock suspension it will be hard to dial in much more oversteer tendency. They have lots of room to go toward understeer, which could be made to work with aggressive camber up front for track use, and it would really bite into the corner hard.

The stiffness numbers come right from Whiteline. Also remember the percentages in the table don't necessarily map over to X increase or decrease of balance on the car.

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2011 Nissan 370Z Touring/Sport, 6MT, KAD

DR_

Nice illustration but once you turn that over and put load and a suspension on the end of it then things start to act differently.

Fishey

No, they don't.

If you think they do then feel free to prove me wrong with some sort of proof.

The example used has differing side to side lengths, and a consistent load. The only thing it is missing from the suspension in terms of physics in the ability to lift the unloaded side of the chassis/carrier because I have it weighed down beyond what the load can lift and its solid mounted. If I felt like dealing with Internet knowledge that hard I could put coil springs on my example and show you the effect it would have on chassis roll and that would only further prove a side to side difference.

-Your Pal
Fishey

DR_

Ask any race team what they do before they corner weigh the car... Disconnect the swaybar... Why?? Once a suspension is loaded the swaybars start to bind. That is why they have adjustable end links to take out all the binding. Once all the binding is out then you have what you describe, one lever point.

Fishey

Yes, you are right we do disconnect the swaybar but it has nothing to do with leverage point along the length of the swaybar ends. It has to do with a thing called Preload not "bind" and we do it so the weights of the car will be more accurate as we adjust corner balance so the swaybars will not give a false reading. As we make this adjustment its extremely rare ride-height will remain constant from left to right side. As a result endlink lengths have to be varied to ensure no preload is placed on the bar.

Now, endlink length will effect handling as it changes suspension geometry but from side to side we are talking a very small amount that no one would ever notice. However, I will add that usually shorter swaybar endlink length will result in a higher resistance across the swaybar much like rod length inside a motor.

What we find on stock cars is no swaybar adjustment and no adjustable endlinks. That is fine as usually on flat ground when the car is settled there is very little to no preload on the bar. Now, if you add adjustment holes and run your bar on even settings this will stay pretty much the same. If you run in staggered holes your going to introduce alot of preload on the bar because the endlink lengths need to be different lengths to produce a no preload setting. Now, as you can imagine if you do this and take out the preload the closer hole is going to have a shorter endlink setting and the further hole will have a longer endlink setting. I am not sure about the 370Z but 90% of the cars I have ever setup the closer hole on the swaybar to the suspension mount point is almost always the harder setting on the bar. So this would only compound your problem of uneven leverage across the bar given not as much.

However, if that is not the case the swaybar endlink length might play in your favor but I must say that the leverage change from swaybar endlink is nothing compared to the leverage change of the length of the swaybar leverage arm.

Overall, I still think its a bad idea to run a staggered swaybar setting as all physics that I can account for tell me its not going to give equal results from right to left side.

-Your Pal
Fishey

Kyle@STILLEN

It is common practice to run staggered holes on sway bars. We have been doing it for years without any negative results.

Before I dive too deep into this subject let me start off with something that I feel needs to be mentioned.

First off, I commend the OP on his efforts to establish a baseline for the sway bar testing. However trying to convert that into a measurable/definitive explanation of what to expect (for example % of over/under steer) is impossible. As the OP pointed out there are just too many variables to consider to give a definitive answer and in all honesty, even trying to assume what the car will do based off facts on a piece of paper without considering those other variables is a major waste of time. Just a few of the variables that need to be considered, tires, weather conditions, and road surface conditions will make for HUGE changes in which sway bar to select. Our sway bars/products are designed for street use, so we develop them to be soft enough for street use yet durable enough for track use. Hence the adjustability of the sway bar. I'll elaborate on this further in my post.

Take for example, our Nissan GT R rally car. When we competed in Targa New Foundland we were dealing with torrential downpours, terrible road conditions, and had to make the tires last an entire week. So we wanted the car to be as soft and compliant as possible. We actually found that in order to achieve our goals we had to run the factory front bar with our rear bar, and an increased ride height.

When preparing the same car for the Spectre 341 hill climb challenge, we lowered the ride height, went full stiff on the front bar and rear bar, and didn't care if the tires melted after two runs because there was no penalty for tire consumption.

Then when we went to Targa New Zealand we increased the ride height a little bit, because this rally is famous for having a few "jumps", also increased spring rate, we also stuck with the STILLEN front bar but backed off the rigidity because the roads are in good shape, and the weather was good but you still want a bit of compliance on a rally car. However, when it started raining, we again, reinstalled the factory front sway bar and softened up the rear bar in order to make the car even more compliant

Getting to the main question: Does staggering the sway bar pre-load the bar and/or negatively affect the handling of the car? In our experience, the answer is no. As it has been mentioned, the proper way to set up a cars suspension is by disconnecting the sway bar, completing your corner balancing, completing your alignment, putting the car back down squarely on all fours, give it a few bounces, make sure everything is happy, and re-installing the sway bar. From our experience we do not see the suspension pre-loading or causing any concern.

