Sway bars

[ModularKid21]

I guess I would ask why bigger sway bars if no track or autocross intent? There are many ways to improve handling without them. If one never gets near the limit, they're a good way to make the car feel stiffer in roll without sacrificing ride much.

If you push it, you'll find there's reasons enough to choose wisely about how to implement them.

To me the car seems pretty neutral with the springs/dampers/bars. I don’t consider the spring rate of the springs on my car to be “high” so the sway bars would help out with accomplishing a firmer, better handling ride without spending $3k on coilovers or something. But I suppose that could be my naivety in the realm of suspension. I do plan on autocrossing the car this year but I set the stiffness settings in the middle so as I learn more about the affects of them, I can change them. I don’t have a crazy budget so it seemed like the “KISS” way to go

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[BlownGP]

That's what I had, a stock GT Premium. The Koni shocks and GT350R springs made a HUGE difference. I also added the BMR CB005 and a GT350R strut tower brace. It was about $1500 for everything, but it totally changes the car. You can knock a few hundred off if you chose a non-adjustable shock and a different strut tower brace, but I liked the looks of the GT350R brace.

YES!!. I need to get the CB005. Forgot about that.
I've had some BMR minimum drop springs in the garage for a while.
Now doing research on shocks/struts.

So the factory gt (non pp) spring rates are 160/668. The springs I have now are 198/874. So if I’m getting this correctly, that increase in spring rate is essentially solely responsible for the increase in my cars handling ability? It’s hard for me to wrap my head around my sway bars not having much of an affect on the handling of the car. Especially when the car handles the way it does. I have yet to drive the car at its limits yet as I just got around to doing the alignment, so I’m still waiting to experience the issues with the roll center. I don’t claim to be a suspension expert so I’m learning just as much from this thread as the next guy

I think the comments were a little misleading.
Sway bars will help, but for you to notice a significant difference, you will have to drive your car pretty hard on some curves.

 

[ModularKid21]

YES!!. I need to get the CB005. Forgot about that.
I've had some BMR minimum drop springs in the garage for a while.
Now doing research on shocks/struts.



I think the comments were a little misleading.
Sway bars will help, but for you to notice a significant difference, you will have to drive your car pretty hard on some curves.

That’s kind of where I’m at with it. Some of the comments seemed to be saying that sway bars don’t do much of anything until at the very limit, which isn’t totally true. I understand that bigger isn’t always better though. Point in case, the gt350r front bar is 34mm. Rear is 24mm. My front sway bar is 35mm so essentially the same there. But my rear bar is 28-29mm (1 1/8”) which may be too much for the car. Perhaps some day I’ll find that it is too much. Then I’ll either have to leave it on full soft or step down

 

[BmacIL]

YES!!. I need to get the CB005. Forgot about that.
I've had some BMR minimum drop springs in the garage for a while.
Now doing research on shocks/struts.



I think the comments were a little misleading.
Sway bars will help, but for you to notice a significant difference, you will have to drive your car pretty hard on some curves.

It's more that the behavior of the car and how it feels can be very different between taking it to 6-7/10ths and actually driving it near the limit. A car that feels pretty neutral at merely spirited speeds can be fairly understeery or snap oversteery once it's really pushed. That's been the point. The swaybar size and adjustment should be determined by the latter criteria rather than the former.

 

[Bluemustang]

I can provide a little comparison because I've been in both camps. I've run BMR SP080s (near stock rates) and BMR sway bars (35mm front/25mm rear) on the middle settings. This falls into the category of light spring, heavier bar camp. It handled decently but to control the body roll I needed the higher bar rate, which is OK except that it had a razor edge, handling balance not withstanding. I didnt have a balance problem I had a setup problem. In fact it felt actually pretty well balanced.

And now I am running BMR SP083 handling springs. Big increase in spring rates (250F/980R) I thought enough to at least put both sway bars on full soft after the swap. But still stiffer bars than OEM. So what happened? I realized I was over steering way to easily. Why? Because of the increase in rear rate bias of the springs rates and the bars rates vs. The OEM values. I had to step down my rear bar to avoid unsettling the inside rear tire in cornering. And it worked. The 22mm GT350 rear bar removed the razor edge and over steering behavior. The BMR front bar still works because it isn't a drastic increase over stock and is basically the same stiffness at the GT350R bar at that setting, which also happens to match up with my spring rates.

Guess which one handles better? SP083 by a mile and a half. Seriously not even close. And the ride while firmer, is way better too with less bar and more spring. As long as the spring can be controlled you'd be surprised how it can ride.

I significantly increased my spring rates and decreased my bar rates. And I came out on the way better end. No tweaking of sway bars was going to make that SP080 setup better than SP083 setup.

 

[Roadway 5.0]

While I agree, you really can't get true oversteer/understeer without being "at the limit", seeming subtle changes to alignments and shock settings can cause some interesting feel changes in how a car rolls through a corner.

Roadway, what wheel widths are you on?

Right now I'm on my winter wheels: 9" front and 9.5" rear. My new summer wheels are 10"F and 11"R and will be putting them on in a few weeks.

 

[NightmareMoon]

That’s kind of where I’m at with it. Some of the comments seemed to be saying that sway bars don’t do much of anything until at the very limit, which isn’t totally true. I understand that bigger isn’t always better though. Point in case, the gt350r front bar is 34mm. Rear is 24mm. My front sway bar is 35mm so essentially the same there. But my rear bar is 28-29mm (1 1/8”) which may be too much for the car. Perhaps some day I’ll find that it is too much. Then I’ll either have to leave it on full soft or step down

Bars have an effect, and I also think a mild spring rate with bigger-than-stock swaybars makes for a nice handling sporty street build. Its just important to temper expectations for what swaybars will do for you. They can make the car more responsive, but they won't increase the raw grip. Their strongest advantages are really only present when driving at the limit and/or when making very quick (unusually quick) transitions from side to side. The car will feel different, and it may feel better to you, but it probably won't be any faster through corners.

Also any increased coupling of the tires on the front or rear axis (as swaybars do) will negatively impact the ride comfort over bumpy roads.

I definitely like beefier swaybars on my personal car, but they won't be for everybody, especially if you aren't driving very hard. The stock PP car is already pretty flat handling IMHO. The base suspension car could definitely use stiffer springs AND swaybars tho.

 

[ModularKid21]

Bars have an effect, and I also think a mild spring rate with bigger-than-stock swaybars makes for a nice handling sporty street build. Its just important to temper expectations for what swaybars will do for you. They can make the car more responsive, but they won't increase the raw grip. Their strongest advantages are really only present when driving at the limit and/or when making very quick (unusually quick) transitions from side to side. The car will feel different, and it may feel better to you, but it probably won't be any faster through corners.

Also any increased coupling of the tires on the front or rear axis (as swaybars do) will negatively impact the ride comfort over bumpy roads.

I definitely like beefier swaybars on my personal car, but they won't be for everybody, especially if you aren't driving very hard. The stock PP car is already pretty flat handling IMHO. The base suspension car could definitely use stiffer springs AND swaybars tho.

That last part is exactly how I feel. After driving both pp and non pp cars before buying my non pp car, I could tell there were apparent differences. I haven’t had the pleasure of being in different cars with different suspension set ups so to me, mine feels fantastic. I almost didn’t buy sway bars as I originally thought I wouldn’t really need them. And I honestly probably don’t, but I’m glad I got them for the reasons you stated.

Could you/someone elaborate on “increased coupling of tires”??

 

[Bluemustang]

That last part is exactly how I feel. After driving both pp and non pp cars before buying my non pp car, I could tell there were apparent differences. I haven’t had the pleasure of being in different cars with different suspension set ups so to me, mine feels fantastic. I almost didn’t buy sway bars as I originally thought I wouldn’t really need them. And I honestly probably don’t, but I’m glad I got them for the reasons you stated.