With that being said, we do not recommend starting out by staggering the sway bar mounting holes. These finite adjustments are intended for the guys who can push their cars 100% and can actually feel the difference. To be honest, the number of people who will be able to feel the difference is slim. However, for the guy(s) that can tell the difference, it is invaluable to have that additional adjustment capability!

To start out, set the bars in the middle setting. We find that most people set the bars here and leave them. Some decide to go full stiff, others go full soft, but the vast majority of our customers set the bars in the middle and never look back. If it were my personal car, and I was working with anywhere from nice smooth roads in the hills leading up to my house, to the terribly choppy and uneven 405 freeway to the god awful, might as well be an off-road track) Redhill outside of STILLEN, I prefer leaving my sway bars in the neutral setting and carrying a tool box with me when I go to the track and worrying about dialing in my suspension there. On the street, I like a nice, tight, firm suspension. More so than stock. However, I find that I don't need full stiff because the roads I travel are too different, and I do like to drive more "spirited" than most so I prefer to adapt my driving style to the changing conditions. However, I do so by starting with a good base, and to me a good base is the middle setting on our sway bars. As I mentioned, for some of our customers it's full stiff, for others it's full soft, it is a very personal choice that has no "right answer."

Trilitheum

Thanks Kyle for your insight into the issue. Like I mentioned I wasn't really trying to directly map the sway bar setting to car performance, just get an idea of the range of adjustability the bars had and how far either side of "stock" they could go using the F/R ratio.

I believe that data shows this adjustability range very well. As I said this does not mean it will translate into X change on the car. I should also clarify, the % change is not an absolute percentage it is only a relative percentage change from the nominal ratio for a given bar setting.

The exercise really showed how much difference there was between different sway bars kits, and how varied the front and rear stiffnesses are between them.

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2011 Nissan 370Z Touring/Sport, 6MT, KAD

Fishey

I certainly agree its hard to do a comparison from bar to bar not only for the reasons posted and would like to add a few more.

1. The Bends of the Swaybar will have some effect on the way it performs.
2. The Swaybar Endlink Length/Design will also have some effect on performance.
3. The body mount bushings might be different material or thickness. A thicker bar for example will have less bushing material in it. This can change deflection and leverage across the bar.
4. The hole placement in the bar ends relative to the body mounts will certainly effect leverage and how the bar responds. I don't think every bar from brand to brand is going to have the same spacing when they don't even have the same number of holes per bar.

Anyways, I also want to comment on staggering the bar.

As we have seen if you stagger a swaybar in simple physics it will dictate a side to side difference that I agree most 99% people will not notice a difference but it doesn't make it right. However, if you for example throw the car on a shaker rig I can assure you that you will see a difference from side to side. To take this a bit further the front bar that is pretty much symmetrical will respond evenly from side to side. The rear bar that isn't symmetrical as a result of necessity I can almost guarantee does not respond the same from left to right side. However, almost no one will notice this and even if they do its very unlikely they will figure out the source. This is why we use shaker rigs so we can find out detailed information about car setup not because it shows us the perfect setup but it shows us things like the above and allows us to make more calculated decisions about our setup when at the track.

-Your Pal
Fishey

Dwnshift

Haven't been on here in awhile and just came across this thread.
Just throwing out my 0.02
You can throw out the whole... By adding more front bar it induces more understeer ...
It can add more rear grip... But also keeps the front hooked .
I can say this... We are well more than twice the "spring rates" for these front bars... And very close to "stock" spring rates on the rear bar.
It's just t nature of the beast.

Fishey

B.J. I am going to have to agree 100% that front bar can increase front grip.

However, I personally think it has to do with the physics behind the way a swaybar works. As you increase thickness of the bar you find that you will increase the resistance across the bar. I generally just think of it as making a independent suspension less independent and more linked to the other wheel to a degree. So as load is applied to one wheel the far side starts to apply load to the ground. So by increasing the bar size you can increase not only spring rate but the unloaded wheels load. (if that makes sense) However, that being said sometimes when I see this it really really makes me question the amount of caster in the car. Since, we know that caster will change load across the car in a pure mechanical fashion as you increase caster you can change the geometry of the loaded and unloaded wheel to achieve similar results from the ratio of camber gain/loss. Altho, I certainly think there is a limit to what can be achieved through caster and its entirely possible you already found a sweet spot on that setting. Another thing I have not messed with all that much is King Pin Inclination and I can certainly see that having some effect on this as well but I don't know enough about it to comment.

I think this is one of the problems we had on the BMW in 2011 since we had to sacrifice caster to increase camber. I think we might have had 4-5 degree of caster in that BMW and a number of 7-8 I think would have been a nice improvement. I know the 3 series cars had this caster advantage over us and as a result we were trying to compensate with a larger front bar to find this grip. As a result our larger swaybar setting made our compliance over curbing less then ideal. Then again this is just a theory.

-Ron