Could you/someone elaborate on “increased coupling of tires”??

I think he means the independence of the wheels. The sway bar or stabilizer bar ties in one side of the car to the other.

If you have too much stabilization from the stabilizer bar, your car will lose independence between the suspension members on opposing sides of the vehicle. The stabilizer bar also affects ride comfort by distributing the effects of bumps in the road to both sides of the vehicle. I alluded to this earlier. Another reason why I have softened my sway bars.

 

[Bluemustang]

The most ideal scenario of a fine-tuned suspension is one that will keep the body flat in turns and not upset the independent movement of the wheels and tires.

 

[ModularKid21]

I think he means the independence of the wheels. The sway bar or stabilizer bar ties in one side of the car to the other.

If you have too much stabilization from the stabilizer bar, your car will lose independence between the suspension members on opposing sides of the vehicle. The stabilizer bar also affects ride comfort by distributing the effects of bumps in the road to both sides of the vehicle. I alluded to this earlier. Another reason why I have softened my sway bars.

Gotcha. I wasn’t sure if the meaning was deeper than the surface

 

[Roadway 5.0]

If you have too much stabilization from the stabilizer bar, your car will lose independence between the suspension members on opposing sides of the vehicle.

I hear this a lot and it got me thinking, is this really possible to the fullest extent? Considering an anti-roll bar is essentially a pair of levers with a connecting bar that rotates, can a bump impacting the right wheel ever really transfer forces at a 1:1 ratio to the left wheel? I think not. I'm not disagreeing that a very stiff swaybar (especially with adjustable holes that shortens the lever length) can make the suspension less independent, but a sway bar is ultimately not a solid axle that would truly transfer weight from one side to the other (nearly) equally. I'm just thinking out loud here.

 

[Bluemustang]

I hear this a lot and it got me thinking, is this really possible to the fullest extent? Considering an anti-roll bar is essentially a pair of levers with a connecting bar that rotates, can a bump impacting the right wheel ever really transfer forces at a 1:1 ratio to the left wheel? I think not. I'm not disagreeing that a very stiff swaybar (especially with adjustable holes that shortens the lever length) can make the suspension less independent, but a sway bar is ultimately not a solid axle that would truly transfer weight from one side to the other (nearly) equally. I'm just thinking out loud here.

You know, I'm not really sure. But I agree with your logic here.

 

[BmacIL]

I hear this a lot and it got me thinking, is this really possible to the fullest extent? Considering an anti-roll bar is essentially a pair of levers with a connecting bar that rotates, can a bump impacting the right wheel ever really transfer forces at a 1:1 ratio to the left wheel? I think not. I'm not disagreeing that a very stiff swaybar (especially with adjustable holes that shortens the lever length) can make the suspension less independent, but a sway bar is ultimately not a solid axle that would truly transfer weight from one side to the other (nearly) equally. I'm just thinking out loud here.

No, it's not 100% connected or equal, but it is more significant the stiffer you bar. The bar is twisted in torsion, and only really rotates when both wheels are moving in the same direction. Otherwise, in roll, one side is pulled up, and that forces the opposite to try and come up as well. The spring and unsprung mass on the other side resists that and causes the torsion force in the bar. The same thing happens when you hit a one-wheel bump.

If your bar's wheel rate is higher than the wheel rate of the spring, it can easily overcome the spring force and lift the inside tire. For my rear springs, that would mean a bar rate of ~420 lb/in. It takes a lot less than that to induce significant oversteer and/or prevent the Torsen from biasing torque.

 

[BmacIL]

I put together a chart that shows the bar rates (published and tested), and the effective wheel rate of the bars. You can add those wheel rates to the spring wheel rates published on Page 8 of the Spring rates sticky thread. This will allow you to see total roll stiffness and bar stiffness contribution to the total. I do not have Steeda front bar rates yet. View attachment 351548

Link to the spring rates:
https://www.mustang6g.com/forums/th...s-all-in-one-thread.44925/page-8#post-1637308

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